[From the U.S. Government Printing Office, www.gpo.gov]



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                       MOULTRIE CREEK - MOSES CREEK WATERSHED


                              BASIN MANAGEMENT PROJECT




                                     Prepared By

                       St. Johns County Engineering Department
                              4020 Lewis Speedway Drive
                            St. Augustine, Florida 32085



                                  Supported Through

                   Florida Department of Environmental Regulation
                              (DER Contract No. CM-217)

            (Funds for this project were provided by the Department of
            Environmental Regulation, Office of Coastal Management using
            funds made available through the National oceanic and Atmo-
            sphere Administration under the Coastal Zone Management Act
            of 1972, as amended.)




                          With the Technical Assistance from

                           U. S. Army Corps of Engineers
                               Jacksonville District
                                      Through
                           U. S- Army Corps of Engineers
                   State Planning Assistance (Section 22) Program



                                    January 1990



         GB
         990,
         S76
         F6
         1990




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                                          CONTENTS


                                                                             PAGE
             LIST OF ILLUSTRATIONS    . . . . . . . . . . . . . . . .           v

             LIST OF TABLES  . . . . . . . . . . . . . . . . . . . .          v!

             LIST OF ABBREVIATIONS    . . . . . . . . . . . . . . . .        vii

             FOREWORD  . . . . . . . . . . . . . . . . . . . . . . .       viii

             EXECUTIVE SUMMARY    . . . . . . . . . . . . . . . . . .        xii


             CHAPTER
                 1   AREA ORIENTATION   . . . . . . . . . . . . . . .      1
                     STUDY AREA   . . . . . . . . . . . . . . . . . .      1
                     WATERSHED LOCATIONAL SIGNIFICANCE    . . . . . . .    1 -  7

                 2   CLIMATE AND RAINFALL    . . . . . . . . . . . . .     2 -  1
                     INTRODUCTION   . . . . . . . . . . . . . . . . .      2 -  1
                     CLIMATIC FACTORS   . . . . . . . . . . . . . . .      2 -  3
                     PRECIPITATION  . . . . . . . . . . . . . . . . .      2 -  8

                 3   GEOLOGY AND LANDFORMS   . . . . . . . . . . . . .     3 -  1
                     GEOLOGY . .  * * * * *  , , * * * *  * *  * * * *  ,  3 -  1
                     LIMESTONE FORMATIONS    . . . . . . . . . . . . .     3 -  3
                     LANDFORMS  . . . . . . . . . . . . . . . . . . .      3 -  9


                 4   SOILS AND WATER TABLE   CONDITIONS   . . . . . . .    4 -  1
                     SOILS . . . . . . . . . . . . . . . . . . . . .       4 -  I
                     RAINFALL CONTRIBUTIONS TO   GROUND WATER    . . . .   4 -  13


                 5   STORM WATER STORAGE   . . . . . . . . . . . . . .     5 -  1
                     WATER CONTAINMENT   . . . . . . . . . . . . . . .     5 -  I


                 6   WATER LOSSES   . . . . . . . . . . . . . . . . .      6 -  1
                     EVAPOTRANSPIRATION    . . . . . . . . . . . . . .     6 -  1
                     RUNOFF .   * * , * *  * , * * , * * * *   * * * *  *  6 -  5
                     WATER LOSS IMPACTS    . . . . . . . . . . . . . .     6 -  12


                 7   FLOOD PRONE AREAS   . . . . . . . . . . . . . . .     7 -  1
                     NATIONAL FLOOD INSURANCE PROGRAM DATA     . . . . .   7 -  1
                     EVALUATION CRITERIA   . . . . . . . . . . . . . .     7 -  3


                 8   ATLANTIC COASTAL RIDGE    . . . . . . . . . . . .     8 -  1
                     WATER RESOURCE STUDY CRITERIA    . . . . . . . . .    8 -  1


                 9   SIGNIFICANT NATURAL RESOURCE AREA
                     MANAGEMENT   . . . . . . . . . . . . . . . . . .      9 -  1



                                              iii














                       GENERAL  . . . . . . . . . . . . . . . . . . . .          9 - 1
                       SIGNIFICANT NATURAL RESOURCE AREAS        . . . . . .     9 - 1
                       WETLANDS REGULATION PROBLEMS .        * * ' *  ' * *   *  9 - 14
                       A FUNCTIONAL BASIS FOR NATURAL RESOURCE        AREA
                       MANAGEMENT    . . . . . . . . . . . . . . . . . .         9 - 15
                       CREATING NATURAL RESOURCE AREAS        . . . . . . .      9 - 16
                       MANAGEMENT CONCEPTS    . . . . . . . . . . . . . .        9 - 21


                  10   WATER MANAGEMENT PROGRAM      . . . . . . . . . . .     10  - 1
                       BASIC PROBLEMS     . . . . . . . . . . . . . . . .      10  - 1
                       ST. JOHNS COUNTY WATER MANAGEMENT
                       PURPOSES    . . . . . . . . . . . . . . . . . . .       10  - 2
                       COUNTY ENGINEERING DEPARTMENT FUNCTIONS        . . . .  10  - 7
                       ST. JOHNS COUNTY DEVELOPMENT PERMIT
                       APPLICATION PROCEDURES                                  10  - 16
                       ENGINEERING DEPARTMENT FI'EL*D*IN*SP*EC*TI*ON*S*        10  - 22
                       ENGINEERING DEPARTMENT     ORGANIZATION   . . . . . .   10  - 24
                       PROJECTED ENGINEERING DEPARTMENT PROGRAM         . . .  10  - 24


                  11   WATER MANAGEMENT FINDINGS     . . . . . . . . . . .     11  - 1
                       INTRODUCTION    . . . . . . . . . . . . . . . . .       11  - 1
                       EXAMPLE ORDINANCES    . . . . . . . . . . . . . .       11  - 2
                       GENERAL FINDINGS     . . . . . . . . . . . . . . .      11  - 4
                       OBJECTIVES    . . . . . . . . . . . . . . . . . .       11  - 6
                       DEFINITIONS   . . . . . . . . . . . . . . . . . .       11  - 8
                       WATER MANAGEMENT PLAN APPLICATION       . . . . . . .   11  - 8
                       WATER MANAGEMENT PLAN CONTENTS        . . .             11  - 10
                       CATEGORIES OF WATER MANAGEMENT      PLANS               11  - 12
                       DESIGN STANDARDS FOR WATER MANAGEMENT
                       PLANS  . . . . . . . . . . . . . . . . . . . . .        11  - 13
                       FEES . .                         ' * * * *   * * *  '  *11  - 17
                       ENFORCEME   T AND' @IO'LA*TIiON*S* . . . . .            11  - 18
                                  N
                       LOCAL GOVERNMENTS PROVIDING      ORDINANCES FO*R
                       THIS STUDY    . . . . . . . . . . . . . . . . . .       11  - 20
              GLOSSARY   . . . . . . . . . . . . . . . . . . .. . . . .          G - 1

              APPENDIX - PHASE 2 STUDY PROCESS        . . . . . . . . . . .      A - 1
                     PROJECT PURPOSE      . . . . . . . . . . . . . . . .        A - 1
                     INSTITUTIONAL CONSTRAINTS        . . . . . . . . . . .      A - 2
                     SOCIAL CONCERNS      . . . . . . . . . . . . . . . .        A - 2
                     THE STUDY PROCESS      . . . . . . . . . . . . . . .        A - 3
                     ST. JOHNS COUNTY DEVELOPMENT MANAGEMENT
                     ACTIONS                                                     A - 3
                     PHASE 1 S@u'DY*P*RO*CE*SS*O*BJ*EC'TI*VE'S                   A - 4
                     PHASE 2   STUDY PROCESS OBJECTIVES      . . . . . . . .     A - 5
                     PHASE 2   TASK SUMMARIES    . . . . . . . . . . . . .       A - 5

              BIBLIOGRAPHY    . . . . . . . . . . . . . . . . . . . . .          B - 1



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                                          FOREWORD



              In October 1987 the Florida Department of Environmental Reg-
              ulation   (DER) provided a grant to St. Johns County to un-
              dertake   this    study of the Lower Matanzas River-Moultrie
              Creek-Moses Creek Watersheds out of concern for the water
              quality degradation previously observed         in the Matanzas
              River (DER contract No. CM-207).        A previous    report pro-
              duced under the Florida     Coastal Management Program (1979)
              had identified septic tank effluent discharges and non-point
              source pollution (including storm drainage) as major threats
              to shellfish growing areas in the Matanzas River.       The first
              phase of the study was completed in May 1989. The Phase 1
              activities     consisted of data collection, development of
              evaluation   methods and techniques, initial Geographic Infor-
              mation system development, and presentation of general condi-
              tions found within the Moultrie Creek-Moses Creek watersheds.

              The St. Johns County Commission responded to the estuarine
              water quality problem identified in the original DER 1979
              study through the adoption of a County-wide drainage ordi-
              nance in 1986.      In spite of these actions, the shellfish
              growing   areas and the general quality of estuarine waters
              within the St. Augustine area continue to be threatened.

              In Augu st 1988 St. Johns County requested, through DER, U. S.
              Army Corps of Engineers (Corps) technical assistance in evalu-
              ating   water resource     conditions related to the St. Johns
              County   stormwater management     concerns already under study
              through the DER grant. The Corps can participate in water
              related   planning investigations under the authority of Sec-
              tion 22,  Water Resources Development Act of 1974 (Public Law
              93-251).  This law provides authority for cooperating with any
              state in  the preparation of comprehensive        plans for water
              resources development, utilization, and conservation.           The
              Corps of  Engineers produced     partial report materials for
              local review in September and October 1989.         A draft docu-
              ment completing the Corps of Engineers participation in this
              study was submitted for finalization by the St. Johns County
              Engineering Department in November 1989.

              This   Phase 2 report in response to DER contract CM-217 pro-
              vides an overview of the water resource management problems
              in   St. Johns    County    using the Moultrie Creek and Moses


                                             viii









              Creek watershed as an example area. The report responds to
              the DER grant purpose of developing a basis for County-wide
              improvements in stormwater      management, flood protection,
              and protection of natural resources.        The report incorpo-
              rates the findings of the Phase 1 efforts of the study acti-
              vities   and subsequent information development undertaken
              through this second phase of the study. The report also pro-
              vides information for use by St. Johns County in the de-
              velopment of a comprehensive plan in response to State of
              Florida growth management requirements.

              Finally,   the primary focus of this report must be oriented
              towards   the satisfaction of the DER contract requirements.
              The content of the Study Process for DER contract CM-217 ap-
              pears   in the Appendix.    Emphasis has been given in the or-
              ganization   and content of this    report to address contract
              required topics.

              A component of this study, of interest to the Florida Depart-
              ment of Environmental Regulation, is the St. Johns County En-
              gineering Department's progress in developing a geographical
              information system. This system has great potential for use
              as a basis for evaluating existing stormwater related problems
              and potential impacts resulting from proposed new develop-
              ments. The study identifies some of the technical constraints
              accompanying the establishment of such a program.

              In support of the report findings and recommendations, the
              County has initiated a computerized Geographic Information
              system (GIS) to most efficiently manage local government oper-
              ations, including evaluation of proposed developments and im-
              provements to existing facilities. The GIS is being designed
              as a product of this basin management program to address sev-
              eral of the tasks within the contractual scope of work. The
              GIS has many practical applications including near instanta-
              neous updating of graphical information layers illustrating
              land use and cover, approved development layouts, soil types,
              topography, ownership boundaries, easements for drainage, sep-
              tic facility location, wetland boundaries, significant ar-
              cheological features, zoning, access, utility location, and
              other characteristics. All of these layers can be used singu-
              larly or in combination to evaluate new development proposals
              and rezonings, modify major utility lines, upgrade existing
              facilities, identify significant natural and cultural resource
              areas, and evaluate new transportation corridors. The GIS has
              tremendous potential for local and regional applications. The
              GIS is a highlight of this study because it serves as the
              mechanism to incorporate the objectives of the study within
              daily local government operations.




                                              ix









              In an effort to enhance the capabilities of the GIS system,
              the County requested, and was granted permission by DER to ac-
              quire a Computer Aided Drafting and Design work station to de-
              velop the priority components of the initial stormwater man-
              agement plan. The CAD system will be used to input new de-
              velopment plans such as Plats, rezonings, DRI's, stormwater
              management system plans, utility location and other in-
              formation directly into the GIS system as well as assist the
              County in inputting existing basin information to be consid-
              ered in the review of new development proposals into the GIS.

              The report is also intended as a document through which the
              Florida Department of Environmental Regulation can provide
              guidance to other local governments on problems to be antici-
              pated in establishing technologically advanced stormwater man-
              agement procedures.     The development of local government pro-
              cedures for approaching stormwater management from a regional
              or watershed perspective is still evolving. The study brings
              together information on aspects of stormwater related problems
              in the Moultrie Creek and Moses Creek watershed and identi-
              fies management procedures for addressing these problems.

              To    identify parallel     management methods used       by other
              local governments, this study included the review of applica-
              ble stormwater management related ordinances used by a vari-
              ety of other local governments in Florida. Guidance from some
              of these ordinances has been incorporated in this study. In
              general, large metropolitan governments in Florida have, in
              varying degrees, recognized and addressed watershed management
              needs.    Acceptable mechanisms by which smaller governmental
              bodies can resolve the regional aspects of stormwater man-
              agement still remain to be developed.

              The study also provides information on changes of manage-
              ment processes within St. Johns County that may improve the
              effectiveness of local water management procedures.            Local
              procedures    for undertaking      management changes is an in-
              ternal    County    matter constrained     by existing practices,
              public perception of      need, available technical        capabili-
              ties, and the County's financial resources or budget limita-
              tions.    In practice, changes in local governmental operations
              generally evolve slowly. Each small change in procedure may
              result in unforeseen problems, and each problem must be re-
              solved in a manner acceptable to all affected activities or
              departments.

              Finally,    each local government is a management entity dif-
              ferent from any       other government.     The St. Johns County
              governmental structure is unique,          and the manner in which
              changes    can be accomplished       in St. Johns County will be
              different than procedures adopted by any other government in


                                                x









            Florida. A significant management problem resolution process
            within the St. Johns County government extending over a pe-
            riod of time should be expected.



















































                                          xi



















                                      EXECUTIVE SUNMARY



              This report focuses upon the stormwater management needs of
              St. Johns County using the Moultrie Creek and Moses Creek
              watersheds as an example area. Stormwater management, as
              used in this report, encompasses a range of interrelated water
              resource management problems of concern to local governments.
              Effective stormwater management within St. Johns County re-
              quires coordinated efforts between      St. Johns County and mu-
              nicipal governments, between St. Johns County and the St.
              Johns River Water Management District, and among the several
              agencies within the County and municipal governments with spe-
              cial responsibilities for specific governmental functions
              identified in this report. While the St. Johns County Engi-
              neering   Department    is primarily responsible for enforcing
              the   St. Johns County Paving and Drainage Ordinance 86-4, ef-
              fective   stormwater management requires an understanding of
              potential   impacts of enforcement measures upon the complex
              factors that reflect upon the adequacy and quality of the
              County's water resources.

              Stormwater management in the Florida environment must con-
              sider much more      than the need to remove excess        surface
              water   from developed areas. The Florida Department of Envi-
              ronmental Regulation initiated this study as a means of as-
              sisting the County to establish practices that would protect
              the water quality of local area estuaries. While water qual-
              ity concerns are important, this study also illustrates hy-
              drology principles that must be applied to stormwater man-
              agement and general water practices in order to preserve St.
              Johns County's ground water supplies and significant natural
              resource areas.


              The State of Florida has determined that wetlands are impor-
              tant natural resources      that   must be protected by local
              and   state governmental actions.     This study identifies sig-
              nificant natural resource areas within the Moultrie Creek and
              Moses Creek watersheds and establishes some simplified cri-
              teria for determining,     delineating, and protecting these
              areas. However, the study     focuses primarily upon the engi-
              neering practices that can be used to permit development and
              still protect significant natural resource areas along stream
              courses and within uplands of watersheds.



                                             xii









              As noted above, an important component of this report is the
              presentation    of the relationship between stormwater        man-
              agement practices and the need to protect the ground water re-
              sources used by all residents living within the County. The
              inherent problems associated      with the long-term practice of
              uncontrolled positive drainage consisting of the ditching,
              draining, and dropping of the     local area ground water tables
              has been given emphasis.

              This report has been organized    to provide nontechnical read-
              ers with a general       understanding of interrelated factors
              influencing surface and ground water resources within the
              County and to assist the reader in understanding the reasoning
              behind the need for improved forms of water resource manage-
              ment practices. At the same time, the report provides infor-
              mation intended for use by the St. Johns County Engineering
              Department.    The information presented provides a framework
              for a long term program that will permit the Engineering De-
              partment to provide practical guidance to individuals inter-
              ested in undertaking development efforts anywhere within the
              County.


              As the pressure of urban growth of metropolitan Jacksonville
              continues to expand into St. Johns County, governmental pro-
              cedures    for reviewing proposed property improvements must
              become more efficient. Informal methods of permit processing
              and   decision making acceptable in a slower paced govern-
              mental    process cannot meet       current nor expected future
              property    development requirements.       Property owners need
              clear, easily understood, and reasonable        requirements that
              permit them to evaluate and undertake development actions.
              This report presents some criteria oriented towards the pro-
              vision of necessary governmental services with objectives and
              procedures that are intended as      clear and simplified guid-
              ance    to property owners who desire to improve their prop-
              erties.


              BASIN MANAGEMENT FEATURES



              Basin Management issues addressed in this report primarily in-
              clude control of stormwater runoff, protection of natural re-
              source areas, recharge and protection of the surficial aqui-
              fer, improvement and protection of surface water quality, and
              prevention of flooding due to rainfall events. Findings and
              recommendations are primarily addressed in chapters 9 and 11
              of this report.     The findings, criteria and recommendations
              discussed in this summary are not inclusive of all the find-
              ings and recommendations of this report. Also, the basin man-



                                             xiii








             agement problems identified in this report are interrelated
             and the long-term impact of these issues going uncorrected is
             tremendous.



             Control of Stormwater Runoff

             Erosion along the banks of the steep stream channels of Moult-
             rie Creek occurs following heavy rainfalls. Unless stormwater
             is retained or detained on lands improved for development, ac-
             celerated eroded materials and contaminants from developed
             lands will be discharged into the Matanzas River in increasing
             quantities over time.     As stormwater is diverted from re-
             charge, the base flow of Moultrie Creek is being eliminated.
             The reduction in base flow of Moultrie Creek will contribute
             towards a decline in the ground water table, and an increase
             in salt water intrusion in the areas around Moultrie Creek.

             Once stormwater from normal annual rainfall is retained, the
             overflow water from the infrequent and heavier rainfalls must
             be detained and safely discharged at controlled rates to avoid
             significant erosion and sedimentation and damages to receiving
             water areas.


             Control of stormwater runoff can be accomplished through de-
             tention or retention storage in any land area capable of hol-
             ding water without causing flooding of structure or roadways.
             outlets can be raised to provide some areas for extended
             detention storage.


             Protection of Natural Resource Areas

             Development within or adjacent to the natural resource areas
             including the drainageway fringe will require consideration
             for the annual rise of the water table in these areas. Any
             effort to drain these lands will have long-term impacts on
             these areas and potential decline of the surficial aquifer
             supplies, potential decline of the natural resource area and
             potential of increased salt water intrusion.     If the ground
             water table is lowered through either overdrainage or through
             deficient recharge, new growth of young plants and regenera-
             tion of new growth will be eliminated.     As this occurs the
             natural area will begin a transitional process where vegeta-
             tion that can sustain itself with less water will begin to re-
             place the original species. Protection of significant natural
             areas in uplands can be accomplished through control of water
             table conditions.


             The environmental health of the natural resource areas is de-
             pendent upon continual ground water seepage from adjacent high-


                                           xiv








              er water table areas and fresh water discharges from Moultrie
              Creek and tributary streams.     Thus, ground water recharge in
              areas upland from natural resource areas is important for the
              continued prosperity of these areas. The prevention of polu-
              tion discharge into natural resource areas and areas dis-
              charging to Moultrie Creek is also recommended for the future
              well being of the natural resource areas.


              Recharge and Protection of the Surficial Aquifer

              The unpredictable nature of precipitation makes control of
              ground water recharge both more difficult and important. Un-
              less the stormwater systems are designed to detain or retain
              the routine daily rainfall amounts expected on an annual ba-
              sis, overdrainage of the surficial aquifer will occur. Re-
              charge to the surficial aquifer can only occur when rain water
              from normal rainfalls expected on an annual basis is retained
              long enough to infiltrate the surface and allowed to slowly
              percolate downward through the water table. Currently, with-
              drawals from the surficial aquifer for public water supplies
              are exceeding the natural rain water recharge in the areas of
              the well fields. From this, further declines in the local wa-
              ter table can be expected.

              Uncontrolled drainage directed to Moultrie Creek removes
              stormwater before it can infiltrate to provide recharge to the
              surficial aquifer. Detention/retention storage or containment
              for ground water supply recharge through infiltration must be
              emphasized in the vicinity of the land surface areas beneath
              which surficial aquifer water is withdrawn. Increasing stor-
              age of stormwater and the diversion of stormwater towards
              cones of depressions are essential to avoid water table de-
              clines in the vicinity of the well fields.

              Septic tank effluents are significant sources of water re-
              charge to the surficial aquifer.     Maximizing rainfall reten-
              tion in these areas would serve to increase recharge and pro-
              vide a means for diluting septic tank effluents. As the cone
              of depression from a well approaches the ground surface, sep-
              tic tank effluents will be drawn downward which may introduce
              pathogens into the well water.

              Recharge of the surficial aquifer is all important due to the
              extreme difficulty in rehabilitating wetlands following over-
              drainage.     Overdrainage of ground water and uncontrolled
              drainage of stormwater contribute to the permanent and even-
              tual lowering of the water table and should therefore be
              avoided.






                                             xv








              Improvement and Protection of Surface Water Quality

              Stormwater detention/retention facilities can help reduce pol-
              lutant loads characteristically found in urban runoff. Reten-
              tion facilities designed to store the first one inch of every
              rainfall would more adequately serve water pollution control,
              water supply recharge, and significant natural resource area
              requirements.   A number of small retention facilities provide
              a distributed and more effective system for ground water re-
              charge than a single large retention facility.

              The entrapment of contaminants from roadway traffic in reten-
              tion storage catchment facilities along Moultrie Creek and the
              Matanzas River is vital for the preservation of the surface
              water quality of the Matanzas River.      Surface water quality
              is also a victim of septic tank effluent which often contains
              materials toxic to the natural biological processes in the
              estuary. In addition, as development increases, the release of
              nutrients as septic tank effluents will also increase and
              will eventually overload those natural processes responsible
              for handling the effluent.


              Prevention of Flooding Due to Rainfall Events

              The actual frequency, duration and volume of rainfall events
              are unpredictable in St. Johns County, therefore it is impor-
              tant that an acceptable design be developed and adhered to on
              the County level. The 10-year 24 hour storm shall be used for
              design of stormwater infrastructure. Under recommendations of
              this st 'ormwater management plan, construction of major roads
              and inhabited buildings will be located above the 100-year
              flood elevation. In addition, the controlled flow of storm-
              water has many advantages       including   prevention of the
              following: erosion of stormwater conveyance systems, sedimen-
              tation to downstream areas, accelerated eutrophication of do-
              wnstream water bodies, and toxic materials entering receiving
              waters and degrading surface water quality.


              Other Developmental Concerns

              The annual high water table should be of great concern. The
              water table naturally fluctuates greatly. As the water table
              approaches within six inches of the subbase of a roadway the
              subbase can become saturated and cause deterioration of the
              subbase and eventual decay of the roadway. Also, as the water
              table approaches the bottom of retention facilities used for
              recharge, they cease to drain, can become flooded with ground
              water, and can cause flooding in the area contributing to the
              pond. It is for this reason that developments should be built


                                             xvi









             above the annual high water table. In the past this was
             accomplished through drainage of the ground water. This has
             become an increasingly unacceptable practice as the longterm
             effects have become known.



             This study serves as the basis for formulation of a County
             wide program for improvements in stormwater management, flood
             protection, and protection of natural resources. This report
             has identified problems, offered recommendations for improve-
             ment, and presented alternatives in use by other local gov-
             ernments to meet the challenges proposed by the ever in-
             creasing demands from growth upon County governments through-
             out Florida.




















































                                          xvii













                                     LIST OF ILLUSTRATIONS



             FIGURE                                                            PAGE

                1-1. Orientation Map      . . . . . . . . . . . . . . .      1 - 2

                1-2.  St. Augustine Harbor, FL    . . . . . . . . . . .      1 - 4

                3-1.  USGS Well SJ 112E Tillman Ridge       . . . . . . .    3 - 7

                4-1.  Localities With Water Tables Rising Above
                      Land Level Part of Each Year     . . . . . . . . .     4 - 6

                4-2.  Annually Flooded Soils and Drainageway
                      Soils   . . . . . . . . . . . . . . . . . . . .        4 - 8

                4-3.  Annually Flooded/Drainageway Soils and
                      Naturally Saturated Soils      . . . . . . . . . .     4 - 10

                4-4.  Well To Excessively Drained Soils       . . . . . .    4 - 11

                7-1.  Flood Hazard Areas Subject To 100-Year
                      Flooding   . . . . . . . . . . . . . . . . . . .       7 - 2

                10-1. Current Organization of the Engineering
                      Department St. Johns County/ Fiscal
                      Year 1990    . . . . . . . . . . . . . . . . . .      10 - 25

                10-2. Proposed Organization of the Engineering
                      Department St. Johns County/ Fiscal
                      Year 1991    . . . . . . . . . . . . . . . . . .      10 - 26



























                                                 v















                                        LIST OF TABLES



            TABLE                                                              PAGE

               2-1.   ANNUAL RAINFALL EXTREMES/ ST. AUGUSTINE,
                      FLORIDA   . . . . . . . . . . . .. . . . . . . .       2 - 9
               2-2.   DAYS WITH RAINFALL/ HASTINGS, FLORIDA        . . . .   2 - 11

               2-3.   AVERAGES OF DAILY RAINFALL AMOUNTS/
                      HASTINGS, FLORIDA     . . . . . . . . . . . . . .      2 - 12

               2-4.   PROBABLE RETURN FREQUENCIES OF
                      PRECIPITATION AMOUNTS/ ST. JOHNS COUNTY,
                      FLORIDA   . . . . . . . . . . . . . . . . . . .        2 - 14


               6-1.   MOULTRIE CREEK WATERSHED POTENTIAL
                      EVAPOTRANSPIRATION    . . . . . . . . . . . . . .      6 - 3


               6-2.   ST. AUGUSTINE RAINFALL AND MOULTRIE CREEK
                      DISCHARGE    . . . . . . . . . . . . . . . . . .       6    11


               8-1.   GUIDELINE HYDROLOGICAL CRITERIA FOR THE
                      ATLANTIC COASTAL RIDGE/ ST. JOHNS COUNTY,
                      FLORIDA   . . . . . . . . . . . . . . . . . . .        8   2





























                                               vi
















                                  LIST OF ABBREVIATIONS



            B.C.C. - St. Johns County Board of County Commissioners

            CAD/GIS - Computer Aided Design/Geographic Information System

            Corps - U. S. Army Corps of Engineers

            cfs    cubic feet per second

            DER    Florida Department of Environmental Regulation

            EPA    Environmental Protection Agency

            ET    Evapotranspiration

            FEMA - Federal Emergency Management Agency

            FIRM -  Flood Insurance Rate Maps

            gpcd -  gallon per capita day

            IFAS -  Florida Institute for Food and Agricultural Sciences

            mg/l -  milligrams per liter

            NGVD -  National Geodetic Vertical Datum

            NOAA -  National Oceanic and Atmospheric Administration

            NRC -  National Research Council


            NWS -  National Weather Service

            ppm -  parts per million

            SCS -  U. S. Soil Conservation Service

            SFWMD - South Florida Water Management District

            SJRWMD - St. Johns River Water Management District

            U.S.D.A. - United States Department of Agriculture

            USGS - United States Geological Survey





                                           vii























                                   AREA ORIENTATION



            STUDY AREA



            General

            St.   Johns County is located in northeast Florida with about
            42 miles of coastline bordering the Atlantic Ocean (Figure
            1-1. Orientation Map).      The County is bounded on the north
            by   Duval County and on the south by Flagler County. On the
            west and from the County's southwest corner to Deep Creek,
            St.   Johns   County abuts Putnam County.        From Deep Creek
            northward,   the western boundary of the         County abutting
            Putnam and Clay counties is within the St. Johns River.

            The study area is in the southeastern part of the County, with
            the boundaries of the study area being State Road No. 207 to
            the north, Interstate No. 95 to the west, State Road No. 206
            to the south, and the Sebastian and Matanzas Rivers to the
            east.


            The   County has a total area of approximately       673 square
            miles, including about 60 square miles of open water. About
            14   square miles of open water exists along the eastern side
            of the County in association with the Intracoastal Waterway.
            About   5 square miles are lakes, borrow pits, and streams.
            Another   41   square miles    of open water occurs along the
            western side of the County within the St. Johns River.

            About 362 square miles of the County drains westward towards
            the St. Johns River. Drainage from the roughly 16 square
            miles   of land area in the general area of Palm Valley flows
            northward   via the Intracoastal waterway and Pablo Creek to
            the St. Johns River. An       estimated eight square miles of
            shoreline area, including 3.2 square miles in the Salt Run
            area (largely St. Augustine Beach), drains to the St. Au-
            gustine Inlet or the ocean, and about 231 square miles drain
            to the Tolomato or Matanzas rivers.     of the area draining to
            the Matanzas River, it is estimated      that 15.8 square miles
            drains via Moses Creek and 41.7 square  miles drains via Moult-
            rie Creek.



                                          1








                                   Figure 1-1. Orientation Map

                                                  N
















                          DUVAL COUNTY















            CLAY COUNTY







                                        12



              - - - - - - - - - - - - - -










                  PUTNAki COUNTY









                           ------------------
                                 FLAGLER COUNTY



         SCALE: 140,000




                                   MAJOR DRAINAGE AREAS

                           PROJECT  S - ST. JOHNS RIVER
                           LOCATION
                      4POR 0        M - MATANZAS RIVER
                                    M-M - MOULTRIE CREEK
       D.E.R. CONTRACT NO. 7CM21171.1 T - TOLOMATO RIVER
           ST. JOHNS COUNTY ENCINEERINC DEPARTMENT - GEOCRAPHIC INFORMATION SYSTEM












            The Tolomato and Matanzas Rivers have been canalized to a
            maintained depth of 12 feet and width of 125 feet as part of
            the Intracoastal Waterway Federal project. The combined water
            area, marsh area, and associated minor drainageways directly
            associated with these two rivers within St. Johns County is
            estimated at about 71 square miles.

            Essentially   all   of the 84 square miles of     the Tolomato
            River drainage    area and about 97 square miles of the 161
            square   mile drainage area of the Matanzas River discharge
            fresh water to    the ocean through the St. Augustine Inlet.
            About 64 square miles of the Matanzas River watershed, essen-
            tially the area between Moses Creek and Pellicer Creek, can
            be expected to discharge to      the Atlantic Ocean through the
            Matanzas Inlet.    The mouth of Moses Creek is almost 6 miles
            from the Matanzas Inlet and about 11 miles from the St. Au-
            gustine Inlet. Fresh water discharges from Moses Creek can
            be expected to provide a greater influence to water quality
            conditions in the vicinity of the Matanzas Inlet.

            Moultrie Creek drains into the Matanzas River at a point about
            5.8 miles south of the St. Augustine Inlet. Moultrie Creek
            is tidally influenced for a distance of about 5 miles upstream
            of its mouth and 3.4 miles upstream of the U.S. Highway *1
            bridge. The southerly extent of reversing tidal influence and
            water   exchange in the Matanzas River from the St. Augustine
            Inlet is unknown.



            St. Augustine Harbor and Inlet

            The St. Augustine Harbor was developed as a Federal project
            (Figure 1-2. St. Augustine Harbor, FL). The harbor consists
            of a stabilized channel 16 feet deep and 200 feet wide across
            the St. Augustine Inlet bar, then 12 feet deep to the In-
            tracoastal Waterway, and a channel ten feet deep and 100 feet
            wide in the San Sebastian River      from the Intracoastal Wa-
            terway to the Kings Street bridge. The St. Augustine Inlet
            was dredged across North Point (Vilano Beach) in 1940. It
            was initially    known as the north entrance or new inlet.
            The original inlet     was located at the' southerly extent of
            Bird Island (now Conch Island) in what is now Anastasia State
            Park. Salt Run is the residual channelway to the original in-
            let.

            Boat   anchorages occur both to north and south of the Bridge
            of Lions in the Matanzas River. Salt Run also            provides
            protected anchorages for boats. The mouth of the San Sebas-
            tian River is about 1.8 miles south of the Bridge of Lions.
            Most of the commercial      terminals in St. Augustine are lo-


                                         1 - 3








                                                                 Figure 1-2. St. Augustine Harbor, FL.








                                                                                  VILANO
                                                                                   BEACH



                              S"R- 16









                                                                                       ANASTASIA
                          KING ST. bRIDCE                                                  STATE

                                                                                             PARK
                                                              0 LIO

                          C.R. 214


                                     7n

















                                               cn










                    SCALE: 1   5.000








                                                              PRoirrr
                                                              LOrMON
                                                              Lo
                D.E.R. CO-NTRACT NO. 7CH217 11,
                         ST. JOHNS COUNTY ENGINEERING DEPARTMENT                GEOGRAPHIC INFORMATION SYSTEM









            cated along the lower 2.5 miles of the San Sebastian River.

            Freshwater discharges from urban areas and activities associ-
            ated with St. Augustine, St. Augustine Harbor, San Sebastian
            Creek, the lower Matanzas River and the Tolomato River are
            well mixed by the reversing tides moving through St. Augustine
            Inlet. Detailed studies would have to be conducted to esti-
            mate the extent of fresh water flushing that occurs through
            the inlet with each ebb or outgoing tide. Correspondingly,
            ocean   water entering     the harbor during flood or incoming
            tides can be expected to mix with the fresher waters within
            the harbor area and distribute     these mixed waters upstream
            into the lower courses of the tributary       streams, including
            Moultrie Creek.

            The   mixing process and redistribution of waters from the
            ocean and the several fresh water sources is ongoing with
            each tide reversal.     The estuarine water quality throughout
            the   area of influence of the        tide reversal mixing pro-
            cess    reflects    the contributions of all sources of water
            within the system.

            The water carried to the ocean through the St. Augustine Inlet
            is picked up and mixed with the ocean alongshore or littoral
            current.    During the winter months of the year, this cur-
            rent   or southerly    drift moves water southward      along the
            coastline.    This movement is caused by wind generated swells
            produced by prevailing winds from the northeast. During the
            summer months, prevailing winds are from the southeast, and
            water from the St. Augustine Inlet becomes part of a north-
            ward littoral current. These alongshore currents are repre-
            sentative of the quality of ocean waters reaching St. Johns
            County shores.


            Tide Ranges

            The mean tide range through the St. Augustine Inlet is about
            4.5 feet, and the mean    spring tide range is about 5.3 feet.
            At the Bridge of Lions    connecting the City of St. Augustine
            with   Anastasia Island   about two miles from the inlet, the
            mean tide range is about  4.2 feet.

            The 1989 mean tide level  at the Bridge of Lions was 0.38 feet
            above the National Geodetic Vertical Datum of 1929 (NGVD).
            NGVD is the national land leveling network upon which all land
            elevations in the United States are based.        Based upon the
            tide   range of 4.2 feet at the Bridge of Lions, the tide
            range at the mouth of Moultrie Creek is estimated at slight-
            ly less than four feet, and the elevation of mean high tide is
            about 2.3 feet above NGVD.



                                          I - 5











              The highest tide on record at St. Augustine occurred during
              Hurricane Dora, September 10 and 11, 1964, when a high water
              elevation of twelve feet was recorded at the St. Augustine
              waterfront.    An October 1944 hurricane that originated in the
              Caribbean,    entered Florida near Sarasota on the west coast
              and   crossed into      the Atlantic     Ocean near Jacksonville.
              This storm produced a hurricane tide           of 7.9 feet NGVD at
              St. Augustine.       The following return frequencies of storm
              surge related flood elevations have been established by the
              Federal Emergency Management Agency (FEMA) for national flood
              insurance purposes on the Matanzas River          at the mouth of
              the San Sebastian River: 10 yr.-4.8 feet; 50 yr.-7.3 feet;
              100 yr.-8.5 feet; and, 500 yr.-10.9 feet.

              Federal    Emergency Management Agency Flood Insurance Rate Map
              (FIRM)    information for St.      Johns County (Community No.
              125147) (dated September 1985) established a 100 year re-
              turn period flood elevation at the mouth of Moultrie Creek at
              8 feet NGVD and       the ten year return period flood elevation
              at about 4.5 feet. These flood elevations would be caused by
              storm tides.



              Sea Level Rise

              Throughout    geologic history, global sea level           variations
              (both rise and fall) have occurred. Some authorities have
              found   evidence to indicate that we may be entering a new pe-
              riod of glacial advance with a resultant future drop in sea
              level.    others argue that increasing atmospheric concentra-
              tions of carbon dioxide and other gases are causing the earth
              to accelerate the warming trend of the current interglacial
              period.    Accelerated warming      would lead to further retreat
              of continental glaciers and a more rapid rise in sea level.

              The   national agency responsible for measuring            sea level
              changes is the National Ocean Survey, a part             of the Na-
              tional    Geodetic Survey. From this agency's publication, sea
              Level Variations for the United States 1855-1980 the trend of
              relative    sea level change is on the order of-a 1.9 mm rise
              in sea level per year. The National Research Council (NRC),
              whose members are drawn from the        Councils of the National
              Academy of Sciences, the National         Academy of Engineering,
              and the Institute of Medicine, has recommended that federal
              agencies should consider the high probability of future sea
              level rise. It may be some time before precise estimates of
              future    sea level rise are possible.        In the meantime, the
              risks associated with a substantial rise should not be disre-
              garded.




                                             1 - 6










            The U. S. Army Corps of Engineers considers that at least
            twenty-five years of additional records will be needed to es-
            timate local effective sea level rise rates with reasonable
            certainty and to reach some consensus on which of the var-
            ious    sea level     rise scenarios is most likely.         For now
            planning should consider       what impact a higher relative sea
            level rise rate scenario would have on the design of projects
            based on the historical rate.         The rate of    change in sea
            level along the eastern Florida coast in           the 1940 to 1980
            time frame has been on the order of 2.4 mm per year. This
            rate    of apparent sea level rise has been used for recent
            Corps of Engineers projects.

            A rate of 1.9 mm per year would produce an apparent sea level
            rise of 3.7       inches in 50 years.       A rate of 2.4 mm per
            year    would produce     a sea level rise of 4.7 inches in 50
            years.     The net effect of these conditions in the Moultrie
            Creek watershed      would be the gradual movement of tidal
            conditions     further upstream within the creek and its tribu-
            taries that discharge to tidewater.        Ground water conditions
            also would be affected with an increased tendency for salt
            water intrusion to penetrate further inland from the Matan-
            zas River and the tidewater part of Moultrie Creek.


            WATERSHED LOCATIONAL SIGNIFICANCE

            The    Matanzas    River, St. Augustine Harbor, and the St.
            Johns County shorelines immediately to the north and south of
            the St. Augustine Inlet are impacted by the volumes and qual-
            ities of the water discharged from the Moultrie Creek wa-
            tershed.     Moultrie Creek is one of numerous stormwater dis-
            charge    sources to the area's estuarine receiving waters,
            and stormwater management practices would have to be applied
            to    all discharge sources to significantly improve water
            quality conditions within these coastal receiving water ar-
            eas.




























                                           1    7




















                                             2


                                  CLIMATE AND RAINFALL



            INTRODUCTION



            An analysis of climate and rainfall serve as the basis for
            sound management of the watershed.       The effect of frequent
            storm events, the associated periods of flooding, and protec-
            tion of the surficial aquifer can be predicted with a greater
            understanding of climate and rainfall characteristics within
            the basin.

            Hydrology deals with the properties, distribution, and circu-
            lation of water in the atmosphere, on the surface of the land,
            and in the soils and underlying rocks. The movement of water
            onto the land as rainfall, into the soils as infiltration,
            back to the atmosphere as direct evaporation and transpiration
            from plants, and as surface water runoff in streams is a pro-
            cess known as the hydrological cycle.

            Current climatic conditions of northern Florida are heavily
            influenced by the large scale weather systems that move across
            the region. St. Johns County climate is also influenced by
            marine conditions and related weather events.        The informa-
            tion provided in this report illustrates the dominant sources
            of rainfall to be expected within the County, general charac-
            teristics of rainfalls, and criteria for managing the result-
            ing stormwater.

            The source of water replenishing the Floridan aquifer under-
            lying St. Johns County is the rainfall received in upland
            areas   of north central Florida. Governmental actions taken
            by St. Johns County cannot control the replenishment of the
            Floridan aquifer.

            Rainfall received in St. Johns County is the source of water
            that replenishes      the surficial     aquifer underlying the
            County.    The primary    source of potable water in St. Johns
            County, water used for human consumption, is the surficial
            aquifer. Protection of the surficial aquifer through man-
            agement procedures assuring adequate recharge for public wa-
            ter supplies and private uses can be controlled by St. Johns


                                        2 - 1










           County. Similarly, actions of County government can reduce
           the effects of flooding due to rainfall events and provide
           protection for some significant natural resources within ju-
           risdictional limits.

           In   this investigation, available hydrological information
           has been reviewed from the perspective of the need to pro-
           vide   for recharge to the surficial aquifer, reduce the ef-
           fects of flooding, and provide protection to some significant
           natural resources through basin-wide stormwater management
           practices.   Drainage of lands, as practiced in Florida until
           very recently, usually ignored the need to retain stormwater
           for aquifer recharge     and natural resource area protection
           purposes.   The   protection of these resources requires some
           modification of   local government infrastructural development
           and maintenance   practices, changes in local governmental de-
           velopment review  practices,   and multiple purpose hydrologi-
           cal analyses and  hydraulic designs for projects.

           Hydrological information provide the basis of engineering de-
           sign of all types of water control works. As a part of this
           project, a review was conducted of the ways in which hydrolo-
           gical information is conventionally used in local government
           development decisions.     Some hydrological analysis criteria
           not generally considered in drainage       design have been in-
           cluded in this report to provide preliminary guidance for
           protecting the aquifer and natural resources have those ar-
           eas. Hydrological analyses methods and engineering evaluation
           procedures    specifically   oriented towards     the design of
           water control facilities are referenced below.

           A   water management handbook will be prepared by the County
           as additional development guidance for property owners. Sev-
           eral publications are used for water management guidelines
           (see bibliography); however these documents do not adequately
           address aquifer and natural resource protection needs of St.
           Johns County. This deficiency frequently results in delays of
           local development approvals while County staff and permit ap-
           plicants attempt to determine effective plans and practices in
           the absence of clear criteria and review procedures. In addi-
           tion to County guidelines, the Handbook will incorporate or
           adapt pertinent engineering criteria for evaluations and meth-
           odologies    developed by the St. Johns River Water Manage-
           ment   District. The Applicant's Handbook forManagement and
           Storage of Surface Waters, containing Water Management Dis-
           trict guidance can be obtained directly from that agency.
           However, St. Johns County criteria, notably those criteria
           necessary    for establishing stormwater retention facilities,
           will prevail in any development        proposal   review. other
           useful    sources of engineering design information are pre-
           sented in the bibliography.


                                      2 - 2













           CLIMATIC FACTORS



           Temperature Influences

           Area temperature characteristics and seasonal changes in tem-
           perature    reflect climatic conditions of the Floridan penin-
           sula that contribute to an understanding of hydrological pro-
           cess   dynamics. St. Johns County has a borderline subtropi-
           cal climate with rare, short-duration freezing events affect-
           ing the area during the late December through February winter
           season.


           Historical     records     for St. Augustine for the        period
           1902 through   1938 indicated an average January temperature of
           58 degrees Fahrenheit with a lowest recorded temperature of
           13   degrees.    The July average temperature for that period
           was approximately 81     degrees with a maximum recorded tem-
           perature of 104 degrees.      Temperature norms for the 1951 to
           1980 period are 51.8 degrees for January and 79.9 degrees for
           July.

           The study area generally is not subject to severe, long-dura-
           tion freezes sufficient to affect road bases and building
           foundations, but exposed water pipes may freeze under occa-
           sional one to two day freezes during the movement of a se-
           vere winter   frontal system through     the area. The westerly
           part of the   study area is subject to slightly cooler winter
           temperatures than typically occur within the areas close to
           the Matanzas  River.

           As   normal winter    conditions within the study area,        ice
           occasionally    has been found on standing shallow water ar-
           eas    near Tillman Ridge, but this occurrence is rare near
           the    Matanzas River.     Some   damage to vegetation has oc-
           curred    during severe freeze events, with more significant
           damage in the interior     parts of the watershed.      Similarly,
           frosts can occur on roofs during December through February
           period.

           winter temperatures are cool enough to give a pronounced sea-
           sonal character to plant growth. Winter cool weather is suf-
           ficient to terminate       growth cycles of some plants, while
           many    others become dormant.      As a result, the removal of
           water    from the surface soils by plant transpiration to the
           atmosphere decreases significantly during the winter months.

           The eastern fringe of the Moultrie Creek watershed is influ-
           enced by microclimatic daily sea breeze conditions. Daily air
           exchange between the land and the ocean is noticeable inland
           to     areas immediately west     of Matanzas River. The effect


                                       2 - 3










            diminishes in importance generally within one half mile in-
            land from Matanzas River. Ocean influenced areas are cooled
            daily by air moving off the ocean        during summer months and
            warmed daily by the ocean effect during winter months.



            Storms

            The daily sea breeze effect can be expected to result in very
            slightly    reduced summer rainfall totals in St. Augustine
            and along the eastern edge of the watershed.         St. Augustine
            rainfall is recorded at Radio Station WFOY located about one
            mile north of the     U. S. Post Office and near the St. Au-
            gustine    Inlet.   This rainfall station is within the area
            influenced by the daily sea breeze effects.         Sea breeze re-
            lated storms     providing rainfalls to land areas along the
            coast occur occasionally.      During    these stormsi     rainfall
            typically is more intense within one or           two miles of the
            coast and diminishes in intensity towards the interior of the
            land area.

            The   familiar summer shower rainfall resulting from heated
            land surfaces     and    cooler air (differential heating and
            cooling    and corresponding    thunderstorms) occurs more fre-
            quently over inland parts       of the County.      This source of
            rainfall is typically provided        by isolated storms passing
            along narrow bands or tracks with short-duration effects.
            These storms move with prevailing air currents as cells of
            thunderstorms typically one       to three miles      across. The
            highly localized rainfall can be intense, on the order of
            one to two inches during      five to thirty       minute periods.
            Part of the rainfall evaporates quickly due to summer temper-
            ature conditions. Sometimes, an intense rainfall from such
            storms     produces short-duration ponded water on properties.
            If allowed to drain from the land, the water provided from
            these storms can be lost as runoff. While producing heavy,
            localized, and short-duration rainfall on small parts of the
            watershed.    The common summer differential heating and cool-
            ing   thunderstorms     contribute only part of the area's warm
            season rainfall.

            Rainfall occurs repeatedly on the watershed from midsummer
            through the winter months when high pressure systems with as-
            sociated cold or cool fronts pass from west to east across the
            country and sometimes penetrate into Florida. In the summer
            months, most frontal systems move to the north of Florida,
            but   these systems can penetrate southward into north Flor-
            ida   almost    any month of the year.      Strong high pressure
            systems passing to the north of Florida can generate persis-
            tent clockwise air movements resulting in winds from the
            northeast that move off the Atlantic Ocean and onto the



                                        2 - 4










            eastern coastline of Florida. These are           the northeasterly
            storms with winds of 20 or more miles per hour              and with
            cloudy, drizzly weather lasting for several days. They can
            provide long-duration, low-intensity rainfalls across large
            areas.    Several inches of rainfall       over a two or three day
            period can be expected from northeasterly storms.

            Heavy    localized rainfall can occur when         frontal systems
            move slowly      across north Florida from north to south or
            northwest    to southeast. The effects can become severe when
            the system stalls for an extended period over a part of the
            peninsula.       As the cooler     frontal system air comes into
            contact with the warmer, moister air             over the Floridan
            peninsula,    gentle, persistent rainfall occurs on the warm
            side of the front. Occasionally, a significant low-pressure
            trough develops      across the peninsula on the southerly and
            warm side of the frontal system. As the frontal                system
            stagnates or moves very slowly southward, very moist air can
            flow from the Gulf of Mexico and move across the peninsula
            providing rainfall along the low-pressure trough. The inten-
            sity    of the low- pressure trough and its duration cannot be
            forecast easily, but these factors essentially determine the
            intensity of the rainfall associated with the event.

            The above type of system was responsible for very heavy rain-
            fall in parts of Jacksonville in August 1989 and again in late
            September 1989.      Recorded rainfall in the second event in
            Jacksonville reached the expected 100-year return frequency
            rainfall of over       11 inches in twenty-four hours in the
            downtown and northwest parts of the city.          Much of the city
            (Duval    County) received      in excess of 4 and 5 inches of
            rainfall.      Comparable conditions have been responsible for
            major flooding events across much of the state of Florida over
            the years.

            The    September 1989 system that affected northeast Florida
            provides a useful example of the character of the rainfall in-
            cidence to be expected under this weather condition.              The
            warm, moist air channeled       towards the      northeast from the
            Gulf    of Mexico was concentrated in a series of cells with
            thunderstorm characteristics moving in bands across the penin-
            sula.    The rainfall from specific cells was intense, and the
            cells deposited differing amounts of rainfall on the areas
            over which they passed. At the same time, only a rela-
            tively small part of Jacksonville experienced an extremely
            heavy rainfall that might be expected on an average of once
            in one hundred years.







                                         2 - 5








            The trough also produced the heaviest rainfall in a relatively
            narrow band.     In northeast Florida, Baker, Duval, and Nas-
            sau counties received very heavy rainfall, while Clay County
            received a lesser amount of total rain, and St. Johns and Put-
            nam   counties received      rainfall amounts that could be ex-
            pected annually from frontal weather systems.

            Another    more typical frontal system moved southward through
            St. Johns County on October 8, 1989. The day started with
            clear skies, but clouds became dominant by midday. The rain-
            fall   began in early afternoon and ended in the early even-
            ing hours.      On that day, radio station WFOY in St. Augus-
            tine recorded a rainfall of 1.09 inches. Conditions became
            atypical when   the front stalled     over central Florida set-
            ting   up unstable atmospheric conditions.        A low pressure
            trough formed above the unstable frontal system setting up
            a movement of moist Gulf air from the southwest. At the same
            time, frontal  systems passing to the east and north of Florida
            set up a northeasterly air movement from the Atlantic Ocean.
            The air moving from the northeast and the cooler Atlantic
            Ocean and the warm, moist air moving from the southwest and
            the   Gulf of Mexico set up bands of rainfall that became
            intense along the coastline between St. Augustine and Mel-
            borne.    The combination of moisture laden warm and cool air
            resulted    in the 11.28 inch daily rainfall recorded at radio
            station WFOY on October 10, 1989. However, a rainfall of 16
            inches was recorded at the Emergency Management Center in St.
            Augustine on October 10.      The official National Weather Ser-
            vice (NWS) four day rainfall recorded       at radio station WFOY
            in St. Augustine between October 8 and 11 was 12.45 inches.

            A   significant part of the late summer, fall, winter, and
            spring rainfall in northeast Florida is provided by, or in
            association with, cold fronts passing southward along the Flo-
            ridan peninsula. Review of storm data records suggest that
            frontal    system rainfall,     including northeasterly storms,
            produce the more significant part of the total annual rain-
            fall received on most of the Floridan peninsula.

            Another    important source of rainfall is associated with
            the passage     of tropical low-pressure systems across the
            peninsula.    Beginning in the 1980's, the National Hurricane
            Center in Coral Gables, Florida, has been reporting the move-
            ment of tropical low-pressure systems that move from east to
            west across the Atlantic Ocean and pass over the Floridan pen-
            insula.

            On    the order of 50 or more of tropical or easterly waves
            form each year and move to the west across the Atlantic
            Ocean    at latitudes of between 10 to 20 degrees. Some form
            into    low-pressure    depressions or troughs that can produce


                                        2 - 6









            significant   rainfall, typically across the southeast part of
            the peninsula. Some of these systems extend northward far
            enough to produce heavy rainfall along the northeast Florida
            coastline.

            When the tropical system becomes organized enough to generate
            a circulating wind pattern with sustained wind speeds of more
            than 39 miles per hour, it is classified as a tropical storm.
            Tropical storms can produce significant rainfall over thou-
            sands of square miles of the earth's surface in their paths.
            In   August 1981 Tropical Storm Dennis       deposited over 20
            inches of rainfall in a twenty-four hour period near Home-
            stead, Florida, and     relatively widespread rainfall across
            much of southeastern Florida. The storm took a track north-
            ward through southeastern Florida and back into the Atlantic
            Ocean near Fort Pierce. On August 19, Tropical Storm Den-
            nis passed to the east of St.     Augustine and northern Flor-
            ida.   Over the 6 day period from August 16 to August 21, St.
            Augustine   received 2.35 inches of rainfall from the dis-
            turbed atmospheric conditions associated with this tropical
            storm.


            When   the circulating wind speeds of tropical storms reach
            sustained velocities of 74 miles per hour, they are reclassi-
            fied   as hurricanes.   These    storms are very rare, and only
            a   few have produced damaging effects in northeast Florida.
            However,   northeast    Florida can receive rainfall from the
            bands of circulating winds       and associated cells of thun-
            derstorms   moving around a hurricane hundreds of miles from
            its center.    In 1985 Hurricane Elena moved from the Carib-
            bean Ocean into the Gulf of Mexico and stagnated for almost
            two days about 75 miles southwest of Cedar Key on Florida's
            west coast. For several days, outer bands         of that storm
            passed across northeast Florida producing significant rain-
            fall amounts. During the two days of August 31 and September
            1,   when Elena was offshore of Cedar Key, St. Augustine re-
            corded rainfalls totaling 4.09 inches. Any hurricane pass-
            ing   within roughly    two hundred miles of northeast Florida
            can be expected to provide some rainfall for local areas.

            The rainfall received in northeast Florida and the study area
            is largely dependent upon weather conditions that cannot be
            predicted   on   any long-term basis. Much of        the annual
            rainfall received occurs as a result of large storm systems
            that   move across    the Floridan peninsula.     The amount of
            rainfall   that is produced by any specific weather system
            is   also essentially unpredictable.      Presently, it is not
            possible to know with any degree of certainty how much rain-
            fall is going to fall daily, weekly, monthly, or annually on
            the Moultrie Creek watershed or any other ground water re-
            charge area in Florida.


                                       2   7














            PRECIPITATION



            Rainfall Records

            St.    Johns    County rainfall is recorded by the           National
            Weather Service as part of the north Florida Climatic Division
            comprised of 20       counties.    The normal annual rainfall for
            the    Division based upon        the 1951-1980 period is 53.61
            inches.     The normal annual rainfall for the Division based
            upon the 1931-1960 period was         52.65 inches. Normal annual
            rainfalls based upon the 1951-1980 period were available for
            Federal Point, in St. Johns County        near the mouth of Deep
            Creek, (52.84 inches),       St.   Augustine (52.6 inches), and
            Jacksonville Beach (50.35 inches).        From these data, an ex-
            pected    annual rainfall of 53 inches would          be generally
            representative of conditions in the Moultrie Creek watershed.

            Monthly rainfall records for several stations in the vicinity
            of St. Augustine dating from 1877 to 1984 were available for
            this study.      The National     Weather Service     has compiled
            composite information for these stations useful for esti-
            mating general rainfall conditions for the St. Augustine lo-
            cality.    These data are also generally representative of the
            rainfall to be expected on the easterly portions of the Moul-
            trie Creek watershed.

            The composite rainfall records for St. Augustine show a varia-
            tion in the annual         rainfall ranging between 29.2 (1956)
            and    79.5 (1953) inches, with a long-term (1917-1984) average
            annual    rainfall of      50.7 inches. No real pattern exists
            to    establish a trend in annual rainfall variation. In il-
            lustration,     the five   years with the highest annual rainfall
            and the five years in      the record with lowest annual rainfall
            are presented in TABLE     2-1. ANNUAL RAINFALL EXTREMES ST. AU-
            GUSTINE, FLORIDA.

            The    National    Weather Service has produced an atlas of
            monthly Palmer hydrological drought indices for the contig-
            uous United States.       The Palmer drought index data for the
            North    Florida Climatic Division was reviewed to determine
            the , duration of periods in the rainfall record with below
            average    rainfall and those periods with above average rain-
            fall.    Drought Index information was available for the 1,032
            month period between 1898 and 1984.

            The data indicated that about 5.2 percent of the record pe-
            riod (54 months) had extended drought conditions, with evapo-
            transpiration     exceeding rainfall on an average for three or


                                         2 - 8













                                          TABLE 2-1


                                 ANNUAL RAINFALL EXTREMES
                                  ST. AUGUSTINE, FLORIDA
                               (Record Period 1877 to 1984)

                  5 Years With Greatest                5 Years With Least
                  Total Annual Rainfall               Total Annual Rainfall


                         Amount                             Amount
                Rank       Year   (Inches)           Rank    Year   (Inches)

                  1        1953    79.91              1      1956     29.20
                  2        1964    79.50              2      1911     31.59
                  3        1972    73.61              3      1954     34.14
                  4        1942    71.84              4      1927     34.41
                  5        1880    67.34              5      1917     34.79




             more   months. The most significant      drought period affecting
             the Moultrie Creek watershed extended for 16 months between
             November 1955 and February 1957.       Recorded monthly rainfall
             for this period at St. Augustine was 32.69 inches, or 54.7
             percent of the normal rainfall.

             Extended wet periods represented 3.1 percent of the record
             time frame.     The longest extended wet period for the North
             Florida Climatic Division extended for 8 months between Octo-
             ber 1947 and May 1948. In the time frame between September
             1947 and March 1948, monthly rainfall at St. Augustine ex-
             ceeded the normal     of 29.23 inches for those months by 37
             percent.

             The   above data were presented to illustrate the likely range
             of extended period rainfall variability which should be ex-
             pected in the Moultrie Creek watershed. Extended periods of
             drought and above normal rainfalls can be expected at any
             time in the future.      Lack of rainfall for extended periods
             is particularly significant in       St. Johns County where the
             surficial aquifer is      used heavily for* potable water sup-
             plies.

             The   extended wet periods also provide information useful
             for stormwater     management planning.      The large areas of
             flatwood soils within the Moultrie Creek watershed have normal
             high   water tables during the winter months of the year. Ex-
             tended wet periods can be expected to result in saturated
             soils and shallow flooding within high natural water table
             areas   during these prolonged wet periods. Consideration of


                                         2 - 9










            wet season water table conditions should be incorporated into
            revisions of water management framework. of special concern
            are the public health and safety needs of people living in
            developments permitted in areas where water tables are nat-
            urally   higher and where shallow       flooding    is   a highly
            probable natural occurrence.


            Average Daily Rainfall

            The available hourly and daily data for rainfall stations in
            St. Johns County were reviewed to develop basic information
            on   the number of rainfall events to expect annually and the
            amounts   of average daily rainfall to expect during in-
            dividual   events. Hourly precipitation data were not avail-
            able for any station that might       be representative of the
            Moultrie Creek watershed.     All stations reviewed had miss-
            ing data, but the Hastings rainfall station had a continuous
            record of daily rainfall amounts for the period from January
            1978 to December 1986, a 9        year period.       The Hastings
            rainfall gage is located at the Agricultural         Center about
            10.5 miles southwest of 1-95 and State Road 207 and            the
            southwesterly part of the Moultrie Creek watershed.

            The total rainfall record period reviewed for Hastings con-
            sisted of 3287 days. During the record period, some rain
            fell on 1041 days, or 30.7 percent of the days in the period.
            However, 388 of the days with rainfall had total amounts of
            less than 0.1 inches, and this rainfall represented only 3.1
            percent of the total received at Hastings during the 9 year
            period.   Daily rainfalls of 0.1 inches approximate the amount
            of water lost each day to evapotranspiration and do not ef-
            fectively contribute to ground water recharge.

            No intense nor prolonged periods of extreme rainfall were re-
            corded.   The maximum daily rainfall recorded for the period
            was   4.68 inches. All of the maximum daily rainfalls can be
            accounted   for in the context of normal events to be expected
            annually or on    a two year expected return frequency basis.
            No   attempt was     made to separate the data into rainfall
            events.   Daily records do not permit the identification of
            storms that begin on one day and end one or more days later.

            Review of the daily data identified numerous periods during
            fall, winter, and spring months when no rainfall was recorded
            for   ten and more days. one time frame of 26 days with no
            rainfall   occurred during the record period.       Some rainfall
            occurred on about 31 percent of the total days in the period,
            but daily rainfalls of more than 0.1 inches occurred on
            only 653 days, about 20 percent of the total days in the 9
            year period. Distributing the 653 rainfalls evenly through-


                                        2 - 10









            out the total period would reflect one day with rainfall of
            more than 0.1 inches on an average of about once every five
            days.

            The daily rainfall recorded at Hastings during the 9 year pe-
            riod is summarized in TABLE 2-2. DAYS WITH RAINFALL HASTINGS,
            FLORIDA, and TABLE 2-3. AVERAGES OF DAILY RAINFALL AMOUNTS
            HASTINGS, FLORIDA. Table 2-2 describes the general distribu-
            tion of days with rainfall grouped by categories of rainfall
            amounts    recorded. This table illustrates the rare condition
            of daily rainfalls       with more than two inches.       The data
            identified only 32 days in the nine year period with daily
            rainfalls of more than two inches; a frequency of 3.5 days per
            year with rainfalls exceeding two inches.

            Table    2-3 summarizes the average rainfall received each year
            by categories of rainfall amounts. The average annual rain-
            fall at Hastings is 53.9 inches. The first 0.5 inches of ev-
            ery    rainfall amounts to an average annual total of 29.5
            inches.    If the    first 0.5 inches of all rainfalls are re-
            tained or stored and allowed to infiltrate into the ground
            as water table      recharge, about      55 percent of the annual
            rainfall would become available for this purpose. Retention
            of the   first 1.0 inch of every rainfall would mean that no
            runoff would be allowed for rainfalls of less than 1.0
            inches.     Under this condition, almost 78 percent of the
            average     annual rainfall would become available for re-
            charge.    Retention of the first 2.0 inches of every rainfall
            would    represent the potential storage of almost 92 percent
            of all normal annual rainfall amounts.



                                          TABLE 2-2


                                    DAYS WITH RAINFALL
                           HASTINGS, FLORIDA (station No. 3874)
                               January 1978 to December 1986

                Daily        Number of         Percent of         Percent of
                Rainfall     Rainfall          Total              3287 Days
                (Inches)     Days              Rainfall           in Period
                                               Days

                0.0 - 0.1      388                37.3                11.8
                0.1 - 0.49     353                33.9                10.7
                0.5 - 0.99     155                14.9                  4.7
                1.0 - 1.99     113                10.8                  3.4
                2.0>             32                 3.1                 0.1
                    Total      1041               100.0               30.7





                                         2     11













                                         TABLE 2-3


                           AVERAGES OF DAILY RAINFALL AMOUNTS
                          HASTINGS, FLORIDA (Station No. 3874)
                              January 1978 to December 1986

               Daily       Average     Annual        Annual       Annual
               Rainfall    Rainfall    Average of Average of      Average of
               (Inches)    Per Year    First 0.5    First 1.0     First 2.0
                           Inches      Inches        Inches       Inches


               0.0 - 0.1      1.7          1.7           1.7          1.7
               0.1 - 0.49   10.5          10.5         10.5         10.5
               0.5 - 0.99   13.6           8.6         13.6         13.6
               1.0 - 1.99   16.6           6.3         12.6         16.6
               2.0>         11.5           2.4           3.6          7.1
                    Annual  53.9           29.5        42.0         49.5




            Daily    rainfalls greater     than 2.0 inches represented        4.4
            inches of the annual average rainfall.

            Until   further studies of rainfall characteristics are under-
            taken   for a larger number of stations, the above data can be
            used    to estimate     annual rainfall characteristics to be
            expected    in interior St. Johns County. Standard urban area
            drainage systems are sized to provide for the removal of ex-
            cess stormwater      from rainfall events with total amounts
            greater than reflected in the above data. Runoff from a 25
            year 24 hour rainfall is sometimes used          to establish the
            maximum capacity of a drainage system. Unless the storm-
            water systems are also designed to detain            or retain the
            routine daily rainfall amounts expected on an annual basis,
            overdrainage and associated long-term local ground water de-
            ficiency problems can occur.


            Expected Rainfall Return Periods

            Economic and engineering evaluations of water management mea-
            sures and facilities requires information on the, expected
            likelihood (return period) of rainfalls of some frequency
            and    duration. Cooperation between the U. S. Weather Bureau
            and the U. S. Department of Agriculture, Soil Conservation
            Service, began in 1955 for the purpose of defining the depth-
            area-duration     frequencies of rainfall in the United States.
            These efforts resulted in the Rainfall           Frequency Atlas of
            the United States, Technical Paper No. 40, published in May
            1961.    This document provided       generalized information for


                                         2 - 12











            rainfall with durations from 30 minutes to 24 hours and re-
            turn periods from 1 to 100 years.

            A   second technical paper was produced by the Weather Bureau
            in 1964 (Technical Paper No. 49). This document provided
            generalized    information    for two- to ten-day precipitation
            for return periods of 2 to 100 years in the contiguous United
            States.    This document was      an extension of the work pub-
            lished   in Technical Paper       No. 40. A final document was
            published in June 1977 that provided five- to 60-minute pre-
            cipitation frequency information for the eastern and Cen-
            tral United States( NWS HYDRO-35). The latest document pro-
            vides guidance specifically for the hydrological planning and
            design for small area drainage areas.

            The map and technical information from the above three docu-
            ments has been assembled to represent probable rainfall re-
            turn   conditions    in St. Johns County. The data derived
            from   the above sources is provided in TABLE 2-4. PROBABLE
            RETURN FREQUENCIES OF PRECIPITATION AMOUNTS ST. JOHNS COUNTY,
            FLORIDA.


            As part of the Weather Bureau's initial study effort, a sta-
            tistical probability analysis was conducted to establish the
            degree that data for a rainfall station represents rainfall
            on    adjacent    areas.      Results    from this part of the
            Weather    Bureau's evaluations    indicate the following: 95
            percent    of   24 hour rainfall     data recorded at a location
            would be   applicable to an adjacent       50 square mile water-
            shed and   about 92 percent    of the rainfall     data would be
            applicable to a 400 square mile watershed.         These findings
            suggest that the daily rainfall recorded at St. Augustine or
            Hastings would be generally representative of rainfall occur-
            ring on the Moultrie Creek watershed.

            The Weather Bureau's findings also indicate that as the dura-
            tion of the rainfall event decreases, the rainfall station
            data    are applicable     to smaller areas. For example, only
            about 70 percent      of a 30 minute rainfall recorded at a
            station    would be expected to directly apply to a nearby 50
            square mile watershed. This        concept reflects the condi-
            tion that localized rainfall systems affecting small areas
            tend to be associated with short-duration        rainfalls. As a
            result of these limitations and as an example, it would not
            be appropriate to directly apply hourly rainfall data from
            the Hastings rainfall station with rainfall and subsequent
            conditions occurring      on the Moultrie Creek watershed, but
            daily rainfall data would generally remain applicable.






                                        2 - 13












                                       TABLE 2-4
               PROBABLE RETURN FREQUENCIES OF PRECIPITATION AMOUNTS
                              ST. JOHNS COUNTY, FLORIDA
                              (PRECIPITATION IN INCHES)



            RAINFALL                        RETURN PERIOD
            DURATION                           (years)
            (Minutes)        2        5       10        25       50      100

                5         0.57     0.62     0.66     0.74     0.79     0.85
               10         0.97     1.09     1.18     1.33     1.44     1.56
               15         1.25     1.41     1.54     1.74     1.89     2.10
               30         1.72     2.07     2.33     2.71     3.00     3.30

            (Hours)
                1         2.2      2.6      3.0      3.4      3.8      4.2
                2         2.7      3.5      3.9      4.5      4.8      5.4
                3         3.0      3.9      4.2      5.0      5.5      6.0
                6         3.6      4.5      5.3      6.0      6.8      7.3
               12         4.4      5.5      6.5      7.2      8.2      9.0
               24         5.0      6.5      7.6      8.8    10.0     11.0

            (Days)
                2         5.5      7.3      8.3    10.0     12.0     12.8
                4         6.3      8.2     10.0    12.1     13.8     14.6
                7         7.5      9.3     10.6    12.7     14.5     16.2
               10         8.2      10.4    12.4    14.5     16.2     18.0

            Probable    maximum    6 hour  rainfall (PMP)  for 10 square miles
            is about     31 inches in northeast Florida.        The main purpose
            of    the PMP value is to provide complete-safety design crite-
            ria in cases where a water control structure failure would be
            disastrous.

            SOURCES:      Values for rainfall durations in minutes were de-
            rived from: Ralph H. Frederick, et. al., FIVE- TO 60- MINUTE
            PRECIPITATION     FREQUENCY FOR THE EASTERN AND CENTRAL UNITED
            STATES, NOAA Technical Memorandum NWS HYDRO-35, Office of Hy-
            drology, National Weather Service (NWS), National Oceanic and
            Atmospheric      Administration    (NOAA), Silver      Springs, Md.,
            June     1977.   Values    for rainfall durations in hours were
            derived from: David M. Hershfield, RAINFALL FREQUENCY ATLAS
            OF THE UNITED STATES       For Durations from 30 Minutes to 24
            Hours and Return Periods from 1 to 100 Years,Technical Paper
            No. 40, Weather Bureau (now the NWS of NOAA), U. S. Depart-
            ment of Commerce, Washington, D. C., May 1961.             Values for
            rainfall durations in days were derived from: John F. Miller,
            Two- to Ten-Day Precipitation for Return Periods of 2 to 100
            Years    in the Contiguous United States, Weather              Bureau,
            U. S. Department of Commerce, Washington, D. C., 1964.


                                          2 - 14














                                         3


                              GEOLOGY AND LANDFORMS



            GEOLOGY



            Upper Surficial. Sediments

            The upper 50 to 60 feet of materials underlying St. Johns
            County and the Moultrie Creek watershed is comprised of sands,
            shells or coquina, and small amounts of clay. These materi-
            als   apparently were deposited during the warm interglacial
            periods   when sea levels were considerably higher than cur-
            rent conditions. Following successive depositions, several
            periods of erosion and redeposition       apparently occurred.
            This process gradually shaped the surface materials to pro-
            duce the characteristics of landforms currently found within
            the County.

            Geologists   have traced a series of continental glacial ad-
            vances and   retreats over the past one to two million years
            which   they identify as the Pleistocene Epoch.        Scientists
            generally    consider that the Pleistocene Epoch ended about
            10,000 years ago, and we are living within a geological pe-
            riod known as the Recent or Holocene age.

            The maximum penetration of the last major glacial advance on
            the North American Continent is now considered to have oc-
            curred about 18 1000   years ago.    Geologists have estimated
            that   ocean levels were over 100 feet lower than present sea
            level during the height of this glacial period.

            A gradual worldwide rise of ocean levels has been occurring
            since the last retreat of the continental glaciers. The last
            continental glacier receded from the United States part of
            North America about 7,000 to 9,000 years ago. As a result of
            studies conducted near Miami in Biscayne Bay scientists have
            concluded that sea level was about six feet below current
            ocean levels approximately 6,000 years before the present.
            We are now living in a geological age with current climate
            and sea level conditions reflecting an interglacial period in
            the geological history of the earth.




                                       3 - 1









              At   least four Pleistocene interglacial ages appear to have
              signifiqance    relative to surficial sediments in St. Johns
              County..@' An interglacial period labeled the Penholoway Age
              produced   remnant terraces in Florida at an altitude of about
              70 feet. During this age, probably all of St. Johns County
              was an offshore bar of an ancient ocean shoreline.

              The    second interglacial period has been termed the Talbot
              Age which resulted in sea cut terraces on the Floridan penin-
              sula   at an altitude of about 40 feet. During this intergla-
              cial period, the Tillman Ridge apparently was a shallow shoal
              and island area with sand dunes rising at least ten feet
              above sea level.      The Moultrie    Creek watershed area would
              have been a gently sloping beach and foreshore area.

              The third interglacial period has been named the Pamlico age
              when terraces were cut at an elevation of about 25 feet above
              current sea level.      Recent scientific studies conducted on
              coral    reef terraces     in the Barbados Islands and in New
              Guinea    have determined that the world's oceans were at an
              elevation of about 20 feet above the current level approxi-
              mately 125,000 years ago.

              Finally, poorly defined Silver Bluff terrace remnants exist
              around    the Floridan peninsula at elevations of between five
              and ten feet above current sea level. The Talbot and Silver
              Bluff interglacial periods could be expected to have pro-
              duced the final shaping of the lower landforms in St. Johns
              County. From these periods to the present, stormwater runoff
              gradually cut Moultrie Creek and its tributary streams into
              the low plateau that is now the Moultrie Creek watershed.


              Lower Sediment Deposits

              Beneath the Moultrie Creek watershed, the upper 50 to 60 feet
              of sediments are underlain by more dense, less permeable
              sand, shells, sandy clay, and clay about 25 to 50 feet in
              thickness.    These materials rest upon the blue to green clay
              materials of the Hawthorn Formation. The Hawthorn Formation
              forms    an aquiclude (an impermeable layer) or aquitard (an
              area of low permeability) that separates the materials iden-
              tified with the St. Johns County surficial aquifer from the
              limestone formations associated with the Floridan aquifer.


              Limestone Formations

              The    top of the limestone formations beneath the Moultrie
              Creek watershed is generally found about 200 feet beneath land
              surface.    South of the Moultrie Creek watershed the top of


                                          3 - 2











            the   limestone occurs about      150 feet beneath land surface.
            The several rock formations extending to about 350 feet be-
            neath land surface     are now    collectively called the Ocala
            Group.    These formations are the primary and more produc-
            tive artesian water supply sources associated with the Flo-
            ridan aquifer.



            LIMESTONE FORMATIONS



            General

            The top of the limestone formations underlying north cen-
            tral Florida     and St. Johns County slope generally from
            southwest     to northeast.    In central Alachua County        and
            western   Marion County, the top of the Floridan aquifer is
            found 50 to 75 feet above mean sea level. The top of the
            limestone    formations in this central Florida area is di-
            rectly overlain by a zone of permeable silica sands. This
            sand zone has been identified as a secondary artesian aquifer
            in St. Johns County.

            The   Hawthorn Formation that functions as an aquiclude or
            aquitard (preventing or retarding the upward or downward move-
            ment of water) is missing from the central Florida uplands
            of western Clay and Putnam counties, and most of Alachua and
            Marion    counties. Additionally, substantial solutioning has
            occurred    within the limestone formations, resulting in sink-
            hole formations where the limestone is near the land surface.
            Where sufficient surface material debris has partially plug-
            ged   the exposed drainage points within sinkholes, surface
            water ponding has occurred.

            In the Moultrie Creek study area, the top of the Floridan
            aquifer is generally found at elevations of 175 to 200 feet
            below   mean sea level.       Along the St. Johns County coast,
            the   top of the Floridan aquifer in the vicinity of Pellic-
            er Creek, at the south boundary of the County, is about 150
            feet below mean sea level. In the Ponte Vedra area on the
            north, it occurs more than 350 feet below mean sea level.


            Water Supply Aquifers

                 Floridan Aquifer

            Rainwater falling on Clay, Alachua, and other interior coun-
            ties infiltrates into       the surface sands or runs off di-
            rectly     into sinkholes.    These localities are considered as
            primary    Floridan aquifer recharge areas that establish the


                                        3 - 3









            water pressure head for fresh water withdrawn from the lime-
            stone formations beneath St. Johns County. Rainwater enters
            the limestone aquifer through permeable materials in areas
            where local water tables are at elevations higher than the
            water pressure head within the aquifer.        The rainwater en-
            tering the Floridan aquifer moves by gravity through solution
            channels in the limestone, along seams between the rock lay-
            ers known by geologists as bedding planes, and through the
            rock   materials. Where the Floridan aquifer is overlain by
            impermeable materials, the pressure exerted by the weight of
            the water within and above the aquifer causes increased move-
            ment of water through the aquifer.

            Some   of    the ground water flow entering       the     Floridan
            aquifer   emerges as seepage back to the land surface at ele-
            vations   below the points where the rainfall infiltrates into
            the ground.     Part of the flow of streams flowing eastward
            from Central Florida (The Oklawaha River,        Rice Creek, and
            Black Creek) is the     result of reemerging Floridan aquifer
            water. Ground water that seeps back to the land surface and
            becomes part of the flow of streams is known by hydrologists
            as base flow.

            The Hawthorn Formation overlies the limestone formations west-
            ward from the Atlantic coast through western Putnam, Clay,
            and Baker counties. This formation traps the ground water in
            the Floridan aquifer,forcing it to flow eastward towards the
            Atlantic Ocean. As a result, wells penetrating into the Flo-
            ridan aquifer in eastern St. Johns County have in the past
            been known to rise in the wells to heights approximating 20
            feet   above sea level. Aquifers with these conditions are
            known as artesian aquifers.      Because land elevations in the
            Moultrie Creek watershed are       generally at altitudes higher
            than 20 feet above sea level, artesian flow to the land sur-
            face does not occur.

            The   potential height to which artesian water rises in a
            tightly contained well is known as the potentiometric head for
            that well. The generalized potentiometric levels for wells
            within a region are known as the potentiometric surface for
            that regional area.

            Within the Moultrie Creek watershed, Floridan aquifer wa-
            ters occur beneath the Hawthorn Formation. Wells drilled to
            depths of 150     or more feet generally will obtain Floridan
            aquifer   water. Due     to the water pressure in the aquifer,
            some   seepage upward, termed leakance by hydrogeologists,
            into, and perhaps through, the Hawthorn Formation can be
            expected.    The   extent    of this upward leakance into the
            sands above the Hawthorn Formation has not been investigated.




                                        3 - 4










            The quantities of Floridan aquifer water available in eastern
            St. Johns County is substantial, though not unlimited. De-
            clines in the potentiometric levels of the Floridan aqui-
            fer   throughout northeast Florida have been widely reported
            since   the 1950's. These declines generally reflect water
            withdrawals in excess of the ability of rainfall in recharge
            areas to replenish the aquifer.

            Investigations of 85 irrigation wells in western St. Johns
            County determined that the upper 50 feet of the aquifer pro-
            vided most of the water      flow zones.     About 50 percent of
            the   wells tested produced water with chloride (salts) con-
            tents of less than     210 parts    per million     (ppm). Wells
            penetrating deeper into the aquifer tended to produce water
            with higher chloride concentrations. Some wells penetrating
            deeper aquifer zones produced water that exceeded 3,000 ppm.
            As withdrawal in the upper aquifer zones were increased, wa-
            ter with higher     chloride contents were drawn upward, con-
            taminating the fresher upper water zones.

            While the Floridan a   quifer is available as a ground water
            supply source in eastern St. Johns County, the water is high
            in   chlorides and other minerals. The U. S. Environmental
            Protection Agency (EPA) and the Florida Department of Envi-
            ronmental Regulation have established potable water limits for
            chlorides at 250 milligrams per liter (mg/1) or 250 parts per
            million.   Water high in chloride content is very corrosive
            to metals, harmful to most cultivated plants, and unpleasant
            to   drink.   A concentration of about 400 ppm can be tasted
            by most people.

            North   of the Moultrie Creek watershed, the Ocala Group of
            the Floridan aquifer generally produces water with chloride
            concentrations of less than 250 mg/l. Beneath the Moult-
            rie   Creek watershed, the chloride content of the upper lime-
            stone formations of Floridan aquifer water is at or greater
            than 250 mg/l.      Towards the south, the chloride content of
            Floridan aquifer     upper water    bearing zones increases to
            1,000 mg/l near the Flagler County line. Throughout St.
            Johns County, the lower limestone formations of the Florida
            aquifer typically produce water with chloride concentrations
            of 250 mg/l or more.


                 Surficial Aquifer

            The surficial aquifer within the Moultrie Creek watershed is
            a composite of confined and unconfined water-bearing zones
            comprised     of the sands, shells, and coquina          occurring
            above the Hawthorn Formation. Most wells used for potable wa-
            ter supplies in the study area are drilled to depths of the


                                        3 - 5











           less than 100 feet below sea level. Some water is obtained
           from wells penetrating sand and shell strata within the Haw-
           thorn Formation. The water from wells open to the surficial
           aquifer generally meets quality standards recommended for
           public water supplies, except for concentrations of iron.
           The iron content of water from most of the wells tested dur-
           ing a study by the United States Geological Survey (USGS)
           conducted in east-central St. Johns County was well above the
           recommended limit of 0.3 mg/l.     High iron contents of water
           are undesirable    because of the taste it imparts and the
           staining effect it has on clothes, faucets and associated fix-
           tures, painted walls, and natural stone. Iron from water can
           be removed at water treatment plants by aeration or filtra-
           tion.

           The surficial aquifer in the Moultrie Creek watershed is re-
           plenished primarily from direct rain water. Recharge to the
           surficial aquifer can only occur when rain water is retained
           long enough to infiltrate the surface sands and slowly per-
           colate downward to the water table.

           The surficial aquifer is widely used by individual prop-
           erty owners for potable and other uses. It was formerly used
           exclusively by the City of St. Augustine, but current demands
           exceed the capacity      of the city's surficial aquifer well
           field yield capacity.

           St.   Augustine and St. Johns County have surficial aquifer
           well fields located along or near Tillman Ridge on the western
           side of the Moultrie Creek watershed. U. S. Geological Sur-
           vey records of two monitoring wells in the Tillman Ridge
           area have detected a progressive decline in the water table
           in the vicinity of these well fields (Figure 3-1. USGS, Well
           Si 112E Tillman Ridge.)     These data suggest that long term
           withdrawals for public water supplies are currently exceeding
           the natural rain water recharge in the areas of the well
           fields.

           The   City of St. Augustine has begun the process of aug-
           menting surficial aquifer water with the saltier water from
           the Floridan aquifer.     This is a temporary measure that will
           require   further surficial aquifer well field expansion as
           public   demand for potable water provided by St. Augustine
           increases.

           Correspondingly, St. Johns County can be expected to be re-
           quired to supply potable water to increasing numbers of
           County residents in the near future. The rural practice
           of using individual surficial aquifer wells for potable water
           in the same locations where septic tank waste disposal is per-



                                      3   6








                                           Figure 3-1. USGS Well SJ 112E Tillman Ridge







                      5






              E-
              Lx-     0













                     -10 -






                     -15
                           1981     1982    1983     19B4     1985    1986     1987     1988   1989


                                       MINIMUM DAILY DEPTH BELOW     LAND SURFACE (FT)












                                                  PROlrrr
                                                  Worm


            D. F. R. CONTRACT NO. CM2171
                    ST. JOHNS COUNTY ENGINEERING DEPARTMENT      GEOGRAPHIC INFORVATION SYSTEM









              mitted can be expected     to lead to increased County public
              health problems as County areas urbanize.


                   Stormwater Management Implications

              As   increased amounts of surficial aquifer water beneath
              the Moultrie Creek watershed      becomes used by St. Augustine
              and   St. Johns County for public water supplies, further de-
              clines in local    water table     conditions can be expected.
              Trestle   Swamp, Cowan Swamp, and other upland natural areas
              will have longer and longer periods when the water table will
              be below the land surface. The weight of          the water re-
              tained in the surficial aquifer        acts against the upward
              leakance potential of the Floridan aquifer. As the water
              table declines, corresponding upward movement        of Floridan
              aquifer waters into and, to some extent, through parts of the
              Hawthorn Formation could be expected to occur.

              In areas of the watershed where septic tanks are used for
              sewage disposal, septic tank effluents are significant sources
              of water recharge to the surficial aquifer. Maximizing rain-
              fall retention in these areas, as opposed to primary depen-
              dence   upon uncontrolled stormwater drainage, would serve to
              increase recharge to the      surficial aquifer and provide a
              means for diluting septic tank effluents introduced into the
              surficial aquifer.

              A perspective of the ground water recharge significance of
              septic tank effluents can be obtained by the following example
              analysis.   Assume a family of four living in a home on a one
              quarter acre lot. Each person uses an average of 100 gallons
              of water per day which is discharged to the septic tank.
              This is an approximate average water usage for urban popula-
              tions using public water supplies.       The total family daily
              water usage is then     400 gallons, or about 53.4 cubic feet
              per day.    The family's property, at one fourth acre, is
              10,890 square feet. If the 53.4 cubic feet per day were dis-
              charged to a septic tank and the resultant effluent was dis-
              tributed across the 10,890 square foot lot, the effluent
              would be roughly equivalent to     rainfall infiltration into
              the soil approximating 0.06 inches every day, 365 days of
              the year. In the event that the above amount of water was
              discharged into a septic tank, the effluent could be equiva-
              lent to the infiltration into the ground of about 20 inches
              per year from rainfall.

              Later   information    in this study shows that the Moultrie
              Creek watershed, on the average, receives about 53 inches per
              year from rainfall, and about 30 percent of any significant
              rainfall is directly discharged to streams as runoff within 4


                                           3 - 8









            days    following the rainfall       event.     At best, about 37
            inches    of   the area's rainfall may infiltrate into the
            ground, but roughly 20 percent of that amount reemerges as
            base flow within three weeks following a rain event.



            LANDFORMS

            The Moultrie Creek watershed is a nearly flat to gradu-
            ally sloping     plateau generally raised 30 to 45 feet above
            existing sea level.        The easterly side of the plateau at
            the    Matanzas River generally has land elevations exceeding
            20 feet.      Land elevations exceeding 40 feet still exist at
            isolated    locations along U.S. Highway #1 north of Moultrie
            Creek.    The westerly side of      the Moultrie Creek watershed
            forms a surface water drainage      divide between runoff drain-
            ing to the Matanzas River and       runoff draining     westward to
            the St. Johns River. The Tillman          Ridge, which forms the
            drainage divide, is      paralleled by Interstate Highway #95
            located about 1 mile to the east as shown in Figure 1-1. The
            Tillman Ridge is a     gradually sloping upland with general land
            elevations of 40 to    48 feet.


            The    landforms of    the Moultrie Creek watershed and all of
            St. Johns County       were formed in association with shore-
            lines    to ancient    seas.   Geologists consider the study ar-
            eas's landforms as     a terrace system formed during previous
            interglacial times      when ocean     levels were 25 to 40 feet
            above present sea      level.   The Tillman Ridge is geologically
            associated with the Atlantic Coastal Ridge that extends for
            most of the length of the Floridan peninsula.           What is now
            the Moultrie Creek watershed was once a very gradually slop-
            ing shoreline related formation, possibly an offshore bar.

            Wave    action    along shorelines produces slight wave cut
            troughs just offshore of beach fronts, with the disturbed
            sands redeposited as low ridges or bars some distance off-
            shore.    As ocean water elevations         become    lowered, the
            former beach sand dunes become sand ridges and the former
            offshore bars become slightly lower ridge line areas.

            Immediately     east of the Tillman Ridge is a large,            par-
            allel depressional      area    known as the Trestle Bay Swamp.
            The    bottom elevation of this swamp is at or above 35 feet.
            About one mile to the east is another parallel depressional
            area known locally as the Cowan Swamp. Between State Roads
            16 and 214, the bottom of the Cowan Swamp is above 30 feet
            in elevation.       Near State Road 214 the beginning of the
            Moultrie Creek channel begins       with a channel flow direction
            towards the south and generally aligned according to the an-
            cient shoreline trough to tidewater.


                                           3 - 9













            The fall of Moultrie Creek from State Road 16 to tidewater is
            on the order of one foot per thousand feet, or a slope of
            slightly less than 0.1 percent. This slope represents a rela-
            tive   balance between slope stability of the area's sandy
            soils and stormwater runoff from the plateau in recent geo-
            logical times.

            Heavy rainfalls and subsequent runoff from the 30 to 40 foot
            high plateau    gradually    cut deep stream channels in the
            fine   ocean deposited sand mantle materials. Continual cut-
            ting or erosion of the sides of the steep stream channels typ-
            ical of Moultrie Creek and its tributaries can be expected to
            occur within the watershed following heavy        rainfalls. As
            development   occurs    and unless stormwater is retained or
            stored on lands improved for development, accelerated erod-
            ed materials and contaminants      from developed lands will
            be discharged into the Matanzas River in increasing quanti-
            ties over time.

            on the plateau of the watershed,       numerous large and small
            shallow depressional areas currently maintain wetland veg-
            etation. Many of these depressions are isolated       or have no
            natural drainage channel to established stream courses. Nor-
            mal rainfalls are retained within        these depressions, with
            some   of the rainfall infiltrating       and percolating water
            to the ground water table. Very heavy rainfalls often fill
            depressions and allow sheet water flow to move across normally
            drier areas to other depressions or to stream courses.



























                                         3 - 10





















                                         4


                        SOILS AND WATER TABLE CONDITIONS



            SOILS



            General


            The term, Soil is typically applied to the weathered surface
            layer of sediment materials.      The science of soils has been
            highly developed by the U.S. Soil Conservation Service (SCS)
            in support of the nation's agricultural needs. The materials
            used in this investigation are       heavily dependent upon in-
            formation provided by the Soil Conservation Service through
            the Soil Survey of St. Johns County, Florida. The Soil Con-
            servation Service classified the soils in the study area ac-
            cording to a variety of characteristics such as soil color,
            texture, size and shape of soil aggregates, kind and amount
            of rock fragments, distribution of plant roots, acidity, and
            other features that would identify the soils.      This informa-
            tion is highly valuable for general identification of ar-
            eas with unique surface sediment characteristics.       The in-
            formation   is suitable for preliminary engineering determina-
            tion   of potential    problems to expect within given areas,
            and   the soil survey information has been used for this pur-
            pose in this study.

            soil survey information does not replace the need for site
            specific field and laboratory analyses required to insure that
            load bearing and other construction design parameters are ade-
            quate for an engineered project.


                 Engineering Factors

            The soils underlying the Moultrie Creek watershed are essen-
            tially comprised of silica sands deposited as marine sedi-
            ments.    All upland soils in the study area, not subject to
            prolonged   flooding, are classified as fine sands with more
            than 50 percent of the material passing a #40 sieve and less
            than 50 percent passing a #200 sieve. Typically, at least 75
            percent of the materials pass the #40 sieve and less than 20
            percent pass the #200 sieve..     Being primarily silica sands,


                                       4 - 1











            the surface materials generally are not subject to liquid lim-
            its and are not plastic. The very fine silts and clay com-
            ponents and organic matter are typically low within those
            soils not subject to periodic and prolonged flooding. Corre-
            spondingly, soils with low clay and organic matter content
            in the study area tend to be highly permeable and typically
            have low available water and low water holding capacities.

            Soils with low available water also are less affected by
            capillary    rise of water in soils. Capillary rise results
            from the direct suction of the atmosphere due to differences
            in pressure between the air and the soil water. Capillary
            rise    is more pronounced in      soils with higher contents of
            clays,    silts, and organic materials.       A capillary rise of
            as much as 18 inches      can be expected to occur in clay and
            clay loam soils.

            In the fine sands typical of the Moultrie Creek watershed,
            a capillary rise of less than six inches would be expected.
            This phenomenon is       an important consideration in roadway
            design.    Roadway    load bearing   capability decreases      when
            the    subgrade supporting the road surface becomes saturated.
            The result is the familiar cracking of pavements into an alli-
            gator hide look. When the surface pavements protecting the
            load- bearing subgrade becomes broken through cracking pro-
            cesses, the roadway quickly deteriorates.

            The alligator cracking roadway deterioration process can be
            alleviated by insuring that the bottom of the road subgrade
            is built above local high water table conditions.         The road
            subgrade    bottom should be further elevated in fine sandy
            soils another 6 or more inches to reduce the soil saturating
            effect of capillary rise of water above the height of the an-
            nual high local water table.

            Roadway construction and repair is a major tax dollar expendi-
            ture 'of the St. Johns County government. Review of water ta-
            ble conditions, subsoils, subgrade materials, roadway con-
            struction    procedures, and local area drainage are essential
            before    the County agrees to accept a privately constructed
            roadway system.

            The following information provides general guidance on the
            natural    soils   and normal water table conditions          found
            within    the Moultrie Creek watershed.     This information also
            provides    useful guidance for determining the stormwater man-
            agement needs within the watershed.







                                        4 - 2











                      Soil Porosity and Water Storage Capabilities

               The     ratio of openings or voids between soil particles and
               the    total volume of the soil matrix is referred to as soil
               porosity.       Porosity is normally presented as a ratio or per-
               centage of void area per total area of the soil matrix. For
               sandy soils, total porosity                  is normally considered as 25
               percent of the total soil matrix.                  Within this 25 percent of
               the soil matrix, part of the void space is                            occupied by
               air. The trapped air reduces the potential for water stor-
               age in the surface soil materials.                    Part of the void area
               is also occupied by capillary water that                         is specifically
               retained or bound to the soil particles.

               In     sandy soils, specific retention losses may be estimated
               at about 15 percent of the total porosity.                         For saturated
               soils,      a generalized         estimate of the specific yield of a
               sandy      soil matrix, or the part of water stored in a soil
               that will drain under the influence of gravity, may be esti-
               mated at 22 percent of the unit area volume. This percent-
               age also provides an approximate estimate of the accessi-
               ble     water in saturated fine                sands. (Center for Environ-
               mental Research 1985, Frevert 1955, Resource Control Depart-
               ment, SFWMD 1983).

               The U. S. Soil Conservation Service provided the following
               estimates of soil water storage capability for the normal
               sandy soils found within the South Florida Water Management
               District.        Until different information is established for St.
               Johns County,          these values         provide preliminary guidance
               for     estimating potential water infiltration volumes into
               local fine sand soil matrix areas.

                       Depth to Water Table               Cumulative Water       Storage

                                   11                                      0.611
                                   21                                      2.511
                                   31                                      6.611
                                   41                                     10.91,



               The above values are applicable to soils in their natural
               state.       The cumulative water storage capabilities of sandy
               soils      that have        been compacted intentionally or through
               usage,       typically those associated with urban activities,
               should be reduced by 25 percent.                       This reduction factor
               would be applied to any proposed use of an open area. Con-
               sideration of the use of soils                 occurring under impervious
               areas, when calculating an area's water storage potential,
               requires still further adjusted                   estimates. Water can be
               introduced beneath impervious                 areas at          reduced percent-


                                                   4 - 3











             ages, as compared with a natural land area, but only when
             sufficient air bleed mechanisms are installed to prevent
             trapped air from further reducing the soil water storage po-
             tential.



                  Soil Permeability

             soil   permeability is the quality of a soil that allows it
             to transmit water or air. Permeability refers to the rate at
             which water moves through the soil. The term should not be
             confused with the perviousness or water storage capabilities
             of soil which determines       the    amount of water that can be
             withdrawn from, or stored within, a soil matrix. The perme-
             ability of soils is        referred to as the percolation rate
             when applied to septic tank drain field requirements. Per-
             meability is measured by engineers and           soil scientists in
             terms of the number of inches per hour water will seep or
             flow (usually downward by gravity) through a cross section
             of soil.

             Soil    survey data indicate that the surface layers of the
             fine sands within the Moultrie Creek watershed would be clas-
             sified    as having rapid permeabilities (5.00 to 10.00 inches
             per hour). The excessively drained soils typical of upland
             sand dunes have      very rapid    permeability rates (over ten
             inches per hour). At varying depths below the surface materi-
             als, soil permeability data show zones with moderately slow
             permeability rates (0.20 to          0.80 inches per hour) in many
             of the area's soils.

             The   upper one or two feet of most soils in the Moultrie
             Creek watershed have rapid permeability ratings.           At vary-
             ing lower depths, permeability becomes moderately slow. The
             lower    permeability rates may result from confining layers or
             saturated    soil conditions. In many localities of the Moult-
             rie Creek watershed, the surface soils are fully capable of
             accepting more      than the first one inch of every rainfall
             within relatively short periods of time.

             The surface soils with zones of lower permeability typically
             are associated with depressions, floodplains,             and flat-
             woods, all areas with naturally high water tables. Zones of
             lower soil permeability within these areas often are associ-
             ated with the top of local water tables. As water percolates
             downward, it carries organic and inorganic sediment fines
             largely developed from decomposed and reduced plant materi-
             als.    Downward percolation of these materials is stopped by
             the density of water near the top of the water table. Con-
             tinued    percolation carrying sediment fines to the vicinity
             of the water table gradually clog the pore spaces between the


                                          4 - 4











            silica sand materials, reducing permeability. A wide variety
            of biological actions and chemical reactions occur to produce
            these zones of lower permeability, but the available informa-
            tion   can be used to generally determine the normal depth to
            water table in localities within the watershed.

            Once   zones of reduced permeability are developed         within
            sandy soils by the above process, increased soil permeability
            in   the affected   zones can only be increased       by perma-
            nently   reducing water table levels in these areas and by
            fracturing or otherwise disturbing the confining zones to re-
            establish permeability.     Both of these practices have been
            widely used in Florida to improve lands for agricultural and
            urban development purposes.


            Watershed Soils Distribution

            Within the numerous shallow depressional areas occurring
            throughout the watershed plateau, decomposition of detrital
            materials   and the transport of these materials with runoff
            from locally higher areas to       the depressions has resulted
            in   localized   and often isolated accumulations of silts,
            clays, and organic   materials. Those depressional areas with
            significant clay and organic     materials accumulations typi-
            cally have high water     table conditions with ground water
            emerging and flooding the depressional       areas for extended
            periods.   Those watershed localities identified in the soil
            survey as having water tables rising above, or flooding, land
            surfaces part of each year are generally displayed on Figure
            4-1. Localities With Water Tables Rising Above Land Level Part
            of Each Year.

            The areas identified in Figure 4-1 include some of the same
            areas described later in this study as significant natural
            resource areas.   The areas displayed on Figure 4-1 include as
            a   grouping the    following soils series found in St. Johns
            County: (A) freshwater depressional areas with muck soils in-
            cluding the following soil series: Samsula muck (26), Hon-
            toon muck (35),     Tomoka muck (41), Bluff sandy clay loam,
            frequently flooded (42), and Bakersfield     muck (69); and, (B)
            freshwater depressional areas with mineral   (silica sand) soils
            including: Myakka fine sand, depressional    (4), St. Johns fine
            sand, depressional (5), and Riviera fine sand, depressional
            (61). Some of these soils series are not     found in the Moult-
            rie Creek watershed but are important on a   County-wide basis.

            soils   subject to extended periods of flooding annually can
            be identified by accumulations of dark colored organic mat-
            ter   as peat or muck, a predominance of mottling with dark
            brown   and grey colors staining     the normally light colored


                                       4 - 5








                                                 Figure 4-1.     Localities With Water Tables
                                             Rising Above Land Level Part of Each Year


                                                                                       a        1E
                             D   R 16





                           C1








                                                              ST      G





                                   0



                                                                'g; -r rJA -LJ
                                                                smo E;S














                                        's



                                                                                          R)
                                                                                          C1




                 SCALE: 110,000




                                                        LEGEND:

                                                 PROJECT       UPLAND DEPRESSIONS (MUCK SOILS)
                                                 LOCATION
                                                 p R'0
                                                               UPLAND DEPRESSIONS (SANDY SOILS)
            D.E.R. CONTRACT NO. 7CM 2117]-,,4                  TIDAL AREA SOILS
                    ST. JOHNS COUNTY ENGINEERING DEPARTMENT -  GEOGRAPHIC INFORNATION SYSTEM











            natural   sands, or the characteristic dark grey color of iron
            accumulating    under anaerobic    conditions characteristic of
            saturated or     flooded soils.    Red stained soils are charac-
            teristic of iron accumulations after oxidation of the iron
            has taken place. The       generalized soil characteristics of
            soils subject to periodic flooding also can be used to iden-
            tify soils that serve as shallow       drainageways      connecting
            larger depressions to more clearly defined stream channels.

            Also included in Figure 4-1 are tidal area soils. These soils
            are flooded periodically due to tide conditions. Tidal area
            soils and immediately adjacent areas are subject to accas-
            sional storm tides reaching elevations of 8 and 9 feet above
            mean sea level in Moultrie Creek. Soils found in tidal areas
            are: Pellicer silty clay loam, frequently flooded (24), Moult-
            rie fine sand, frequently flooded (49), Durbin muck, fre-
            quently    flooded (52), and Tisonia mucky peat, frequently
            flooded (67).

            The Moultrie Creek watershed has a poorly defined natural
            drainage     system.    Figure 4-1, above,      displayed     those
            fresh   water areas normally flooded for parts of each year.
            Many of the soil series that identify shallow drainageways
            carry surface water      as runoff   only following     rare, very
            heavy rainfalls. In character with poorly drained flatwoods
            soils,   the shallow drainageway soils tend to become fully
            saturated during part of each year as a result of high water
            table conditions. Some of these soils are also found on the
            floodplains of established streams.

            Figure 4-2. Annually Flooded Soils and Drainageway Soils,
            displays    the relationship of annually flooded soils with
            natural drainageway soils. The soils displayed in Figure 4-1
            appear   in Figure 4-2 grouped as upland annually flooded
            soils. Also displayed      in Figure 4-2 as a second group are
            the soil series classified as shallow drainageway soils in
            St. Johns County including: Floridana fine sand, frequently
            flooded (18), Pompano fine sand (19), Manatee fine sandy loam,
            frequently flooded (22), Parkwood fine sandy loam, frequently
            flooded (25), Wesconnett fine sand, frequently flooded (30),
            Riviera fine sand, frequently flooded (36),Tomoka muck (41),
            Bluff sandy clay loam, frequently flooded (42) (a muck soil of
            drainageways and floodplains), Holopaw fine sand, frequently
            flooded (47), winder fine sand, frequently flooded (48), and,
            Terra Ceia muck, frequently flooded (66) (a deep muck found on
            the floodplains of rivers and streams).        Some of these soil
            series are not found in the Moultrie Creek watershed but are
            important on a County-wide basis.

            Figure 4-2 provides a generalized display of the natural sur-
            face water storage and drainageway system in the Moultrie


                                          4 - 7









                                               F
                                                Tyure 4-2.  Annually Flooded
                                                Soils and Drainageway Soils


                                                                         1E




                                            C)    v
                                                   ST A








                    0














                                                ST A
                                                so u: 7r
                          cl





                                          CRY.



                                                   t
                                                   AU C;  INE
                                                      0
                                                     u,



















            SCALE: 110,000




                                          LECEND:

                                                UPLAND ANNUALLY FLOODED SOILS
                                     iocmu



                                                DRAINAGEWAY SOILS
         Dl-R. CONTRACT NO. CAf 2717
              ST. JOHNS COUNTY ENGI.IVEER[NC DEPARTMENT - GEOGRAPHIC INFORMATION SYSTEM











            Creek watershed.   Adjacent to this system are poorly drain-
            ed  drainageway fringe     and flatwoods soils.     Figure 4-3.
            Floodprone/Drainageway Soils and Naturally Saturated Soils,
            displays the relationship of the natural surface water stor-
            age and drainageway system with the drainageway fringe and
            flatwoods soils. These soils typically become saturated dur-
            ing a part of each year or have water table waters rising to,
            or within one foot below, the land surface. Naturally satu-
            rated soils identified in the soil survey include: Myakka fine
            sand (3), Immokalee fine sand (7), Pomona fine sand (9),
            Smyrna fine sand (11), Ona fine sand (12), St. Johns fine sand
            (13), Floridana fine sand, frequently flooded (18), Pompano
            fine sand (19), Wabasso fine sand (21), Manatee fine sandy
            loam, frequently flooded (22), Parkwood fine sandy loam, fre-
            quently flooded (25), Wesconnett fine sand, frequently flooded
            (30), Tocoi fine sand (34), Riviera fine sand, frequently
            flooded (36),Pottsburg fine sand (40), Bluff sandy clay loam,
            frequently flooded (42), Holopaw fine sand (46), Holopaw fine
            sand, frequently flooded (47), Winder     fine sand, frequently
            flooded (48), Immokalee-Urban land complex (53), Eau Gallie
            fine sand (58), Floridana fine sand (62), Placid fine sand
            (63), Ellzey fine sand (64), Riviera fine sand (65), Terra
            Ceia muck, frequently flooded (66), and Winder fine sand (68).

            Any developed use (including roadways, buildings and other fa-
            cilities   or   structures) on the drainageway      fringe and
            flatwoods soils will require control of, or consideration for,
            the   annual rise of the water table.      Any effort to drain
            these lands should be undertaken with a full understanding of
            the long range impact of total area development drainage upon
            local ground water table conditions, the potential decline
            of   surficial aquifer    water supplies,    and the resulting
            potential of increased salt water intrusion from the Flori-
            dan aquifer and sea water into the surficial aquifer.

            Under   significant rainfall     events, flatwoods areas also
            are affected by extensive, shallow flooding. Historical de-
            velopment practices    have simply resorted to ditching and
            draining.    Some draining   combined with     adequate deten-
            tion/retention   storage systems, controlled drainage systems,
            and a variety of development      control measures can provide
            for development in flatwoods areas of the Moultrie Creek
            watershed and    still protect     the area's ground water re-
            sources and significant natural areas.

            Based upon soil survey information, significant parts of the
            Moultrie Creek watershed are free of potential flooding or can
            be developed with minimum negative impact upon ground water
            table conditions.    Figure 4-4. Well To Excessively Drained
            Soils displays those soil series within the watershed with
            well to excessively drained soils and local water table con-


                                         4 - 9







                                               Figure 4-3. Annually Flooded/Drainageway
                                                           Soils And Naturally Saturated Soils


                                                                                               9         1E

                                   SR 16    SD                                                      0


                                                                          -Sr









                                                                    g-b"-A C;



                                                                            Ogg


                                                                            HS




















                 SCALE: f 10,000




                                                            LEGEND:

                                                     PROarr        UPLAND ANNUALLY FLOOD EDID RAINAGEffAY SOILS
                                                     LOCATION      NATURALLY SATURATED SOILS

                                                                          *(ANNUAL WATER TABLE RISES TO WITHIN
             D.E.R. CONTRACT NO. CM2171                                     I FOOT OF LAND SURFACE)
                     ST. JOHNS COUNTY ENGINEERING DEPARTMENT - GEOGRAPHIC INFORMATION SYSTEM









                                            Figure 4-4.        Well To Ercessively Drained Soils





                                   SR Is




                                                                        (7ST A.



















                                                              tip


                                                                               STIT*J



                                      13




























                                                                           R 2





                SCALE@ 1  10,000




                                                           LECEND:

                                                                   SOILS WITH WATER TABLES 1.5 TO 6 FEET
                                                    I.OrArl
                                                                   BELOW LAND SURFACE


                                                                   SOILS WITH WATER TABLES MORE THAN
            D.E.R. CONTRACT NO. CM2f7                              6 FEET BELOW LAND SURFACE

                    ST. JOHNS COUNTY   ENCINEERING   DEPARTMENT     GEOGRAPHIC INFORMATION    SYSTEM











           ditions where ground water does not reach the land surface.
           The group of soils identified as having ground water tables
           more than six feet below ground surface include: Astatula
           fine sand, 0 to 8 percent slopes (2), Paola fine sand, 0 to 8
           percent slopes (23), Fripp-Satellite complex (31), Palm Beach
           sand, 0 to 5 percent slopes (32), and, Astatula Urban land
           complex (54). These soils occur along the plateau edge and the
           tidal portions of Moultrie Creek      and the Matanzas River.
           The plateau in this locality is 20 or more feet above sea
           level. The water table is well below  ground level because the
           ground water is flowing by gravity to sea level and emerges as
           seepage where the land merges with the tidal flats.

           Further inland along Moultrie Creek and upstream of tidal in-
           fluence, the incised stream course occurs at elevations rang-
           ing from sea    level at tidewater to less than 15 feet at
           State Road 207. The average plateau land surface throughout
           this area is at an elevation of nearly 30 feet. The gravity
           flow of ground water in this part of the watershed would be
           towards the lower land elevation of the stream bed with a re-
           sultant effect of a significantly lowered ground water ta-
           ble in areas adjacent to the stream course.

           Inland and upstream along Moultrie Creek from the localities
           with water tables at least six feet below the land surface
           are   soils with intermediate depth water tables. Figure 4-4
           displays as a second group the soils with water tables at
           least 1.5 feet below land surface. In St. Johns County, these
           soils include: Adamsville fine sand (1), Tavares fine sand, 0
           to 5 percent slopes (6), Zolofo fine sand (8), Cassia fine
           sand (14), Pomello fine sand, 0 to 5 percent slopes (15), Ors-
           ino fine sand, 0 to 5 percent slopes (16), St. Augustine fine
           sand (27), Satellite fine sand (29), Jonathan fine sand (33),
           Sparr fine sand, 0 to 5 percent slopes (44), St. Augustine
           fine sand, clayey substratum      (45), Narcoossee fine sand,
           shelly substratum (50), St. Augustine-Urban land complex (51),
           and Adamsville Variant fine sand (57).      Some of these soils
           may   not occur within the Moultrie Creek watershed, but are
           important for County-wide application.

           The soils having intermediate height water tables occur be-
           tween the more poorly drained flatwoods soils and the exces-
           sively drained soils. The water table heights probably are
           controlled by the natural slope of the water table as the
           ground water flows by gravity from the highly saturated in-
           terior soils of the plateau towards lower land surface eleva-
           tions along Moultrie Creek and finally to tidewater and sea
           level.







                                        4 - 12













            RAINFALL CONTRIBUTIONS TO GROUND WATER



            Infiltration and Percolation

            As   rainfall occurs, part of the rainwater infiltrates          or
            seeps into the soil. once in the soil, it moves by gravity
            or percolates downward to the water table. The rate at which
            the water is able to move through the soil matrix is referred
            to as the soil permeability. The terms soil permeability and
            soil hydraulic conductivity are essentially the same.

            The rate at which rainfall infiltrates into the soil varies
            with soil structure, soil compactness,         and the degree of
            wetness of the surface soil particles. Water can move more
            rapidly   into course sands than into fine sands because of
            the   larger void areas between the particles in the course
            sands.    Water infiltrates very       slowly into soils high in
            very fine silt and clay particles.         Recently disturbed or
            broken soil surfaces      permit more rapid water infiltration
            than well compacted or undisturbed soils.         When soil sur-
            faces are completely dry, water      tends to bead on the soil
            particles until the weak electromagnetic         bond between the
            soil and air molecules is broken.         The time required for
            this   process to take place varies with different types of
            soils, temperature conditions, and with the degree of dryness
            of the soil.

            Percolation    within the soil matrix is also dependent upon
            soil wetness. Water moves more rapidly through wet soils. If
            soil is allowed to dry out to significant depths, percola-
            tion will be slowed until the soil matrix becomes thoroughly
            wet.


            Urban area soils tend to be compacted, and when overdrained,
            the soil surface and upper several inches of soil can become
            extremely dry, with temporarily reduced permeability.            In
            Florida's sandy soils, a vegetation cover retards the soil
            drying process by shading the soil surface and by lifting wa-
            ter from lower elevations through the plants' root system.
            The vegetation mat of detrital material and the decomposed or-
            ganic matter in the upper soil horizon provide the means for
            sandy soils to hold water. The water, in turn, slows down the
            oxidation rate of the organic fraction of the surface soil ma-
            trix.

            Unshaded    sands   can become dry to depths of six or more
            inches during the spring and summer months within a week or so
            following a rainfall.      When these conditions are allowed to
            occur, rainfall that does not pond for a sufficient time for
            the   infiltration process to occur must runoff. Under these


                                          4 - 13











            conditions, the typically short-duration, relatively intense,
            annually   occurring summer showers contribution        to ground
            water recharge requirements can become very limited.


            Water Table Conditions

                 General Concepts

            Water that percolates downward continues to move to a point
            where gravity forces and forces associated with 6apillary wa-
            ter   movement, or suction forces, become balanced. If enough
            water enters the soil, it eventually percolates to the water
            table, the natural level within the soil mantle or matrix be-
            low which all voids between soil particles contain water. In
            most parts of St. Johns County, the water table is also the
            effective top of the surficial aquifer.

            The water table beneath the Moultrie Creek watershed is not a
            flat   surface.    Under every knoll or ridge, the water table
            is higher than under swales or depressions.          Rainfall on
            knolls   and ridges percolates to the soil matrix saturation
            zone directly beneath the knoll or ridge land surface. These
            localities, being at higher elevations, are the primary ground
            water recharge areas within the County. From the saturated
            soil zones under knolls and ridges, the ground water moves
            by gravity along a hydraulic gradient to the saturated soil
            zones of land surfaces with lower land elevations. The lower
            land surfaces may be natural swales, or larger depressions.

            When depressions have standing water, the elevations of that
            standing   water generally reflect the height of the local wa-
            ter table.    The wet edges of the depressions identify the
            seepage points from which ground water is slowly moving down-
            ward along a hydraulic gradient from beneath adjacent knolls
            and ridges and is emerging as surface water in the depression.

            The movement of ground water and seepage is generally imper-
            ceptible, except during periods immediately following heavy
            rainfalls on the adjacent uplands. Whenever wet perimeters
            or   seepage zones are observable along edges of depressions,
            the water table under adjacent uplands is higher than the ob-
            served seepage zone.

            The hydraulic gradient or slope created by the water under up-
            land areas flowing to depressions is steepest immediately fol-
            lowing periods of high infiltration rainfalls. Gradually, the
            mounded ground water decreases in height as it is lost to
            seepage and other factors.       As the height of the water be-
            comes reduced and the slope to the seepage point is lowered,
            the movement or flow of the ground water also diminishes.


                                          4 - 14












            As a result of the above process, the ground water table is in
            a continual state of fluctuation. Every major rainfall allows
            some water to infiltrate. Repeated moderate rainfalls of in-
            tensities low enough to allow infiltration to take place can
            provide    significant recharge to the water table.          Because
            soils accept water slowly, intense rainfalls result in high
            runoff from the land and the water is largely lost relative
            to ground water recharge needs.

            At   the opposite extreme, prolonged drought periods typi-
            cally result in a        progressive decline in the height of
            the water table.      Based upon St. Johns County Soil Survey
            information, natural water table fluctuations on the order of
            three    or more feet are normal each year beneath flatwoods
            soils.    The ground water is always moving along some hydrau-
            lic gradient to points of lower land elevation.


                 Moultrie Creek Effects

            The stream bed of Moultrie Creek is the most significant low
            land surface point within the interior part of the basin.
            Unless repeated recharge occurs at land elevations adjacent to
            and extending from Moultrie Creek, prolonged drought condi-
            tions can result in significantly lowered ground water ta-
            bles    extending outward     on either side of the incised por-
            tions of the      Moultrie Creek     stream course.     The lowered
            ground water table and excessively drained soil conditions
            in the watershed noted        in the Soil Survey       are directly
            related to the affected soils' close proximity to the lowest
            land elevations along Moultrie Creek and the Matanzas River.

            Uncontrolled    drainage directed to Moultrie Creek removes
            stormwater before it can infiltrate and provide recharge to
            the ground water. Because this water has been diverted, the
            source of water that permits extended base flow in Moultrie
            Creek is being eliminated.      As this base flow and the general
            ground water table is allowed to decline in the vicinity of
            Moultrie Creek, salt water can be expected to move slowly into
            those areas previously supplied by the gradual movement of
            ground water from areas of higher elevation.

            During normal seasonal low elevation periods of the water ta-
            ble, surface water in the fresh water natural resource areas
            (depressions and natural drainageways) become lowered or dis-
            appear. As long as the bottom materials of these areas remain
            moistf the natural regeneration of vegetation in these areas
            can    continue. If, however, extended drought conditions oc-
            cur, new growth and young plants with shallow roots can be
            lost.     An uncontrolled drainage program that permanently


                                           4 - 15











            lowers the water table beneath these areas will also pre-
            vent any regeneration of new        growth. The     natural area
            will then begin a transitional process where vegetation that
            can sustain itself with less water will begin to replace the
            original species.


                 Perched Water Tables

            The extent of perched water table conditions within the water-
            shed is unknown. A perched water table usually occurs in a
            depressional    area where local conditions prevent downward
            percolation of     ground water to the area-wide water table.
            When the general area water table permanently falls below the
            bottom elevation of a depressional area and wet soils in the
            depression persist,     the condition     is representative of a
            perched, and highly localized, water table. These areas typ-
            ically reflect former natural water table conditions.

            Upland   depressional areas tend to accumulate detrital mate-
            rials and sediment fines that are transported with runoff from
            adjacent lands of higher elevations.       Chemical and bacterial
            action within the depressional environments act to convert
            organic materials into fine organic and inorganic compounds
            and combine the compounds into stable, often denser materials.

            As a result of the above processes, dense and relatively im-
            pervious clays tend to underlay depressions with continually
            saturated soils.     Where this phenomenon occurs, a periodic
            water   table decline below the bottom of the depression may
            have   a delayed impact on the vegetation growth cycle in the
            depression.    To the degree that thick water holding materials
            can be maintained in such depressions, existing vegetation
            characteristics can be maintained for long periods of time.
            Maintenance or restoration of perched water table areas re-
            quires the application of sufficient         water to reestablish
            near natural hydroperiod conditions.


            Water Table Management

                 Initial Considerations

            For development purposes, the height of the water table in
            local areas must be known, and the height to which the water
            table   is to be maintained must be determined.           The Soil
            Survey   information provides general information on the natu-
            ral height of water table conditions for specific series of
            soils.    Correlation of this information with one foot con-
            tour information will provide guidance for determining natu-
            ral water table heights and seasonal variations , of these


                                          4 - 16











            heights.    Once governmental policy determines the area fea-
            tures and ground water conditions essential for residents'
            health and welfare, engineering analysis can establish the
            criteria and methods for accomplishing the policy decisions.


                 Development Alternatives

            Unless specifically designed for high water table conditions,
            all load bearing foundations of structures and subbases of
            roadways must remain above normal water table heights to re-
            tain structural integrity.       As noted previously, normal cap-
            illary rise of water in sands with some fines will normally
            be less than six inches. Therefore, as a minimum engineering
            requirement, the bases of roadways and foundations should be
            at least six inches      above expected annual heights of local
            water tables.     Under those conditions where road bases are
            close to the annual high water table, road base and foundation
            designs would have      to accommodate the reduced load bearing
            capabilities of periodically saturated soil conditions.

            Four courses of action are open for development on high water
            table soils. Traditional practices consist of permanent low-
            ering the water table by positive and uncontrolled drainage.
            This practice results in the total drying of surface soils
            during seasonal and extended drought periods.

            The   second course of action consists of the           recontouring
            and raising     of the land beneath all load bearing facili-
            ties.     The bases of both roadways and structure foundations
            can be raised. In both cases, the practice of constructing
            roads and structure foundations        on compacted non-plastic
            fill materials is now common in Florida.           Monolithic home
            slabs constructed on      three and four feet of compacted fill
            have become routine      construction practice in some Florida
            communities.    Raising roads above 100-year flood elevations
            ensures user safety during flooding emergencies and provides
            for emergency vehicle access to and from flood prone areas.

            A third option consists of the specific design of road bases
            and foundations for high water table conditions. Under heavy
            loads, saturated fine sands can move very rapidly from a
            nonplastic material to a liquid state with greatly reduced
            load    bearing capability.     Hydrated lime mixtures with added
            fines    have been successfully used to stabilize saturated
            fine    sand soils     in Florida.     Soil cement mixtures are
            also usable when      the water content of the          soil can be
            carefully    controlled during      the curing process. As with
            hydrated lime stabilization, soil cement requires the addi-
            tion of some fines to achieve         sufficient      load bearing
            strength.     Spread footings of soil cement or hydrated lime


                                           4 - 17












           also can be used as bases for structure foundations in wet
           areas.


           A fourth option consists of mixtures of the first three ap-
           proaches.     In upper flatwood soils areas, some lowering of
           the    ground water table may be possible without signifi-
           cantly    impacting overall   water table conditions. In lower
           flatwoods and drainageway soils areas, however, positive
           drainage could be expected       to negatively    impact the water
           table, and compacted fill practices would           be necessary.
           For example, the placement    of two feet of compacted fill to
           raise roadways and two feet   of compacted fill for house pads
           (an elevated base upon which concrete house slabs are plac-
           ed) would eliminate most property flooding potentials, pro-
           vide for safe road access to properties,         and provide for
           temporary water storage in remaining open areas during the in-
           frequent heavy rainfalls characteristic to Florida. Where de-
           velopment is essential and fill practices cannot provide sat-
           isfactory results,      design practices for high water table
           conditions may become necessary.


                 Public and Private Property Owner Concerns

           Because of generally lower initial costs, positive and un-
           controlled drainage to permanently lower water tables is a
           preferred action by developers, while designing for building
           and    roadway structural integrity, safe use of roadways and
           access to properties       during infrequently heavy rainfalls,
           and storage of stormwater in areas of high water table or
           saturated soil conditions have higher associated development
           costs.    The County's    concern is the integrity of the con-
           struction practices for the long-term health and welfare of
           citizens. It remains for private entrepreneurs to determine
           whether the costs of proposed developments achieve required
           short term profitability.        The County    is also concerned
           about the costs of infrastructural repair and maintenance.
           For example, a roadway constructed as a private venture can
           only be accepted as a public facility when the County can be
           assured    that sound engineering practices are followed by
           the constructor of that road.



                 Management Criteria

           The    natural annual fluctuation of localized         area water
           table heights provides the best general guidance available
           for    establishing    criteria    for the design of     stormwater
           management systems in high water table areas. The annual low
           elevation    of the water table in high water table locali-
           ties     reflects    the maximum    safe depths for constructing


                                          4 - 18











           drainageways and channels. The annual high elevation of the
           water table in high water table localities reflects the low-
           est elevation at which water      storage containment facilities
           can be assured of functioning at complete capacity throughout
           the year. Design of stormwater        management facilities to
           these criteria will assure the     maximum possible protection
           to the surficial aquifer and significant natural resource
           areas.


           simplifying the above and providing for a standardized proce-
           dure for the entire County is necessary. Any parcel pro-
           posed for development in the County should have the maximum
           and   minimum land elevation of that parcel and immediately
           adjacent parcels established. The points of maximum and min-
           imum should be identified and clearly marked on the develop-
           ment drainage plan. Large parcels and parcels with signifi-
           cant land contour changes would need determinations by seg-
           ments   with common characteristics. Using this information,
           the localities on the parcel representing the mean land ele-
           vation should be presented. This process will establish the
           natural sheet flow, infiltration, water table, and ground wa-
           ter hydraulic gradient tendencies of a parcel.

           The   annual high water table will be assumed to extend to
           within one foot of the land surface at the parcel's mean land
           elevation unless Soil Survey data or documentation by a regis-
           tered engineer are provided to establish a different natural
           annual high water table elevation for critical segments of
           parcels.    An approved annual high water table condition for
           the parcel or delineated segments will be used as the base
           elevation for the design of stormwater containment facilities.






















                                         4   19




















                                           5


                                  STORMWATER STORAGE



           WATER CONTAINMENT



           General Considerations

           Depressional areas represent natural rain water storage loca-
           tions within a watershed.       As these areas become filled,
           the water begins to move via a drainageway to some nearby de-
           pression or to a stream course. A primary focus of drainage
           engineering is the estimation of the amount of water likely
           to runoff from a watershed under some given rainfall condi-
           tion and the design of some water control works to safely
           move the runoff from one place to another.

           Stormwater management oriented towards the most useful reten-
           tion of water for ground water recharge and significant natu-
           ral   area protection    has   a different engineering focus.
           These   purposes require the design of storage facilities to
           retain    runoff from normal   rainfalls expected on an annual
           basis. once this requirement is met, the overflow water from
           the infrequent and heavier     rainfalls must be detained and
           safely removed at controlled rates to avoid significant ero-
           sion and sedimentation damages to receiving water areas.

           In   hydrological analyses of potential runoff from a water-
           shed, estimates are made of the amount of rainfall received by
           a watershed that is retained or lost before runoff begins.
           This initial retained     or lost amount is referred to as the
           initial    abstraction, a best initial estimate of water losses
           due to water storage and other factors to be subtracted from
           the calculated runoff.      For normal or non-compacted soils,
           the U. S. Soil Conservation uses an estimate of 0.2 inches as
           an initial abstraction estimate.       The drainage engineer's
           efforts then focus upon the additional rainfall amount that
           produces runoff water and how to design water control struc-
           tures to accommodate such flows.

           Part   of the water lost to runoff through storage on the
           land infiltrates into the soil matrix and is gained by the
           ground water storage system. Revisions in drainage system de-


                                      5 - 1










            sign criteria are required to give greater emphasis to the
            retention   of normal annual rainfalls while still providing
            for removal of unusual or infrequent rainfall events.        Engi-
            neering analysis to determine       the greatest beneficial uses
            of stormwater     prior to runoff has now become the area of
            concern in the design of stormwater management systems.


            Stormwater Containment Purposes

            Detention/retention storage or containment for ground water
            supply   recharge through infiltration     must be emphasized in
            the vicinity of the land surface areas beneath which surficial
            aquifer water is withdrawn.     As water is withdrawn from the
            surficial aquifer     at depths of 90 or 100 feet below land
            surface, water moves slowly towards the well head from all
            directions.    The pumpage effects cause a lower water pres-
            sure to develop at the well head.         As more water is with-
            drawn, a decreased pressure zone forms from the well head as
            the apex, the area of decreased pressure, extends outward and
            upward towards the land surface with an expanding circumfer-
            ence creating the general form of a cone. This is called the
            cone of depression for that well, and ground water moves from
            all   points with greater     amounts of water at higher pres-
            sures   towards    the apex of the cone. As the cone of de-
            pression extends to the land surface, the water table within
            that cone of depression declines, and the overlying surface
            soils begin to dry out.

            The size of the cone of depression depends upon the well size
            and withdrawal rates. Major agricultural and municipal system
            wells may be expected to measurably influence water tables
            in   sandy soils for distances of 1,000 or more feet from the
            well.   Without adequate    recharge, the water table declines
            can become progressively      extended over larger areas. In-
            creasing storage of stormwater       and the diversion of storm-
            water towards cones of depressions are essential if the lo-
            cally severe water table declines in the vicinities of large
            well fields are to be avoided.

            Protection   of significant natural areas in uplands can be
            accomplished through control of water table conditions. Main-
            tenance of high water tables requires retention and detention
            storage and control of runoff. Increased use of stormwater
            storage facilities designed to retain most of the expected
            annual rainfall can provide long-term protection of natural
            water table conditions. continuation of positive drainage pro-
            grams in the interior flatwood soil areas of the Moultrie
            Creek watershed will result in the gradual drying of nearby
            depressional areas.




                                       5 - 2










            In   areas with excessively drained soils and where septic
            tanks are used, detention/retention storage and subsequent
            infiltration    can   be expected to augment the diffusion of
            septic   tank effluents that can percolate towards the water
            table.    Most of these areas occur along the tidal portions
            of Moultrie Creek and the Matanzas River.          Numerous indi-
            viduals within     these areas also use private wells, some
            which may serve as sources of potable water.       Two ground wa-
            ter problems are apparent in this part of the watershed. As
            development    increases and more people utilize individual
            wells,    water withdrawals can be expected to exceed natural
            recharge capabilities in local areas. As this occurs, as it
            has in communities all around coastal Florida, saline ocean
            water   will    move into the composite      cones of depression
            formed by the close groupings of the withdrawal wells.

            The second problem is public health related. Water wells in
            the surficial     aquifer are typically drilled to depths of
            less than 100 feet.     As the cone of depression formed by a
            single well or a close grouping of wells approaches the land
            surface, septic     tank effluents    will be drawn downward.
            Septic   tank drain fields function        by distributing efflu-
            ents into the upper 18 inches of the          soil matrix where
            aerobic bacteria can render        pathogens  harmless. The pro-
            cess requires that the effluents remain       in the upper soil
            zones for some extended period of time for the soil bacteria
            to render them harmless.

            Numerous studies have been conducted around the country il-
            lustrating    that some pathogens can remain viable for many
            days   and weeks under anaerobic conditions characteristic of
            saturated soil matrix materials in the surficial aquifer.
            Excessive   water withdrawals     can lead to the introduction
            of   these pathogenic materials into the well water withdrawn
            from the aquifer.

            Finally,   numerous studies nationwide have determined that
            stormwater detention/retention facilities can help reduce pol-
            lutant loads characteristically      found in urban runoff. The
            Florida   Department    of Environmental      Regulation has es-
            tablished a state policy for the retention of the first one
            half inch of runoff from storms.



            Stormwater Containment Criteria

            In an effort to reduce the water pollution impacts of storm-
            water runoff upon lower property owners, public stormwater
            conveyance facilities, and as a water pollution reduction mea-
            sure, St. Johns County has adopted the following stormwater
            containment measures.      Any parcel proposed for commercial or


                                        5   3










            industrial use and any parcel proposed for use as a resi-
            dential   subdivision is required      to provide retention fa-
            cilities   for stormwater.    A single containment facility or
            the composite capacity of several facilities will be sized to
            accept a volume of water     equivalent to the greater volume
            of either one half inch of runoff       water distributed across
            the entire parcel or one inch of runoff water distributed
            across the total impervious area within the parcel.

            Under primarily rural development conditions, the above con-
            tainment measures would provide some protection for water el-
            evations    in the surficial aquifer     where extensive posi-
            tive surface water drainage had not been practiced. Under
            the population increases occurring within the County and pro-
            jected populations in the immediate future, the above crite-
            ria can be expected to result in a continued decline in water
            tables and long term water supply potentials of the surficial
            aquifer.

            As   an immediate measure, retention facilities designed to
            store the first one inch of every rainfall from the drainage
            area   of that    facility would more adequately serve water
            pollution    control, water supply recharge, and significant
            natural    resource area    requirements.    on larger land par-
            cels, a number of small retention facilities would provide a
            distributed and more     effective system for ground water re-
            charge than a single large retention       facility. The poten-
            tial benefits of storing the first one inch of rainfall appear
            in Table 2-2.

            Storing the first one inch of every rainfall on developed
            properties should be considered as an interim and minimum wa-
            ter resource protection measure.        The preliminary informa-
            tion    presented in this report suggests that more stringent
            measures actually may be necessary to assure the long-term
            viability of the County's water resources.         More detailed
            studies of the County's total water resource needs will be
            needed to make that determination.


            Preliminary Design Concepts

            In    recent years, stormwater detention and retention facili-
            ties have been incorporated into the stormwater control design
            process.    As definitions for use in this study, a detention
            facility is designed for the collection and temporary storage
            of stormwater to provide for treatment with subsequent gradual
            release of the stormwater. A retention facility is designed
            to prevent the discharge of a given volume of stormwater run-
            off by complete on-site storage. These definitions are now



                                        5 - 4









            being used with increased frequency by urban hydrology spe-
            cialists in Florida.

            A   detention facility will have an outlet designed to re-
            lease stormwater at controlled rates from some defined rain-
            fall for the design drainage area until full draw down occurs
            near the end of      the design period. A retention facility
            has no controlled outlet but extends the draw down period by
            percolating stormwater runoff into the soil. In both cases,
            the effective stormwater containment capacity of each facility
            is based upon an available         containment     area above the
            height of the seasonal high water table conditions for the es-
            ign drainage area.

            The focus of most research on urban stormwater detention/re-
            tention facilities has been oriented towards their effective-
            ness in reducing the impacts of pollutants in stormwater run-
            off. Reducing the impacts of pollutants in stormwater run-
            off through detention/retention is an important consideration
            for    justifying the use of these types of facilities. This
            purpose applies to the entire Moultrie Creek watershed.

            Stormwater detention and retention facilities can be built in
            a wide variety of forms. They can be built to replicate
            natural depressions characteristic of an area.          In devel-
            opments    near significant    upland natural areas, it may be
            possible    to divert some stormwater into natural depres-
            sions.     Depressional areas can      be constructed adjacent to
            natural drainageways or depressions to augment the vegeta-
            tive environment of the natural areas. Overflow channels in
            developments can be built to simulate the characteristics of
            natural drainageways.      They can be part of golf courses,
            parks, and constructed semi-natural woodlands. They can be
            slightly depressed areas of lawns, or gardens on individual
            properties.    They can be designed as extensions to existing
            ponds    or lakes with controlled release structures. Stormwa-
            ter storage areas can be well landscaped earthen areas of al-
            most any description      or they can be concrete boxes simply
            built    to hold rainwater. Stormwater can be retained or de-
            tained on the roofs of buildings, in containers constructed
            alongside buildings, or in galleried or entrenched areas un-
            der parking lots and driveways. All of these practices are
            technically possible.

            The design of stormwater detention/retention facilities re-
            quires engineering evaluations of probable impacts upon col-
            lector drainage systems and receiving streams.          The Engi-
            neering Department must have a reasonably clear understanding
            of the water carrying capacities of the larger systems into
            which storage facilities gradually release stormwater. Col-
            lector systems in low water table areas will be designed to


                                        5 - 5










            provide for ground water recharge while accepting controlled
            release stormwater from a system       of smaller storage facili-
            ties. In high water table areas, collector systems will drain
            to larger storage facilities before       releasing stormwater to
            receiving streams, natural drainageways, or natural depres-
            sion areas.



            Maintenance Considerations

            Surface water containment facilities require maintenance in
            order to retain the effectiveness of their intended func-
            tions.     Stormwater detention/retention facilities need to be
            cleaned    periodically.    Numerous    examples are now apparent
            of   facilities constructed below        seepage zones permitting
            extensive growths of cattails and related vegetation. Cat-
            tails grow prodigiously in saturated soils, and their detri-
            tal materials quickly accumulate. Where          allowed to become
            established, expanses of cattails quickly reduce the effec-
            tive storage capacities of open containment facilities.

            Vegetation growth in constructed detention/retention facili-
            ties is to be expected, and the facilities must be sized on
            the   basis of the expected reduction in capacity due to de-
            trital and sediment materials buildup over a projected time-
            frame between clean out periods. Additionally, the entities
            responsible for maintenance of these facilities must be de-
            termined prior to establishment.       Access and adequate right-
            of-way for maintenance and inspection        equipment also must
            be part of facility design.       Finally, measures for assuring
            that maintenance actually will be performed are needed.

            Various    types of exfiltration procedures have been used
            for distributing stormwater. Exfiltration techniques include
            buried perforated storm drains surrounded by highly permeable
            material that would allow rapid water percolation. Experience
            shows    that the silts     and clays associated with the fine
            sands    typically found      in St. Johns County       are easily
            eroded and are carried with high velocity flows of stormwater.
            These materials quickly plug storm sewer drain perforation lo-
            cations and the surrounding exfiltration material. Because
            storm sewers are buried, inspection is usually not possi-
            ble and maintenance of perforation locations in the sewer
            lines is not practical. When these facilities cease to func-
            tion effectively, lower property owners can be subjected to
            unwarranted discharges of stormwater from          higher property
            owners.


            Exfiltration facilities include French drains and all sim-
            ilar techniques.        Use of these methods require periodic
            maintenance, and their design must accommodate these rou-


                                        5 - 6










            tine   needs.     Wide variety    in the design of containment
            systems is possible,       and their use is practical when de-
            signed to permit easy and       periodic maintenance.        Buried
            storm   sewers intended for exfiltration purposes cannot be
            inspected easily, cannot be effectively maintained as an ex-
            filtration system, and will not be permitted.


            Example Design Concepts

            ï¿½ one acre parcel of land is an area with 43,560 square feet.
            ï¿½ one fourth acre parcel contains 10,890 square feet. one
            inch of water distributed across a one fourth acre parcel is
            equivalent to 907.5 cubic feet of water. This volume of wa-
            ter can be contained in a shallow depression one foot deep,
            10 feet wide, and 100 feet long. one side of a typical one
            fourth acre lot is often about 100 feet long, and a typical
            drainage easement on a parcel is 20 feet wide. A one inch
            storage requirement can be provided for by property owners
            with little modification to         existing subdivision regula-
            tions.    The one inch    containment requirement can be met
            through a single shallow swale or it can           be met through
            very    shallow depression contoured      areas within lawn ex-
            panses.    It also can be met by constructed containers.of any
            configuration.

            In subdivisions, road rights-of-way, sidewalks, and normal
            stormwater    systems typically use between one fourth and one
            third    of the total pre-subdivided parcel. On the basis of
            a   one acre parcel subdivided into three building lots, the
            developer would have to provide for the one inch containment
            equivalent    to one fourth acre as part of the total infra-
            structural system.       Numerous techniques can be devised at
            moderate costs for accomplishing this containment criteria.
            For larger subdivisions, numerous widely dispersed contain-
            ment areas designed as part of the landscape           provide the
            greatest benefits for ground water recharge. Much of the cost
            for constructed open space areas (recreation areas, parks,
            woodlands, lawn expanses, flower gardens, and entranceways)
            can be designed so that the composite of all areas are equiva-
            lent to the one inch stormwater volume criteria for the total
            parcel.


            Natural Depressional Areas

                  Potential Uses for Stormwater Containment

            Natural depressional areas may be useful for stormwater stor-
            age under specific and controlled conditions. When these ar-
            eas    contain wetland vegetation and are classified as sig-


                                        5 - 7










            nificant natural resource areas, acceptable stormwater loading
            rates will have to be determined.         Existing wetland vege-
            tation exists in specific areas due to present climatic con-
            ditions and the resulting natural hydroperiod regime. The
            hydroperiod regime consists of a natural rise and fall of
            water on a periodic basis within the locality with desirable
            wetland vegetation.

            The    natural hydroperiod      of specific    depressional areas
            with desirable wetland vegetation is difficult to determine
            with    any degree    of precision.    Depressional areas in the
            Moultrie Creek watershed typically have poorly defined bound-
            ary conditions; the land surface slopes towards adjacent up-
            lands very gradually from low points within depressional ar-
            eas.


            Technical    determination of boundary areas can be made when
            an    acceptable    high water elevation for desired         wetland
            vegetation protection      for a specific area is determined.
            The acceptable high water elevation determination is a judg-
            mental decision.      A typical practice       is to look for evi-
            dence of annual high       water marks and      vestiges of higher
            water marks on woody       vegetation. Once the field evidence
            establishes preferred high and low water heights, a survey
            can establish the controlling water elevation and range of
            acceptable elevations for that depression.

            Survey    procedures then can establish the land elevation
            of acceptable high water conditions and the cross sectional
            character of the depressional area containing the desired
            wetland vegetation. Available aerial photogrammetry and spa-
            tial analysis techniques (geographic information system pro-
            cedures)    then    can be used to delineate the area encom-
            passed within      the specified elevations of the high water
            condition area.

            The    next step requires the determination of the areal extent
            of the natural watershed draining to the depression of con-
            cern.    For smaller depressions a volumetric analysis can pro-
            vide an estimate of the volume of runoff water supplied to
            the depression from storms of specific return frequencies.
            This analysis will establish the height of water rise (water
            stage) to expect in the depression from some design rainfall
            and    the resultant approximate expansion of water surface
            area of the depression.

            Using available evapotranspirational data and infiltration
            rates for the soil conditions characteristic of the de-
            pression, an average surface water recession rate can be es-
            tablished for the design rainfall condition. The recession
            rate data establishes time durations expected for the sur-



                                         5 - 8










           face water to remain at specific water stages and the total
           length of time required for       the water surface to fall to
           some specified elevation.

           Once    these data are available, a judgment decision must be
           made to estimate the maximum height and duration of flood-
           ing    that would be     acceptable without causing significant
           injury to the desirable vegetation. The comparison of this
           judgmental decision and the natural runoff water estimates
           will determine the     volume of additional water under given
           storm conditions that could be supplied to the depressional
           area.



                 Legal Considerations

           Some of the major depressional areas in the Moultrie Creek
           watershed (examples are Cowan     Swamp and Trestle Swamp), have
           been parceled and are now in multiple private ownership. A
           number    of residences      have  been constructed on platted
           parcels    within some natural    depressional areas. Care must
           be taken when considering the       discharge of stormwater into
           depressional areas to guard       against injuring other land-
           owners.     The legal implications of modifying the natural
           flow of water to large natural depressional areas in multiple
           ownership    are complex. The lower infiltration rates to be
           expected in depressional areas due to natural         soil matrix
           characteristics and naturally high water table          conditions
           contribute    to   prolonged periods of natural      flooding in
           these areas. The use of depressional areas held in multiple
           ownership cannot be recommended as receiving areas for in-
           creased    stormwater discharges until all property owners are
           in agreement with the proposed action (As an initial refer-
           ence on legal ramifications, see Maloney, 1980).



















                                       5   9




















                                             6


                                       WATER LOSSES



            EVAPOTRANSPIRATION

            Evapotranspiration (ET) is the collective term applied to the
            combined effect of direct evaporation of water from land and
            water surfaces to the atmosphere and the transpiration of
            water   from plants    through    their respiration processes.
            The concept of evapotranspiration       is well understood, but
            estimation of the amount of water returned to the atmosphere
            by this process can only be roughly approximated. Too many
            highly variable factors influence evaporation and transpi-
            ration rates, and the unique characteristics of every wa-
            tershed prevent easy analysis of actual evapotranspiration
            conditions at any given locality.

            The   evapotranspiration process requires energy, and the rate
            at which the net process can function varies daily and season-
            ally at any location according to net solar radiation re-
            ceived by soil, water, and plants. Direct evaporation from
            soil   surfaces    also varies    according the wetness of the
            soil   surface.    Saturated soils    will permit more evapora-
            tion than dry soils,       and soils totally dry to depths ex-
            ceeding their capillary rise ability will permit essentially
            no evaporation. Unshaded shallow water areas permit the max-
            imum evaporation. Transpiration from plants varies according
            to plant species throughout the annual growth cycle of each
            species.     Plants adapted to dry or xeric conditions can
            conserve    water and transpire less than plants adapted to wet
            or hydric envir9nments.

            within the Moultrie Creek watershed, less evapotranspiration
            can be expected to occur in those localities with excessively
            drained soils, low water tables, and coverings of sand pine,
            scrub    oaks, and similar vegetation adapted to dry condi-
            tions.     Increased evapotranspiration can be expected in the
            flatwoods and drainageway soil areas within the watershed. The
            maximum    evapotranspiration can be expected to occur within
            shallow water bodies and upland depressions during the periods
            when inundation extends to the edges of these areas.





                                        6 - 1









            Evapotranspiration is maximized during the summer daytime pe-
            riods immediately     following    rainfalls.    The sun heated
            soils   permit rapid evaporation to occur. The higher summer
            air   temperatures also    permit the atmosphere to absorb and
            hold more moisture in vapor form before releasing it again
            as rainfall.


            The National Weather Service has conducted studies to de-
            velop criteria for estimating potential evapotranspiration for
            any locality within the United States. An Evaporation Atlas
            for the Contiguous United States has been prepared based upon
            the national network of pan evaporation stations. The Na-
            tional   Weather Service methods are used in this study to ex-
            press the approximate potential evaporation from a shallow wa-
            ter surface and the potential evapotranspiration to be ex-
            pected to occur from a vegetated surface with an unlimited
            supply of water.

            Previous research had established that net radiation received
            on the earth's surface is dominantly influenced by lati-
            tude   and altitude. Evaporation summary data for Gainesville
            (altitude 100 feet) and Lake City (altitude 200 feet) were
            used to establish an estimate for the Moultrie Creek water-
            shed (altitude 30 feet). The mean of the summary data for
            Gainesville and Lake City was used to approximate daily and
            monthly potential evapotranspiration conditions in the Moult-
            rie Creek watershed. These daily and monthly potential evap-
            otranspiration estimates appear in TABLE 6-1. MOULTRIE CREEK
            WATERSHED POTENTIAL EVAPOTRANSPIRATION. St. Augustine is lo-
            cated at a latitude 12 minutes to the north       of Gainesville
            and 22 minutes to the south of Lake City. Due to the minor
            pan evaporation data differences between the two stations,
            developing a weighted average would not have meaningfully im-
            proved the estimate for St. Augustine.

            The potential evapotranspiration estimates shown in Table
            6-1 would apply primarily to areas with shallow surface wa-
            ter conditions    and to vegetation       adapted to saturated
            soil   conditions.      Vegetation adapted to saturated and
            flooded soil conditions is now generally classified as wetland
            vegetation. Wetland vegetated areas remove significantly more
            water to the atmosphere through     evapotranspiration than up-
            land vegetated areas.

            Numerous theoretical methods have been devised over the years
            to provide useful potential evapotranspiration estimates for
            commercially   important    vegetation species.    These methods
            have   been developed    largely to estimate potential evapo-
            transpiration   from land areas and transpiration from plants
            to identify the optimum amount of water to be applied or that




                                       6 - 2










            would be needed for maximum production.        The Florida Insti-
            tute for Food and Agricultural Sciences (IFAS) has under-


                                         TABLE 6-1


                                MOULTRIE CREEK WATERSHED
                              POTENTIAL EVAPOTRANSPIRATION


            MONTH     AVERAGE DAILY     AVERAGE MONTHLY       PERCENT OF
                        (Inches)            (Inches)           TOTAL

            JANUARY       0.08                2.48              4.9
            FEBRUARY      0.10                2.80              5.5
            MARCH         0.14                4.34              8.5
            APRIL         0.17                5.10             10.0
            MAY           0.20                6.20             12.2
            JUNE          0.19                5.70             11.2
            JULY          0.18                5.58             11.0
            AUGUST        0.17                5.27             10.3
            SEPTEMBER     0.15                4.65              9.1
            OCTOBER       0.12                3.60              7.1
            NOVEMBER      0.09                2.70              5.3
            DECEMBER      0.08                2.48              4.9
            TOTAL                             50.90           100.0

            Source:     Derived from criteria in   Evaporation Atlas for the
            Contiguous 48 United States, NOAA Technical Report NwS 33, Na-
            tional Weather Service, National Oceanic and Atmospheric Ad-
            ministration, June 1982, based upon evaporation            data for
            Gainesville and Lake City, Florida.



            taken a series of studies for these purposes. These studies
            provide useful guidance for understanding         potential evapo-
            transpiration as the amount of water lost to the atmosphere by
            evaporation and transpired by plants in given localities when
            the water necessary for the plants is supplied. By comparing
            these    estimates with average monthly rainfall data or ob-
            served rainfall, agriculturalists can estimate the net irriga-
            tion requirements for maximizing crop production.

            Field studies oriented towards the measurement of poten-
            tial evapotranspiration also have been undertaken for many
            crops.    one study with useful       guidance for this analysis
            (Stewart, 1967) measured      the monthly evapotranspiration of
            St.   Augustine grass over a five year period at the Planta-
            tion Field Laboratory      near Fort Lauderdale.     The plantings
            were observed under normal local rainfall conditions but with
            saturated soils maintained at depths of 12 inches, 24 inches


                                        6 - 3










             and 36 inches. The average annual evapotranspiration                  (ET)
             amounts      resulting from this study were: 12 inch water ta-
             ble     43.68 inches ET; 24 inch water table =             42.77 inches
             ET;    36 inch water table = 42.05 inches              ET.     The mean
             evapotranspiration         was 42.84 inches with           ET     amounts
             varying monthly from 1.92 inches in December to 4.81 inches in
             July.    The findings of this study illustrate perennial up-
             land vegetation requirements in the Fort Lauderdale area and
             the    more general effects of lowered water tables on evapo-
             transpiration rates.

             While     the monthly ET rate for St. Augustine grass in St.
             Johns County may be slightly less than in Ft. Lauder-
             dale due to cooler winter temperatures in north Florida, the
             summer-to-winter difference in ET rates (about 1.9 inches in
             December and 4.8 inches in July) is significant                 to water
             management in the Moultrie Creek watershed. High water ta-
             bles occur in St. Johns County during the winter months. This
             condition     can be accounted for, in large part, by cooler
             temperatures      and the dormancy and slower growth of perennial
             vegetation during the winter months. These factors result in
             lower ET water losses to the atmosphere during the winter
             months.

             Potential     evapotranspiration       is a measure      of evaporation
             and transpiration from vegetated areas when all the necessary
             water is provided from maximum plant growth. Potential evapo-
             transpiration      estimates do not reflect the actual evapo-
             transpiration conditions to be expected in watersheds. The
             highest land areas in a watershed may have very dry surface
             soils,     deep    water     tables,    and xerophytic        vegetation.
             These locations would have very            low actual      evapotranspi-
             ration water losses. Natural upland depressions with ponds,
             swamps, and marshes; hydric soils; and hydrophytic vegetation
             have high evapotranspiration rates. High evapotranspiration
             rates also occur along stream flood plains and around shallow
             water bodies. As the antecedent period between rainfalls be-
             comes extended, evapotranspiration           water losses are highest
             immediately following a rainfall and gradually diminish until
             the next rainfall. For water management purposes, it is im-
             portant to have an understanding of the actual evapotranspi-
             ration characteristics of each watershed.

             Some efforts have been taken by the United States Geolog-
             ical Survey to establish general information on actual evapo-
             transpiration       for large drainage basin areas by comparing
             estimates of rainfall         with measured runoff.        The term ap-
             plied to these estimates is areal evapotranspiration.                 From
             the United States Geological           Survey information         (Hughes,
             1976)     and a conceptual       modeling effort (Morton, 1976),
             areal annual evapotranspiration at the north Florida border


                                            6 - 4











            was estimated at 37.4 inches and in central Florida at 42
            inches.    From these data, a general areal evapotranspiration
            estimate of 38 inches annually for the Moultrie Creek water-
            shed and St. Johns County may be assumed. Disaggregation of
            the above      annual    areal evapotranspiration       estimate to
            monthly values for use in hydrological analyses can use the
            "Percent of Total" column data presented in Table 6-1 applied
            to 38 inches to establish areal average monthly and areal av-
            erage daily evapotranspiration rates.



            RUNOFF



            Concept

            Runoff is rain water moving as surface water flow from one
            location to another following a rainfall after the immediate
            localized    demands of soils,      vegetation, and the process of
            evaporation are met.        Runoff can be increased by positive
            drainage programs,       compaction of soils by urban land uses
            and    the construction of impervious areas, removal of natu-
            ral water storage areas, disturbances of surface soils con-
            taining long-term accumulations of detrital materials, and re-
            moval of high water utilization vegetation.            Reduction in
            runoff    can be accomplished through          controlled drainage
            programs, maintenance of natural vegetated areas and man-
            agement practices to maintain          soil in permeable       condi-
            tions, creation of additional water containment areas, and
            by    constructing natural     wetlands.     Public    policy deter-
            mines    which of the above actions are acceptable practice.
            Engineering     design    of works to provide for         development
            needs within the public policy framework then can be applied.


            Drainageways

            Throughout     the upland areas of the Moultrie Creek water-
            shed, broad, flat areas serve as sheet flow drainageways when
            unusually large rainfalls fill          adjacent depressional ar-
            eas.     The Soil Survey information in Figure 4-2 generally
            identifies natural drainageway localities.            Over time, re-
            peated stormwater runoffs from adjacent higher lands have
            carried sediments and detrital materials into the drainageways
            giving the soils a different color           and slightly     changed
            constituent characteristics.         In many cases, only a few
            feet in land elevation mark the difference            between sheet
            flow drainageways and adjacent knolls. Under natural condi-
            tions, these areas provide some level of control of runoff
            flow from one depressional area to another.



                                         6 - 5










            Development   within the Moultrie Creek watershed is ongoing,
            and property    owners have ditched and drained the lands
            through   and across natural drainageways.    Parcels have been
            platted over the years in gridiron fashion with essentially
            no consideration -for natural drainageways or depressional
            area conditions.    scattered lots subsequently have been de-
            veloped within natural drainageways with associated property
            perimeter ditching and draining efforts practiced.      Property
            owners   in these areas,     understandably, generally desire
            improved drainage programs.

            The   gridiron platting and resulting      development process
            has altered the natural runoff to depressional areas that
            public policy    normally would now consider as significant
            natural   resource areas. The long-term maintenance of sig-
            nificant natural resource areas can only be assured when they
            are able to receive runoff waters periodically in the vol-
            umes necessary for their sustenance.


            Drainageway Management

            once significant natural resource areas are identified and
            their runoff water supply needs are estimated, engineering
            works   can provide for designed systems that either supple-
            ment or replace original natural drainageways. Within this
            stormwater   management system framework and other conditions
            essential for protecting     the health and welfare of citi-
            zens, property owners can undertake development actions.

            Following development of public policy and general runoff
            system design criteria, private property owners will be able
            to   construct systems in any configuration that meet govern-
            mental criteria and are not detrimental to the rights of ad-
            jacent   property owners.     Where private drainage projects
            already   exist, some remedial     action by government may be
            necessary   with attending legal ramifications. Where lands
            have been platted but remain undeveloped, other governmen-
            tal actions may become necessary- The greatest flexibility
            for preserving, supplementing, or replicating natural drain-
            ageways are in those areas not yet platted. In these areas,
            the essential functions of natural drainageways can be de-
            termined   by government or as     a private development re-
            quirement.    The necessary system can be designed to pre-
            serve the effectiveness of significant natural resource areas
            likely to be impacted by development        actions within the
            proximity of the natural drainageway.







                                       6 - 6










            Controlled Drainage Criteria

            A controlled drainage system will provide for the maximum ex-
            filtration   from the system and infiltration into the ground
            water table. It will be designed to retard the effects of
            erosion   and the transport of the silts and clays associated
            with the sandy soils found throughout       St. Johns County.
            Also, by controlling fine organic materials the system con-
            fines pollutants and protects water quality.       It will also
            provide for the rare rainfall from major storms. A system
            channel with a controlled flow capacity will be designed to
            provide for stormwater from rainfalls expected on the 25
            year 24 hour return frequency basis, or a total of about 8.8
            inches for the rainfall event.     Finally, any system consid-
            ered   for operation and maintenance by the County, will be
            designed   with overflow areas to accept the 50 year, 24 hour
            rainfall   event runoff, or 10 inches of rainfall, with all
            structures   designed to maintain structural integrity under
            the same event condition.

            Silts, clays, detritus, and very fine sandy soils become sus-
            pended   in water flowing at rates in excess of 1.5 cubic
            feet per second.    Broad channels, distributed flow channels,
            and the use of low flow water control structures providing
            effective   flat bottoms or near zero profile slopes between
            structures   for low and intermediate flows can reduce flow
            rates and eliminate erosion from annual and higher rainfall
            condition storms. Construction of downstream weir crests and
            inverts of culverts at raised elevations to create an ef-
            fectively flat channel    will provide sediment      control to
            trap initial construction    disturbed very fine sands, silts,
            and clays to weir crest levels.

            Exfiltration estimates of open channel bottoms will be based
            upon potential infiltration rates of the sediment fines trap-
            ped within the drainage channel and the height of the channel
            bottom   above average annual high water 'table conditions for
            the   parcel proposed for development. Drop boxes, inverts
            of culverts, and sills of weirs will be designed to maintain
            required flow rates.

            While channel depths constructed to the lower point of an-
            nual natural water table conditions may become necessary,
            maximum exfiltration    will occur when the channel is con-
            structed at an elevation above the annual natural high water
            table conditions. Where the lower depth channels are nec-
            essary, outflow points from       the system will be controlled
            by raised culverts and weirs to elevations        determined by
            the Engineering Department to assure that overdrainage will
            not occur.




                                       6 - 7










            Channels    will have outfall structures at final discharge
            points    to control discharge flows. All systems will be
            designed    for zero      discharge from the first one inch of
            runoff expected from the drainage area (see Tables 2-1 and
            2-2).    After retaining     the first one inch of rainfall, a
            maximum    discharge equivalent      to about two inches of con-
            trolled runoff per day from rainfalls of up to three inches
            per day would provide for normal rainfalls expected annually
            (see Table 2-3). An additional         discharge capacity of three
            inches per day of controlled         runoff from the still larger
            and the extremely rare rainfall events will accommodate flood
            protection needs while providing controlled flow protection to
            the County infrastructure and the natural environment.

            The Engineering Department will further evaluate the possibil-
            ity of using simple volumetric analyses of expected runoff for
            smaller areas. The use of the above controlled flow concepts
            will permit the use of simpler           calculation methods for
            achieving acceptable water detention/retention for recharge
            and controlled discharge purposes.         For example, the Ratio-
            nal Method for estimating runoff peak flows and the Ratio-
            nal Mass Curve Method for estimating required storage vol-
            umes can be simply calculated.         These methods provide rea-
            sonable approximations useful for small area analysis. As the
            size of the area becomes larger, these calculation methods
            progressively     overestimate runoff and storage volume re-
            quirements.      From the County's management perspective, the
            use of these methods to determine detention/retention facil-
            ities, controlled flow conveyance systems, and runoff con-
            trol structures results in          increased system capacities.
            The use of these simpler techniques benefits the public due
            to the conservativeness of      the    resulting controlled       flow
            systems and the simplified permit application review pro-
            cess.      The use of these     simpler computation methods       can-
            not be recommended          for the design       of large         area
            uncontrolled-flow discharge        systems.      From a developer's
            perspective, these simpler      methods reduce   the costs of anal-
            yses    as compared with more complex evaluation procedures,
            but their use for large areas         results in      increased con-
            struction costs due to system over design.



                  Natural Streams

            The    riverine (above tidewater) part of Moultrie Creek and
            its tributary stream courses receive and discharge the runoff
            waters to tidewater. This fresh water mixes with ocean water
            to    form estuarine waters of progressively increasing sa-
            linity    in    the lower course of the Moultrie Creek to its
            mouth at the Matanzas River.




                                         6 - 8









            A significant part of riverine flow is derived from ground
            water seepage. Rain water infiltrating into the ground flows
            from high water    table areas and emerges as seepage along
            stream   courses. Stream flow derived from seepage is termed
            base flow. Rain water infiltrating the ground can provide
            seepage or base flow water to the riverine part of Moultrie
            Creek for several weeks following a heavy rainfall.            The
            length of time that base flow contributes to stream flow is
            dependent upon the replenished       or maintained height of
            the water table in adjacent upland areas.

            During extended drought periods, base flow in Moultrie Creek
            can cease.    Review of The United States Geological Survey
            maintained stream      discharge gage at State Road 207 (ID
            02246900)   indicates an increasing number of days with lit-
            tle or no flow in      recent years.   This condition reflects
            decreased rainfall amounts      and the effects of development
            with uncontrolled storm drainage in the watershed above the
            gage.



                 Documented Stream Flows

            The   stream gage at State Road 207 (ID 02246900) measures
            flow from a 19.8 square mile area of Moultrie Creek water-
            shed (49 percent of the watershed) above the gage. The datum
            of the gage is 14.24 feet above the National Geodetic Verti-
            cal Datum of 1929 (about mean sea level), an elevation fif-
            teen or more feet     lower than the elevation of the average
            land surface in the vicinity of the gage.        The information
            referenced below is based upon the time period from October
            1961 through September 1988.

            The   minimum water surface elevation in the record was 1.84
            feet above the datum on July 15, 1981. Zero stream flow oc-
            curs   when the    gage height     (water surface) is less than
            about   2.2 feet above the datum.        The highest gage height
            recorded   for the 27 year record period was 9.16 feet above
            the datum on September 21, 1969, when the maximum discharge
            of 860 cubic feet per second (cfs) occurred.

            During the October 1987 through September 1988 period or the
            1988 water year, 60 percent of the days recorded flows of less
            than   1 cfs and numerous days in the months of October and
            November 1987 and June and August 1988 recorded zero flows.
            Low flows of 0.06 and 0.05 cfs were recorded during the months
            of July and September 1988.     The discharge data for the 1988
            water year reflected an average daily flow rate at the gage
            of 15.2 cfs.    This average value      represents a 1988 water
            year runoff from the watershed above the gage equivalent to
            10.4 inches of watershed      rainfall.    The 27 year average


                                       6 - 9










            daily flow at the gage is 17.7 cfs, equivalent           to 12.14
            inches of rainfall.

            Provisional   data for a second stream gage (ID02247012) on
            the Moultrie Creek tributary (Tributary No. 4 in the Federal
            Emergency   Management Agency Flood Insurance Study) at State
            Road   207 were also reviewed. This gaging station was estab-
            lished in March 1988.     The provisional data showed zero flow
            periods during the 1988 water year similar to Moultrie Creek.
            The maximum discharge recorded was 41 cfs in November 1988.
            only three days indicated flows in excess of 10 cfs. Dis-
            cussions with a United States Geological Survey represen-
            tative revealed that water diversions may be occurring up-
            stream of the gage as a result       of private development ac-
            tions.



                Stream Discharge Characteristics

            The   stream discharge     characteristics of Moultrie Creek
            were reviewed.     Data were assembled from daily stream flow
            records to establish the runoff characteristics from a vari-
            ety   of storms. The      available data indicated that stream
            flow at the State      Road 207 gage typically peaked approxi-
            mately twenty" four hours following       a rainfall event, Ini-
            tial runoff discharges are considered to reflect a three to
            four day period following rainfalls.        The stream gage data
            indicates that      discharge     volumes recorded    prior to an
            event typically return to the         pre-event volumes within
            about   four weeks following      the event.      These findings
            suggest   that initial runoff ends within roughly four days
            following an event, and a gradually declining        and delayed
            runoff   and base flow continues for several weeks following
            an event.


            TA13LE 6-2. ST. AUGUSTINE RAINFALL AND MOULTRIE CREEK DISCHARGE
            MARCH 1 THROUGH MARCH 26, 1980 presents data for a March 1980
            rainfall for St. Augustine and March 1980 stream discharge
            data ( Station ID 02246900) for the 19.8 square mile drainage
            area of Moultrie Creek upstream of State Road 207. The pri-
            mary rainfall occurred on March 9 and 10, amounting to 4.12
            inches.   This was a minor annual rainfall, not even equiva-
            lent to the two year, two day expected rainfall.       The period
            preceding the rainfall was six days, including March 3 with
            a trace of rainfall recorded.        During    the event period
            from March 3 to March 27, when a new rainfall event occurred,
            three rainfalls events occurred. The average antecedent pe-
            riod between the rainfall events was five days.

            The stream gage data shows a progressive decline from March
            2 through March 8.      A slight increase occurred on March 9,


                                        6 - 10










            with    a major increase in discharge on March 10. The dis-
            charge peaked on March       11, with a rapid decline through
            March    13, indicating completion      of the initial storm run-


                                         TABLE 6-2


                  ST. AUGUSTINE RAINFALL AND MOULTRIE CREEK DISCHARGE
                             MARCH 1 THROUGH MARCH 26, 1980

                     Day        Daily Rainfall           Discharge
                                   (Inches)       Cubic Feet Per Second

                     1                  0                    8.7
                     2                  0.15                 8.9
                     3                  Trace                8.1
                     4                  0                    7.4
                     5                  0                    7.0
                     6                  0                    6.6
                     7                  0                    6.2
                     8                  0                    5.8
                     9                  0.65                 7.7
                    10                  3.47              157.0
                    11                  0                 269.0
                    12                  0                 166.0
                    13                  0.18              120.0
                    14                  0                   93.0
                    15                  0                   71.0
                    16                  0                   59.0
                    17                  0                   52.0
                    18                  0                   45.0
                    19                  0                   39.0
                    20                  0                   35.0
                    21                  0.3                 32.0
                    22                  0                   28.0
                    23                  0                   24.0
                    24                  0                   21.0
                    25                  0                   19.0
                    26                  0                   16.0
                                                  Total 1246.0
                    27 Beginning of New   Rain Event



            off. Of the total volume of water discharged between March
            10 and March 26, the       four day period of March 10 through
            March 13 accounted for 57.1 percent of the total. The remain-
            ing 42.9 percent of the stream flow would be representative of
            delayed runoff and seepage flows.




                                        6 - 11











           WATER LOSS  IMPACTS



           A   perspective of  the significance of water loss'factors is
           provided   by the   following example analysis. The volume of
           water represented by the 4.6 inch rainfall occurring between
           March 9 and March   26, 1980, an the 19.8 square mile Moultrie
           Creek watershed approximates 4857.6 acre feet. The total
           discharges noted in Table 6-2 for the March 9 to March 26 pe-
           riod are equivalent      to about 2471.3 acre feet of water or
           about   50.9 percent (2.34 inches) of the total 4.6 inches of
           rainfall received by the 19.8     square mile watershed. Areal
           evapotranspiration    at 0.105 inches per day for that same
           period represents     about 1.785 inches of rainfall. Runoff
           and evapotranspiration can account for all but 7 percent of
           the rainfall during the 17 day period.

           Had   another    storm not occurred on March 27,      the daily
           stream discharges would have continued to recede slowly each
           day for about 10 more days before declining to 5.8 cubic feet
           per second, the discharge recorded on March 8 and the day be-
           fore the March 9 rainfall. Estimated discharges for the ad-
           ditional   10 days would approximate     about 196 acre feet of
           water discharged to the stream essentially as seepage. The
           total runoff, including base flow for a 27 day period could
           account for about 55 percent or 2.53 inches of the rainfall
           received on the watershed during this example event. Areal
           evapotranspiration for a 27 day period in March would be ap-
           proximately equivalent to another 2.84 inches of the rainfall.
           Without another rainfall, the entire 4.6 inches of example
           rainfall can be accounted for in evapotranspiration and run-
           off, and the continued water losses would result in a defi-
           ciency   of 0.77 inches of rainfall. The process of rainfall,
           continual evapotranspiration, runoff, and a three to four
           week period of delayed runoff and slow seepage providing base
           flow to the stream, as exemplified in Table 6-2, is ongoing.

           Evapotranspiration is a highly variable and an essentially un-
           controllable   process. Vegetated areas with saturated soils
           evapotranspire    water at a rate of about 50.9 inches per year
           in St. Johns County. An average, estimated actual, or areal
           evapotranspiration rate of 38 inches per year is more repre-
           sentative   of the varied conditions on the watershed. The
           United States     Geological Survey estimates that runoff ac-
           counts for about 12 inches of annual rainfall. For an aver-
           age rainfall year of 53 inches, only 3 inches of rainfall
           remain for ground water recharge      or water use if a balance
           between rainfall and water use is to be maintained.

           The   practical significance of the need to retain more water
           on the land for recharge can be illustrated through           the


                                      6 - 12










           following example.     If a family of four uses 400 gallons of
           water per day, they will, in one year, use 146,000 gallons
           of water. One      acre inch of water is equivalent to 27,155
           gallons, and one inch of water per square mile is equivalent
           to   17,380,000 gallons     of water. Therefore, 119 families,
           each with four people, would use one inch of rain water that
           has managed to infiltrate into a one square mile land area
           and recharge the surficial aquifer.

           As   another example, assume      20,000 people, at an average
           per capita use of 100 gallons of water per day, are supplied
           from a well field withdrawing water from the surficial aqui-
           fer.    Assume also that three inches of rain water could in-
           filtrate    into   the soil and recharge the aquifer.       The 3
           inches of     recharge would be required from a land area of
           about 14 square miles for the recharge to balance the wa-
           ter use. This simple      example assumes that three inches of
           rainfall could be saved and allowed to         infiltrate and re-
           charge the surficial aquifer with      no additional losses of
           evapotranspiration, runoff, or agricultural         or industrial
           withdrawals from that same supply. The example also assumes
           that the average annual 53 inches of rainfall will occur. Fi-
           nally, the 100 gallons per capita per day water use estimate
           is used here for simplification. Urban area estimates of per
           capita daily water uses are typically higher; an estimate of
           133 gallons per capita per day (gpcd) is widely used for St.
           Johns County.






























                                       6 - 13




















                                           7


                                   FLOOD PRONE AREAS



           NATIONAL FLOOD INSURANCE PROGRAM DATA



           The Federal Emergency Management Agency completed a flood in-
           surance    study for the unincorporated areas of St. Johns
           County (Community Number 125147), dated September 18, 1985.
           This study includes peak discharges, floodway, and base flood
           elevations for Moultrie Creek       and three tributaries.     The
           three tributaries studied drain from the north in the devel-
           oping parts of the Moultrie watershed between Moultrie Creek
           and the Matanzas River. This study and companion Flood In-
           surance Rate Maps establish a 100-year flood elevation (base
           flood    elevation)    along the     studied    stream courses.
           Figure   7-1. Flood Hazard Areas Subject To 100-Year Flooding,
           depicts the special flood hazard areas subject       to 100-year
           flood conditions as determined by the Federal Emergency Man-
           agement Agency.

           Tributary #1 drains a small 1.5 square mile area located east
           of State Road 5A. The mouth of this small stream is located
           immediately    west of Shore Drive.    The 100-year flood eleva-
           tions    along this stream range from 8 feet NGVD at the stream
           mouth to 25 feet NGVD at Lewis Point Road. Upstream of Lewis
           Point Road, a generalized area is depicted on the Flood Insur-
           ance Rate Maps identifying a Zone A, a special flood hazard
           area with no base flood elevation determined.

           In those cases where the Federal Emergency Management Agency
           does not establish      base flood elevation, the interagency
           agreement with the local government requires that the lo-
           cal    government establish    an interim base flood elevation
           applicable to local development actions.        Zone A locations
           in    the Moultrie Creek watershed are typically upland de-
           pressions, natural drainageways, and some flatwoods soils
           area that would be subject to        shallow flooding    under a
           storm of an intensity capable of producing a 100-year return
           frequency flood.

           Tributary #2 drains a small area on the south side of Moul-
           trie Creek that      was not studied.    Tributary #3 drains a


                                       7 - 1








                                                                  Figure 7-1. Flood Hazard Areas
                                                                       Subject To 100-Year Floodi-
                                                                   -,V@\j                             x



                                    R 16



                                                                  C05






                                                                                              0
                                                                                               0
















                                                                      ST
                                                                      sou


                                       0


                                       0



                                                                              ES
















                                                                             Sao 2=DS







                 SCALE: 1  10,000


                                                                LEGEND:

                                                      PROJICT
                                                      10CITION             AREAS OF fOO-YEAR FLOODING
                                                      P'
                                                      11)1A
             D.E.R. CONTRACT NO. CM7217
                     ST. JOHNS COUNTY ENGINEERING DEPARTMENT - GEOGRAPHIC INFORMATION SYSTEM








               small 0.7 square mile area on the north of Moultrie Creek
               between ..: the Florida East Coast Railroad and State Road 5A.
               Base   flood elevations ranging from 9 feet NGVD at tidewater
               to 21 feet NGVD at a point 5800 feet upstream of the tribu-
               tary's mouth. A generalized area upstream of 5800 feet along
               the tributary's stream course is delineated as a Zone A.

               Tributary #4 drains a 4.1 square mile area located immediately
               to the west of Tributary #3. Delineated base flood elevations
               range from 9 feet        NGVD at tidewater to 35 feet at State
               Road   207. Upstream of that location, a generalized Zone A
               area is delineated.

               On   Moultrie Creek, flood elevations are provided from tide-
               water to State Road 214. The following are base flood ele-
               vations in feet above NGVD obtained from stream profile data:
               Osceola Trail, 10.7;       State Road 207, 25.8; Lightsey Road,
               30.2,   Florida East Coast Railway, 32; and State Road 214,
               34.2. An extended area upstream of State Road 214 is delin-
               eated as a Zone A.



               EVALUATION CRITERIA



               Construc tion of roads and inhabited buildings above the 100--
               year flood elevation will be required.          The National Flood
               Insurance Program      has    established    the 100-year      return
               frequency    flood condition as the base elevation for insured
               habitable structures. The need for emergency access to prop-
               erties, the protection of the public from injury resulting
               from flooding of roads, and the obligation of local govern-
               ment to provide for the safe       movement of people on public
               roads dictates the need to establish          the 100-year return
               frequency flood as the elevation         above which roads should
               be constructed.

               In those parts of the watershed where National Flood Insur-
               ance flood information is available, the elevations               es-
               tablished through that program will be used. In those areas
               where the base flood elevation must be estimated, the follow-
               ing procedure will be used.

               The 100-year return frequency 24-hour rainfall (12.8 inches)
               will be used. The normal annual high water table condition
               and    the SCS Runoff Curve Number applicable to the area in-
               cluded in the proposed development will be used to estab-
               lish a soil infiltration runoff         reduction estimate. Large
               developments encompassing many different water table and soil
               conditions will be segmented into representative soil charac-
               teristic subareas.



                                              7 - 3










              The   planned stormwater containment facilities for the pro-
              posed development will be used to estimate initial abstrac-
              tion   land storage and retention requirements. The proposed
              channels   and other components of the development stormwater
              management system will    be used to establish rainfall depth
              reductions to be      expected from runoff during and immedi-
              ately following the rainfall event.     Open land areas of the
              parcel or surface water storage areas sufficient to detain
              or retain the remaining rainfall will be estimated.

              All parcel land elevations above the maximum water eleva-
              tion required to contain or otherwise manage the 100-year
              rainfall will be considered as above the base flood elevation.
              All public roads will be constructed with road surfaces above
              the base flood elevations. Access to public facilities, and
              all structures used as residences and as established locations
              of employment will be constructed     with habitable or occu-
              pied first floors above the base flood elevation.



































                                          7    4






















                                            8


                                ATLANTIC COASTAL RIDGE



            WATER RESOURCE STUDY CRITERIA


            The    information assembled provides       guidance for evaluating
            hydrological analyses conducted in the Moultrie Creek water-
            shed :     In addition to the review of existing information
            previously presented, TABLE 8-1. GUIDELINE HYDROLOGICAL CRITE-
            RIA FOR THE ATLANTIC COASTAL RIDGE ST. JOHNS COUNTY, FLORIDA
            has been prepared as initial guidance for application to the
            Tillman Ridge part of the Moultrie Creek watershed. Until
            rainfall gage data becomes available for the interior part of
            St. Johns County, these data provide information that may be
            applied to all of the Atlantic Coastal Ridge portions of the
            County.

            The    monthly rainfall estimates presented in Table 8-1 are
            composites     of mofithly averages obtained from the unedited
            or non-normalized data available for Hastings and St. August-
            ine.     Hastings data are based upon the 1978 to 1986 record
            period and St. Augustine         data are based upon the 1973 to
            1986    record period.       The reduced average monthly rainfall
            for July reflects decreased rainfall for that month at St.
            Augustine during the record period.

            Because rain gaging stations are not available for the west-
            erly parts of St. Johns County from Switzerland northward,
            the data presented in Table 8-1 may be applied to analyses
            conducted     in northwestern St. Johns County. Hastings data
            provides guidance for the southwestern part of the County,
            Marineland     for the southeast, St. Augustine for the central
            coastal area, and Jacksonville          Beach for the north coastal
            areas.     The data for these stations are generally available
            from the United States Weather Service.            Later studies may
            find that a single composite set         of data may be appropriate
            for the entire coastal portion of the County.

            The average daily evapotranspiration data presented in Table
            8-1 were derived from the annual estimate of 38 inches used to
            represent     areal evapotranspiration in this study. This an-
            nual    estimate was then disaggregated based upon the average


                                          8 - 1













                                      TABLE 8-1


                              GUIDELINE HYDROLOGICAL CRITERIA
                             FOR THE ATLANTIC COASTAL RIDGE
                                 ST JOHNS COUNTY, FLORIDA

              MONTH      AVERAGE AVERAGE      AVERAGE    EVAPOTRANSPIRATION
                         RAINFALL NUMBER OF NUMBER OF MONTHLY         DAILY
                         (Inches) RAINFALL    ANTECEDENT (Inches) (Inches)
                                   DAYS       DAYS


            January    3.2      4.8        6           1.86       0.06
            February   3.4      5.0        6           2.09       0.07
            March      3.9      5.6        5           3.23       0.11
            April      3.4      3.8        5           3.80       0.13
            May        3.5      3.9        5           4.64       0.15
            June       6.7      7.9        4           4.26       0.14
            July       5.8      9.3        3           4.18       0.13
            August     6.8      9.3        3           3.91       0.13
            September  7.3      8.5        3           3.46       0.12
            October    3.6      4.8        6           2.70       0.09
            November   2.3      4.6        6           2.01       0.07
            December   3.1      4.9        6           1.86       0.06

            Note:    Slight anomalistic characteristics     appearing in
                   the average rainfall data are believed to be due
                   to the short time frame of the database.



            monthly potential evapotranspiration values as percents of to-
            tal potential annual evapotranspiration noted in Table 6-1.

            The average number of rainfalls per month and the average
            number of antecedent days between rainfalls were developed
            from    an evaluation of the available Hastings record (TABLE
            2-2 and TABLE 2-3). These values are intended as guidance un-
            til further studies are conducted for more stations in north
            Florida with longer periods of records.

            Additional    studies are also needed using hourly          rainfall
            data.    Average Daily rainfall data do not reflect rainfall
            events    adequately for some design purposes. Review of sta-
            tions that may be representative       of conditions in St. Johns
            County is needed, and procedures for           incrementally pro-
            gressing    rainfall through a system of characteristic, but
            hypothetical, storms would provide improved           criteria for
            evaluating storm effects. Generalized procedures are avail-
            able for this purpose, but no standardized procedure is yet





                                         8 - 2












           available that can provide reasonable assurance that the re-
           presentations used are applicable to St. Johns County con-
           ditions.

           Finally, studies are needed to correlate observational surfi-
           cial aquifer water well log data with rainfall to estab-
           lish   well recovery    extents following rainfalls of varying
           intensities    and durations under existing conditions. Wells
           withdrawing    water from different    depths can be expected to
           recover    differently. Similarly, wells penetrating differ-
           ing soils matrix materials also will react differently to
           rainfall events. Information from this type of analysis will
           have to be spatially correlated with land        use and natural
           resource areas within the theoretical       recharge localities
           of the observational wells to establish the extent and de-
           pendability of natural recharge capabilities.      The final re-
           sults of these analyses will provide fundamental information
           on the effectiveness of differing engineered water management
           facility configurations.     These study efforts will provide
           necessary information for establishing cost-effective measures
           and final Engineering Department criteria for basin-wide man-
           agement of stormwater.
































                                       8   3






















                                           9


                     SIGNIFICANT NATURAL RESOURCE AREA MANAGEMENT



           GENERAL



           Those    natural areas within the County that require special
           governmental management procedures have been identified as
           "Significant Natural Resource Areas." These areas include
           important wetlands of state and national concern and other
           natural environmental areas of importance to the well being
           of residents of St. Johns County.       Significant natural re-
           source areas include surficial aquifer recharge areas, riv-
           erfront areas, shorelines, water bodies, wetlands, wood-
           lands, wildlife sanctuaries, and     archaeologically important
           locations.

           Developments    permitted adjacent and near to these areas re-
           quire special     pre-project review.   Natural conditions re-
           quired to preserve these areas are to be maintained if the
           natural area is to remain viable and not move into a grad-
           ual process of decline. Cultural developments that may im-
           pact upon these areas also must be reviewed         to determine
           the significance of     negative impacts resulting     from the
           development.     Where possible, government guidance can be
           provided to property owners to assist them to undertake de-
           velopment efforts that could lead to the         enhancement of
           significant    natural resource areas. To be encouraged, are
           those    private efforts to create new natural resource areas
           and efforts to augment or extend existing significant nat-
           ural resource areas.



           SIGNIFICANT NATURAL RESOURCE AREAS



           Tidal Wetlands (Moultrie Creek Estuary)

                 General Protection Needs

           The    Moultrie Creek estuary and associated tidal       wetlands
           extend for approximately five miles upstream of the river's
           confluence with the Matanzas River. The natural vegetation


                                      9 - 1











            consists of seashore saltgrass, bushy sea-oxeye, glasswort,
            and    needlegrass rush. This is an important wildlife area.
            The native vegetation and fauna are important links in the
            food chain for many sport and commercial finfish and shell-
            fish.

            The    environmental health of the natural area is dependent
            upon   continual ground water seepage from adjacent higher wa-
            ter    table areas    and fresh water discharges from Moultrie
            Creek and tributary       streams.     A primary hazard to this
            natural area is the      introduction of pollutants and exces-
            sive sediments      with   stormwater discharges from roadway
            drainage systems and     urban developments     in the watershed.
            Excessive    nutrients   introduced    with effluents from septic
            tanks and waste water treatment plants         are also potential
            hazards affecting the    balance of biological processes within
            the estuary.


                  Contamination From Roadways

            A primary source of pollutants occurs with runoff from road-
            ways. As roadway traffic loads increase with development, the
            practice of positive uncontrolled drainage from these road-
            ways is introducing increasing loads of oils, greases, tars,
            rubber and other tire composition materials, oxides from au-
            tomobile exhausts, and a host         of other types of particu-
            late    matter associated with modern vehicular traffic into
            the estuary. The entrapment of these contaminants in reten-
            tion storage facilities constructed as roadway drainage facil-
            ities is essential for preservation of the biological pro-
            cesses    in the Matanzas River and St. Augustine Harbor es-
            tuary.


                  Roadway Retention Storage Catchment, Benefits

            No technical reason exists for avoiding the use of roadway re-
            tention    storage    catchments along Moultrie Creek and the
            Matanzas River. The natural water tables in these areas are
            found    generally at six or more feet below ground eleva-
            tion.     The water holding capacity        of the first four feet
            of     soils immediately adjacent      to the estuarine parts of
            Moultrie Creek are       on the order of ten inches or more of
            equivalent rainfall. The permeability or rate at which the wa-
            ter percolates through these soils is very high.           Retention
            basins constructed in these low or deep water table, highly
            permeable soils would remain dry except         for short periods
            following the most intense rainfalls.          Materials entrapped
            in these basins would be reduced by aerobic          organisms and
            conservative materials (heavy metals) would electro-chemically


                                         9 - 2











            bind to fine silts and clays washed into, or formed by reduc-
            tion   processes, within the catchments.       When     constructed
            above the natural high water table, catchments constructed
            in these areas would require very infrequent maintenance.

            The extensive use of retention storage catchments throughout
            the low or deep water table localities also provides for the
            continued    base flow essential for maintaining fresh water
            flows    into the Moultrie Creek estuary. The fresh water head
            created by the infiltration of trapped rainfall also serves
            to reduce the potential of salt water intrusion into the surf-
            icial aquifer     adjacent to the tidal parts of the Matanzas
            River and Moultrie Creek.



                 Contamination From Septic Tanks

            St. Johns County has permitted urban development with septic
            tank effluent disposal along the Matanzas River and Moultrie
            Creek estuaries. When properly operating, septic tank drain-
            age   releases nutrient rich effluents that move with ground-
            water    seepage into the estuaries.       As long as population
            densities remained low, these enriched septic tank effluents
            with high levels of nitrogen, phosphorous,          and other nu-
            trients    could be accommodated      by biological       processes
            within the estuary.

            As development increases throughout the St. Augustine metro-
            politan area, the increasing release of nutrients from septic
            tanks, waste treatment plants, and natural vegetative sources
            can overload the natural biological nutrient processing ca-
            pacity of the estuarine system. The result will become no-
            ticeable by increased vegetation growth, increased quantities
            and   accumulations of detritus (plant remains) in shallow
            waters, increased buildup of resulting organic            materials
            filling    in shallow waters, increased biochemical reduction
            of these organic materials through anaerobic processes with
            resulting increases in hydrogen sulfide, methane, and similar
            anaerobic process gas releases; and subsequent decline in the
            suitability of extended areas of the estuary as food produc-
            tion and protection areas for juvenile finfish and shellfish.

            Septic    tank effluent releases pose still other problems
            for protection of the estuarine waters. Modern urban living
            has come to depend upon a host of highly toxic cleaning and
            other    materials.    Many homeowners have little concern for
            the   biological processes that make a septic tank reduce hu-
            man waste into relatively harmless sediments and a liquid,
            nutrient rich effluent that is        released through    a drain
            field. Household      cleaners,   paint    products, pesticides,
            etc.,    can easily reduce the' effectiveness       of the system


                                        9 - 3











            and permit the release of human waste pathogenic materials and
            the toxic materials in the septic tank effluents. No known
            process   exists for readily determining the extent of misuse
            of septic tanks.

            Septic   tanks also require cleanout periodically in order
            to continue to function properly. As the sediments (sludges)
            gradually build up within the tank, the efficiency of the
            system declines. -Eventually, very poorly treated effluents
            are released into the environment.      No County program exists
            to certify to the proper operation of septic tanks.


                 Dredge and Fill Problems

            The environmental health of tidal portions of the Moultrie
            Creek watershed requires the preservation of wetlands vegeta-
            tion in the estuary and the biological processes associated
            with those vegetated areas.         Construction activities in
            estuarine wetlands remove some vegetation. When construction
            actions are not extensive, reestablishment of the original
            vegetation can occur within three to five years following the
            construction activity.

            construction    activities also disturb wetlands bottom mate-
            rials and/or upland soils matrix materials. In the process,
            runoff from the land carries increased loads of silts and
            clays.   Tidal exchange waters then carry the silts and clays
            from uplands and from the disturbed bottom materials to other
            locations within the Matanzas River and into the greater St.
            Augustine   Harbor area. The construction related increases
            in suspended sediments creates turbid waters that reduce the
            normal biological processes within the greater estuary. In
            sufficient quantities,     the introduced silts and clays can
            smother benthic organisms and destroy significant areas of
            sessile vegetation within the estuary.

            For the continued and normal environmental health of the
            greater St. Augustine Harbor estuary, all construction activi-
            ties   likely to cause high levels of water turbidity or oth-
            erwise affect the quality of the water in the estuary must be
            managed to assure the minimum of short- and long-term damage
            from the activity occurs. Federal and State of Florida pro-
            grams exist to provide protection from direct disturbances
            of wetlands from urban development actions.









                                        9 - 4











                 U. S. Army Corps of Engineers Regulatory Program

            The   U. S. Army Corps of Engineers regulates activities in
            open waters and wetlands under the following four separate but
            related laws:

                  1.   The Rivers and Harbors Act of 1899 which requires
                  authorization for activities such as constructing piers,
                  bulkheads, subaqueous pipe- lines, filling, dredging,
                  stream channelization, and similar works in navigable
                  waters    of the United States.       In response to 1968
                  court rulings, permit application reviews now include
                  protection of fish and wildlife, conservation, pol-
                  lution, esthetic, ecology, and general public interest;

                  2. The Federal Water Pollution Control Act of 1972 re-
                  quiring the restoration and maintenance of the chemical,
                  physical,    and biological integrity of the nation's
                  waters.    Section 404 of the Act established the permit
                  program to regulate discharges of dredged or filled ma-
                  terial into waters of the United States;

                  3. The Clean Water Act of 1977 expanded the'Corps Sec-
                  tion 404 authority to include, but not be limited to,
                  all coastal and inland waters, lakes, tributaries to
                  navigable waters, wetlands adjacent to navigable waters,
                  and certain isolated wetlands and water bodies;

                  4.   The Marine Protection Research and Sanctuaries Act
                  of 1972 authorizes the Corps of Engineers, under Section
                  103, to issue permits for the transportation of dredged
                  material for ocean disposal.

            In   general, Corps of Engineer permits are required for any
            construction in all tidal areas channelward of mean high water
            lines in the Moultrie Creek estuary. Complete information on
            Corps   of Engineers regulatory requirements can be obtained
            from: Regulatory Division, P. 0. Box 4970, Jacksonville, Flor-
            ida, 32232-0019. Telephone: 904/791-1676.


                 Florida Department of Environmental Regulation Permits

            The Florida Department of Environmental Regulation exercises
            regulatory jurisdiction over dredge and fill activities in wa-
            ters of the State to their landward extent. Landward extent
            is determined by the dominance of certain wetland indicator
            vegetation species defined in Chapter 17-4 of the Florida
            Administrative Code.       The State Wetlands Protection Act of
            1984    (Chapter 403, Florida Statutes) authorizes regulation
            of wetlands to protect and preserve water quality and pre-


                                        9 - 5









               serve fish and wildlife habitat.        Determination of regula-
               tory jurisdiction is based upon an area's regular and peri-
               odic inundation, physical waterbody connections to "waters of
               the State," and dominance by the specified wetland indicator
               species.    Waters of the      State are     rivers, streams and
               their tributaries, bayous, sounds, estuaries and bays and
               their natural tributaries, most natural lakes and the Atlan-
               tic ocean and Gulf of Mexico to the seaward limit of the
               state's territorial boundaries.

               The Florida Department of Environmental Regulation develop-
               ment action review evaluates        the potential impact of a
               proposed project on the waters of the State. This review
               process is intended to assure that the project will not:

                     1.   Obstruct or alter the natural flow of navigable wa-
                     ters;

                     2.   Induce harmful or increased erosion, shoaling of
                     channels, or create stagnant areas of water;

                     3.   Interfere    with the conservation of fish, marine
                     resources and wildlife, or other natural resources;

                     4. Induce destruction of oyster beds, clam beds, or ma-
                     rine productivity including, but not limited to, de-
                     struction    of natural marine habitats and grass flats
                     suitable as nursery or feeding grounds for marine life.

               More   complete information on the Department of Environ-
               mental Regulation rules may be obtained from: Office of Pub-
               lic Information, Florida Department of Environmental Regula-
               tion, 2600 Blair Stone Road, Tallahassee, Florida 32301.


                    Florida Department of Natural Resources Review

               Under   the authorization of Chapter 253, Florida Statutes and
               in   accordance    with Rule 16 of the Florida Administrative
               Code, the Florida Department of Natural Resources (DNR) con-
               ducts the following evaluations of development actions rela-
               tive to,tidal portions of Moultrie Creek:

                     1. The water dependency of the project;

                     2.   The setback of the project from the          applicant's
                     riparian lines;

                     3. The project's consistency with other policies, stan-
                     dards, and criteria set forth in the Florida Adminis-
                     trative Code Rule 16Q-21.04.


                                           9 - 6










              More complete information on the above regulatory procedures
              may be obtained from the Bureau of Beaches and Shores and the
              Bureau of State Lands, Florida Department of Natural Re-
              sources,    3900 Commonwealth Boulevard, Tallahassee, Florida
              32303.



                    St. Johns County Tidal Wetland Criteria

              In order to avoid duplication of regulatory measures dealing
              with dredge and filling ot waters impacting national navigable
              waterways, St. Johns County shall develop review procedures
              incorporating the process established by the U. S. Army Corps
              of Engineers. Similarly, the       Florida Department of Environ-
              mental Regulation's wetland protection criteria and the Flor-
              ida Department of Natural Resources criteria shall be incor-
              porated into the County review process.          The primary envi-
              ronmental criteria of concern in the dredge and fill permit-
              ting process include:

                     1.   The potential impact of the action on the essential
                     and sustainable quality of waters in the County;

                     2.   The potential effect of the action of the propaga-
                     tion and sustenance        of wildlife, fish and aquatic
                     plants    and animals important to the food chain of com-
                     mercial and sport fish and wildlife;

                     3.   The potential impact of the action on the health
                     and welfare of property owners fronting the impacted
                     water body, users of that water body and the general
                     public of the County;

                     4. Other reasonable, practical, and implementable envi-
                     ronmental concerns of regional, state, and federal gov-
                     ernmental agencies and professional bodies.


                     St. Johns County Tidal Wetland Management Alternatives

              The maintenance of water quality conditions suitable for fin-
              fish and shellfish within the Moultrie Creek/Matanzas Riv-
              er/St. Augustine Harbor estuary will require coordinated man-
              agement    efforts between St. Johns County and the municipali-
              ties of St. Augustine and St. Augustine Beach. Actions to
              alleviate existing and projected problems by any single gov-
              ernmental entity in the area would have limited effective-
              ness.    Effective protection     of the estuarine       environment





                                           9 - 7











            will require common and consistent procedures adopted by all
            of the governmental bodies regarding stormwater runoff and
            waste management.

            The   problems identified in this report regarding the tidal
            portions of the Moultrie Creek watershed also apply to every
            watershed that discharges stormwater runoff and waste efflu-
            ents   into the Matanzas and Tolomota River systems. Stormwa-
            ter management practices by the County and without cooperation
            from St. Augustine and St. Augustine Beach can only provide
            partial protection for the greater St. Augustine Harbor estu-
            ary.

            An   effective estuary resource management program would       re-
            quire participation from the three local governments whose
            practices determine     the environmental health of the total
            St.   Augustine estuary.    Coordination of stormwater manage-
            ment practices among the three governments at policy levels
            and at governmental operational levels would be a major focus
            of such a program.     Parallel functions in each governmental
            body impacting upon environmental conditions within the es-
            tuary would be identified.     Information on problems and po-
            tential solutions to specific problems would be exchanged
            among the three governments. Technical assistance procedures
            among the three governments would be established, and coordi-
            nated    means  for dealing with emergency      situations that
            impact upon the estuary conditions would be developed. Inter-
            governmentally  coordinated procedures for obtaining state and
            federal assistance to resolve St. Augustine metropolitan area
            problems associated with the estuary will gradually evolve
            from the process.


            Fresh Water Wetlands


                 Basic Processes

            Wetlands   exist in upland depressions, along flood plains
            of streams, and along the edges of base receiving water
            areas (upland depressions, lakes, and ponds). All wetlands
            have   one primary characteristic. All wetlands are receiving
            or transition locations      of runoff of surface waters and
            seepage of ground waters.      They function as nutrient sinks
            or   temporary storage areas for surface water runoff. In
            that capacity, all wetlands function to delay the movement of
            water.   The time delay of water movement through wetlands al-
            lows biological and chemical actions to reduce detrital ma-
            terials and provides time for the chemical bonding of con-
            servative materials to sediment fines in the wetland. The
            sediment fines are introduced into the wetland through runoff




                                       9 - 8









              or are created within the wetland through biological           or
              chemical-detrital reduction actions.

              As water  moves through and out of wetlands, minerals and nu-
              trients are introduced from the wetland into adjacent water
              bodies.   Under low or controlled water flow conditions, the
              transported minerals and nutrients from wetlands provide es-
              sential   materials for sustenance of biological processes in
              adjacent water areas.      Under high water runoff conditions
              through   wetlands,    large amounts of detrital materials and
              sediment  fines with chemically bound contaminants can be
              washed out of the wetlands and into the adjacent waters.


                   Factors Affecting Upland Wetland Function Declines

              Wetlands can persist only when they are able to receive regu-
              lar and controlled     amounts   of surface water runoff      and
              ground   water seepage from the adjacent upland watershed sup-
              plying the depressional area. once drainage programs alter
              the natural movement of water from the adjacent uplands or
              drain water to other locations, the original wetland begins
              a slow process of change.

              Forested   wetlands or swamps, bayheads, and hydric hammocks
              are primary sources of cypress and a variety of hardwoods
              used   for commerce in Florida. As the uplands that formerly
              supplied   the surface    water   runoff and ground water that
              seeped   into these areas are converted to agricultural and
              urban land uses and the natural       movement of water is al-
              tered, these areas also      begin a gradual     conversion    to
              mixed mesic woodland or pine flatwood communities.

              Without the regular supply of water from adjacent higher land
              areas, upland wetlands and their associated vegetation will
              gradually' convert to areas with different soil characteris-
              tics and with    different vegetation characteristics.        The
              preservation of any upland wetland requires the hydrologi-
              cal determination of the regime of water flow or movement to
              the depression essential for sustaining a depressional area
              as a wetland with some desired vegetation characteristics.

              In   areas where the water table has been lowered         through
              water withdrawals and overdrainage of surface waters, tempo-
              rary   sustenance    of wetlands occurs due to the compacted
              bottoms. of wet depressions that prevent or retard the infil-
              tration and percolation of surface water. In these areas of
              perched water tables, the perched condition will persist for
              some time.    As the available water declines,         vegetation
              roots will penetrate the      impervious clay layers in their
              search for water. Gradually,      through the     culmination of


                                         9 - 9









               life cycles of this vegetation, progressive generations of
               this pr 'ocess, and subsequent root reconversion       to natural
               elements,   percolation through the clay bottom slowly in-
               creases.


               Much of Florida was formerly in wet meadow vegetation. Prai-
               ries, meadows, or grassy wetlands all over Florida have been
               converted to agricultural and urban uses. High water tables
               due to lack of drainage prevailed       wherever extensive flat-
               land   areas   existed.    soils    in these areas were soggy
               through much of the year, and progressive generations of
               grasses had produced accumulations of organic materials in
               the upper horizons of the soils.        As the detritus       broke
               down and released nutrients and sediment fines, percolation
               carried these materials to the water table and formed imper-
               vious   layers.    These impervious    layers    helped    to per-
               petuate the natural wet meadow conditions.

               When   these areas were drained, usually for agriculture, the
               hot Florida sun caused oxidation of the organic materials
               that   had collected on and in the surface soil materials.
               Agricultural practices broke up the upper soil matrix layers
               and   the sun's actions caused further oxidation of organic
               fractions within the soils. As water tables were dropped and
               impervious soils layers were altered, water percolated down-
               ward and away from the soil surface.

               When   water tables are dropped more than roughly two feet
               below the land surface, the ability of grasses to obtain
               sufficient water without irrigation results in their reduced
               productivity. As vegetation functions decline, evapotrans-
               piration   also declines,      and stormwater runoff has to in-
               crease.   To compensate, agriculturalists       have constructed
               larger   and more efficient drainage systems. Similar prac-
               tices have been followed by urban developers.          The final
               result is the inability of the      land to hold enough water
               to provide essential natural resource functions.          In many
               parts of Florida where the surface soils have been drained,
               the water holding capacity of the sandy surface soils and
               the essential high water table conditions needed to sustain
               former wetlands no longer exists.


                    Long-Term Effects of overdrainage

               The following is an extreme example of the difficulty of at-
               tempting to rehabilitate wetlands following urban develop-
               ment   and agricultural     overdrainage practices.      The water
               table   aquifers    along    the Orlando Ridge, the Lake Wales
               Ridge, and the Osceola Plain in Central Florida formerly
               provided ground water seepage flows to sustain extended flood


                                           9 - 10











            plain marshes along the Kissimmee River. The water levels in
            the Floridan aquifer along the Orlando Ridge at the head of
            the Kissimmee River have dropped    largely through agricultural
            and urban development actions on    the order of 35 feet over
            the last fifty years.      Formerly high water tables and near
            saturated surface soils existed     from Orlando    southward on
            uplands   of the basin through      the 19601s.     The formerly
            soggy surface soils typical of      the basin's upland areas now
            are dry sands.

            The   formerly high water tables on the uplands surrounding
            the Kissimmee River flood plain will have to be recreated to
            provide ground     water    that can move as gravity flow and
            gradually    seep onto   the river flood plains.      This cannot
            occur today because      the potentiometric    elevation of the
            Floridan aquifer throughout the area is very low, and in-
            filtrating rain water percolates by gravity downward to the
            lower potentiometric levels of the Floridan aquifer.            To
            redirect the movement of water table aquifer waters hor-
            izontally to the Kissimmee River flood plain will require the
            entrapment of enough rain water to recharge the Floridan
            aquifer to something near former potentiometric levels.

            Assume,   as an example of the difficulty of restabilizing
            former floodplain conditions, the Floridan aquifer can store
            an average of 3 inches of water per foot of elevation, and 3
            inches   of annual rainfall could be trapped and allowed to
            infiltrate into the      aquifer    on all of the upland areas
            around the Kissimmee River. Under this condition, it would
            take at least 35 years, assuming no incidents of prolonged
            droughts were     to occur, to reestablish the ground water
            seepage    flows necessary     to sustain the former wetland
            flood   plains of the Kissimmee       River.    The Orlando area,
            Lake Wales ridge area,      and Osceola County     are developing
            rapidly, and water demands        are increasing commensurately.
            The technical likelihood of       reestablishing    the Kissimmee
            River flood plain wetlands is not promising.           The above
            example is an extreme      simplification of     the overall re-
            gional   problem of the Kissimmee        River watershed. Solu-
            tion of the Kissimmee River ground water recharge part of the
            watershed    problem would require the coordinated efforts of
            Orange, Osceola? Polk, Highlands, and Okeechobee counties
            and numerous municipal governments.


                 St. Johns County Upland Natural Resource Concerns

            The   St. Augustine metropolitan area partially depends upon
            the surficial aquifer beneath the Tillman Ridge for public
            water supplies.     On a average, every 1,000 new people will
            require at least 100,000 gallons of water per day or 35 mil-


                                        9 - 11










            lion gallons of water per year. The existing withdrawals are
            already resulting in water drawdowns and less ground water
            seepage to Trestle Swamp and the headwaters area            of the
            Moultrie Creek watershed.        Unless rainfall     water storage
            practices are initiated in St. Johns County,            neither the
            surficial    aquifer water supplies nor the existing Trestle
            Swamp wetlands can       be preserved. It is far simpler and
            more    cost effective to begin the process of protecting the
            County's    water resources for various purposes early in the
            area growth process than to attempt to restore the resource
            at some later date.

            The Cowan Swamp at the head of the Moultrie Creek channel is
            also in jeopardy. old gridiron plats and scattered residen-
            tial development      now exist within the depression storage
            area    of Cowan Swamp.     Ditching and draining is now occur-
            ring.    As more people purchase properties in this area they
            will demand drainage improvements.         Because the County per-
            mitted this type of development, the County is now obligated
            to provide for a healthy living environment for these resi-
            dents.    The preservation of the wetlands environment in
            Cowan Swamp is essential for continued base flow in Moultrie
            Creek and for the sustenance of the environment in the tidal
            estuary part of Moultrie Creek. The incompatibility of past
            governmental actions, the health of the area's environment,
            and    the public health needs of residents will require re-
            medial governmental actions        that will be costly to County
            taxpayers.    The County need only look at the multi-million
            dollar    drainage programs now being demanded by Jacksonville
            residents to see the future of the existing conditions in the
            Cowan Swamp area.

            The difficulty of preserving the Cowan Swamp is further com-
            pounded    by the extensive uncontrolled positive drainage oc-
            curring    to the east of Moultrie Creek. The water table re-
            duction    required for    the coquina mining operations can be
            expected    to gradually result in a long-term decline in the
            water table beneath Cowan Swamp          and much of the land area
            south of State Road 16. As the dewatering of the area con-
            tinues, Moultrie Creek can be        expected to experience more
            days of zero flow and longer extended        periods of zero flow.
            The dewatering effect on the general area also           can be ex-
            pected to gradually affect water levels in Five Mile Swamp
            and Four Mile Swamp.

            Finally, as the demand for potable water from the surfi-
            cial aquifer increases, and positive uncontrolled drainage







                                         9 - 12







            continues, the inevitable declines in water table conditions
            can be expected to result in the following:

                  1.   Increasing residential demands for lawn watering
                  to support landscape vegetation;

                  2.   Progressive salt water intrusion into surficial
                  aquifer areas adjacent to Moultrie Creek and the Matan-
                  zas River;

                  3.   Progressive incidents of upwelling saline water
                  from the Floridan aquifer as the weight of the fresh
                  water in the surficial aquifer is removed;

                  4.   Progressive deterioration of wetland conditions in
                  the 'tidal    parts of Moultrie Creek as fresh         water
                  discharges change from the former steady base flow rates
                  to pulses of heavy runoff following rainfalls;

                  5.   Increasing loads of sediments carried into the
                  tidal part     of Moultrie Creek along with increasing
                  runoff from rainfall;

                  6.   A gradual extension of the deteriorated estuarine
                  conditions from Moultrie Creek throughout the greater
                  St. Augustine Harbor estuary.


                 Federal Fresh Water Wetland Permits

            The U. S. Army Corps of Engineers regulatory program considers
            as waters of the United States all tributary streams to
            navigable waters to a point where flows are less than five
            cubic feet per second.      In general, this criterion is being
            interpreted as the uppermost five square miles of all water-
            sheds, but actual determination      is made on a case-by-case
            basis.    The determination of federal jurisdiction of a pro-
            posed project will be made by       the Corps of Engineers. All
            proposed development actions by private individuals or public
            agencies are subject to Corps of Engineers regulatory review.


                  Florid a Department of Environmental Regulation Permits

            Previously cited Florida Department of Environmental Regula-
            tion evaluation criteria for tidal wetlands also are appli-
            cable to fresh water wetlands.








                                        9 - 13









                    St. Johns River Water Management District Criteria

              The St. Johns River Water Management District (SJRWMD) consid-
              ers wetlands as hydrologically sensitive areas and conduct
              regulatory review of proposed developments in these areas in
              accordance with Section 373.016, Florida Statutes (Section
              40C-4.021(5),   Florida Administrative Code). Information on
              the St. Johns River Water Management District's wetland reg-
              ulatory procedures may     be obtained from: office of Rules
              and Policy Development,     St.   Johns River Water Management
              District, P. 0. Box 1429, Palatka, Florida 32078-12429.



              WETLANDS REGULATION PROBLEMS



              The enforcement powers of the federal and state government
              are being applied   to all proposed development actions that
              directly disturb    tidal and fresh water wetlands.        Govern-
              mental actions to   evaluate the effects of upland areas devel-
              opment   that can   functionally   deprive existing wetlands of
              the   surface and   ground   water essential for their mainte-
              nance is normally given limited consideration.

              Primary governmental efforts directly focus upon existing wet-
              land conditions and areas. Field inspections typically give
              limited review to the long-term functional condition of ob-
              served hydric soils, the vegetation indications of an expand-
              ing or contracting wetland condition, and the hydrological
              regime   necessary for sustaining wetland conditions for a
              given depressional area of some determined size.

              The differing jurisdictional reviews of upland wetlands are
              based upon different criteria used by the reviewing agencies.
              Private property owners still do not have clear non-conflict-
              ing   criteria to follow that may be acceptable to all permit-
              ting agencies.

              Field interpretation procedures used by the differing regula-
              tory agencies are not consistently determined among differ-
              ing   field inspection    personnel in any of the regulatory
              agencies.    The three primary field inspection criteria (hy-
              dric soils, indicator vegetation,       and actual hydrological
              conditions) require cross training and significant field ex-
              perience before consistency        in judgmental decisions is
              achievable.

              Finally, the emphasis given by all regulatory agencies is fo-
              cused upon the ability of the agency's enforcement power to
              regulate.    The desire to provide practical and useful guid-
              ance to improve the proposed development action in a manner


                                         9 - 14











            that could achieve the practical purposes of environmental
            management in an expanding urban          environment is generally
            lacking.    As a result, advocacy, confrontational, and avoid-
            ance positions      are often resorted     to by private property
            owners.



            A FUNCTIONAL BASIS FOR NATURAL RESOURCE AREA MANAGEMENT



            Natural resource areas have functional utility beneficial to
            the well being of St. Johns County residents.            These areas
            perform    a number    of functions that enhance the County's
            natural environment. These functions include:

                   1.   Retarding stormwater runoff by serving as tempo-
                   rary water storage areas;

                   2.   Serving as drainageways and flow-ways that re-
                   lieve flooding      in urban areas while also          slowing
                   stormwater runoff;

                   3.   Serving as sediment and nutrient sinks where mate-
                   rials are slowly       reduced and nutrient and mineral
                   components essential for other biological processes are
                   slowly released to streams and estuaries;

                   4. Serving as wildlife retreats or protected areas in
                   uplands    and as nursery and feeding areas for wild-
                   life, fin fish, and shellfish in estuaries;

                   5.   Serving as protected corridors for migrating wild-
                   life;

                   6. Providing commercially useful wood and other vegeta-
                   tion based materials;

                   7. Functioning as natural green space areas within de-
                   velopments separating urban land use functions;

                   8.   Functioning as a resource for local nature study
                   of climax and transitional natural vegetation;

             As    St. Johns County continues to evolve from a predomi-
            nately rural to a highly urbanized County, the need to protect
            existing natural resources and support the creation of new
            natural resource areas will become increasingly apparent. A
            balance between subdivisions and natural areas is highly de-
            sired by Florida residents.       A County management program to
            encourage the protection and enhancement of existing natural
            areas and the construction of new wetlands and woodlands as



                                         9 - 15










            stormwater    storage and drainageways would serve many County
            resident's desires.

            Management practices are needed that serve to encourage pri-
            vate property     owners to incorporate new natural        resource
            management concepts into their projects. The present emphasis
            upon    protection    of wetlands     by governmental powers at
            state    and federal levels without commensurate emphasis upon
            assistance to property owners to provide functionally effec-
            tive natural     areas achieves     little more than submission
            without empathy. The       continued loss of essential natural
            resource areas can be expected from the existing governmen-
            tal divisiveness in wetlands regulation.

            A County program that provides clear development criteria can
            be established to meet the stated intents of all state and
            federal wetlands legislation.         Such a County program will
            include    improved policy level and technical level coordina-
            tion with regional and state development review agencies. As
            the County program evolves, the need for intensive state
            and federal review will become more perfunctory.



            CREATING NATURAL RESOURCE AREAS



            Retention Storage Areas

            Retention storage requirements to accommodate the first one
            inch of all rainfalls can be constructed in a wide variety
            of forms depending upon the natural storage capacity of local
            soils.     The basic storage capacity of soils can be deter-
            mined from available Soil Conservation Service runoff curve
            number    information. All types of minor depressions can be
            created at elevations above local area annual high water ta-
            ble conditions. Swales, or elongated         depressions without
            outlets or with controlled overflow outlets, are the most
            common type of retention facility       now in use in Florida,
            but all slightly lower land          areas between raised resi-
            dence    pads and raised roadways can be used.           On essen-
            tially    flat lands with normally high water tables, raising
            residential    house pads and roadways by two or more feet
            can effectively provide the necessary detention/retention
            storage while preventing flooding of structures and flood-
            ing related transportation hazards.

            Created    sloping topography     with low berms along contours
            can serve to retain low intensity rainfalls. On slightly
            sloping land, flat benches also can be created along contours
            to     retard the sheet flow runoff.       The extensive use of
            broad, low elevation recontouring of subdivision, commer-


                                         9 - 16











            cial,    and industrial open space areas can provide the re-
            quired retention storage requirement        while effectively re-
            ducing sediment transport potentials. Where extensive re-
            working of the land surface occurs during the project con-
            struction phase, the construction of sediment basins may be-
            come necessary until a new vegetation cover is established.
            Care    in the design of the construction sediment           basins
            permit their continued use as a permanent detention/retention
            areas.


            Retention areas should be designed with overflow locations
            capable of passing the very infrequent and heavier rainfalls.
            overflow should be directed into detention storage basins,
            drainageways, flow-ways, or controlled flow discharge chan-
            nels.



            Detention Storage Areas

            Detention    storage areas are intended as temporary storage
            areas built to accommodate water depths from heavier rain-
            falls that must be stored for a short time within a develop-
            ment while discharge channels release stormwater at a con-
            trolled rate.     Any land area capable of holding water with-
            out causing flooding of structures and roadways can serve
            as detention storage areas.         These areas may be extensions
            of retention areas where the       first one inch from a subwa-
            tershed area is not      released, but water runoff accumula-
            tions to depths in excess of the one inch retention require-
            ment are released through saddles or limited capacity drain
            pipes to the major storm sewer or surface drainage system.
            Playgrounds,    general recreation areas, golf courses, wood-
            lands, created wetlands, etc., can serve as detention storage
            locations.    Where shallow drainage channels are constructed,
            tieback areas from the discharge location weir, flume, drop-
            box, etc., can be raised sufficiently and extended as low
            levees or broad berms connected to higher ground to form an
            extended detention storage area.


            Drainageways and Flow-ways

            Constructed    drainageways are intended as very low profile
            slope systems extending across broad areas that allow storm-
            water to flow      slowly.   Natural    systems may be wooded or
            wet    meadows.   When constructed within the annual elevation
            range of a local water table, the drainageway will evolve into
            a natural wetland typical of       a slough.      A natural slough
            may have a width       of several hundred feet, very gradual





                                        9 - 17










            side slopes, and maximum cross sectional depths of three or
            four feet.     Created drainageways      will   be similarly con-
            structed.

            Within developments, black willow and cattails tend to become
            the first opportunistic        vegetation to occupy these areas.
            A wide variety of other vegetation natural to north Flor-
            ida can be planted to accelerate the establishment of natu-
            ral   woodland or meadowland       conditions. As the vegetation
            becomes    established, the hydraulic roughness of the drain-
            ageway    will increase.      The design of the system will be
            based upon the flow roughness expected from the mature sys-
            tem.   Again, by weiring or other       means these areas can be
            designed to provide some detention         storage from the infre-
            quent periods of heavy rainfall.

            Flow-ways    are vegetated areas designed to accommodate the
            overflow    from    drainageways and carry runoff       from heavy
            rainfalls around drainageways or water storage facilities. As
            with   drainageways, flow-ways will restrict discharges to a
            rate of 1.5 cubic feet per second to prevent sediment trans-
            port and land erosion.        Flow-way design permitting a short
            term 2.3 cubic feet per second discharge velocity for runoff
            equivalent to the amount       expected from     the five year, one
            hour rainfall occurring on saturated soils will be accepted.
            This higher discharge velocity will be used to estimate po-
            tential runoff expected only as peak discharge            from those
            infrequent 24 hour storms expected on a return frequency ba-
            sis of 25 years and less frequent storms with still great-
            er rainfall depths.         Routine distribution of runoff from
            the 25 year, 24 hour, rainfall anticipates a short period of
            more intense rainfall.

            Flow-ways associated with drainageways have bottom elevations
            at or slightly above the normal high water table elevation
            for    the local    area.    A constructed flow-way can be flat
            bottomed or slope slightly away from the drainageway towards
            higher ground. The profile       slope of the flow-way will par-
            allel the similar slope of the drainageway. The width of the
            flow-way will be determined by hydrological analysis to, as a
            minimum, carry the remainder of the 25 year, 24 hour, runoff
            from the local watershed that is beyond the carrying capacity
            of the drainageway.

            Flow-ways    may be designed as a separate major stormwater
            runoff collectors of a total system.        These facilities will
            have bottom elevations above normal high water table condi-
            tions for a local area and will remain dry except during pe-
            riods of heavy rainfall.      A flow-way will be constructed with
            broad and shallow cross sections and with gradual sloping
            sides on the order of 1:4 (one foot rise per four feet hor-


                                         9 - 18










            izontal) or less.      Any considered     use of     steeper side
            slopes will require periodic placement of egress means to
            permit safe exit by children and animals.

            If vegetated side slopes and flow-way bottoms are to be part
            of the design, the bottom will be sufficiently broad to
            permit vehicular access within the flow-way for maintenance.
            Vegetation within the flow-way system will be limited to
            grasses and sedges.

            Broad   flow-ways    also will be designed with maintenance
            accessways on each side of the flow-way.            Open woodland
            vegetation planted outside      of grassed accessways on either
            side of a flow-way would improve the aesthetic acceptability
            of system within urban        areas.     The integration    of the
            flow-way system with other open space functions such nature
            trails or walkways and parks is encouraged.

            All   storm    sewer    feeders lines and     secondary     surface
            drains providing runoff to the flow-way will have controlled
            flow outlets and sufficient armoring of tailwater areas to
            assure   that discharge water velocities will not erode the
            flow-way's    bottom or sidewalls.      Where trails and walkways
            are designed as part of the system, outlet structures can be
            modified for use as pedestrian bridges or viewing locations.

            Outlet    localities of flow-ways will be at locations where
            flow velocities     must be increased due to designed system
            changes    of profile slope. These locations will be armored
            to prevent erosion. A wide variety of system designs can be
            used.   Gunnited or simulated rock garden spillway and water
            velocity absorbing areas can be constructed and incorporated
            into   a development's     landscaping plan.       Where such ef-
            forts   are undertaken, hydraulic design to accommodate the
            50 year or 100 year stormwater runoff conditions will assure
            a longer life for the outlet locality of the flow-way.


                 Ponds and Lakes

            Constructed    ponds and lakes have long been used in Florida
            to augment subdivisions. Most are actually borrow areas from
            which fill has been obtained to provide a desirable contoured
            landscape for the development. The use of ponds and lakes in
            new developments is an attractive amenity when properly
            constructed.    Grassed side slopes should be at least 1:4 (one
            foot vertical to 4 feet horizontal), for resident safety and
            erosion    prevention.    Gradual slopes should extend into the
            pond or lake for a distance of at least 10 feet from the nor-
            mal water elevation       shoreline. The area above the normal




                                        9 - 19










            high water table elevation of ponds and lakes can be used for
            water detention storage.

            Where    constructed in close proximity to residential units,
            the need for lakes and ponds to be able to accept runoff from
            heavy rainfalls may preclude their consideration as reten-
            tion/detention      storage facilities.      Lakes and ponds con-
            structed as an urban area amenity must retain water.             Many
            such facilities have impervious bottoms      to retain surface wa-
            ters,    and, therefore, have limited        retention potential.
            Capacity, outlet facility capability, and discharge channel
            capability    calculations will have to demonstrate the abil-
            ity    of these facilities to function effectively for both
            purposes.



                 Borrow Pits

            Borrow    pits are considered as material extraction areas with
            no further end use        anticipated. The need for sand and
            coquina extraction      for various development purposes in St.
            Johns    County is expected to expand with urban development
            and the construction of new roadways. A finish design that
            will reduce the hazard potential of these areas is neces-
            sary.    Borrow pits normally are deep excavations with steep
            side slopes.     Because the     excavation extends      below the
            normal water table, borrow        pits fill     with ground water
            seepage.

            To   reduce the hazard potential to humans and            livestock,
            these areas     will be constructed with a minimum 10 foot
            wide access roadway at normal ground elevation around the en-
            tire perimeter of the        pit. Outside of this accessway, a
            swale type parallel depression          at least 15 feet wide and
            extending to a depth of at least three            feet will be con-
            structed around the pit.       one 10 foot wide entranceway will
            permit access to the edge of the pit. Upon completion of
            use, the entranceway will be blocked by fencing or other
            means.


            The above criteria will provide a created depression             sur-
            rounding the      borrow pit that will evolve into an wetland
            populated    with opportunistic     vegetation.      Any sheet flow
            moving    towards the excavated area will first pass through
            the created wetland      environment.     Similarly, any overflow
            from the excavated area will again first pass through the
            created wetland depression.        The system normally will not
            have an overflow outlet, but a constructed drainageway to a
            nearby natural drainage system will be permitted.





                                         9 - 20













                 Greenbelt Woodlands

            Larger   developments have the opportunity to preserve           or
            create extended     greenbelt woodlands.     These areas may be
            transitional zones     extending from wetlands.       They may be
            created   extensions of existing upland woodlands. Greenbelt
            woodlands perform the a variety of functions in urbanizing
            areas.    As extensions      to drainageways, they provide pro-
            tected corridors for the migration of wildlife. In an urban
            environment, woodlands serve as recreation areas for observing
            wildlife and other nature related experiences..          Woodlands
            serve as visual natural area breaks between urbanized areas.
            Such areas also serve to alter wind flow patterns.

            Even small developments can improve the amenity value of
            properties by preserving patches of natural woodland. These
            areas   can be extended by lineal plantings of native vegeta-
            tion within     and adjacent to drainage easements and con-
            structed flow-ways.

            Created woodlands can be planted with a variety of trees na-
            tive to north Florida that provide food for desired wildlife.
            Along the fringes of created woodlands, a variety of food
            bearing vines and grasses       also can be planted to support
            desired   wildlife.    North Florida     has a rich variety of
            natural vegetation that provide sources of food and shelter
            for   wildlife and are adaptable to         urban    environments.
            Guidelines for use by property owners for this purpose can
            be prepared and distributed by the County within the context
            of its development management program.          These guidelines
            could   be developed as extensions to the St. Johns County
            Landscape (Green Law) ordinance No. 79-19.


            MANAGEMENT CONCEPTS



            Data and Information Needs

            Large land areas of St. Johns County are undergoing conver-
            sion from open space and agriculture to urban uses.             The
            current conversion is expected to continue through the fore-
            seeable future. More effective methods are needed for eval-
            uating   the impacts of proposed developments. Improved meth-
            ods for evaluating potential impacts of development are need-
            ed before land parcels are committed for development if es-
            sential County resources and existing natural areas are to be
            protected.

            This   report has identified the need to review proposed de-
            velopment actions with recognition of potential long-term im-


                                        9 - 21










           pacts upon natural resource conditions in the County important
           to the majority of residents.        A first step has been taken
           to   begin the process of developing basic and objective in-
           formation on conditions within the Moultrie Creek watershed.
           This information is now being incorporated into a computer
           geographical information system. This system and its associ-
           ated database will      permit spatial analyses that will more
           clearly pinpoint potential problems within watersheds. With
           this information, means for alleviating      existing urban area
           problems and avoiding future problems associated with proposed
           development actions can be more       clearly identified.      The
           continued extension of the process started in the Moultrie
           Creek watershed provides the most cost-effective means for
           avoiding future problems associated with expected urban devel-
           opment within the County.

           The County could benefit from revisions in the -development
           permit application process that provide for permit application
           information    to be routinely entered into      the geographic
           information system and other departmental databases. Much of
           the information presently prepared is procedural in nature and
           is readily adaptable to entry and recall as computer proce-
           dures are expanded.

           As the County moves to greater dependence upon computer sys-
           tems, procedures can be modified to reduce the departmental
           work    loads related to the permit application review process.
           Changes in the review process also would benefit applicants
           as   procedures are clarified and simplified for data entry
           and recovery purposes.

           Additionally, most property owners are unaware of the details
           of    the County's need to permit economic development while,
           at the same time, providing for the health and welfare of all
           citizens.    It is incumbent upon the County to provide clear
           information    on the   purposes of essential restrictions, as
           well as the dictates of those restrictions.

           The    process of revising development related ordinances and
           preparing    public information on the purposes and essential
           conditions of     such ordinances will require         substantial
           inter-agency     coordination    within the County government.
           This    is an internal     governmental process that can be ex-
           pected to require a significant and long-term effort.


           Natural Resource Diversity Needs

           A    need also exists to maintain a diversity of natural re-
           source areas within the County.        This can be accomplished
           through    the protection of existing areas, where practical,


                                       9 - 22











           and the creation of new areas to perform essential functions
           of natural resource areas as integral parts of new develop-
           ments within the County. The following outline lists the
           steps required to establish County-level management proce-
           dures for protecting and enhancing significant natural re-
           source areas.


                  1. Define the conditions that identify significant nat-
                  ural resources.

                  2.   Identify subtypes of each category of area that
                  would require different governmental review and action
                  procedures.

                      Develop technically supportable, and legally bind-
                  ing procedures for delineating these areas.

                  4.   Provide clear statements of the significance        of
                  each area.

                  5. Develop internal review procedures for proposed de-
                  velopment actions.

                  6.   Develop database and geographic information sys-
                  tem analysis procedures for evaluating development ac-
                  tions   and for maintaining records of the character of
                  each area, its condition, and requirements for mainte-
                  nance.


                  7.   Prepare urban and agricultural development compati-
                  bility   guidance to assist adjacent and nearby property
                  owners to undertake property improvements that will
                  not   detract from, and may improve, adjacent signifi-
                  cant natural resource areas.

                  8.   Prepare performance standards applicable to fu-
                  ture adjacent and nearby property improvements.

                  9.   Prepare a clear and simplified application and a
                  one-stop    development approval process to be fol-
                  lowed by property owners.

                  10.   Provide, as available and where applicable, tech-
                  nical guidance, assistance, and support to property
                  owners when parallel development approvals must be ob-
                  tained from regional, state, and    federal offices.

                  11. Develop and consistently implement, reasonable, le-
                  gally    unambiguous,    and cost effective enforcement
                  mechanisms applicable     and applied evenly to all pro-
                  posed   development actions to assure that the County's


                                       9 - 23











                 natural resources and conditions that protect the pub-
                 lic health and welfare are preserved or enhanced by
                 each proposed development action.


           General and Public Information Needs

           Additional general information on the area's resource manage-
           ment problems is needed. Information that would permit gov-
           ernmental operations personnel to recognize the need for
           changes in operations practices would be highly beneficial.
           Information that would permit policy-level bodies to respond
           to, and apply,     the most cost-effective     measures for the
           benefit of all      residents also    should be prepared. Fi-
           nally, property    owners who wish to invest in         the area
           should be able to  obtain clear guidance on County management
           purposes, as well  as the letter, of development restrictions.

           The general public also needs improved information on the
           meaning of regional      water management and how changes in
           policies    and practices will affect their lives and the cost
           of living within the area.       The process of regional water
           management will require improved educational Anformation
           for use in County schools. Information is needed on real
           problems in St. Johns     County and how     individuals make a
           difference in solving problems and in creating a more de-
           sirable living environment for everyone.      The above actions
           provide a means for developing the support and the consent
           from    St. Johns County residents for improved       County re-
           source management practices.























                                      9    24


















                                             10


                                 WATER MANAGEMENT PROGRAM



              BASIC PROBLEMS



              This study has identified a broad range of water related prob-
              lems that are interrelated. The general public has a very
              limited perspective of County water management needs. Gen-
              eral County government concepts focus primarily upon the need
              to drain areas and prevent     flooding.     The public tends to
              become concerned with a government's water management pro-
              gram for short periods following     rare and extremely heavy
              rainfalls   or storms    that cause catastrophic conditions.
              Many years may elapse between natural events that cause se-
              rious   problems. The governmental related problems result-
              ing from each event are remembered by too few people.

              As   St. Johns County continues to develop, the individuals
              who witnessed previous heavy rainfalls, flooding events, and
              the host of problems associated with such natural occurrences
              will become smaller proportions of the County's total popula-
              tion. The newer population will be unaware of potential wa-
              ter   related problems and will be less tolerant of resulting
              conditions.

              For   example, earlier residents of Florida living in a more
              relaxed environment were much more tolerant of street flooding
              than current populations.     St. Johns County is rapidly be-
              coming a residential County for people working in the greater
              Jacksonville metropolitan area.      These newer residents will
              be less tolerant of periodically flooded streets that hinder
              daily activities or make living conditions more hazardous.

              All residents are concerned about the increasing cost of gov-
              ernmental functions. The water management program outlined in
              this report will result in some increased governmental imple-
              mentation costs.      Either the increased costs are levied
              against new developments by initially requiring the use of
              higher levels of technology,      or the costs are transferred
              to the general population at a later time through higher lev-
              els of governmental facility repair and future remedial ac-
              tions.



                                           10 - 1










             Sound   engineering   practices exist to prevent     or reduce
             water related infrastructural problems and natural resource
             deterioration.   The following information is provided as sug-
             gested   guidance for a County-wide water management program.
             The   information is    intended only for use as a base for
             internal discussions within St. Johns County during the de-
             velopment of a scope and structure of a program acceptable
             within the County.



             ST. JOHNS COUNTY WATER MANAGEMENT PURPOSES



             Basic Concepts

                   1.   St. Johns County is a highly desirable place to
                   live, but experience shows that haphazard development
                   can   be detrimental    to the interests and concerns of
                   the majority of the area's residents.

                   2.   Development will continue to occur throughout the
                   County and it must be accommodated.

                   3.   The County can absorb all prospective growth with-
                   out resorting to progressive destruction of the region's
                   water and other natural resources.


                   4.   County water and other development management ac-
                   tions can provide      for sound economic growth while
                   continually improving the living amenities of the area.

                   5.   Careful review of proposed development actions and
                   pre-development resolution of potential problems are
                   more cost effective actions benefiting the majority of
                   St.   Johns County residents than future remedial ac-
                   tions that may become necessary to correct development
                   related problems.

                   6.   County governmental review of proposed       develop-
                   ments must focus upon the potential long-range costs
                   to   County residents of a proposed development and the
                   manner in which a proposed development will impact upon
                   .area environmental amenities    and the social and eco-
                   nomic well being of the majority of County residents.

                   7.   Private property owners and developers must recog-
                   nize that the potential profitability of a proposed de-
                   velopment action is     a private concern to be evaluated
                   within the framework of County development constraints
                   considered by the majority of residents as essential for


                                          10 - 2











                  the maintenance of    their health, social and economic
                  well being, and the area's natural resources.

                  8. The majority of individual property owners, develop-
                  ers, and associated legal and technical representatives
                  do care about the local area and are willing to ensure
                  the long-term contribution of their development to the
                  area's well being through careful actions and adherence
                  to County water and natural resource management con-
                  cerns.


                  9.   The County government is obligated to develop and
                  maintain a comprehensive understanding of the social
                  and economic concerns of residents, general growth man-
                  agement needs, and criteria essential for designing and
                  developing projects     that will not damage and can im-
                  prove   the infrastructure, water, and other natural re-
                  sources within basins or other regions in the County.

                  10. The County government is further obligated to pro-
                  vide essential guidance and assistance to individual
                  residents and property owners to assure that proposed
                  development actions are undertaken within the framework
                  of County water and natural resource management goals,
                  objectives, and development constraints.

                  11.   Strong and effectively implemented county pro-
                  project, construction period, and post-project enforce-
                  ment measures are necessary and essential to protect
                  the   County's resources,     the public health, and the
                  social and economic well being of 'Majority of the County
                  residents.



           Moultrie Creek Watershed


                 Concepts

                  1.   The water supply and environmental resources of
                  the entire St. Augustine metropolitan area are af-
                  fected   by County water management decisions made re-
                  garding proposed developments in the Moultrie Creek wa-
                  tershed.

                  2. The region's economic growth potential, individual's
                  costs   of living, and the St. Augustine metropolitan
                  area's social, economic, and environmental amenities
                  will be detrimentally affected by continuation of hap-
                  hazard development and uncoordinated proposed develop-
                  ment review procedures in the Moultrie Creek watershed.



                                         10   3











                  3.   Basic information being prepared for the Moultrie
                  Creek watershed is still incomplete, but newly assembled
                  materials identify problems sufficiently to provide di-
                  rection for County actions needed to further improve
                  the County's ability to provide for the health and so-
                  cial and economic well being of Moultrie Creek water-
                  shed residents.

                  4.   Coordinated development review procedures will be
                  required among County government agencies          with re-
                  sponsibilities for protecting the public health, social
                  and economic well being of residents, and the County's
                  infrastructural base (rcads, drainage, and utilities).

                  5. Coordinated programs, with direct and continual par-
                  ticipation    among all local governments, will be re-
                  quired    to assure the adequacy in quality and quantity
                  of the regional water supplies and the protection of
                  the region's environmental attributes.

                  6.   An expanded program is needed immediately within
                  the County     Engineering    Department to prepare       and
                  distribute improved development related guidance for use
                  by individual property owners and large land developers
                  based upon sound and current engineering principles
                  that reflect the total water       management needs of the
                  County within the Moultrie Creek watershed.


                 Subbasin Stormwater Management

            Engineering    Department capabilities currently       are being
            fully utilized      for permit application        reviews,     pre-
            application    site inspections, and emergency field inspec-
            tions.   Further formalization of these current activities to
            provide information suitable for identifying subbasin loca-
            tions of inspected sites can provide much of the required da-
            tabase information necessary for subbasin analyses.              As
            capabilities within the Engineering Department increase and
            fuller data are entered into the geographical          information
            system,   further development     of information    on     existing
            stormwater management systems     essential for subbasin evalua-
            tions can be assembled.

            Subbasin stormwater management    procedures consist of analyses
            of existing systems in platted    areas to determine operational
            functions    and improvement needs.      The analyses provide a
            means   for the Engineering Department to determine potential
            effects of new developments which propose to connect to old-
            er conveyance systems.       This process will be applied to all
            problem   areas where new subdivisions have been constructed


                                          10 - 4











           in recent years and still additional new development is pro-
           posed within a subbasin.      The process is specifically needed
           to establish the potential, long-term impacts of continued
           and total development upon natural stream courses and final
           receiving water bodies.

           Eventually, the County will have to undertake the rehabilita-
           tion of older systems within some platted areas. Master plan
           preparation     and the construction of systems within exist-
           ing    platted areas    also will have to be undertaken by the
           County.    Subbasin analyses of these areas by the Engineering
           Department will provide necessary information on the reha-
           bilitation needs of      older drainage systems accepted by the
           County.

           The following information outlines stormwater management an-
           alysis    procedures useful for subbasin level evaluations of
           potential    impacts from new development       and for remedial
           stormwater system rehabilitation and reconstruction. Primary
           evaluation considerations      for the above purposes would in-
           clude  the following:

                  1.   Segmentation of watersheds and delineation of sub-
                  basin hydrological units       or areas with similar types
                  of   Water conveyance. Wetland      preservation analyses
                  would require such delineations to include the proba-
                  ble ground water contribution areas and surface water
                  drainage area supplying water for the wetland's suste-
                  nance.


                  2. Field inspection of all conveyance units (natur-
                  al streams and      drainageways, channels,      and struc-
                  tures) to establish     existing conditions and need for
                  improvement of each unit identified. The condition and
                  capacity of each conveyance segment and each structure
                  must be established. This process requires a standard-
                  ized evaluation process based upon previously accepted
                  engineering criteria.      The conveyance capabilities of
                  natural and constructed segments must be determined.
                  The field inspection process also will identify those
                  natural systems that can be      improved and those sys-
                  tems that must be preserved in existing conditions.

                  3. Subbasin hydrology will establish expected run-
                  off conditions, retention storage requirements, and the
                  hydraulic    adequacy of the existing natural and con-
                  structed conveyance systems. For new subdivisions, the
                  developer      is required    to   prepare a hydrological
                  analysis.      Once the County accepts plats and con-
                  structed   drainage systems, maintenance and rehabilita-



                                          10   5











                  tion normally become County or homeowner association re-
                  sponsibilities.

                  4    The hydraulic analysis of existing conveyances
                  will include    identification of utilities,       roadway
                  segments, private ingress points to roadways, and other
                  factors   that are affecting the overall system's per-
                  formance. A rating system for determining the signifi-
                  cance of each constraining     factor will be developed
                  as a basis for determining necessary improvement and
                  for scheduling such improvements.

                  5. The above rating system will include means for eval-
                  uating impacts upon natural areas and constructed con-
                  veyance system components. Included in the rating system
                  will be an estimate    of direct costs for improvements
                  and cost estimates     for subsequent improvements re-
                  quired at downstream locations.

                  6.   The above information will provide estimates of
                  costs to the County resulting from continued develop-
                  ment   within subbasins.   This information will permit
                  the   County to establish potential impacts on existing
                  systems resulting from new subdivisions. The informa-
                  tion also provides a basis for determining County costs
                  for improving stormwater management systems in older
                  platted areas.

                  7.   once basic subbasin hydrological and hydraulic
                  data have been developed, the probable effectiveness of
                  detention and retention storage procedures can be as-
                  sessed more completely.    These assessments are partic-
                  ularly important for maintaining      significant natural
                  resource areas.     In upland    areas, the assessments
                  will establish the water regime provided to wetlands.
                  In tidal areas, the concern is oriented towards a re-
                  duction of strong pulses of stormwater immediately fol-
                  lowing rainfalls and the need to increaselin base flow
                  from ground water seepage.

                  8. A program to address the ongoing and existing prob-
                  lems in watersheds and subbasins of each watershed pro-
                  vides   the basis for watershed stormwater management.
                  The   effort requires the development of hydrological
                  and hydraulic data, evaluation of existing conditions,
                  determination of impacts from new developments, esti-
                  mates of costs for necessary improvements undertaken
                  by the County, and a schedule for undertaking the re-
                  quired improvements.





                                        10 - 6











           The above process will require the County Engineering Depart-
           ment to allocate some part of its routine operations to the
           identification of primary stormwater management problem areas
           within the County. Field inspections have already been con-
           ducted to determine      the conditions of major structures in
           the Moultrie Creek watershed. The conveyance unit condition
           and capacity determinations remain to be undertaken. These
           data are being placed in the geographical information sys-
           tem database as non-priority entry items.

           The   Engineering Department has the technical capabilities
           for undertaking the subbasin analysis process, and necessary
           analyses can    be undertaken as sufficient staff engineers
           and engineering technicians are trained to conduct other re-
           view and inspection functions.     Subbasin analyses and master
           plan type system rehabilitation     analyses are normally un-
           dertaken by internal staffs of large municipalities and coun-
           ties.

           Effective   stormwater management coupled with broader water
           management needs of St. Johns County require the development
           of an active program for subbasin analyses within the Engi-
           neering Department. Computer technology for undertaking nec-
           essary evaluations are now readily available and inexpensive.
           Microcomputers sufficient for these analyses are being used
           within the Engineering Department.      The geographical infor-
           mation   system database information is being assembled. A
           program for the gradual development of the subbasin analysis
           process   can be accomplished    as departmental staffing needs
           are met.



           COUNTY ENGINEERING DEPARTMENT FUNCTIONS



           Program Development Efforts

           The   St. Johns County Commission recognizes the need for an
           improved   operational program within the County Engineering
           Department.   Changing long standing practices is a complex
           and difficult process. Sound engineering decisions require a
           staff of trained professionals.       Modern water management
           practices in Florida require that professional engineers and
           technicians in the County Engineering Department have compe-
           tent backgrounds in current techniques for evaluating exist-
           ing and potential effects of ground water and surface water.
           The County Engineering      Department must be able to provide
           current technology guidance to County officials and the public
           on: (1) flood potentials, (2) reducing flood hazards,(3) pro-
           tecting   ground water resources, (4) providing water control
           measures   to protect    and enhance significant natural re-


                                        10 - 7











            sources   within the County, (5) assuring that private water
            control measures do not pose a future hazard that may result
            in damages to public and private properties or harm to resi-
            dents, (6) and assuring that sound, up-to-date engineering
            principles are used in the construction         and maintenance of
            the County's very high cost infrastructure (roads, drainage
            systems, and utilities).

            Over   the past several years, the County Commission has pro-
            vided for the gradual transition of the County Engineering
            Department operations to provide for the ongoing and future
            growth   within the County.      As part of this transition pro-
            cess, the study of the Matanzas River - Moses/Moultrie Creek
            watersheds was initiated to identify water related develop-
            ment problems and a means for resolving existing and pre-
            venting future water management problems within these wa-
            tersheds. This initial study        effort was oriented towards
            the assembly of base level information needed for water man-
            agement purposes.

            The second phase of the study effort has focused on the Moul-
            trie Creek watershed.       A concentrated effort has been un-
            derway to finalize the assembly of basic technical infor-
            mation   on the watershed, while,        at the same time, pre-
            liminary    departmental procedures for using the newly avail-
            able information were identified and initiated. Part of this
            process has included improved inter-departmental coordina-
            tion and immediate use of newly developed data and informa-
            tion.   A final part of this study effort has been oriented
            towards the identification of changes needed in the Engineer-
            ing Department's water management procedures and operations.
            While the focus of the study has been on the Moultrie Creek
            watershed, the watershed has served primarily as a model for
            improving the Engineering Department's response to development
            problems throughout the County.


            Basic Data and Information Development

                 Purpose

            The County Engineering      Department has been faced with the
            problem of reviewing development requests while technical
            information needed      to determine the regional water, other
            natural    resource, and infrastructural       effects of proposed
            development actions have been lacking.         Under conditions of
            slow growth, small population centers, and primarily distrib-
            uted rural land use patterns, pressures on County water re-
            lated resources were limited. This condition           has changed,
            and urban development pressures exist and are expanding
            throughout much of the County.


                                           10 - 8











            Without adequate data and information and a development re-
            view   program applicable to, and evenly applied to,            all
            proposed development projects,       little potential exists to
            maintain   or enhance the County's water and other natural re-
            sources.    Failure to implement      a fair and effective pro-
            gram   applicable to all potential development actions will
            result in: (1) the continued      deterioration of the County's
            natural resources, (2). the ultimate spread of the deterio-
            rated urban blight conditions in those developments which do
            not   provide suitable living conditions required by future
            residents, and (3) extremely high future costs to long term
            County   taxpayers for remedies to solve problems created by
            permissive   governmental actions.      A number of very large
            scale developments are currently in planning stages in St.
            Johns   County.     Numerous other smaller satellite projects
            also are already underway or are being planned. The quality
            of   future water and other natural resource conditions and
            the general quality and cost of living in St. Johns County
            will be heavily impacted by the combined effects of these
            current and planned development projects.


                 Geographical Information System

            In   recognition of the need to begin the process of devel-
            oping improved base data, The County Commission authorized the
            purchase and     development    of a computer-based     geographic
            information    system.    Initial development      of this system
            also was supported by the Florida Department of Environ-
            mental Regulation as part of the Moultrie Creek watershed
            study.

            A   computer-based geographical information system permits
            the development, maintenance, and evaluation of data in more
            effective formats than were previously possible. The process
            requires the digital coding of specific types of data keyed
            to a location. Wide       varieties of data can be entered and
            recalled   for evaluation.      Any combination of data can be
            recalled   for a single location or locality            for visual
            review.   This aspect of the system is now in use by the
            Engineering   Department for      those locations and localities
            with data entered into the system.

            Basic information being coded into the system includes Soil
            Survey Data, topographic data, natural drainage system data,
            property plat data, roadway data, water and sewer utilities
            data,   constructed drainage facilities data, floodway and
            flood prone area data, and natural resource areas data. Zon-
            ing data remain to be entered into the system. Various types
            of socioeconomic and land use information being developed by


                                          10 - 9











            consultants will be entered into the system as the data be-
            come available.      Plans are underway to expand soil survey
            data to include more engineering         criteria available       for
            soils conditions and data on natural water table conditions.
            A wide variety of other specialized types of information are
            being considered for entry into the system by other County
            agencies.    System expansion and networking procedures           for
            these    purposes are     underway.    Also being     studied, are
            data exchange programs with regional, state, and federal agen-
            cies.     A variety of     data on St. Johns County are being
            collected    and maintained on other database systems. Proce-
            dures and arrangements for obtaining data useful for County
            management purposes need to be developed.

            As the above information is entered into the system, it is be-
            coming practical for the County to provide property owners
            with improved data essential for designing projects and for
            meeting County development constraints. Much of the infor-
            mation being incorporated into the system was previously
            unavailable to property owners and small developers in under-
            standable forms      and at a reasonable cost.         A program is
            planned to     develop procedures to make basic information
            available at a reasonable cost and to permit controlled ac-
            cess to the system by technical professionals who are will-
            ing to obtain training in the use of the system.

            A geographic information system represents a level of tech-
            nology that requires care in development and operations.
            Personnel entering data into the system require training in
            the    system operations and an understanding of the signifi-
            cance of the data being entered.           Academic and commercial
            training    programs    for these purposes      are not available,
            and on-the-job training in County Engineering Department op-
            erational, requirements is needed and must           be developed.
            Effective use of the system         will be dependent      upon the
            quality of the people employed by the County to operate and
            maintain the system.

            A    geographic information system is not viable as a pur-
            chased service. Engineering Department review personnel must
            be trained in data entry and access procedures to be able to
            perform    their normal     functions. Two levels of data entry
            are required. Initial digitizing or scanning can be accom-
            plished    by individuals with limited training. Some Engi-
            neering    Department    technical review personnel are already
            trained to undertake the first step of digitizing incoming
            data.     A second step  consists of editing the digitized in-
            formation before final   entry into the system.

            Editing and finalizing data require a more complete under-
            standing of the performance          levels required by users of


                                           10 - 10







            the   system. Complete documentation procedures for train-
            ing   personnel    and monitoring     both levels of data entry
            need to be developed for each type of data being incorpo-
            rated into the system.       This process has been started but
            must be fully developed and applied to each new type of en-
            tered data.

            The start-up of the system also identified the need for stan-
            dardizing database system management.      Initial data has been
            entered for     the Moultrie Creek and Moses Creek watershed
            studies.     As data for other parts of the County or for use
            by   other County departments are entered into the system,
            standardized    procedures for entering and accessing data for
            the entire County will     have to be fully       documented. As
            the information is assembled in standardized forms, it will
            become practical to array and display various types of infor-
            mation for any small or large        geographical area     in the
            County.   Similarly, numerical data representing any desired
            area   in the County will become easily accessible, and mea-
            surements    of area-wide conditions or attributes at some
            location will become available for evaluating             proposed
            developments.

            Geographical information system management decisions will have
            to be made for every new system user within the St. Johns
            County government.     Decisions    will be needed to       deter-
            mine whether information suggested for incorporation into the
            system is critical or not essential information. Every type
            of data to be entered has a cost. Data must be developed,
            entered   into the system, and stored as part of the system.
            Costs are associated with each of these functions. If de-
            sired data are not to be used widely or regularly, a decision
            will have to be made on whether the costs of assembly and en-
            try are worthwhile.

            As   data are entered into the system, the database storage
            requirements for each attribute or overlay must be determined.
            If stored off the system, procedures must be developed for
            loading and unloading      the data for some use.       Management
            decisions    to control access to the system also must be de-
            veloped.   Complete documentation of the geographical informa-
            tion management process and       a priority schedule for system
            development within available County budget constraints also
            must be developed.

            The   development of the system management process is un-
            derway within the Engineering Department.         A framework for
            the   management process and a schedule for the long term de-
            velopment    of critical database information for other areas
            within the County      and other user departments within the
            County will be prepared during the current fiscal year.


                                          10 - 11















                Guidelines

            The   Engineering Department recognizes the need to provide
            improved guidance to individual property owners and large de-
            velopers    desiring to undertake      developments within the
            County.   This report provides outlined information on many of
            the water management related types of information that must
            be developed.     Individual property owners and small devel-
            pers do not have access to the full range of professional
            engineering        services   available    to large developers.
            0

            Additionally, many small engineering        firms do     not have
            ready access to adequate technical information for evaluat-
            ing   the inter-relationships     of ground and    surface water
            management.     Similarly, it is difficult, confusing,          and
            costly for    individuals    to be responsive to      the varied
            environmental rules     of local, regional, state, and federal
            enforcement agencies.

            The   Engineering Department has begun the process of devel-
            oping fundamental information for use by private individuals
            reguesting applications for developments. The initial guide-
            lines   will consist    of hydrological and hydraulic analysis
            procedures   that will be acceptable to the Department. Much
            of the information outlined in this report gradually will
            be expanded upon and restructured as guideline information
            to be provided for use by individuals        interested in some
            form of development action.      The Engineering Department will
            coordinate'the guideline preparation efforts with other local
            and regional agencies in an effort       to incorporate simpler
            and more consistent procedures for individuals to follow dur-
            ing a development action.

                 Technical Investigations

            This study of the Moultrie Creek watershed identified prob-
            lems    and conditions which require further investigation.
            The   study has raised questions concerning an apparent need
            to improve  water recharge to the surficial aquifer lying be-
            neath the   watershed. Questions have been raised about cur-
            rent drainage practices and potential impacts upon signifi-
            cant natural resource areas.     The need to develop clear means
            to delineate areas considered as significant natural resource
            areas also was     noted. Concerns     have been raised by the
            Department   of Environmental Regulation about potential pol-
            lution of the greater St. Augustine estuary from roadway
            drainage and other urban activities. Potential hazards from
            septic tank effluents draining into estuarine waters or con-
            taminating ground water supplies have been raised.



                                          10 - 12











            The above issues represent potential problems within the Moul-
            trie Creek watershed that require further evaluations. A need
            exists to determine the significance of identified potential
            problems to establish which of these concerns require immedi-
            ate   governmental actions and the degree of action needed to
            resolve each problem. In some         cases, early governmental
            action can be      adopted and effectively administered          to
            reduce potential hazards to        the health, and socioeconomic
            welfare of residents, and water and, other natural resources.
            In   other cases,    further evaluations       to establish the
            most cost effective measures to be undertaken by the County
            would be the more prudent     governmental    action.    A number
            of the problems identified require further discussions with
            residents    of the County to determine the extent of local
            concerns.    This process of public discussion of potential
            problems   is highly recommended.      Residents' concerns and
            their   willingness to support measures that require higher
            levels of technical information and greater governmental con-
            straints on development actions       must, in effect, guide the
            decisions of the County Commission.

            As development pressure occurs in other parts of St. Johns
            County,   some problems similar to those identified in the
            Moultrie Creek     watershed will be identified.       The County
            does   not have sufficient funds to undertake detailed in-
            vestigations    of all potential problem areas.        A priority
            schedule of topics and locations where detailed technical
            studies are needed must be developed.       This effort is being
            undertaken by the Engineering Department.          A schedule of
            needed investigations     will    be developed during the 1990
            fiscal year.

            Every effort will be made by the Engineering Department to ob-
            tain supporting assistance for needed studies from other
            sources.   This report was prepared with technical assistance
            from the U. S. Army Corps of Engineers through the Corps of
            Engineers    State Planning Assistance      (Section 22) Program.
            The   Moultrie    Creek study was initiated through a Coastal
            Zone Management Grant from the Florida Department of Envi-
            ronmental    Regulation.     St. Johns County is now initiating
            a shared effort with the St. Johns River Water Management Dis-
            trict to develop basic topographic       and soils     information
            for that portion of the lower St. Johns River basin located
            within St. Johns County which is currently under heavy devel-
            opment pressure.     Soils data for the Moultrie Creek and
            Moses Creek watershed were digitized for inclusion          in the
            County   database through an agreement with the U. S. Soil
            Conservation    Service.     Similar   data for    the lower St.
            Johns River basin will become available within the next year.
            Additional studies are needed to determine stream flow char-
            acteristics    in watersheds under development pressure. The


                                          10 - 13










           Engineering Department is investigating current needs and the
           ability of the County to obtain assistance from the United
           States Geological Survey for necessary information. Efforts
           by the Engineering Department      to extend essential technical
           information needed for effective water management          through
           cooperative    efforts and various     forms of interagency as-
           sistance will continue.

           Finally,     the findings of studies      will be prepared for
           distribution and will be provided to County residents. In
           some   cases, complete reports will be reproduced for dis-
           tribution    at nominal costs.     In other cases, summary data
           and information will be prepared for general distribution.
           Much of the technical      data gradually will be incorporated
           into the County database system for use by County agencies
           and the public. Findings of investigations also will be dis-
           tributed to other governments on a reciprocating basis.


                Public and Educational Information

           The   primary functions of the County Engineering Department
           can only be accomplished when the majority of residents un-
           derstand and accept the County's resource management needs.
           Highly    technical information must be summarized and pre-
           sented    in terms readily understandable by residents. The
           previously noted guidelines represent one type of such infor-
           mation.    However, a need exists to prepare general infor-
           mation on technical     aspects of water     and other natural
           resource management as a service to County residents.

           The   County's water and other natural resource         management
           needs are appropriate topics for study and discussion in local
           schools. The County will cooperate with school system rep-
           resentatives in the development of resource materials for lo-
           cal educational purposes.


           Intra-Agency Coordination

           Coordination with other agencies of the St. Johns County gov-
           ernment    occurs at administrative and technical levels.      The
           County Engineer is responsive to activities of other depart-
           ments      that require Engineering     Department     assistance.
           Throughout the Moultrie Creek study period, new information
           developed as a result of the study has been reviewed to deter-
           mine applicability for use by other departments.          Meetings
           have been held with other departments      to exchange pertinent
           information and to determine the future course of action
           needed.




                                         10 - 14













            On   technical staff levels, information        exchanges between
            the Engineering Department and other departments are essen-
            tial.     The Engineering Department routinely provides,other
            departments with a variety of technical information.


            Inter-Agency Coordination

            The   County Engineer regularly meets with counterparts            in
            other local     governments and with representatives        of re-
            gional,    state, and federal      agencies. Each major develop-
            ment   action requires significant       coordination efforts to
            resolve    management level problems evolving from the action.
            Differing technical positions among agencies must be under-
            stood and resolved in a manner        that satisfies County con-
            cerns.

            Engineering    technology is continually advancing and tech-
            nical positions of regional, state, and federal agencies pe-
            riodically change. The County Engineer is required to attend
            meetings    with other governmental bodies when proposed rule
            changes and     technical requirements of those agencies are
            likely to impact upon St. Johns County.

            Through the above coordination activities, the County Engi-
            neer can more effectively convey St. Johns County interests
            and concerns to other agencies. Technical discussions of new
            engineering advances and other technological changes advanced
            during the coordination process permit the County Engineer to
            identify    new programs    and sources of technical assistance
            that would benefit the County.

            Coordination with other governmental agencies also is under-
            taken by the Engineering Department's technical staff. Much
            of   this process occurs during the exchange of technical in-
            formation.    The process provides valuable insight into the
            technical    operations     of other agencies.        This process
            provides guidance on technical procedures that may improve
            the Engineering Department's operational practices.             Reg-
            ular   discussions are held between the County Engineer and
            internal staff to identify factors that may lead t       o improved
            inter--governmental coordination results.










                                           10   15












            ST. JOHNS COUNTY DEVELOPMENT PERMIT APPLICATION PROCEDURES



            Clearance Sheet Procedures

            The following is a summary of the current process required by
            any individual interested in undertaking a development action
            within St. Johns County-

                   1.   A Clearance Sheet must be obtained from the 911 of-
                   fice.


                       a. The St. Johns County Clearance Sheet for Build-
                   ing Permits outlines      the entire process required for
                   all construction and mobile home permits.

                       b.   The 911 office maintains a database of street
                   addresses    for mailing and emergency purposes.          This
                   office requires the applicant to verify the property
                   owner, legal description       of the property, the public
                   street   to which    the property driveway is connected,
                   and the address of the property.        The office then re-
                   cords the real estate tax number and a tax assessor's
                   map number on the Clearance Sheet.

                       C.   The 911 office is located at 4425 Avenue A,
                   Building A, located immediately off Lewis Speedway Drive
                   and   across the street from the County Administration
                   Building.

                       d. Telephone Number (904) 829-5722.

                   2.   Once the Clearance Sheet process at the 911 office
                   is complete, the applicant continues the processing
                   procedure at the Engineering Department. The Engineer-
                   ing   Department assigns a file number to the Clearance
                   Sheet and performs the following:

                       a.   establishes a census tract location for the
                   property;

                       b.   determines the National Flood Insurance Program
                   zone number,     Flood Insurance Rate Map Panel Number,
                   determination     of whether the property is subject to
                   flooding or     is in a floodway or velocity zone, the
                   first floor elevation criteria requirement;

                       C.   determines whether the property is located on
                   undrained hydric soils. Proposed developments on und-
                   rained hydric soils normally may require wetland permits
                   from the St. Johns River Water Management District, the


                                           10 - 16











                  U.  S. Army Corps of Engineers, and/or the Florida De-
                  partment of Environmental       Regulation.    The wetlands
                  permit will establish the jurisdictional line for the
                  wetland and those development actions that are permit-
                  ted in the wetland. The Engineering Department notes
                  the jurisdictional line, and;

                      d.    establishes   the types of utilities       planned
                  (well, public water system, septic tank, sewer system)
                  and written proof     of the arrangements undertaken for
                  these   services. An Engineering Department release is
                  part of the Clearance Sheet process if the applicant
                  intends to apply to the Health Department for a septic
                  tank permit. The Engineering Department also;

                      e.    establishes,    as applicable, the location of
                  the proposed development with respect to the County's
                  coastal building zone;

                      f. establishes the type of access required for spe-
                  cific types of developments abutting specific classes
                  of roads in the County;

                      9.    establishes   criteria and adequacy of plans
                  for, property drainage.

                      h.    The Engineering Department is located in the
                  County Administration Building at 4020 Lewis Speedway
                  Drive;

                      i. Telephone Number (904) 824-8131, extension 207.

                  3. Following completion of the Engineering Department
                  review, the next permit processing step requires a re-
                  view by the Planning and Zoning Department. The Zoning
                  review:

                      a.    establishes the property zoning category and
                  zoning district;

                      b.    establishes pertinent physical characteristics
                  of the property;

                      C.    establishes any other zoning restrictions or
                  problems associated with the property;

                      d.    determines whether County subdivision require-
                  ments are met;

                      C.    establishes other significant information to
                  be noted regarding division of the land, and;


                                          10 - 17














                      f.   for commercial and multifamily properties, de-
                  termines the applicability of the County Landscaping re-
                  quirements.

                  4.   Application    for an actual building permit from
                  the Building Department follows the above steps. The
                  Building Department requires completed Clearance Sheet
                  information as a basis for a separate application pro-
                  cess to obtain a building permit,        electric permit,
                  plumbing   permit, and mechanical permit. In addition
                  to Clearance Sheet information, the Building Department
                  requires the following prior to issuance of a building
                  permit:

                      a. Notice of Commencement;

                      b.   Completed arrangement for utilities and/or nec-
                  essary Health Department permits;

                      C.   Completed and signed building permit applica-
                  tion;

                      d.  Building Department information sheet;

                      e.  Three sets of structure design plans;

                      f.  Completed energy compliance forms;

                      9-   Flood hazard information and first floor eleva-
                  tion restrictions, as applicable.

                      h. The Building Department is also located in the
                  county Administration Building.

                      i. Telephone Number (904) 824-9185.


            During the above process, the      Engineering Department must
             pprove   final   paving    and drainage plans and     road and
            bridge plans for projects requiring site plan review and ap-
            a

            proval, pursuant   to the ordinance 86-4. These approvals are
            required prior to  issuance of a building permit. Due to man-
            power limitations, no further Engineering Department reviews
            are normally conducted prior to final issuance of a Certifi-
            cate of Occupancy.






                                         10   18










            Permit Application Improvement Needs

            The above Clearance Sheet process is complex, costly to ap-
            plicants, and costly to taxpayers to implement.       The diffi-
            culties encountered     by a first-time applicant proceeding
            from   initial contact with the 911 office to completion of a
            project are substantial.       The complexity of the existing
            process is not conducive to the development of even greater
            development    constraints that may be necessary to protect
            and enhance County water and other natural resources.

            As growth continues, changes in the current development ap-
            plication process will be mandated. Confusion in the mind
            of an applicant becomes translated into frustration. Appli-
            cant   views of    governmental    bureaucracy and inefficiency
            tend   to emerge. These views        often become attitudes that
            can lead- to difficult discussions       related to the applica-
            tion process at each stop the applicant must make.       The pro-
            cess can lead to substantial difficulties for application re-
            view personnel in each department.

            The  Engineering Department presently does not have enough
            trained personnel to perform necessary reviews and inspec-
            tions.   Increasing levels of water, other natural resource,
            and roadway needs require well-trained staff personnel, and
            these are difficult to find at salaries the County gov-
            ernment can afford to pay. The ability to obtain and retain
            well   qualified personnel can be expected to become more dif-
            ficult.

            The additional staff required by the Engineering Department
            will dictate the need for more physical space. other permit
            application    review departments can be expected to experi-
            ence similar   conditions.    The permit application process can
            be expected    to result in continually increasing cost to St.
            Johns County residents.       A need exists to clarify and sim-
            plify the existing permit application process.


            One-Stop Permit Process

                 Management Premise

            A   well-managed government conveys to the public an image
            of providing a positive and desired service. Each contact a
            government    representative has with any resident or his rep-
            resentative conveys      a view to the public of governmental
            management    effectiveness    and   efficiency.    The following
            process   outlines some methods by which a positive image of
            government can be conveyed and actual efficiencies in the
            permit application process can be obtained.


                                          10   19















                 Clearance Sheet Process

           The     Clearance Sheet Process can be improved by the fol-
            lowing actions.

                   1.    A general guideline document of the' development
                   permit application process steps is needed. This docu-
                   ment   would serve     as an initial training device for
                   new governmental employees and as a clear guide useful
                   to all individuals      who wish to know more about the
                   governmental development       management processes.       The
                   guideline    document would be written to help the public
                   understand the purposes of governmental imposed con-
                   straints upon developments.         It would be written to
                   provide clear guidance on the information and materials
                   that must be supplied to the government by the individ-
                   ual.   Where additional guidance and detailed direction
                   is necessary, the guideline would provide clear instruc-
                   tions on where to go and what must be done by the ap-
                   plicant to satisfy additional governmental procedures.

                   Satisfying    the complex requirements of the develop-
                   ment permit application process requires significant
                   technical capabilities.      The guideline document would
                   clearly describe those technical capabilities necessary
                   for preparing materials for the process. The need for
                   knowledge of sound engineering       methods and construc-
                   tion methods would be emphasized.          Clear outlines of
                   the technical concerns of the Engineering Department,
                   Planning and Zoning Department, Health Department, and
                   Building Department would be presented.          Supplemental
                   guidelines or codes used by each department would be
                   noted and guidance for obtaining these materials would
                   be provided.

                   Finally,    the guideline document would detail the steps
                   of the permit application process. The Clearance Sheet
                   checkpoint and sign-off requirements would be clearly
                   documented and examples        of all other    necessary de-
                   partmental    forms would be displayed in the document.
                   Included also would be a       description of the stages of
                   the   review process and       how the    permit application
                   moves through the several      departments. Telephone num-
                   bers   of each department      would be provided to permit
                   the individual to check on     the progress of the review
                   process. Every essential aspect of the permit appli-
                   @ation process would be identified in the document,
                   including    an applicant's waiver and recourse rights
                   and actions.



                                           10 - 20











                   The guideline document would be prepared as.an 8 1/2 by
                   11 inch document printed in one color for ease in re-
                   production.     it   would be structured      to represent
                   government effectiveness, without excess. A reasonable
                   price, including publication and expected distribution
                   costs, would be established and noted on the document.
                   The document would be provided without cost to educa-
                   tional institutions and other governments. First time
                   Developers normally would obtain, at a cost, the doc-
                   ument as part of a permit application         package. The
                   permit application package would include other more de-
                   tailed department guidelines and criteria.

                   2.   With the guideline document, an applicant could
                   submit an initial application for a 911 review in per-
                   son   or by mail. Instructions in the guideline docu-
                   ment   would be complete enough      to permit individuals
                   familiar   with    the system    to begin the process by
                   mail. Signature and       other required verification re-
                   quirements could be accomplished by any Notary Public
                   prior to application submittal.

                   An internal permit application review flow process would
                   be established.     Each reviewing office or department
                   would receive the application through an internal mail
                   or messenger system.       A check sheet would be prepared
                   to   note the time and date        of receipt and time and
                   date   of process completion. Each office or department
                   would have a specified time allocated for initial re-
                   view.   If the application could not be processed within
                   the stated time, the applicant would be notified of the
                   delay by phone and a time      extension would be noted on
                   the application check sheet.

                   If a problem is noted, the applicant would be contacted
                   by phone or in writing, depending upon the number and
                   extent of problems involved, and an appointment could
                   be set up for a discussion session. In some cases, a
                   decision may be made by the applicant to have the en-
                   tire application package returned by mail. once an ap-
                   pointment is made with an applicant, that time period
                   is his and any walk-ins or extended meetings would
                   be abbreviated to accommodate the individual holding
                   the appointment time.       All phone calls and personal
                   discussions would be noted on the application check
                   sheet.   This check sheet would be retained with the
                   permanent    file of the application as a reference of
                   the entire process.





                                           10   21










                   if   a problem is minor and only procedural, resolution
                   may be possible through a telephone discussion with the
                   applicant.    For minor    development permits or permits
                   applied for by individuals knowledgeable of the process,
                   it may become possible for most of the process to be
                   conducted by telephone and by mail, with only a limited
                   actual appearance of the applicant.

            The    above process greatly reduces the need for individuals
            to appear at governmental offices. Having an applicant func-
            tion    as his own permit application messenger is not cost
            effective to either the individual nor to governmental de-
            partments.      Fewer direct contacts with departmental review
            personnel    required by individuals       provide more internal
            reviewer    processing     time through the elimination of unnec-
            essary and sometimes unproductive discussions with frustrated
            applicants.

            Much    of the Check sheet information is procedural.               As
            County database information is expanded and the geographical
            information system has wider areal application, the time re-
            quired    in each department        for permit application review
            will    decrease.    Where the review process identifies condi-
            tions that require       additional application constraints, the
            applicant would be notified          immediately    and,    as noted
            above, a decision would be made with the applicant on nec-
            essary follow-up activities.

            As    the above process is implemented and greater use is made
            of computer based data and information management, the num-
            ber    of review personnel and space required in each depart-
            ment     can    be better controlled.      Emphasis then could be
            given to obtaining the highly          qualified engineering and
            other    specialists needed to manage complex technical sys-
            tems and perform essential technical evaluations.


            ENGINEERING DEPARTMENT FIELD INSPECTIONS



            General

            Field    inspections are essential aspects of the Engineering
            Department's routine functions. Staff limitations currently
            restrict field inspections to critical problems or emergency
            situations.      Every    inspection requires travel time to and
            from    the inspection site, time spent at the site, and time
            spent    preparing documentation of the inspection. Many in-
            spections require the participation of two people. with the




                                           10 - 22












           Department's    current developing    staff, on-the-job training
           is provided during some routine and emergency field inspec-
           tions.

           As noted previously, each field inspection provides an oppor-
           tunity   to add pertinent information on existing stormwater
           management systems, roadways, and natural areas to the ge-
           ographical information system databases. Field inspection
           forms designed to permit    subsequent data entry into appli-
           cable databases will accelerate the department's data devel-
           opment process.


           Application Inspections

           Preapplication inspections are conducted for larger and com-
           plex developments.     Applicants desiring to undertake        de-
           velopments    in   wetland environments often request       County
           review of project areas.

           Current and expected requests for subdivision development per-
           mits exceed the manpower capabilities of the Engineering De-
           partment. Preapplication field inspections of such de-
           velopments would require the full time effort of at least one
           trained inspector.


           Construction Completion Inspections

           Construction completion inspections prior to issuance of Cer-
           tificates of occupancy are not conducted for most development
           actions due to manpower limitations.      only larger commercial
           developments with complex road and drainage systems are regu-
           larly inspected.


           Emergency Inspections

           Emergency situations are reported to the Engineering Depart-
           ment on the      average of several times each week.         These
           consist    of various   drainage and roadway problems.        Each
           such    inspection represents several man-hours of effort. An
           estimate 1.5 man-days of effort per week are required by the
           Engineering Department to respond to the emergency requests.








                                         10 - 23












           ENGINEERING DEPARTMENT ORGANIZATION



           Current Structure


           Figure 10-1. Current organization of the St. Johns County En-
           gineering Department depicts the staff positions currently
           funded to undertake daily Engineering Department functions
           including permitting information management and special pro-
           jects.

           Projected Requirements

           Figure 10-2. Proposed Organization of the St. Johns County En-
           gineering Department depicts the immediate staffing needs of
           the Engineering Department to be requested for funding in the
           next fiscal year.


           PROJECTED ENGINEERING DEPARTMENT PROGRAM



           Activity Expansion Needs

           Additional capabilities are needed to conduct preapplication
           and pre-Certificate of occupancy inspections. One new pro-
           fesional engineer recently has been added to the Engineering
           staff, but an estimated two additional full-time employees are
           needed for these activities.

           A   departmental executive assistant is needed immediatel@r.
           This individual must be capable of providing routine adminis-
           trative and supervisory functions     while the County Engineer
           is not present.      The individual   need not be a registered
           engineer but must be      fully knowledgeable   with reference
           to   departmental procedures and functions. This individual
           must be capable of providing     routine operational    practice
           guidance   to the technical staff      in the absence    of the
           County Engineer. Incoming communications,       mail and tele-
           phone,   would be directed through the executive assistant
           to the County Engineer.

           Additional technical personnel are needed to expand the de-
           velopment of database information associated with the geo-
           graphical information system. Cost effective operation of the
           system would entail weekend and nighttime data entry and ed-
           iting of database information.

           Dependence    upon the geographical information system and
           its expansion is expected.     A complete management system is
           needed to assure the proper use and controlled expansion of


                                        10 - 24










                    Current Organization of the St. Johns County Engineering Department                     FIGURE 10-1





                                                              DIRECTOR OF ENGINEERINC





                                              3PECIALIST II






                                    PEP.,11TTlyc I.VB

                                     OF     Y,
                                  SENIOR ENGINEER                 GRAPH IC SYSTETJ               =R I  GHT OF IrAY AGENT
                                                                     MANAGER

                                     TECH III                                                           CIVIL ENCINKER
                                                                      TECH 11
                                      TECH I                                                                 I
                                                                                                        TRAFFIC SAFETY
                                      TECH I                                                              SPECIALIST



                                                                                                        CONSTRUCTION
                                OFFI      CIALI                                                          INSPECTOR
                                    CE SPE
                                                                                                            T
                                                                                                    Lc_o-y 7rUDEVTS









                       Proposed Organization of the St. Johns County Engineering Department                 FICURE 10-2



                                                               DIRECTOR OF ENGINEERING


                                                     @&@x



                                            ICE SPECIALIST II















                                                            ARCHITECTURAL          GEOGYAPHICAL
                                                               GRAPHICS              MAPPING
                                                              SPECIALIST            SPECIALIST
                                                                                                          REAL ESTATE
                                                                                                         PROFESSIONAL
                                                                        @0 -@Q
                                      -S)PIVIOR ENGINEER
                                                                                                        CIVIL ENGINFEED

                                                                                                        TRAFFIC SAFETY
                                                                                                          SPECIALIST

                                  TECH III
                                                                                                         CONSTRUCTION
                                                                                         nent

















                                                                                                           ;'I F CIAI,







                                   TECH I                                                                  IKSPErTOR
                                                                                                          Z@                        I
                                                                                                            P 3
                                   TE CH I








             the technology. The design of the management system should
             be developed with a high degree          of departmental control.
             A technical specialist capable of designing and implementing
             a full range of management procedures        is needed. The man-
             agement system would be developed to assure adequate and
             proper use of the technology by all departments within the
             County government.    The individual also would be expected
             to develop management procedures for the inter-governmen-
             tal    transfer of database data to and from other regional,
             state, and federal agencies.


             Engineer Technician Training

             The    department is going to continue to depend upon engi-
             neering technicians for application review and field inspec-
             tions.     These individuals will need progressive on-the-job
             training.    They also will be cross trained as geographical
             information system      operators. All engineering technicians
             will be expected to access and interpret routine information
             available through the geographical information system. They
             also will be responsible for      entering new data into digi-
             tized form for use in the       system    when data editing is
             complete.    Those technicians with an interest         and demon-
             strated    capability will be given further training in final
             data editing.


             Geographical Information System Development

             In coming years, the geographical information system will be-
             come a 'primary source of information used for routine and
             special functions       of the Engineering    Department.     Other
             County    departments also will become increasingly dependent
             upon the technology.

             The    progressive expansion of County capabilities in the use
             of this technology must be carefully developed to assure
             continued cost effectiveness. The current equipment must be
             maintained.    Data storage management will require increasing
             levels    of control. Operations will require increasing ac-
             cess control measures and priority use measures. A schedule
             of expected system expansion requirements must be developed.
             Cost estimates of equipment,         space, and manpower require-
             ments    and a priority    schedule for system expansion within
             budget constraints must be developed. Cooperation procedures
             and cost contributions by other departments           also must be
             developed.     System networking potentials       and limitations
             with    potential users in other departments       must be deter-
             mined.     The special needs of other departments may dictate
             the    need for independent systems, and data exchange proce-


                                          10 - 27








             dures then would have to be considered. Finally, the techni-
             cal decision process regarding the above must be developed
             and fully documented.


             Public Involvement Procedures

             County   administration decisions would be required prior to
             consideration of changes in the permit application process.
             The Engineering Department would be willing to develop the
             guideline document necessary for the process. The Engineer-
             ing   Department also intends to develop technical guideline
             information for use by individuals who must prepare drainage
             and paving plans.













































                                         10   28




















                                 WATER MANAGEMENT FINDINGS



             INTRODUCTION



             This report section presents guideline information on water
             management    criteria   for consideration in revising the St.
             Johns County Paving and Drainage Ordinance. The information
             included represents requirements for an urbanizing area where
             the    interrelated problems of water supply, aquifer recharge,
             flood control, stormwater management, and significant natu-
             ral resource area maintenance must given consideration.

             Without    consideration of the above multiple purposes, the
             long-term effects upon taxpayers of inaction by a governmental
             entity can be illustrated by the following extracts from a No-
             vember 19, 1989, Florida Times-Union newspaper article found
             on pages A-1 and A-16.

                           By David Hosansky, Staff Writer

                    The   $23 million that Jacksonville is spend-
                    ing on drainage projects is just a "drop in
                    the bucket" compared with what needs to be
                    spent on drainage citywide, officials say.

                    Jacksonville's long-neglected flooding prob-
                    lems have become so overwhelming that an
                    estimated $50 million to $100 million will
                    be needed to provide drainage to just a few
                    of the most frequently flooded areas, such
                    as Hogans and McCoys creeks, officials say.@

                    At   least 137 areas in the city exist where
                    flooding can become so serious that people
                    may drown, and evacuation routes and emer-
                    gency vehicles become blocked, said prelimi-
                    nary information in the city's master storm-
                    water management plan....

                    After   September floods    killed two peop  le
                    and   stranded hundreds of others, Hazouri








                     (Mayor) promised      a "hurry-up offense" to
                     get   proper    drainage to aging neighbor-
                     hoods....

                     officials don't even know the full extent of
                     the   flooding problems in the city much of
                     which lie in a natural       floodplain.    A $2
                     million study on the      situation should be
                     completed in two years.

                     Sixteen    projects now are under construction
                     or being designed....

                     Once    the city does get financing for a pro-
                     ject,    three to five years may be needed to
                     build it, assuming the project is not put on
                     hold.    It usually takes that long for city
                     employees or consultants to survey the neigh-
                     borhood,    design the project, acquire right
                     of way, apply for environmental permits and
                     coordinate construction with utility compa-
                     nies.

                     The city has kept drainage projects on the
                     back burner for decades.       Unlike other pub-
                     lic works projects, drainage         is important
                     only in bad weather.



              EXAMPLE ORDINANCES



              Ordinances from a number of Florida counties and communities
              were reviewed to determine methods used by other jurisdic-
              tions    that could have applicability in St. Johns County. As
              one example, an ordinance structure            has been adopted by
              Seminole     County that incorporates drainage,          dredge and
              fill    permitting, wetlands protection,        paving, subdivision
              regulations, and zoning regulations into a land development
              code.    The code presents the individual         ordinances in a
              standardized format        and represents       a movement by the
              County towards a coordinated process for managing land devel-
              opment activities. The separate departmental responsibilities
              are clearly identified.

              The Seminole County example represents a simplified codifica-
              tion process useful for clarifying individual departmental
              functions while eliminating overlapping or ambiguous regula-
              tory    statements that can occur in separate ordinances. The
              procedure also permits improved standardization of termi-




                                              11 - 2









              nology   and a movement towards a more readable and under-
              standable ordinance presentation format.

              The ordinance used by the City of Ormond Beach establishes
              procedures   for a city utility to provide stormwater manage-
              ment   services. This ordinance also stipulates the prepara-
              tion of a water management plan for every new development.
              Additional   useful guidance appears in the fee schedule for
              development reviews and enforcement functions noted in this
              ordinance.

              The Orange County site development ordinance establishes cat-
              egories for land development.      This procedure provides for
              improved flexibility in the review of proposed develop-
              ment actions. Design criteria for stormwater management ap-
              pears in the Orange County subdivision regulations.

              Finally, Hillsborough County has established a development re-
              view department to manage development actions.         Stormwater
              management purposes appear in the County's site development
              regulations   and subdivision regulations.      These ordinances
              provide information on purposes, procedures, fees, enforce-
              ment, and penalties applicable to stormwater management and
              roadways.   The County ordinances reference the Hillsborough
              County Storitrwater Management Technical Manual, as the source
              of design criteria and analysis methods for stormwater manage-
              ment applicable within the County.     Similarly, a Highway and
              Bridge Technical Manual, provides design criteria and analysis
              methods for roadway design. The use of these methods frees
              the County ordinance from the need to include design crite-
              ria that-require periodic modification.

              ordinances   adopted at different times and for specific pur-
              poses essentially reflect orientations, attitudes and in-
              terests of individuals involved in       preparing the origi-
              nal   development restrictions.    Revisions undertaken at dif-
              ferent times tend to be simple      amendments to the original
              documents.    These conditions result in wide variances in
              different   ordinance structures, presentation forms, and re-
              sultant interpretations.

              St.   Johns County could benefit from a review of existing
              land development    management ordinances and some form of
              unification   of separate ordinances. This study has focused
              upon water management needs within St. Johns County.          The
              following   water management criteria reflect some of the man-
              agement concerns that could be incorporated into a more gen-
              eral codification of land development management procedures.





                                           11 - 3













            GENERAL FINDINGS



            Purpose

            Findings    statements are normally included in ordinances.
            These statements generally reflect the basis of the ordinance.
            Governmental      bodies    normally include in the findings
            statement    the general public perceptions of the problem be-
            ing addressed in an ordinance.

            General public attitudes towards stormwater are largely ori-
            ented towards     drainage, the      simpler removal    of water.
            Developing concern for the effects of overdrainage on water
            supplies    and natural resources still requires emphasis. Wa-
            ter shortages     are now occurring in northeast Florida, but
            the relationship      between drainage     practices and the in-
            creased need for landscape irrigation,        possibly the major
            consuming use in urban areas, is not well understood.

            Many    developers in St. Johns County are following practices
            of cutting roadways down to obtain fill for raising resi-
            dential units above 100-year flood levels. This            practice
            has   been followed      by developers     in Jacksonville       and
            elsewhere.     When allowed in floodplains and on flatlands
            with high water tables, the roadways flood following heavy
            rainfalls.     over time,     as storm sewers and other compo-
            nents of the local drainage system deteriorate, the flood-
            ing problems become       compounded.      The long-term result
            of this practice is illustrated in the above newspaper           ar-
            ticle on Jacksonville's flood problems. This type of devel-
            opment action, in effect, transfers a development cost from
            the developer to a future governmental body and the general
            taxpayers.

            Numerous examples of methods and practices exist for prevent-
            ing a wide range of future problems requiring solutions which
            eventually    become    high cost burdens of     long-term county
            residents.     Comprehensive     stormwater   management     in St.
            Johns County     is readily achievable. The costs of implemen-
            tation    would be largely a developer's        immediate cost and
            not a general taxpayers future cost.


            Findings Statement

            Uncontrolled    drainage and development of land have a variety
            of significant adverse impacts upon the County's long-term
            economic development potential; long-term County infrastruc-





                                           11 - 4











            tural   management costs; and the health, safety, and welfare
            of the residents of the County. More specifically:

                  1. Uncontrolled drainage can reduce water recharge to
                  the surficial aquifer used as a source of potable water;

                  2.    Uncontrolled drainage lowers water tables, and,
                  thereby, removes      water from the surficial aquifer by
                  lowering    ground water conditions. This action subse-
                  quently deprives wetlands of essential ground water, re-
                  duces essential base flow waters necessary to sustain
                  low flow conditions in streams, and results in the
                  need for increased water use for landscape irrigation;

                  3.    Impervious and compacted urban development land
                  surfaces increase the volume and rate of surface water
                  runoff,    allowing    less water to percolate into the
                  soil and thereby decrease ground water recharge;
                  4. Construction requiring the alteration 'of the natu-
                  ral topography     and    removal of vegetation      without
                  compensating water management     control measures results
                  in increased stormwater runoff    and an increased erosion
                  potential;

                  5.    Uncontrolled    stormwater   runoff can damage, by
                  floodwaters erosion and sedimentationP public storm-
                  water    conveyance systems,    roadways, and other essen-
                  tial     components   of the publicly maintained      infra-
                  structure essential to residents and, thereby, results
                  in increased costs to residents     while also placing the
                  safety and health of residents in jeopardy;

                  6.    Uncontrolled stormwater runoff can damage and cause
                  the suspension of services        provided by public and
                  private utility systems upon which residents depend,
                  and, thereby,     can create hazards to the safety and
                  health of residents;

                  7.    Uncontrolled stormwater runoff can cause damages to
                  lower properties through flooding, erosion, and sedi-
                  ment deposition, and these actions can create direct
                  safety     hazards resulting     in the endangerment       to
                  residents;

                  8.    Uncontrolled    stormwater runoff from streets and
                  land areas carries increased levels of pollutants into
                  receiving water bodies, degrading water quality and en-
                  dangering natural biological processes;




                                          11   5








                   9. The increase in nutrients supplied to receiving wa-
                   ters through stormwater runoff from all sources accel-
                   erates eutrophication of receiving waters, adversely af-
                   fecting flora and fauna;

                   10.   Improperly managed surface water runoff interferes
                   with the maintenance of optimum salinity in estuarine
                   receiving waters.



             OBJECTIVES



             Purpose

             The   objectives statement in an ordinance establishes       the
             legal purpose of the ordinance. The objectives statement be-
             comes the basis of criteria and specifications to be followed
             in the preparation    of water management plans and in the
             construction of stormwater management systems.


             Criteria

             The County recognizes the need for, and encourages, land de-
             velopment that will be undertaken and constructed with:

                   1.   Full regard of the long-term socioeconomic well be-
                   ing of the majority of current and future residents of
                   the County;

                   2. Full recognition of the development's long term po-
                   tential impacts upon the area's public and private in-
                   frastructure   and the developer's responsibility to un-
                   dertake the development in a manner that will not cause
                   preventable future infrastructure repair, maintenance,
                   and rehabilitation costs attributable    to the develop-
                   ment to be absorbed by the County and the majority of
                   residents;

                   3.   Full understanding that the County is obligated to
                   protect, maintain, and enhance the immediate and
                   long-term health, safety, and general welfare of all
                   residents;

                   4.   Full recognition that by affixing ones signature
                   to an application for a development permit constitutes
                   a legal and binding agreement between the signer and
                   the   County that establishes the signer's acknowledge-





                                         11 - 6








                     ment of personal responsibility for accepting and adher-
                     ing to the following land development objectives:

                            a.   To permit and encourage development actions
                            that   will not attempt, by any means, to transfer
                            development    related costs, that should be borne
                            by the developer through full compliance            with
                            established land development         and water manage-
                            ment    criteria, to other residents of the County
                            by lack of compliance or other actions to avoid
                            compliance;

                            b.   To prevent individuals, business organiza-
                            tions,    and governments from causing harm to the
                            County by activities which adversely affect water
                            resources;

                            C.   To protect, restore, and maintain the chemi-
                            cal,    physical, and biological integrity of sig-
                            nificant natural resource areas and water bodies
                            within and contiguous to the County by requiring
                            the preparation of water management plans for all
                            new development actions that:

                                   (1) result in controlled discharge drain-
                                   age   systems designed to provide flood and
                                   stormwater control without damaging water
                                   and other natural resources, and           which,
                                   where applicable, provide for ground water
                                   recharge;

                                   (2)   provide protection of natural systems
                                   and use them in ways which do not impair
                                   their beneficial functioning;

                                   (3)   provide designed water control systems
                                   that function to protect and augment the
                                   functions of natural systems;

                                   (4)   minimize the transport of excessive
                                   nutrients    and pollutants to waters within
                                   and adjacent to the County;

                                   (5)   maintain ground water levels at eleva-
                                   tions    sufficient    to protect water sup-
                                   plies, wetlands, and natural stream base
                                   flow conditions;

                                   (6) protect, maintain, or restore natu-
                                   ral salinity levels in estuaries;




                                              11 - 7








                                 (7) minimize erosion and sedimentation;

                                 (8)    maintain, to the most practical de-
                                 gree,    natural fluctuations     in levels of
                                 ground water and surface water;

                                 (9) protect, restore, and maintain habitats
                                 for fish and wildlife.



              DEFINITIONS



              Definitions required for clarification of water management de-
              velopment criteria appear in the Glossary of this report.
              Specific terms applicable to individual ordinances and to
              referenced guidelines normally would appear in each document.


              WATER MANAGEMENT PLAN APPLICATION



              Purpose

              The   simpler    concept of drainage is now included          in a
              broader purpose of stormwater management. As an example eval-
              uation,    the Moultrie     Creek    watershed study served       to
              identify     basin-wide stormwater management concepts. The
              concepts   identified included the need       to consider the ef-
              fects of   drainage on the surficial aquifer and the need to
              maintain   water table conditions through increased ground wa-
              ter recharge. High water table conditions are also necessary
              to protect wetland natural resource areas and to extend base
              flow conditions in natural streams. Runoff water to wetlands
              must be sufficient to maintain these natural          systems, but
              runoff to the systems also must be controlled.

              Runoff also must be controlled to prevent erosion and sedi-
              mentation    in natural streams.      By retaining and detaining
              runoff    on properties, the first flush of pollutants is mea-
              surably    reduced, and recharge      of the surficial aquifer is
              increased.     Detained runoff     released to natural systems at
              controlled rates carries less toxic materials and nutrients
              to receiving waters.       Toxic materials in runoff from road-
              ways are major pollutants, and all public and private road-
              ways should be managed to reduce          pollutants from these
              sources.


              The    above and other purposes presented as County objec-
              tives should be addressed before any development action is ap-
              proved.    A water management plan is a means for presenting


                                            11 - 8








              an   applicant's proposed      actions    to address all of the
              County's stormwater management concerns.


              Criteria

              A   water management plan shall be submitted to the County
              Engineering Department and approved before any private or
              governmental water management development action is undertaken
              including:

                    1. A plat is recorded or land is subdivided;

                    2. A building permit is issued;

                    3.    Any existing public or private stormwater manage-
                    ment system, or attribute thereof, is altered, rerouted,
                    deepened, widened, enlarged, obstructed, or filled;

              A water management plan is not required for the following de-
              velopment activities:

                    1.    Agricultural or siviculture      activity being con-
                    structed and operated in a manner consistent with widely
                    recognized best management practices and not involving
                    artificial drainage of land;

                    2.    Any maintenance, alteration, use, or improvement to
                    an existing      structure not changing or affecting the
                    quality, rate, volume, or location of surface water dis-
                    charge.


              A   water management plan is not required for any emergency
              act necessary to prevent the material harm to, or destruc-
              tion   of, real    or personal property as a result of condi-
              tions,    including, but not      limited to, fire and hazards
              resulting    from violent   storms or hurricanes or when a prop-
              erty is in imminent peril and obtaining a permit is imprac-
              tical.      Following the emergency action by public agencies
              or private  individuals, a  report of the emergency action shall
              be provided to the County   Engineer by the responsible admin-
              istrator of the action agency or by the        person responsible
              for management of a private property within a reasonable pe-
              riod,    but not to exceed ten (10) days, following the in-
              cident.     The County Engineer or his designee shall conduct a
              field inspection of the site and determine whether remedial
              action may be     needed by    the County or private property
              owner.    The County     Engineer shall provide      to the County





                                            11 - 9








              Administrator a cost estimate       and recommendations for any
              required remedial action.



              WATER MANAGEMENT PLAN CONTENTS



              Purpose

              Explicit    presentation   of the acceptable contents       of a
              water management plan clearly establishes those items that
              will   be emphasized during the County Engineering Department
              review.   The County Engineering Department has the responsi-
              bility for assuring that every proposed development is re-
              sponsive to    the County's stormwater management objectives.
              The   types of information required       extend far beyond the
              simpler   discharge computations typically used to determine
              how large a ditch is necessary to get rid        of water.     The
              County must provide     clear information      to applicants, in
              part, to assist the applicant to follow and the public to
              accept the County's larger water management concerns. The
              water management plan content information presented in the
              ordinance is complex, and will have to be supplemented with
              additional guidance.


              Criteria

              it   is the responsibility of an applicant to prepare a
              water management plan with sufficient information to demon-
              strate    full adherence to County water management objectives.
              All information submitted to the County shall conform with
              the ordinary professional skill        and diligence of accepted
              engineering    standards. The information shall be sufficient
              to permit the County Engineer to evaluate:

                    1.    The proposed development's impacts upon existing
                    environmental characteristics of potentially affected
                    areas;

                    2.    The potential and predicted impacts of the pro-
                    posed activity on waters within and adjacent to the
                    County, and;

                    3. The essential performance and effectiveness of mea-
                    sures proposed by the applicant for accomplishing the
                    water management objectives of the County.

              The   water    management plan shall contain maps,         charts,
              graphs, tables, photographs, narrative descriptions, explana-
              tions, system component      design specifications, and cita-


                                            11 - 10








              tions   to supporting references based upon the best current
              and available technology, data, and information, as appro-
              priate   for communicating the information required to sat-
              isfy St. Johns County water management objectives, including
              the following:

                    1.   The names, mailing addresses, and telephone numbers
                    of the applicant, property owner, developer, and their
                    agents including, legal and technical representatives.

                    2. The legal description of the property and its lo-
                    cation referenced by state plane coordinates or geo-
                    graphical coordinates and such landmarks as major wa-
                    ter   bodies, adjoining roads, railroads, subdivisions,
                    and governmental jurisdictional boundaries clearly de-
                    picted on a map.

                    3. A map of the watershed in which the property is lo-
                    cated including, sufficient       watercourse information
                    to    support hydrological and hydraulic determinations
                    of natural and stormwater flows upstream of the proposed
                    development and     development    runoff discharge down-
                    stream of the development to a point where development
                    discharge impacts are negligible.

                    4.   The existing environmental and hydrological condi-
                    tions    of the site, the site outfall locality, the wa-
                    tershed area also contributing to flows at the site
                    outfall locality,     and detailed conditions of the re-
                    ceiving waters at the site outfall locality including:

                          a.    The direction, flow rate, and volume of sur-
                          face water runoff under existing conditions;

                          b.    The location of detention and retention areas
                          on the site where surface water collects or per-
                          colates into the ground, including estimates of
                          percolation rates;

                          C.    A description of existing conditions of all
                          watercourses,    waterbodies, and natural resource
                          areas on and within 1,000 feet of the site.

                    5.   Site conditions and proposed site alterations in-
                    cluding:

                          a.    Seasonal natural water table elevations, the
                          existing seasonal      fluctuation of    water table
                          elevations,     and changes in the existing water
                          table elevations proposed;



                                           11









                            b. The delineated locations of flood hazard ar-
                            eas and determined elevations, as applicable;

                            C.    Natural vegetation areas and proposed plant-
                            ings;

                            d. Existing and proposed site topography;

                            e.    Soils as determined from the Soil Survey for
                            St. Johns County, Florida;

                            f.    Existing and proposed impervious           surface
                            areas;

                            9.    The locations and sizes of buildings and
                            structures;

                            h.    Plans and specifications for all stormwater
                            management structures including estimates of oper-
                            ational    system water surface elevations and dis-
                            charge rates;

                            i. Plans for control of erosion and sedimentation
                            which describe in detail the type and location of
                            control measures,      the stage of development at
                            which they will be put into place or used, and
                            provisions for their maintenance;

                            j.    other such information which the developer
                            or    the County    Engineer believes is reasonable
                            and necessary for an evaluation of the develop-
                            ment.



               CATEGORIES  OF WATER MANAGEMENT PLANS



               Purpose

               It would be unrealistic to require a small residential prop-
               erty owner wanting       to build an addition to his home to
               produce    a complex water management plan. Abbreviated forms
               of   the basic management plan         requirements are needed for
               minor    development actions.      Each of the topics may require
               some statement from      an applicant, but the expected perfor-
               mance and design specifications of stormwater management mea-
               sures presented in a submitted water management            plan may
               be abbreviated. The actual criteria          for types of develop-
               ments that should be largely exempted from one or more of the
               management plan component requirements are subjects for St.




                                              11 - 12








              Johns County to determine.     For example purposes, criteria
              developed for use in Orange County are noted below.


              Example Criteria from Orange  County

                    1.   Category One - Development that currently contains
                    mostly impervious area and where additional development,
                    and/or site modifications, will cause no increase in im-
                    pervious area.

                    2.   Category Two - Development not covered in Category
                    one above, and is less than ten (10) acres total.

                    3. Category Three - Development not covered in Category
                    one above and is ten (10) acres or more total.

              The   above criteria require great care in interpretation.
              For example: Category One could apply to a shopping center
              or   it could apply to a residence that, together with a ga-
              rage, driveway, patio, and swimming pool, had more than fifty
              percent of the property in impervious area.

              if   the County adopts some form of the above type of proce-
              dure, the preparation      of criteria to establish a locally
              acceptable category system requires careful review. The pos-
              sible inclusions and exceptions to each category must be
              weighed to determine that the County objectives will be ade-
              quately met through the use of the system of categories se-
              lected.



              DESIGN STANDARDS FOR WATER MANAGF14ENT PLANS



              Purpose

              The   design of     water control systems to accomplish        St.
              Johns County objectives will require a means for informing
              applicants of all required evaluation criteria. Technical re-
              quirements   for undertaking    necessary evaluations requires
              higher   levels of professional competence than.,are required
              for simple ditching and draining.

              Design requirements appear within the body of ordinances of
              many local governments. For example, Hillsborough County uses
              Technical   manuals    to supplement local    development ordi-
              nances.    The Hillsborough     County Stormwater       Management
              Technical     Manual    provides    a useful example for this





                                           11 - 13








              study.    The purpose    of the Hillsborough County technical
              manual is stated below:

                     The   purpose of this Manual is to guide engineers,
                     architects, planners, and developers in the design
                     of stormwater management      systems in Hillsborough
                     County.   The manual integrates recommended method-
                     ologies, design procedures, standards and County
                     stormwater criteria into a single-source document.
                     The intent of the Manual is to (1) standardize cri-
                     teria and present suggested procedures and design
                     aides,   (2) make it compatible to the Hillsborough
                     County Capital Improvement Program and Stormwater
                     Management Element of the Comprehensive Plan. This
                     manual   represents a coordinated      effort to bring
                     water   resource managers, developers and designers
                     up-to-date with the regulations and criteria appli-
                     cable to stormwater management design in Hillsbor-
                     ough County. As an integral part of the Hillsbor-
                     ough County Stormwater Management Master Plan, this
                     manual will     be utilized by Hillsborough County
                     for permitting, study, review, and design.

              The    complexity of modern water management technology re-
              quires substantial technical definitions and specification de-
              tails    that can be readily separated from the legal and ad-
              ministrative    body of an ordinance.      Technical criteria and
              design standards can be incorporated into separate technical
              guideline documents. These guideline documents would be re-
              ferred to in the actual      ordinance and,     by such reference,
              become addendum documents to the ordinance with a legal ba-
              sis parallel to the ordinance.

              Producing technical criteria and design standards in a sepa-
              rate guideline document has the following advantages:

                     1. - The technical guideline document can be expanded
                     without modifying the basic ordinance as methodologies,
                     material specifications, and technical criteria change
                     to   meet new needs and changing technology. Revisions
                     could be handled administratively under the direction of
                     the County Administrator.

                     2.   The document can be expanded to include examples
                     of acceptable procedures for meeting County criteria.
                     These   procedures     would be presented as suggested
                     methods and would not be considered as mandatory.

                     3.   The document could also serve as a single source
                     of criteria, standards, and suggested procedures for
                     use   by the County government, for all stormwater man-


                                             11 - 14








                    agement   works constructed for the County, and for all
                    stormwater management works constructed by individuals
                    with the intent      of.requesting the    County to accept
                    the works within a public system.

                    4.   The document could serve as a training and educa-
                    tional device for new employees and as educational in-
                    formation for the     public. As an educational     device,
                    the information included could be further expanded to
                    illustrate County purposes for the required criteria and
                    standards.



              Technical Guideline Outline

              The    following   outline    is based upon    the Hillsborough
              County Stormwater Management Technical Manual. The outline is
              intended as an example only.       The contents of a guideline
              document   prepared for use in St. Johns County would present
              those   criteria, design    standards, procedures, and other
              materials considered locally applicable.


                                STORMWATER MANAGEMENT
                                  TECHNICAL MANUAL


                                  TABLE OF CONTENTS


                    1.  Introduction
                        Purpose
                        objectives
                        organization of the Manual

                    2.1 County Ordinances, Regulations and Policies
                        Introduction
                        Subdivision Regulations
                        Land Alteration and Landscaping Ordinance
                        Park Site Improvement Ordinance
                        Flood Damage Control Ordinance
                        Land Excavation Ordinance
                        Site Development Ordinance
                        Zoning Ordinance
                        Building Code
                        Comprehensive Plan Land Use Element
                        Comprehensive Plan Drainage Element
                        Water Pollution Rules
                        Wetlands Rules








                                           11 - 15








                    3. General Drainage Standards/Criteria
                        Requirements Applicable to all Developments
                         Requiring Review
                           Drainage Review
                           Outfall Conditions
                           Capital Improvement Program Coordination
                        Developments in Floodplains
                           Criteria For Development
                           Interagency Jurisdiction
                        Stormwater Management Data Requirements
                           Drainage Area Maps
                           Stormwater Design Calculations
                        Drainage Easement Criteria
                           General Criteria
                           Enclosed Stormwater Conveyance Systems
                           Canals and Ditches
                           Detention and Retention Ponds
                           Ingress/Egress

                    4. Determination of Storm Runoff
                        General
                        Rainfall Criteria
                           Rational and Modified Rational Methods
                           SCS Synthetic Unit and Santa Barbara Urban
                             Hydrograph Methods
                        Time of Concentration
                        Rational Method
                        Modified Rational Method Inflow Hydrograph
                         Approach
                        SCS Synthetic Unit Hydrograph Method
                        Santa Barbara Urban Hydrograph Method
                        Modified Santa Barbara Method Computation Format

                    5.  Culvert and Bridge Design
                        General
                        Culvert Design Criteria
                        Culvert Design Procedures
                        Materials Specifications for Culverts to be
                         Maintained by the County
                        Bridge Design

                    6.  Storm Sewer Design
                        General
                        Design Criteria
                        Design Procedure
                        Storm Sewer Tabulation Form









                                           11 - 16









                    7.   Detention and Retention Ponds
                         General Criteria
                         Detention Ponds
                         Retention Ponds
                         Detention/Retention Pond Analysis

                    8.   Roadway Underdrain Design
                         Roadway Underdrain Criteria

                    9.   Non-roadway Ditch Design
                         General Design Criteria
                         Utilities Crossing Ditches

                    10.  Roadway (Pavement) Drainage Design
                         General
                         Elevation of Low Edge of Pavement
                         Minimum Roadway Grades
                         Minimum Roadway Cross Slope
                         Design Frequency
                         Runoff Determination
                         Concrete, Curb, Gutter, and Sidewalks
                         Grassing, Mulching, and Sodding
                         Roadway Ditches
                         Street Drainage


              Many of the topics included above would be appropriate for use
              in a St. Johns County Technical Guide.          All criteria and
              specifications presented in local ordinances applicable to
              stormwater management       would be included in the technical
              guide.    St. Johns County review agencies regularly encounter
              a variety of difficulties in the application review process.
              Prepared information to address many of these problem areas
              can be usefully expanded upon in the prepared technical guide.



              FEES



              Purpose

              Significant    costs are incurred by St. Johns County during
              the review of an application for a development permit. Much
              of these costs should be a burden of the applicant.

              A   pre-application     conference is highly desirable.        This
              meeting probably should be a County cost, but its use would
              result in fewer application processing problems and subse-
              quent negative applicant actions.





                                            11 - 17









              Example Fee Schedule

              The    following   standardized fee schedule used      by Ormond
              Beach provides some guidance for consideration:

                  Industrial, Commercial, Subdivisions, and Multi-Family
              Residential, Including PUD's

                     BASE FEE                                     $200.00
                           Plus $15.00 per acre for each acre or fraction
              thereof up to 10 acres
                           Plus $8.00    per acre for each acre or fraction
              thereof over 10 acres up   to 40 acres
                           Plus $5.00    per acre for each acre or fraction
              thereof over 40 acres up   to 160 acres
                           Plus $2.00    per acre for each acre of fraction
              thereof over 160 acres



                  Miscellaneous

                     BASE FEE                                     $100.00
                           Plus $7.50    per acre for each acre or fraction
              thereof up to 10 acres
                           Plus $4.00    per acre for each acre or fraction
              thereof over 10 acres up   to 40 acres
                           Plus $2.50    per acre for each acre or fraction
              thereof over 40 acres up   to 160 acres
                           Plus $1.00    per acre for each acre or fraction
              thereof over 160 acres



              ENFORCEMENT AND VIOLATIONS



              Purpose

              The purpose of a water management ordinance and     the meaning-
              fulness of the stated County objectives are determined by the
              willingness of the County to undertake enforcement actions.
              Enforcement    actually begins with the actions of the County
              Engineer    in approving and disapproving proposed development
              actions.     Each reversal of a departmental determination by
              administrative action sets precedence for development actions
              unacceptable to the County. When       administratively approved
              development actions      are outside of the terms of the ordi-
              nance criteria and design specifications, the administrative
              action    constitutes a precedent that can diminish the ef-
              fectiveness of the ordinance. Other individuals learning of
              an accepted action not in conformity with the ordinance can




                                            11 - 18









              legally demand equal or Parallel treatment.       The ordinance
              can then become essentially void and noneffective.

              The   ordinance is also reduced in effectiveness when viola-
              tions are overlooked or are forgiven. The strictness of
              enforcement actions     must be acceptable to the public, and,
              therefore,   the structure of the ordinance and the design of
              enforcement   mechanisms    for   stormwater management in St.
              Johns   County must     be developed with the consent of resi-
              dents.



              Criteria


              Enforcement actions should be standardized and documented.
              Environmental enforcement procedures in federal and state a-
              gencies are moving towards the greater use of administrative
              processes for civil actions.

              Once   a standardized    administrative fine system is estab-
              lished, the Engineering Department would make the determina-
              tion   of actions occurring in violation of County criteria
              and design specifications.     The County Administrator or his
              designee would then levee the fine.

              The   administrative enforcement procedure would be estab-
              lished through the local ordinance process as one of a sys-
              tem of enforcement mechanisms.        Included in the ordinance
              could   be a parallel system for resolving violations using
              the state judicial system.       Under the above administrative
              process, the judicial process normally would be a recourse
              action for an individual.

              The   ordinance also could include other actions of the County
              to insure maximum compliance with established criteria and
              specifications.    County Engineering Department criteria and
              design specifications should be based upon current and appli-
              cable   professional standards. Registered professionals who
              affix   their signatures and registration seals to documents
              are   certifying that the ordinary standards of their profes-
              sion have been applied to the information in that document.
              Significant deviations from professional      standards on the
              part of, members     of registered professions        are matters
              that should be directed to state professional registration
              agencies.   The County's intent to follow such redress ac-
              tions   should be included in      an ordinance,    in guideline
              documents, and on development permit application forms.







                                           11 - 19










             LOCAL GOVERNMENTS PROVIDING ORDINANCES FOR THIS STUDY


                      Alachua County
                      Clay County
                      Duval County (Jacksonville)
                      Flagler County
                      Hillsborough County
                      Orange County
                      Pinellas County
                      Seminole County
                      Volusia County
                      City of Jacksonville Beach
                      City of Ormond Beach
                      City of Port Orange














































                                          11   20


















                                       GLOSSARY OF TERMS



              Adverse   Impacts - Any modifications, alterations, or effects
              on    a feature or characteristic of waters within or adjacent
              to the County and significant natural resource areas, in-
              cluding their      quality,    quantity, hydrodynamics, surface
              area,    species composition, living resources, aesthetics or
              usefulness for human or natural purposes which are or may be
              potentially harmful or injurious to human health, welfare,
              safety,    or property; to biological productivity, diversity,
              or stability; or which unreasonably interfere with the enjoy-
              ment of life or property, including outdoor recreation.

              Alligator Cracks - Interconnected cracks forming a series of
              small blocks resembling an alligator's skin or chicken-wire.
              These cracks are caused by excessive deflection of the surface
              over unstable subgrade usually as a result of saturated granu-
              lar bases or subgrade.

              Applicant - Any property owner or person, partnership, or
              corporation, agent, or duly authorized representative who ap-
              plies for a development permit.

              Aquifer.-- A water bearing stratum of permeable rock, sand or
              gravel.    A body of saturated rock or sediment through which
              water can move readily.

              Artesian Water - Water confined under hydrostatic pressure
              which will rise in a well when tapped.

              Base flood - The flood having a one percent chance of being
              equaled or exceeded in any given year, according to FEMA.

              Base flood elevation - The elevation measured in feet above
              mean sea level, as shown on a Federal Emergency Management
              Agency Flood Insurance Rate Map.

              Base Flow - Release of water from subsurface storage to a
              stream flow.

              Benthic Organisms - Those organisms which occur at the bottom
              of a body of water or at the depths of the ocean.





                                              G - 1









              Bond - A form of surety or guarantee agreement which contains
              the promise of a third party to complete or pay for the cost
              of remedial action       or completion of a construction con-
              tract, a subdivider's agreement, a developer's agreement, or
              a    condition or finding certified by an agent which subse-
              quently does not perform as certified.

              Borrow Pits - Location of excavation of soil to be used in
              another location as fill.

              Capillary Rise - The distance above the water table and into
              the less saturated soil that water rises by capillary forces.

              Commensurately - Corresponding in size, measure, or amount.

              Cone Of Depression - Water-table shape resulting from flow to
              a well.

              Clearing - The removal of trees and brush from the land but
              shall not include mowing.

              Construction - Any activity including land clearing, earth-
              moving or the erection of structures which will result in the
              creation of a system.

              County - Unincorporated St. Johns County.

              Detention - The collection and storage of surface water in a
              manner that provides for treatment through physical, chemi-
              cal,    or biological processes      for subsequent discharge at a
              rate which is less than the rate of inflow.

              Detrital       A product of disintegration, destruction or wear-
              ing away.

              Detritus      Loose material (as rock fragments or organic part-
              icles) that results directly from disintegration. Product of
              disintegration or wearing away.

              Developer - Any person who acts on his own behalf or as the
              agent of an owner of property and who engages in alteration
              of land or vegetation in preparation for construction activ-
              ity.

              Development     - Any man-made change to improved or unimproved
              real    estate, including, but not limited to, buildings or
              ?ther structures, mining, dredging, filling, clearing, grad-
              ing, paving, excavating, drilling operations, or permanent
              storage of materials.





                                              G - 2









              Direct Evaporation - Evaporation directly from the surface of
              a body of water.

              Discharge point - The outf  low of water from a project, site,
              aquifer, drainage basin, or facility.

              Drainage   system, natural drainage system      - Surface water
              streams or wetland natural resource areas which convey water
              to natural points of discharge.

              Drainageway Soils -    Soils occurring in drainageways as re-
              ported by the SCS in the soil descriptions of the Soil Survey
              of St. Johns County, Florida.

              Dropbox - Also called a drop structure.        A grade control
              structure which provides for a vertical drop in the channel
              invert between the upstream and downstream sides.

              Enforcement   official - The County engineer or his duly ap-
              pointed   representative responsible for enforcing the provi-
              sions of these criteria and insuring plan adherence during
              and following construction phases.

              Engineer   - A professional engineer registered in the State
              of Florida, or other person exempted pursuant to the provi-
              sions of Chapter 471, Florida Statutes, who is competent in
              the field of civil engineering.

              Engineer of Record (EOR) - Any individual registered by the
              State of Florida as a Professional Engineer. Further, the
              individual must be competent to perform engineering assign-
              ments   in the specific technical field of Civil Engineering
              and such engineering practice      must not be in conflict of
              Rule 21H-19.01 of the Rules of the Department of Profes-
              sional Regulation, Board of Professional Engineers.

              Estuary     A water passage where the tide meets a river cur-
              rent.


              Eutrophic    Rich in dissolved nutrients but often shallow and
              seasonally deficient in oxygen.

              Eutrophication - The process by which a body of water becomes
              either naturally or by pollution rich in dissolved nutrients
              (as phosphates) and often shallow with a seasonal deficiency
              in dissolved oxygen.

              Evapotranspiration -    Loss of water from the soil both by
              evaporation and by transpiration from the plants growing
              thereon.




                                           G - 3








               Existing    The average condition occurring immediately before
               development or redevelopment commences.

               Final Discharge Points - Point at which the entire flow being
               considered is discharged into another region or larger body of
               water, usually a lake or the ocean.

               Flatwoods -     This type of ecological community         occurs on
               nearly level land. Water movement is very gradual to the nat-
               ural drainageways, swamps, ponds, and marshes associated with
               this community. Wet conditions prevail during the rainy sea-
               son with the water table at or near the surface. It is easily
               identified by the flat topography and characteristic vegeta-
               tion.   Types of flatwoods include South Florida Flatwoods,
               North Florida Flatwoods, and Cabbage Palm Flatwoods.

               Flood   or flooding - A general and temporary condition of
               partial   or complete inundation of normally dry land from
               the overflow of inland or tidal waters or the unusual and
               rapid accumulation of stormwater runoff.

               Flood plain or flood prone area - Any land area susceptible
               to being inundated by water from any source.

               Floodway    - The channel of a stream plus any adjacent flood
               plain   areas that must be kept free of encroachment in a
               manner that the 100-year return frequency flood discharge can
               be carried without increasing flood heights by more than one
               foot. The location and extent of floodway areas are defined
               in   the Flood    Insurance Study for St. Johns County, pub-
               lished   by the Federal Emergency Management Agency (FEMA),
               revised'September 18, 1985, and as may be amended from time to
               time.

               Flood   hazard area - A land area within          St. Johns County
               determined     by the Federal Emergency     Management Agency and
               displayed    on Flood Insurance      Rate Maps prepared by that
               agency   as being subject to flooding from a 100-year return
               frequent flood event.

               Flume -   An open channel constructed of wood, steel, or rein-
               forced concrete and used to convey water for various purposest
               including grade control.

               Hardwoods - Periodic or seasonal flooding is characteristic
               of this ecological community. Hardwoods are often associated
               with adjacent swamps.

               Hydric      Characterized by or requiring an abundance of mois-
               ture.





                                              G - 4








              Hydric Hammocks - Moderately moist regimes without excessive
              water or drought conditions characterize this community.

              Hydric Soils -    Soils that are sufficiently wet under und-
              rained conditions to support the growth and regeneration of
              hydrophytic vegetation. The list of these soils includes hy-
              dric soils that are either drained or undrained; therefore,
              not all areas of hydric soils support predominantly hydro-
              phytation and thus are not wetlands. Soils designated by the
              SJRWMD which have the characteristics of being inundated or
              saturated on an average of 30 consecutive days per year.

              Hydraulic Gradient -     The total head loss divided by the
              length of flow in a drainage structure.

              Hydrologic Cycle - The movement of water and water vapor from
              the sea to the atmosphere, to the land, and back to the sea
              and atmosphere again.

              Inundation - Completely covered by a flood.

              Land - The earth, water, air, above, below, or on      the sur-
              face, including any vegetation, improvements      or structures
              customarily regarded as land.

              Liquid Limit - The moisture content at which the soil passes
              from a plastic to a liquid state.

              Lot - A portion of land identified as a single unit in a
              subdivision   and intended for lease, transfer of ownership,
              use, or.. improvements; or a parcel, or a tract. Such land
              consisting   of sufficient size to meet minimum development
              requirements,   and such land having an assigned number, let-
              ter, or other name through which it may be identified.

              Mounded Ground Water - Groundwater which follows the contours
              of the land surface through an increase and decrease in eleva-
              tion (as in a hill).

              Muck - Dark colored, finely divided, well decomposed organic
              soil material.

              Natural flow - The rate, volume, and direction of the surface
              or   ground water flow occurring under natural conditions in
              any given portion of the County.

              100-Year Return Frequency Event - A precipitation event which
              can be expected to occur on the average of once every 100
              years or which has a 1/100 (1 percent) chance of occurring in
              any given year.




                                           G - 5









             Parent Material - The unconsolidated organic and mineral ma-
             terial in which soil forms.

             Peat - Unconsolidated material, largely undecomposed organic
             matter, that has accumulated under excess moisture.

             Perched Water Table - A surficial aquifer, usually limited in
             extent, above an impervious stratum which separates the
             perched water table from a larger, more significant aquifer.
             A water table separated from the main water table beneath it
             by a zone that is not saturated.

             Percolation -    The downward movement of water through the
             soil.


             Permeability - The quality of the soil that enables water to
             move downward through the soil profile.

             Perviousness - The degree of permeability.

             Plastic - Capable of being deformed continuously and perma-
             nently in any direction without rupture.

             Plat - A map or a delineated representation of the subdivi-
             sion of lands.

             Porosity - The ratio of the volume of intertices of a mate-
             rial to the volume of its mass. The percentage of a rock's
             volume that is taken up by openings.

             Positive Drainage - Drainage of a soil, usually an aquifer,
             which removes more water than can naturally or than is artifi-
             cially recharged. This type of drainage permanently lowers the
             water table below the level at which the water table naturally
             occurs.


             Potentiometric Surface - The level to which water rises with-
             out pumping in a tightly cased well.

             Prairies - occur in shallow depressions in pine flatwood and
             dry sand pine/scrub oak communities. Inundation is typically
             seasonal, ranging from 0.5 to 2 feet. Soils are typically
             shallow organics overlying clay or compact sands.          Water
             reaches prairies either from direct rainfall or runoff from
             immediately adjacent uplands. Prairies are typically small,
             isolated perched wetland systems in the upper portion of the
             watershed.

             Private Roads - A cleared or improved street or road located
             within a right-of-way or easement owned by a home owners asso-
             ciation, private individuals or any entity other than St.


                                          G - 6








             Johns County or the State of Florida. ownership of private
             roadways shall be vested jointly in all abutting land owners
             or in a home owners association whose voting members consist
             of such abutting land owners. ownership of the private road-
             way by the developer is not permitted after construction of
             the private roadway unless he is the sole owner of all abut-
             ting properties and agrees that any properties abutting the
             private roadway which may be conveyed to others in the future
             will include the use of the private roadway by the lot owners,
             their guests, invitees, successors and assigns.

             Public Roads - A street or road located within a right-of-way
             owned by St. Johns County or the Florida        Department of
             Transportation. The street must have been dedicated or deeded
             to, and accepted by, either agency.

             Predevelopment   conditions - Those conditions which existed
             before alteration, resulting from human activity, of the nat-
             ural topography; vegetation; and rate, volume, or direction of
             surface or ground water flow, as indicated by the best avail-
             able technical data and information.

             Receiving bodies of water - Any water bodies, water courses,
             or wetland natural resource areas into which surface water
             flows or ground water seepage reemerges or results in satu-
             rated surface soils.

             Recharge Capabilities - The ability to annually replace vol-
             umes of groundwater.

             Retention - The collection and storage of stormwater runoff
             without subsequent discharge to surface waters.

             Return Frequency - Time interval between storm events which
             produce -similar predetermined intensity and runoff volumes
             which are used in designing surface and stormwater management
             systems.

             Right-of-way - Land dedicated, deeded, used, or to be used
             for   a street, alley, walkway, boulevard, drainage facil-
             ity, access for ingress or egress, or other purpose by the
             public, certain designated individuals, or governing bodies.

             Riparian Lines - Bank of a watercourse.

             Runoff - The precipitation discharged into stream channels
             from an area. The water that flows over the surface of the
             land without percolation into the soil.






                                          G - 7








              SCS Curve Number - Values ranging between 1 and 100 that are
              used in calculating runoff rates by the SCS method. The more
              impervious a surface, the higher the curve number.

              Saddles - Drainage structures to limit discharge.

              Saturated Soils - Soils in which all the interstices are com-
              pletely filled with water.

              Sediment - Fine particulate material, whether mineral or or-
              ganic,   that is in suspension in a water column or has been
              transported by flowing water and has settled on land or within
              a water body.

              Sedimentation facility - Any structure or area which is de-
              signed   to hold runoff water until suspended sediments have
              settled.

              Sheetflow - Uniform flow of water in thin layers on a sloping
              surface.

              Significant Natural Resource Areas - Conservation areas and
              preservation areas which include but are not limited to the
              following types of wetlands, natural water bodies, and up-
              lands: freshwater marshes, shallow grassy ponds, hardwood
              swamps, cypress swamps, natural shorelines other than natural
              beaches and dunes, Class III Waters, and sand pine-scrub com-
              munities.   Preservation Areas include the following types of
              wetlands, natural water bodies and uplands: coastal marshes,
              mangrove swamps, marine grassbeds, natural beaches and dunes,
              Class I and II Waters, aquatic preserves, critical habitat for
              endangered, threatened or rare species, and State wilderness.

              Site - Any tract, lot,     or parcel of land or combination of
              tracts, lots, or parcels   of land which are in one ownership,
              or are contiguous and in   diverse ownership where development
              is to be performed as      part    of a unit, subdivision,       or
              project.

              Slough - An ecological community which appears as an open ex-
              panse of grasses, sedges, and rushes in areas where the soil
              is saturated during the rainy season. Most sloughs are rela-
              tively long and narrow and slightly lower in elevation than
              the surrounding flatwoods or hammocks.

              Soil Horizon - A layer of soil approximately parallel to the
              surface, having distinct characteristics produced by soil-form-
              ing processes.

              Soil Matrix -     Structure and arrangement of soil particles
              within the soil horizon.



                                             G - 8










              Soil Mottling - Irregular spots of different colors that vary
              in number and size. Mottling generally indicates poor aerea-
              tion and impeded drainage.

              Soil Profile - A vertical section         of the soil extending
              through all its horizons and into the parent material.

              Species - A class of individuals having common attributes and
              designated by a common name.

              Stormwater - The flow of water which results from, and which
              occurs immediately following, a rainfall event.

              Stormwater Management System - The designed collection of fa-
              cilities, improvements,     or natural systems of the project
              which collect, convey, channel, hold, inhibit, detain, retain,
              release, or divert the movement of stormwater in a controlled
              manner. Includes dams, impoundments, reservoirs, and appurte-
              nant works.

              Structure - That which is built or constructed, an edifice or
              building of any kind, or any piece of work artificially built
              up or composed of parts joined together in some definite man-
              ner.


              Surficial Aquifer - An aquifer that is at atmospheric pres-
              sure.


              Surveyor of Record (SOR) - An individual registered under
              Chapter . 472, Florida Statutes. Further, the individual must
              be in good standing with the Florida Board of Professional
              Regulation.

              Swale - -A man-made trench which:
                    A)   Has a top width-to-depth ratio of the cross-section
              equal to or greater than 6:1, or side slopes equal to or
              greater than three (3) feet horizontal to one (1) foot vert-
              ical: and,
                    B)   Contains contiguous areas of standing or flowing
              water only following a rainfall event: and,
                    C)   Is planted with or has stabilized vegetation suit-
              able  for soil stabilization, stormwater treatment, and nutri-
              ent uptake: and,
                    D)   Is designed to take into account the soil erodibil-
              ity, soil percolation, slope, length, and drainage area so as
              to prevent erosion and reduce pollutant concentration of
              any discharge.

              Swamps - A poorly drained depression in which water is at or
              above the surface periodically throughout the year.


                                            G - 9










              Transpiration -     The passage of watery vapor from a living
              member through a membrane of pores.

              Turbid Waters - Stream flow that is thick or opaque with
              sediment.

              Vegetation - All plant growth,        especially trees, shrubs,
              vines, ferns, mosses, and grasses.

              Water - Any and all water on or beneath the surface of the
              ground or in the atmosphere. This includes the water in wa-
              ter courses, waterbodies, and      natural or constructed drain-
              age systems.    Water also     includes diffused surface water
              and   water percolating, standing,       or flowing beneath the
              surface   of the ground.

              Water Management Plan - The detailed analysis and materials
              prepared to display and provide information regarding any and
              all development actions that impact water.

              Water Quality - Characteristic of the water based on relative
              turbidity, temperature,     amount of dissolved oxygen, and
              amounts and types of contaminants.

              Water Table      The upper limit of the soil or underlying rock
              material that is wholly saturated with water.

              Watercourse       Any natural or     constructed stream, river,
              creek, drainageway, flow-way, channel,       ditch, canal, con-
              duit, culvert, drain, waterway,         gully, ravine,     slough,
              spillway, swale, wash, and similar natural or          constructed
              area in which water flows in a definite direction, either
              continuously or intermittently, and which has a          definable
              channel, bank, and bed or bottom.

              Waterbody - Any natural or artificial pond, lake, reservoir,
              borrow   pit, or other area which ordinarily or intermit-
              tently contains water and which has a discernible shoreline.

              Watershed - A region or area bounded peripherally by a water
              parting and draining ultimately to a particular watercourse or
              body of water.

              Weir - A dam in a waterway to raise the water level or divert
              its flow. An instrument for measuring or regulating surface
              water discharge.







                                            G - 10








            Wetlands    Those natural resource areas with normally and pe-
            riodically   saturated soils or with shallow flooded areas
            and with dominant plant communities adapted to saturated
            soils and shallow flooding conditions.
















































                                        G   11



















                                            APPENDIX


                                     PHASE  2 STUDY PROCESS



               PROJECT PURPOSE


               A 1979 study was conducted in the Matanzas River under the
               Florida Coastal Zone Management Program to determine means for
               saving the local shellfish growing areas for human use. Sep-
               tic tank drainage and stormwater runoff were identified as the
               major sources of decreased water quality and contamination of
               shellfish areas within the Matanzas River.

               The progressive deterioration of water quality in the estua-
               rine water in the Matanzas River gradually can be expected to
               extend to all the water bodies served by the St. Augustine In-
               let and to the coastlines adjacent to the inlet. Unless im-
               proved management practices are adopted and adhered to by St.
               Johns County and the City of St. Augustine, the loss of the
               local estuary's water quality can be expected to be progres-
               sive.   Shellfish harvesting is now generally prohibited, with
               some remaining areas "conditionally approved," and the water
               quality of the estuary now generally falls within a Class III
               category or waters suitable for fishing and swimming. Only
               the caring application of well-known management practices re-
               lated to urban development throughout St. Johns County can
               arrest this progressive trend towards further estuarine water
               quality deterioration.

               Subsequent to the 1979 study, the St. Johns County Commission
               adopted   a County-wide drainage ordinance and strengthened
               regulation of septic tanks. However, progressive deteriora-
               tion of water quality in the Matanzas River and adjacent wa-
               ters has continued.

               The Florida Department of Environmental Regulation has recog-
               nized that a local comprehensive basin-wide approach to man-
               agement of stormwater and other point and nonpoint sources of
               water pollution is necessary to arrest the ongoing water qual-
               ity deterioration problem in the St. Augustine area estuary.
               DER has noted that project by project review and approval of
               developments without consideration of basin-wide conditions




                                              A - 1










            and project impacts is resulting in continued deterioration of
            estuaries throughout the state.

            As a means of assisting St. Johns County and other smaller
            governments to develop capabilities to undertake the level of
            management necessary to protect the state's waters, DER sup-
            ported the County Engineering Department's efforts to under-
            take a comprehensive surface water condition and management
            analysis of the Moultrie Creek and Moses Creek Basins. The
            analysis of surface water conditions was conducted as Phase 1
            of the study completed in May 1989. The Phase 2 analysis and
            the primary focus of this report, is the development of a
            conceptual stormwater management process for the Moultrie
            Creek and Moses Creek Watersheds and the development of a com-
            puterized information management system that could support wa-
            tershed level stormwater management in St. Johns County.



            INSTITUTIONAL CONSTRAINTS



            The St. Johns County Engineering Department has the technical
            capabilities for undertaking an analysis of existing surface
            water conditions within the study area. The Department also
            can conduct comparative evaluations of technical alternatives
            for reducing pollution to estuaries carried with surface water
            runoff from roadways and land developments.       The existing
            County Paving and Drainage Ordinance (No. 86-4) provides very
            limited capabilities for Engineering Department control needed
            for more comprehensive basin-wide stormwater management pur-
            poses.

            Effective management of pollutants being discharged to the Ma-
            tanzas River and other important natural resource areas re-
            quires a comprehensive approach to point and nonpoint source
            pollution discharges with positive participation from a number
            of local governmental agencies. The effort would require co-
            operation between the County government and the City of St.
            Augustine.   As importantly, the residents of the County and
            St. Augustine would have to strongly support governmental ac-
            tions to undertake a basin-wide approach to reducing the dis-
            charge of contaminants to the County's estuaries



            SOCIAL CONCERNS



            The need for comprehensive basin-wide management of pollution
            sources has been recognized by technical specialists in the
            United States for several decades. The ability to develop ef-
            fective measures to reduce the effects of pollution have been


                                          A - 2











            limited because of the numerous ways that pollutants enter the
            environment.    All governmental agencies are segmented into
            specialized departments, and the responsibilities and abili-
            ties of any single department to participate in a comprehen-
            sive program to control pollution is very limited. Finally,
            most solutions are based upon obscure or technical and costly
            premises that are difficult to understand and accept.

            Technically sound engineering practices that can reduce pollu-
            tion discharges in stormwater can only be applied to the de-
            gree that the residents of the County can understand and ac-
            cept the usefulness and added costs to projects of these prac-
            tices.    The County Engineering Department rules must balance
            the application of technically based restrictions to proposed
            projects and local comprehension and willingness to accept
            these restrictions. Therefore, the structure of a conceptual
            basin-wide stormwater management process must balance the
            technically based constraints of the management             process
            against the community understanding and acceptance of such
            practices.

            Moreover, the County Engineering Department's rules and devel-
            opment evaluation procedures are responsive to only the storm-
            water discharge part of the pollution affecting the Matanzas
            River. Technical evaluations of the significance of the vari-
            ous sources of pollution presently cannot determine which pol-
            lution sources are more significant than others. Therefore,
            it is not possible to determine whether more stringent Engi-
            neering Department actions, without commensurate actions by
            other agencies, will be significantly effective in an immedi-
            ate future time frame. Unless public benefits can be clearly
            described, public acceptability of a comprehensive basin-wide
            stormwater management program cannot be assured.



            THE STUDY PROCESS



            The study's Master Work Plan identified seven major tasks as
            project objectives.      Phase 1 of the study focused upon the
            completion of tasks I through 5. The primary emphasis of the
            Phase 2 study efforts were oriented towards the accomplishment
            of tasks 6 and 7.



            ST. JOHNS COUNTY DEVELOPMENT MANAGEMENT ACTIONS



            St. Johns County is undergoing development pressure that re-
            quires expanded capabilities for providing for the citizens of
            the County. The need for improved methods for dealing with


                                           A - 3









             development actions in fair and technically responsible man-
             ners has been recognized by the County Commissioners and the
             County Administration.    The Moultrie Creek-Moses Creek wa-
             tershed Study provided timely assistance to the County by per-
             mitting the Engineering Department to focus efforts on the
             preparation   of   improved   development   evaluation tools.

             Under the auspices of the above noted study, the Engineering
             Department established a computerized geographic information
             system (GIS).    The initial system is now being- expanded to
             permit wider use of the GIS capabilities for a variety of en-
             gineering and other departmental uses through the addition of
             a computer aided design (CAD) component which will allow imme-
             diate transfer of a floppy disk provided by the developer into
             the County GIS.



             PHASE 1 STUDY PROCESS OBJECTIVES



             Specific Phase 1 work objectives were as follows:

             1.   Develop a comprehensive inventory of areas within the wa-
             tershed that deserve special management consideration. This
             inventory will be used as a basis for the following:

                  a. Improving coordination and regulation consistency be-
             tween St. Johns County, the St. Johns River Water Management
             District, the U. S. Army Corps of Engineers, and DER;

                  b. Revising the County's Comprehensive Plan; and

                  C.   Future resource investigations by state and local
             agencies.

             2.   Develop detailed information on topography, soils, flood
             prone areas, land use, and other conditions pertinent to
             achieving stormwater management, flood prevention, and re-
             sources protection objectives for the study area.

             3.   Evaluate County ordinances, plans procedures, and coordi-
             nation requirements regarding development reviews and stormwa-
             ter management considerations. Identify needed improvements.

             4. Use products developed for special area management in the
             project areas as a prototype for improving flood protection
             and stormwater controls in critical resource areas throughout
             the County.






                                          A - 4










              PHASE 2 STUDY PROCESS OBJECTIVES


              Specific Phase 2 work objectives are as follows:

              1. Development of basin-specific management tools such as de-
              tailed future land use map, plan and permit application review
              guidelines, etc.

              2.   Assessment of potential stormwater management, flood pro-
              tection, natural resource protection problems, and management
              options.

              3.   Development of recommendations on stormwater performance
              criteria and formulation of basin stormwater management plans
              which address priority resource protection and growth needs.

              4. Improvement of consistency and support between County, wa-
              ter management district, and state programs regarding stormwa-
              ter management and infrastructure planning.


              PHASE 2 TASK SUMMARIES



              Task 6: Assessment of Potential Stormwater Management, Flood
              Protection, and Natural Resource Protection Problems and Eval-
              uation of Management Options.

              This   task focused on the review of potential stormwater,
              flooding, and natural resources problems resulting from pro-
              jected basin development patterns, uses, and intensities, as
              well as general population growth requirements.       During the
              evaluation process, regulatory, infrastructure, and other man-
              agement considerations in the watershed were evaluated. The
              development impacts on wetlands and water quality are reviewed
              and evaluated in terms of basin resource protection strategy
              alternatives.     The evaluations undertaken during this task
              provided a focus for describing Engineering Department water
              management program concerns.

              The assessment process was undertaken within      the context of
              current local government requirements for comprehensive plan
              updates,' growth management planning, development of regional
              impacts reviews, Florida Quality Development program reviews,
              routine County clearance sheet reviews required for construc-
              tion and mobile home permits, and dredge and fill permits.
              The local agencies responsible for applicable planning and/or
              review functions were identified.          The Engineering     De-
              partment's review processes were described and means for pos-



                                            A - 5







              sible improvem@nt to current evaluation practices were identi-
              fied.

              The Geographic Information System is perceived as a mechanism
              to most efficiently manage local government operations, in-
              cluding management of growth and development. The GIS has been
              designed as a product of this basin management program to ad-
              dress several of the tasks within the scope of work. The GIS
              has many practical applications including near instantaneous
              updating of graphical information layers illustrating land use
              and cover, approved development layouts, soil types, topogra-
              phy, ownership boundaries, easements for drainage, septic fa-
              cility location, wetland boundaries, significant archeological
              features, zoning, access, utility location, and other charac-
              teristics.   All of these layers can be used singularly or in
              combination to review      new development    proposals and re-
              zonings, retrofit stormwater management facilities, install
              and modify major utility lines, identify significant natural
              and cultural resource areas, and evaluate new transportation
              corridors. The GIS has tremendous potential for local and re-
              gional applications.     A result of Phase 1 of this study has
              been joint funding between St. Johns County and the St. Johns
              River Water Management District for digitized soil coverage
              for the entire County.     In addition, during Phase 2 of this
              study St. Johns County has jointly contracted with the St.
              Johns River Water Management District for approximately sixty
              square miles of topographic aerials to expand the        concepts
              developed be this study County-wide.

              A major effort of the study was the formulation         of a GIS
              implementation program to apply the information generated.
              The first step was to expand the GIS program beyond the@ Engi-
              neering Department to include the County departments with the
              most immediate need. The departments selected to use the GIS
              during this trial period in cooperation with the Engineering
              Department are Planning and Zoning, Emergency 911 (Sheriff's
              office), Health Department, and the water and wastewater util-
              ity known as Anastasia Sanitary District. Several terminals
              have been purchased and are being installed for the inputting
              of data and viewing of information by each department. The
              reference maps for data entry are the County property owner-
              ship maps and the topographic aerials acquired as part of
              Phase 1. The property ownership maps are manually prepared by
              the Property Appraiser and then digitized by the Engineering
              Department for GIS implementation.

              The GIS was a highlight of this study because it served as the
              mechanism to incorporate the objectives of the study within
              daily local government operations. The tasks within the scope
              of work were reviewed in light of the specific applications of
              the GIS. Some of the tasks have received less effort than



                                            A - 6









              others because a more practical use of DER Coastal Zone Man-
              agement funds was made through the implementation of the GIS
              than could have been made without the GIS data in other non-
              funded areas such as the retrofitting of facilities.

              The County has a tremendous need for uniform, up to the minute
              maps depicting the existence and characteristics          of road,
              structures, stormwater management facilities,          natural re-
              sources, etc. The uniformity of these maps is critical for
              consistency from County department to department. The County
              has had a severe problem with map updating because, as in most
              counties, the property appraiser's maps upon which all other
              maps have been historically based are only updated once a
              year.   This means that all new development is undocumented
              graphically for up to twelve months after completion. This
              delay can seriously misrepresent conditions related to well
              and septic tank location, vegetation and wetlands alterations,
              new drainage facilities, changes in land use and zoning, and
              other vital information. Development of the computerized Geo-
              graphic Information System enables the County to update in-
              formational maps instantaneously.        As new subdivisions and
              other types of land use changes are completed, the information
              will be submitted by the developers and immediately input into
              the system. The maps will be available to those County de-
              partments requiring this sort of information for daily op-
              erations.    A major emphasis of this study was the design and
              formulation of a computerized information system which will
              meet the County's informational needs.

              Some recommended changes to the existing development regula-
              tions as they relate to County Engineering Department func-
              tions have been identified        as a     part of this study.
              These recommendations include design criteria for stormwater
              management system performance,and minimum finished floor ele-
              vations for structures and access roads serving new develop-
              ment.

              Flood control and flood protection measures were applied
              within the basin through careful consideration of existing
              conditions and regulation of new construction within the ba-
              sin.   These objectives were accomplished in two ways: iden-
              tification of more stringent development regulations, and for-
              mulation of a means to update and maintain up to the minute
              information on development patterns within the basin through
              use of the GIS.

              The identification of corrective measures for existing flood-
              ing problems received minimal effort due to limitations in
              funding. The focus on new construction through revisions to
              growth management regulations will enable the county to keep



                                             A - 7









             pace with its inevitable growth while searching for funds to
             retrofit existing facilities.

             Provision for the protection of natural resource areas was
             satisfied by recommended changes to the St. Johns County Pav-
             ing and Drainage Ordinance No.86-4, utilization of the map
             layers depicting soil types, land cover and flood plain infor-
             mation within the GIS, and through plans to implement of a
             digitized jurisdictional wetlands map to be prepared and pro-
             vided by the St. Johns River Water Management District.

             Revisions to the existing County Paving and Drainage Ordinance
             have been initiated during this study.     The County Attorney
             has completed reconstruction of the Ordinance framework to fa-
             cilitate ordinance implementation and enforcement. one of the
             major problems with the  administration of the existing ordi-
             nance has been the lack  of specific and enforceable penalties
             for failure to comply.   This report presents revised design
             criteria for stormwater  management system performance. Some
             new sections within the  ordinance will be written to address
             the objectives of this   study and the recommendations within
             this report. An applicants handbook will also be prepared to
             present performance standards and procedures for permitting of
             construction activity within the Moultrie/Moses Creek basin
             and beyond.

             Land Use plans, Zoning and Building Codes will not be ad-
             dressed in this revision process. Revisions to these regula-
             tions will take years to draft and adopt and therefore are
             considered beyond the scope of this study.


             Task 7: Development of Priority Components of a Comprehensive
             Basin Management Program

             During this task, the Engineering Department prepared basic
             information on local stormwater management requirements. A
             conceptual County program was identified to incorporate habi-
             tat/wetland enhancement features for fresh water discharges
             into an estuarine environment. The interface factors between
             a County prepared stormwater management plan for the study
             area, revisions needed in the St. Johns County Drainage Ordi-
             nance, and Engineering Department rules and procedures and
             suggestions for local actions were addressed.

             A Computer Aided Design (CAD) system, has been acquired as
             part of Task 7 to input new development plans such as Plats,
             rezonings, DRI's, stormwater management system plans, utility
             location and other information directly into the GIS system.
             The CAD will facilitate immediate? automated transfer of de-
             velopment information provided by the developer by floppy disk


                                          A - 8









             directly from the floppy disk via CAD into the GIS system, and
             eliminate the need to manually digitize all plans, plats, etc.
             from print drawings into the GIS. It will also assist the
             County in inputting existing basin information to be consid-
             ered in the review of new development proposals into the GIS.
             The time limitations inherent in the contract study process
             prohibited completion of the applicants handbook and adoption
             of ordinance revisions within the time allowed by the grant
             contract.    Therefore, the acquisition of the CAD system will
             serve as the first step in developing the primary components
             of the stormwater management plan. The CAD will serve as the
             mechanism to implement many of the goals and findings of the
             study within the daily operation of the County government pro-
             cessing of building permits, right of way improvements, storm-
             water management system upgrades and development of a County-
             wide system of development plan documentation and updating.





































                                            A   9













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               Asphalt In Pavement Maintenance.         "Manual Series No. 16
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               Bermes, B. J., et. al. Geology and Ground-Wa    ter Resources of
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               Donthamsetti,   V.    Rao. Rainfall Analysis       for Northeast
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