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

                                                    Tcgoi        P14 1191@






                       5YDROLOGIC RESTORATION OF
                       SOUTHERN GOLDEN GATE ESTATES


















                     FINAL SUBGRANT PERFORMANCE REPORT





                                 Prepar ed for
                       Florida Coastal Manag nt-Program,

                                      by

                               Big Cypress Basin
                    South Florida Water Hanag  nt,     ct
                                Naples, Florida


                                 November 1994




                         TA-Is










                                         CONTENTS
                                                                      Page

          1.   INTRODUCTION                                            1

          11.  CALIBRATION ANALYSIS - PHASE THREE                      2
               A.    METHOD OF CALIBRATION                             2
               B.    LOCATION OF CALIBRATION STATIONS                  3
               C.    PERVIOUS LAND SEGMENTS AND REACH-RESERVOIR
                     NETWORK FOR PHASE THREE SIMULATION                3
               D.    PERIOD OF CALIBRATION                             5
               E.    INITIAL CONDITIONS                                5
               F.    SENSITIVIT`Y ANALYSIS OF CALIBRATION PARAMETERS   6
               G.    SUMMARY OF CALIBRATION FOR PHASE THREE            6
               H.    FINAL CALIBRATION PARAMETERS                      10


          III. VERIFICATION                                            16


          IV.  EVALUATION OF MODEL PERFORMANCE                         18
               A.    PRESENCE OF HIGH GROUNDWATER TABLE
                     IN SOUTH FLORIDA HYDROLOGY                        18
               B.    SHEEI FLOW HYDRAULICS                             18
               C.    REACH-RESERVOIR (RCHRES) MODULE IN HSPF           18
               D.    ASSUMPTIONS IN ALTERNATIVES ANALYSIS              19
               E.    OVERALL COMPLEXITY OF MODELING SGGE               20

           V.  ASSESSMENT OF HYDROLOGIC CONDITIONS FOR THE SGGE
               REGION                                                  21


          VI.  DEVELOPMENT OF ALTERNATIVE RESTORATION PLANS            24
               A.    CRITERIA FOR PLAN DEVELOPMENT                     24
               B.    IDENTIFICATION OF ALTERNATIVES                    25
               C.    HYDROLOGIC AND HYDRAULIC SIMULATION OF
                     ALTERNATIVES                                      37


          VI[. EVALUATION OF ALTERNATIVE PLANS                         40
               A.    HYDROLOGIC PERFORMANCE OF ALTERNATIVE ONE         40
               B.    HYDROLOGIC PERFORMANCE OF ALTERNATIVE TWO         40
               C.    HYDROLOGIC PERFORMANCE OF ALTERNATIVE THREE       54
               D.    ECONOMIC EVALUATION                               54
               E.    HYDROLOGIC IMPACT ASSESSMENT                      72


          VIII. RECOMMENDED PLAN                                       73


           IX. CONCLUSIONS                                             .74


          APPENDIX A









                                                  LISF OF FIGURES

             FIGURE 1.      Calibration Locations for Phase Three

             FIGURE 2.      Observed vs. Simulated Average Montly Stage - Merritt Canal

             FIGURE 3.      Observed vs. Simulated Average Monthly Stage - North Miller Canal

             FIGURE 4.      Observed vs. Simulated Average Monthly Stage - Miller Canal at Weir No. 1
             FIGURE 5.      Monthly Hydrograph at Faka Union Weir No. 1 for Model Verification

             FIGURE 6.      Surficial Aquifer Flow Vector During Dry Season

             FIGURE 7.      Conceptual Plan of Alternative One

             FIGURE 8.      Conceptual Plan of Alternative Two

             FIGURE 9.      Conceptual Plan of Alternative Three

             FIGURE 10.     Conceptual Plan of Spreader Channel and Canal/Swale Blocks - Alternate Three

             FIGURE 11.     Spreader Channel Cross-Section

             FIGURE 12.     Pump Locations

             FIGURE 13.     Spreader Channel Cross-Section

             FIGURE 14.     Downstream Berm of Spreader Channel

             FIGURE 15.     Canal Plug Locations

             FIGURE 16.     Upper Zone Soil Storage - Existing vs. Alternative Two (1970-1975)

             FIGURE 17.     Upper Zone Soil Storage-Existing vs. Alternative Two (1976-1981)

             FIGURE 18.     Upper Zone Soil Storage-Existing vs. Alternative Two (1982- 1987)

             FIGURE 19.     Upper Zone Soil Storage-Existing vs. Alternative Two (1988-1992)

             FIGURE 20.     Lower Zone Soil Storage - Existing vs. Alternative Two (1970-1975)

             FIGURE 21.     Lower Zone Soil Storage - Existing vs. Alternative Two (1976-1981)

             FIGURE 22.     Lower Zone Soil Storage - Existing vs. Alternative Two (1982-1987)

             FIGURE 23.     Lower Zone Soil Storage - Existing vs. Alternative Two (1988-1992)

             FIGURE 24.     Active Groundwater Storage - Existing vs. Altemat ive Two (1970-1975)








             FIGURE 25. Active Groundwater Storage - Existing vs. Alternative Two (1976-1981)

             FIGURE 26.     Active Groundwater Storage - Existing vs. Alternative Two (1982-1987)

             FIGURE 27.     Active Groundwater Storage - Existing vs. Alternative Two (1988-1992)

             FIGURE 28.     Upper Zone Soil Storage - Existing vs. Alternative Three (1970-1975)

             FIGURE 29.     Upper Zone Soil Storage - Existing vs. Alternative Three (1976-1981)

             FIGURE 30.     Upper Zone Soil Storage - Existing vs. Alternative Three (1982- 1987)

             FIGURE 31.     Upper Zone Soil Storage - Existing vs. Alternative Three (1988-1992)

             FIGURE 32.     Lower Zone Soil Storage - Existing vs. Alternative Three (1970-1975)

             FIGURE 33.     Lower Zone Soil Storage - Existing vs. Alternative Three (1976-1981)

             FIGURE 34.     Lower Zone Soil Storage - Existing vs. Alternative Three (1982-1987)

             FIGURE 35.     Lower Zone Soil Storage - Existing vs. Alternative Three (1988-1992)

             FIGURE 36.     Active Groundwater Storage - Existing vs. Alternative Three (1970-1975)

             FIGURE 37.     Active Groundwater Storage - Existing vs. Alternative Three (1976-1981)

             FIGURE 38.     Active Groundwater Storage - Existing vs. Alternative Three (1982-1987)

             FIGURE 39.     Active Groundwater Storage - Existing vs. Alternative Three (1988-1992)










                                           LL13T OF TABLES


           TABLE 1.    Final Parameters for HSPF Simulation of SGGE

           TABLE 2.    Simulated Water Budget for Existing Conditions and
                       Alternatives Two and Three

           TABLE 3.    Preliminary Cost Estimate for Alternative One

           TABLE 4.    Preliminary Cost Estimate for Alternative Two

           TABLE 5.    Preliminary Cost Estimate for Alternative Three










                                                    1. UqMODUCIION

                     The planning process for formulation of a set of economically and environmentally

              feasible measures for restoration of Southern Golden Gate Estates (SGGE) involved development

              of a continuous process hydrologic-hydraulic simulation model of the watershed by the U.S.

              Environmental Agency's watershed     modelingprogram package Hydrologic Simulation Program-

              Fortran (HSPF). A quantitative evaluation of the impacts of large scale land development in the

              Golden Gate Estates on the overall hydrology of the area was performed by continuously

              simulating the hydrologic-hydraulic characteristics of the watershed for a 23-year period.

              Detailed descriptions of model development, earlier phases of the calibration and verification of

              various model segments and assessment of the human induced impacts on the overall hydrology

              of the region was provided in the first three quarterly reports. The first report reviewed the

              project background and the historical development of Golden Gate Estates. A description of the

              existing hydrology was included, as well as a detailed summary of the study design and the

              formulation of the required data base. The second report describes the development of the

              model and of the phase I calibration results for the northern Faka Union Canal subbasin. Report

              three recounts the second phase of calibration, presents some preliminary observations of the

              model performance and existing conditions in the SGGE basin and proposes three preliminary

              alternative scenarios. This report provides a summary of the last phase of model calibration and

              the verification process, identification of alternative hydrologic restoration measures, evaluation

              of the performance of those alternative measures, and presents a recommended restoration plan.










                                      IL CALIBRATION ANALYSLS-PHASE THREE


              A.     METHOD OF CALIBRATION

                     The process calibrating the hydrologic-hydraulic model for the Southern Golden Gate

              Estates (SGGE) watershed was extended to cover each of the subbasins where recorded data on

              canal stages and flows were available. The iterative process of comparing the simulation results

              with observed historic data for the Faka Union Canal at its outlet was also continued in this


              phase to refine the model.

                     In general, the following four-step method for calibration was performed.

                  1) Water Balance Equation:

                     The basic water balance equation for the hydrologic processes simulated in HSPF is:

                     Precipitation - Actual ET + Storage ï¿½ Basin Transfers = Runoff

                     where

                      Storage = total moisture stored in the six simulated surface and subsurface storage zorkes, namely the

                             interception, surface, interflow, upper zDne, lower zone, anddctive groundwater storages

                      Basin Transfers = flows across the watershed boundaries (Le underflow at gage locations)

                      Runoff = observed runoff at a gage

                      ET = Evapotranspiration

                     The purpose of looking at this equation first is twofold. First, it allows the modeler to

                     make sure that all of the incoming precipitation is accounted for and that the amounts

                     are reasonable. Secondly, it allows for an initial overall estimate of runoff and

                     evaporation volumes of the overall hydrologic budget.

                  2) Seasonal or low flows

                     The second step involves adjusting those parameters that affect low flows or

                     groundwater flows in the surficial aquifer.

                  3) Hydrograph shape and peak strearnflows


                                                             2








                     It is assumed through steps one and two that volumes and low flows are calibrated. This
                     step involves trading surface flow for interflow and vice versa to better match peak

                     flows, time to peak, and the rising and the recession limbs of the hydrographs.

                  4) Refinement

                     This step involves looking at specific events and trying to improve simulation without

                     undoing anything done in steps one to three. One example of "fine tuning" refinement

                     is trying to better simulated storms that break dry periods.

              Each of these steps were followed in the three calibration phases for the SGGE area.

              B.     LOCATION OF CALIBRATION STATIONS

                     During phase two calibration, the approach was to find an overall calibration of the

              whole basin using the strearnflow and stage data near the outlet of the Faka Union Canal and

              then narrow it down to improve individual subbasin calibration. The remaining subbasins that

              were looked at during the phase three calibration were (Figure 1):

                     1) Stumpy Strand - Lucky Lake Strand Area using 12 months of stage data at north

              Merritt canal (55th Avenue SE);

                     2) the subbasin contributing to north Miller canal using nine years of stage data recorded

              at north Miller canal (26th Avenue SE);

                     3) the southwestern subbasin using seven years of randomly collected stage data at Miner

              Canal Weir No. 1.


              C_     PERVIOUS LAND SEGNIENTS AND REACH-RESERVOIR NETWORK FOR PHASE
                     THREE SHAULATION


                     The SGGE study area and canal system were divided into 35 pervious land segments

              (PLS) and 34 reach-reservoir (RCHRES) segments during phase two calibration. The PL5

              divisions were based on homogeneity of land use, topography, soils data and similar

              meteorologic influence as discussed in previous reports.             Each RCHRES possessed

                                                              3



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                                                                                                          N
                                         CALIBRATION
                                         LOCATION 02



                                                                                     CALIBRATION
                    t----WLDF-M GATE =MAL                                              LOCATION #1
                       (ALL'Ult" ALL_--fl

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                                                                                                            ;R
                                         CALIBRATIO
                                         LOCATION
                                                                    mor-                     I
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                     21.




                                      ol >
                                                                                                           >









                          FIGURE 1. Calibration       Locations for      Phase  Three


                                                           4








              similar hydraulic characteristics and terminated at critical points in the canal system. This same

              model configuration for the SGGE watershed and canal system was maintained during phase

              three calibration.


              D.     PERIOD OF CALIBRATION

                     The time periods used for calibration in phase three were based solely on the availability

              of data. The periods of calibration were:

                     1)       Merritt Canal at 55th Avenue SE 1992

                     2)      Miller Canal at 26th Avenue SE       1983-1992

                     3)      Miller Canal at Weir No. 1           1986-1992

              One drawback of the longer simulation period (i.e. greater than 3-5 years) is that it is difficult

              to find a longer time period where residential and agricultural developments have not influenced

              the runoff characteristics of the basin. This is the case for calibration locations two and three.

              However, it was decided to use all available data to provide a great variety of meteorological

              conditions and use as many data points as possible. Stage data at Miller Canal Weir No. 1 was

              collected randomly at approximately seven to ten day intervals. Therefore, using all seven years

              of observed data allowed more data points to be compared.

              E.     INITIAL CONDMONS


                     The initial estimates of the input parameters for the hydrologic simulation were those

              parameters that were calibrated during the first two phases. The ranges of the typical values

              of the Pervious Land Module (PERLND) parameters were adapted for south Florida hydrologic

              conditions from such sources as the HSPF Application Guide, several earlier HSPF application

              project reports, and consultation with Dr. Norm Crawford, the principal author of the program.

              Some of the parameters were further adjusted so as to better simulate the individual subbasins

              yet maintaining the overall balance obtained for the entire basin.


                                                              5










              E      SENSMVITY ANALYSIS OF CALIBRATION PARANIETERS

                     The sensitivity of the selected calibration parameters on the overall simulation of the

              hydrologic processes of the SGGE was discussed in the last two quarterly reports and showed

              similar characteristics in phase three calibration.

                     In addition to adjusting the prominent parameters on soil storages, sources and sinks and

              various coefficients as described in the last report, the function tables (FTABLES) or "function

              tables" which describe the stage-volume-discharge relationship for the canals were modified for

              additional hydraulic calibration. Additional columns were added to the Faka Union Canal

              FTABLES to represent blockages to flow (both aquatic weeds and flashboards) and groundwater

              seepage from the canal near the Naples wellfield. The use of multiple columns did improve the

              results of simulation.


              C.     SUNEWARY OF CALIBRATION FOR PHASE THREE

                     The model simulation results that compare observed and simulated canal stages at the

              calibration points on the Miller and Merritt canals are shown in Figures 2 through 4.

                     The results from the phase three calibration for the three subbasins were a significant

              improvement over the first two phases of calibration. The factors that influenced the observed

              runoff, such as time variant changes in the canals and to the weirs as discussed in the last

              quarterly report, still complicate the modeling. However, better calibration results were

              observed. One reason could be that the observed data is of more reliable quality. Another

              reason is the use of stage values rather than discharge measurements. The discharge

              measurements used for calibration in phase two were extrapolated from rating curves that

              related to the observed stage values with discharge. The frequency of some discharge

              measurements were very widely distributed and did not adequately reflect the operation of stop

              logs at the water control structures. The use of weekly measured stage records to calibrate


                                                             6






                              Observed and Simulated Average Monthly Stage
                                     Merritt Canal at 55th Ave SE (Dec 1991 - Nov 1992)

                10 -



                                        Observed         Simulated





           D)

           U)

                 4




                 2
                    Dec-91   Jan-92   Feb-92   Mar-92    Apr-92   May-92   Jun-92   Jul-92   Aug-92 Sept-92    Oct-92   Nov-92
                                                               Time (Months)


                                                                  I FIGURE 21






                                           Observed and Simulated Average Monthly Stage
                                                       Miller Canal at 26th St. SE (May 1983 - Nov 1992)

                       14


                       12                                                        -Observed                   -Simulated


                       10


                 a)     8
                 CD

     co
                W
                        6                                                                                                                 -41                      V

                        4


                        2                                                   1 1 LU_IAJ_LLLLLLiIA_LLIA_A 1J.14-IJI-1-11ILLI M LLLI-I-A-IJJ-L-LL-Lt-UA-]I-U-[AA-LA--L-U-IA-LI MI LI_UJ_
                             May-83         May-84         May-85         May-86         May-87         May-88         May-89         May-90         May-91         May-92
                                                                                          Time (Months)


                                                                                               [FIGU      RE 3






                                      Observed and Simulated Average Monthly Stage
                                                         Miller Canal at Weir #1 (Jan 1986 - Dec 1992)

                    10

                     8                                                                      Observed                      Simulated
                                                                                      ------------------------------ ----------------------






            (D       6


                     4



                     2                                                           1 1 1 L I I                       1 -1 L-1 -I J-A-L-L-LI-L-1 "-L-1 "-L,-L-t t I I I LL It I
                         Jan-86                 Jan-87                 Jan-88                  Jan-89                 Jan-90                 Jan-91                 Jan-92
                                                                                              Time (Months)



                                                                                                        IGURE 4

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









              the model at Miller Canal Weir No. 1, Faka Union Canal Weirs No. 2 and 4, and continuous

              records on Miller Canal at 26th Avenue SE and Merritt Canal at 55th Avenue SE provided a

              better database for calibration. Another factor is the shorter simulated period used for the

              Stumpy Strand-Lucky Lake Strand subbasin for the Merritt Canal. The use of only one year of

              data for calibration is easier to perform than calibrating for several years. With the exception

              of Faka Union Weir No. 5 location, the calibration locations near the headwaters of the canals

              showed better results than those further downstream. Some accuracy was lost in hydraulic

              routing by use of the equation of continuity in the hydraulic section (HYDR) of the Reach-

              Reservoir (RCHRES) module as the runoff is conveyed through the canals. The Faka Union

              Canal flow characteristics have varied more over the years than those of the Miller and

              Merritt canals due to operation with more water control structures.

              H.     FINAL CALIBRATION PARANETERS

                     The final set of calibration parameters used for the simulation of SGGE are shown in

              Table 1. A list of parameter abbreviations from the HSPF program is shown in Appendix A.




















                                                            10










                                                         TABLE I

                               FINAL PARAMETERS FOR HSPF SIMULATION OF SGGE


              Parameter Set 1
              PLS      FOREST         LZSN   INFILT         LSUR   SLSUR          KVARY          AGWRC
              1        0              8      0.09           1660   0.00061        1.0            0.980
              2        0              8      0.04           1660   0.00032        0.0            0.940
              3        0              4      0.04           1660   0.00019        0.0            0.940
              4        0              4      0.04           1660   0.00016        0.0            0.940
              5        0              8      0.09           1660   0.00014        0.0            0.960
              7        0              6      0.09           1660   0.00033        0.0            0.960
              8        0              4      0.09           1660   0.00035        0.0            0.940
              9        0              4      0.04           1660   0.00014        0.0            0.940
              10       0              2      0.04           1660   0.00008        0.0            0.940
              11       0              4      0.04           1660   0.00032        0.0            0.940
              12       0              4      0.10           1660   0.00013        0.0            0.940
              13       0              4      0.09           1660   0.00013        0.0            0.940
              14       0              4      0.04           1660   0.00002        0.0            0.940
              15       0              4      0.10           1660   0.00019        0.0            0.940
              16       0              4      0.04           1660   0.00002        0.0            0.940
              17       0              4      0.04           1660   0.00038        0.0            0.940
              18       0              6      0.09           1660   0.00021        0.0            0.940
              19       0              2      0.04           1660   0.00021        0.0            0.940
              20       0              2      0.04           1660   0.00030        0.0            0.940
              21       0              8      0.09           1660   0.00013        0.0            0.940
              22       0              4      0.04           1660   0.00012        0.0            0.940
              23       0              4      0.04           1660   0.00032        0.0            0.940
              24       0              4      0.04           1660   0.00018        0.0            0.940
              25       0              4      0.04           1660   0.00025        0.0            0.940
              26       0              4      0.04           1660   0.00013        0.0            0.940
              27       0              2      0.04           1660   0.00008        0.0            0.940
              28       0              2      0.04           1660   0.00008        0.0            0.940
              29       0              2      0.04           1660   0.00008        0.0            0.940
              30       0              4      0.04           1660   0.00042        0.0            0.920
              31       0              4      0.06           1660   0.00032        0.0            0.940
              32       0              4      0.04           1660   0.00018        0.0            0.940
              33       0              4      0.04           1660   0.00008        0.0            0.920
              34       0              4      0.04           1660   0.00032        0.0            0.940
              35       0              6      0.06           1660   0.00032        0.0            0.940
              36       0              4      0.04           1660   0.00020        0.0            0.920
              37       0              4      0.04           1660   0.00020        0.0            0.920

              PLS      Pervious Land Segment
              FOREST = fraction of winter forest transpiration
              LZSN = lower zone nominal soil storage (in)
              INFILT = index to mean infiltration rate (in/hr)
              LSUR = length of overland flow plane (ft)









                                                  TABLE 1 (Continued)

              SLSUR = slope of overland flow plane
              KVARY     groundwater recession behavior parameter (1/in)
              AGWRC      active groundwater recession coefficient (1/day)

              Parameter Set 2


              PLSPETMAX     PETMIN         INFEXP         INFILD         DEEPFR        BASETP AGWETP


              1-4    40     35             2.0            2.0            0.5           0.0            0.40
              5-6    40     35             1.0            2.0            0.1           0.0            0.40
              7      40     35             1.0            2.0            0.3           0.0            0.40
              8-9    40     35             2.0            2.0            0.3           0.0            0.40
              10     40     35             2.0            2.0            0.3           0.0            0.60
              11     40     35             2.0            2.0            0.3           0.0            0.70
              12     40     35             2.0            2.0            0.3           0.0            0.40
              13     40     35             2.0            2.0            0.3           0.0            0.40
              14     40     35             2.0            2.0            0.3           0.0            0.60
              15     40     35             2.0            2.0            0.3           0.0            0.40
              16     40     35             2.0            2.0            0.3           0.0            0.60
              17     40     35             2.0            2.0            0.3           0.0            o.70
              18     40     35             2.0            2.0            0.3           0.0            0.70
              19     40     35             2.0            2.0            0.3           0.0            0.40
              20     40     35             2.0            2.0            0.3           0.0            0.70
              21-26  40     35             2.0            2.0            0.3           0.0            0.40
              27     40     35             2.0            2.0            0.3           0.0            0.60
              28     40     35             2.0            2.0            0.3           0.0            0.60
              29     40     35             2.0            2.0            0.3           0.0            0.60
              30     40     35             2.0            2.0            0.3           0.0            0.70
              31     40     35             2.0            2.0            0.3           0.0            0.40
              32     40     35             2.0            2.0            0.3           0.0            0.40
              32     40     35             2.0            2.0            0.3           0.0            0.40
              33     40     35             2.0            2.0            0.3           0.0            0.70
              34     40     35             2.0            2.0            0.3           0.0            0.40
              35     40     35             2.0            2.0            0.3           0.0            0.60
              36-37 40      35             2.0            2.0            0.3           0.0            0.70

              PETMAX      air temperature which signals a change in ET calculation
                        (F), only used if snow is considered
              PETMIN = air temperature which signals a change in ET calculation
                        (F), only used if snow is considered
              INFEXP = exponent in infiltration equation
              INFILD = ratio of max/min infiltration rate
              DEEPFR = fraction of groundwater lost to deep aquifer
              BASETP = fraction of ET from active groundwater outflow
              AGWETP = fraction of ET from active groundwater storage


                                                             12








                                                    TABLE 1 (Continued)
              Parameter Set 3
              PLS     CEPSC          UZSN           NSUR           INTFW          IRC             LZETP


              1       0.100          1.80           0.70           5.00           0.90            0.50
              2       0.100          0.50           0.70           5.00           0.95            0.30
              3       0.150          0.50           0.70           5.00           0.95            0.70
              4       0.150          0.50           0.70           5.00           0.95            0.80
              5       0.150          0.50           0.70           5.00           0.90            0.80
              6       0.150          0.50           0.70           5.00           0.90            0.80
              7       0.100          0.50           0.70           5.00           0.90            0.60
              8       0.150          0.50           0.70           5.00           0.95            0.80
              9       0.150          0.50           0.70           5.00           0.90            0.80
              10      0.150          0.50           0.70           5.00           0.95            0.70
              11      0.150          0.50           0.70           5.00           0.90            0.70
              12      0.150          0.50           0.70           5.00           0.95            0.70
              13      0.150          0.50           0.70           5.00           0.95            0.70
              14      0.100          0.50           0.70           5.00           0.95            0.40
              15      0.150          0.50           0.70           5.00           0.95            0.70
              16      0.150          0.50           0.70           5.00           0.95            0.70
              17      0.150          0.50           0.70           5.00           0.95            0.70
              18      0.150          0.50           0.70           5.00           0.95            0.70
              19      0.100          0.50           0.70           5.00           0.95            0.40
              20      0.150          0.50           0.70           5.00           0.95            0.70
              21      0.100          0.50           0.70           5.00           0.95            0.30
              22      0.150          0.50           0.70           5.00           0.95            0.70
              23      0.150          0.50           0.70           5.00           0.90            0.70
              24      0.100          0.50           0.70           5.00           0.95            0.40
              25      0.150          0.50           0.70           5.00           0.90            0.80
              26      0.150          0.50           0.70           5.00           0.95            0.70
              27      0.150          0.50           0.70           5.00           0.95            0.70
              28      0.100          0.50           0.70           5.00           0.95            0.40
              29      0.150          0.50           0.70           5.00           0.95            0.70
              30      0.200          0.50           0.70           5.00           0.95            0.90
              31      0.150          0.50           0.70           5.00           0.95            0.80
              32      0.150          0.50           0.70           5.00           0.95            0.40
              33      0.150          0.50           0.70           5.00           0.95            0.90
              34      0.150          0.50           0.70           5.00           0.95            0.70
              35      0.150          0.50           0.70           5.00           0.95            0.40
              36      0.200          0.50           0.70           5.00           0.95            0.90
              37      0.100          0.50           0.70           5.00           0.95            0.40

              CEPSC     interception storage capacity (in)
              NSUR      Manning's n for overland flow
              UZSN      upper zone nominal soil storage (in)
              INTFW = interflow inflow parameter
              IRC = interflow recession rate (1/day)
  0           LZETP = lower zone evapotranspiration parameter
                                                              13





             Monthly Variable Parameters          TABLE 1 (Continued)

             LZETP
             PLS     JAN    FEB     MAR    APR    MAY     JUN    JUL    AUG     SEP    OCT     NOV    DEC

             1       .25    .25     .25    .25    .40     .40    .40    .40     .25    .25     .25    .25
             2       0.2    0.2     0.2    0.2    0.2     .05    .05    .05     .05    .05     0.2    0.2
             3       .25    .25     .25    .25    .40     .40    .40    .40     .25    .25     .25    .25
             4-6     0.4    0.4     0.5    0.6    0.7     0.7    0.6    0.5     0.4    0.4     0.4    0.4
             7       0.3    0.4     0.4    0.4    0.5     0.5    0.4    0.3     0.3    0.3     0.3    0.3
             8-13    0.4    0.4     0.5    0.6    0.7     0.7    0.6    0.6     0.5    0.5     0.4    0.4
             14      0.2    0.2     0.2    0.2    0.2     0.2    0.2    0.2     0.2    0.2     0.2    0.2
             15-17   0.4    0.4     0.5    0.6    0.7     0.7    0.6    0.5     0.4    0.4     0.4    0.4
             18      0.4    0.4     0.5    0.6    0.7     0.7    0.6    0.5     0.4    0.4     0.4    0.4
             19      0.2    0.2     0.2    0.2    0.2     0.2    0.2    0.2     0.2    0.2     0.2    0.2
             20      0.5    0.6     0.7    0.7    0.8     0.8    0.7    0.7     0.7    0.6     0.6    0.5
             21      0.2    0.2     0.2    0.2    0.2     .05    .05    .05     .05    .05     0.2    0.2
             22      .25    .25     .25    .25    .40     .40    .40    .40     .25    .25     .25    .25
             23      .25    .25     .25    .25    .40     .40    .40    .40     .25    .25     .25    .25
             24      0.3    0.4     0.4    0.4    0.5     0.5    0.4    0.4     0.4    0.3     0.3    0.3
             25      0.6    0.7     0.8    0.8    0.9     0.9    0.8    0.8     0.8    0.7     0.7    0.6
             26      0.5    0.6     0.7    0.7    0.8     0.8    0.7    0.7     0.7    0.6     0.6    0.5
             27      0.5    0.6     0.7    0.7    0.8     0.8    0.7    0.7     0.7    0.6     0.6    0.5
             28      0.3    0.4     0.4    0.4    0.5     0.5    0.4    0.4     0.4    0.3     0.3    0.3
             29      0.5    0.6     0.7    0.7    0.8     0.8    0.7    0.7     0.7    0.6     0.6    0.5
             30      0.7    0.8     0.8    0.9    0.9     0.9    0.9    0.9     0.9    0.8     0.8    0.7
             31      0.4    0.4     0.5    0.6    0.7     0.7    0.6    0.6     0.5    0.5     0.4    0.4
             32      0.3    0.4     0.4    0.4    0.5     0.5    0.4    0.4     0.4    0.3     0.3    0.3
             33      0.7    0.8     0.8    0.9    0.9     0.9    0.9    0.9     0.9    0.8     0.8    0.7
             34      .25    .25     .25    .25    .40     .40    .40    .40     .25    .25     .25    .25
             35      0.3    0.4     0.4    0.4    0.5     0.5    0.4    0.4     0.4    0.3     0.3    0.3
             36      0.7    0.8     0.8    0.9    0.9     0.9    0.9    0.9     0.9    0.8     0.8    0.7
             37      0.3    0.4     0.4     0.4   0.5     0.5    0.4    0.4     0.4    0.3     0.3    0.3

             LZETP = lower zone evapotranspiration parameter

             Parameters for Initial Conditions


             PLS    CEPS,   SURS           UZS            IFWS          LZS            AGWS           GWVS


             1      0.00     0.0           0.0            0.0           6.0             1.7           0.00
             2      0.00     0.0           0.0            0.0           6.0             1.7           0.00
             3      0.00     0.0           0.0            0.0           6.0             3.5           0.00
             4      0.00     0.0           0.0            0.0           6.0             2.0           0.00
             5      0.00     0.0           0.0            0.0           6.0             1.7           0.00
             6      0.00     0.0           0.0            0.0           6.0             2.0           0.00


                                                            14









                                                   TABLE 1 (Continued)

              PLS   CEPS    SURS            UZS            lFWS           US            AGWS            GWVS

              7     0.00     0.0            0.0            0.0            6.0            2.0            0.00
              8     0.00     0.0            0.0            0.0            5.0            1.7            0.00
              9     0.00     0.0            0.0            0.0            5.0            2.0            0.00
              10    0.00     0.0            0.0            0.0            4.0            2.0            0.00
              11    0.00     0.0            0.0            0.0            4.0            2.0            0.00
              12    0.00     0.0            0.0            0.0            4.0            1.7            0.00
              13    0.00     0.0            0.0            0.0            4.0            2.0            0.00
              14    0.00     0.0            0.0            0.0            4.0            2.0            0.00
              15    0.00     0.0            0.0            0.0            4.0            1.7            0.00
              16    0.00     0.0            0.0            0.0            4.0            2.0            0.00
              17    0.00     0.0            0.0            0.0            3.0            2.0            0.00
              18    0.00     0.0            0.0            0.0            4.0            2.0            0.00
              19    0.00     0.0            0.0            0.0            3.0            2.0            0.00
              20    0.00     0.0            0.0            0.0            3.0            2.0            0.00
              21    0.00     0.0            0.0            0.0            6.0            1.7            0.00
              22    0.00     0.0            0.0            0.0            6.0            3.0            0.00
              23    0.00     0.0            0.0            0.0            4.0            2.0            0.00
              24    0.00     0.0            0.0            0.0            4.0            3.0            0.00
              25    0.00     0.0            0.0            0.0            4.0            1.7            0.00
              26    0.00     0.0            0@0            0.0            4.0            2.0            0.00
              27    0.00     0.0            0.0            0.0            4.0            1.7            0.00
              28    0.00     0.0            0.0            0.0            4.0            2.0            0.00
              29    0.00     0.0            0.0            0.0            3.0            1.7            0.00
              30    0.00     0.0            0.0            0.0            4.0            2.0            0.00
              31    0.00     0.0            0.0            0.0            4.0            2.0            0.00
              32    0.00     0.0            0.0            0.0            4.0            3.0            0.00
              33    0.00     0.0            0.0            0.0            3.0            2.0            0.00
              34    0.00     0.0            0.0            0.0            4.0            2.0            0.00
              35    0.00     0.0            0.0            0.0            3.0            2.0            0.00
              36    0.00     0.0            0.0            0.0            4.0            2.0            0.00
              37    0.00     0.0            0.0            0.0            3.0            2.0            0.00

              CEPS = interception storage at the start of the simulation (in)
              SURS = surface storage at the start of the simulation (in)
              UZS = upper zone soil storage at the start of the simulation (in)
              IFWS = interflow storage at the start of the simulation (in)
              US = lower zone soil storage at the start of the simulation (in)
              AGWS = active groundwater storage at the start of the simulation (in)
              GWVS = index to groundwater slope at the start of the simulation (in)





  0                                                          15










                                                   IlL VERIFICAUON

                    The model was tested for verification using a seven-year simulation period of 1985 to

             1992 and using flow data collected at Faka Union Weir No. 1. This station was used for

             verification because it records the outflow from the entire watershed and has continuous records

             of outflow from 1969. The period 1 985 to 1992 was chosen because this period covers dry years

             of 1988-1990, a representative cycle of drought and wet years including the wet years of 1991

             and 1992. The results as shown in Figure 5 were similar to the calibration results at weir No.

             1 for 1970 to 1984. The overall evaluation of model performance to simulated SGGE is discussed

             in the next section.












































                                                            16








                              Monthly Hydrographs of Model Verification
                                          Faka Union Weir #1 (Jan 85 - Dec 92)

              1200


                                                Observed Flow   Simulated Flow
              1000

         oo-.
         U)
         LL  800


             600
                                                                   j4
          2)
          cc

             400


             200




                                                     -i L
                 0
                  Jan-85    Jan-86    Jan-87    Jan-88    Jan-89    Jan-90    Jan-91    Jan-92
                                                     Time (Months)



                                                        FIGURE 5










                                   IV. EVALUATION OF MODEL PERFORMANCE

             A.      PRESENCE OF HIGH GROUNDWATER TABLE IN SOUTH FLORIDA HYDROLOGY

                     One unique element in South Florida hydrology is a seasonally varying water table with

             a large amplitude. During the wet season it can come up very close to the land surface. The

             overland flow module of HSPF does not adequately simulate South Florida's sheefflow through

             wetlands. Throughout a typical year, the water table may vary by several feet, rising above the

             land surface during the wet season and dropping during the dry season. These cyclic

             groundwater levels affect such hydrologic processes as soil storages, evapotranspiration from the

             upper and lower zones of soil horizon, runoff and direction of shallow groundwater flow. Some

             seasonal variation of parameters is allowed in HSPF (i.e. seasonal canopy changes), but not to

             the extent that it can model a seasonal high water table.

             B.      SHEETFLOW HYDRAULICS

                     When the water table rises above the land surface and large land areas are flooded, the

             existing Pervious Land (PERLND) module of HSPF does not model the sheetflow characteristics

             adequately. A typical expanse of natural south Florida wetland has the ability to store an

             enormous amount of water. The existing overland flow algorithms do not represent the storage

             effects of these wetlands and thus result overpredicting the runoff peaks. Also evaporation

             from overland flow is not represented in the model. In wetland areas where overland flow may

             last weeks, evaporation should be accounted for. Further enhancement to the PERLND module

             to account for these unique features of south Florida wetlands has been proposed in a recently

             undertaken study by the District. The enhanced program will be applied later to update the

             SGGE model.


             C.      REACH-RESERVOIR (RCHRES) MODULE OF HSPF

                     The outflow hydrograph is sensitive to the function tables (FTABLES) which represents


                                                            18








              the stage-storage-outflow characteristics of the canals. In phase three calibration, the runoff
              hydrographs were better matched at Miller Canal at 26th Avenue SE than at Miller Canal Weir

              No. 1, a location farther downstream. It is possible that as the runoff is routed through the

              canals some accuracy is lost. The modification of the RCHRES module to dynamically route
              flows through canals with flat bed slopes and various control structures should enhance the

              simulation of flow characteristics in South Florida canals.

              D.      ASSUMPTIONS IN ALTERNATTVE ANALYSIS

                      Though the application of the PERLND and RCHRES modules of HSPF may provide a

              fair representation of the existing SGGE hydrology, the alternatives analysis creates new

              challenges. Traditional applications of HSPF have included reservoir operations analysis,

              stormwater management plan development and water quality studies related to waste treatment,

              urban and/or agricultural management practices. The task of representing alternative measures

              for restoration of wetland hydrology of SGGE is a unique application. The spreader channel

              along the north boundary of SGGE is simulated as a reach discharging into a land segment. This

              is not the conventional direction of flow in the runoff hydrologic cycle. A necessary assumption

              for representing the spreader channel in this way is that the water from the spreader is spread

              out evenly over the entire land segment and not along a "line" as in the real physical world.

                      As SGGE is reflooded, one might assume certain HSPF parameters as infiltration factor

              (INFILT) and those representing soil storages would be different due to the new nearly saturated

              or saturated conditions. However, the calibrated parameters are for existing conditions, not for
              reflooded conditions because the model was not calibrated for the virgin conditions prior to the

              development of SGGE. In more conventional applications, those alternatives that require straight

              forward input modifications are easier to analyze. Additionally, looking at specific model output

              for alternative analysis such as daily surface storage may not represent the physical reality if the


                                                               19









             runoff flow paths are not correctly represented in the model.

             E.      OVERALL COMPLEXM OF MODELING SGGE

                    The SGGE hydrologic regime is complex in that there is strong interactions between the

             surface runoff processes, and groundwater table levels, areas of surface inundation, and even

             canal water levels. The hydraulics in the canals are influenced by backwater effects, unrecorded

             structural and canal alterations, well pumpage, and adjacent groundwater levels. The modeling

             of these complexities were inadequate due to the limitations of the current version of HSPF in

             representing unique South Florida hydrologic conditions such as the overland runoff and

             infiltration components for high groundwater table.































                                                            20










                     V. ASSESSNIENT OF HYDROLOGIC CONDITIONS FOR THE SGGE REGION

                     Based on the detailed investigation and modeling of the SGGE region, the following

             observations of the existing hydrologic conditions were made:

                     1.     The canals largely control the present hydrology of SGGE. Any sheetflow that

             exists is quickly intercepted by a swale and directed to one of the four main canals. During the

             dry season, the canals collect groundwater from the adjacent land and discharge it into the Gulf

             of Mexico. The average discharge from the Faka Union Canal at the outlet of the basin is 250

             cfs with average wet season flows over 600 cfs. Using a drainage area of 189 square miles, the

             runoff amounts to 18 inches per year.

                     2.     The changing vegetation pattern, field observations (Swayze and McPherson,

             1977), and studies by Black, Crow and Eidsness and Flora C. Wang have shown a gradual

             lowering of the groundwater table.

                     3.     A surficial groundwater movement vector, based on three-dimensional finite

             difference modeling of western Collier County, is illustrated in Figure 6. The surficial

             groundwater flows are in an east to west direction into the Faka Union Canal both at a location

             just east of the north Faka Union Canal near Stumpy Strand and also just east of the Faka Union

             Canal between weirs No. 2 and 3. Additionally, groundwater flows from the western portion

             of the Fakahatchee Strand State Preserve into the Prairie Canal. These surficial groundwater

             flow directions vary seasonally. During the wet season when the groundwater levels are high,

             the flow patterns are in a south to southwest direction. As dry season progresses, the

             groundwater movement shifts direction to an east-west pattern, draining directly into one of the

             north-south canals.

                     4.     As the dry season approaches it appears the groundwater flow at Faka Union

             Canal near weir No. 1 recedes at a faster rate during the early years (1970 to 1975) after the


                                                            21





                                         (Z66T TTadV "M TOUqDTW '439UUOff)
   NnoO 308NOIN       UOsvaS Aaa 2uiana lUaM9AOK TP3UOZT
                                                   .10H jajTnbV TVTDTjanS -9 ZHnDja






                                                                      N*







             A A 41 4 d


               j 4 4 4 4


               4 4 4 4 41       4' A 4 d




                                     I d I


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                                                             Ln
                                                            ;Dr

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                                                   A      A      A





                                                       - - - - - - - - - - -
                   d                         DD  .                             L
  d'          4 4 4                              - e did
                                                      1
               4      A . . . . . . . . .
            k  A  7
                     4                               did
          A          4 .1

                                                             44









              canals were built than later years (1976 to 1984). This indicates that the construction of the

             canals not only increases surface runoff, but increases the rate of groundwater outflow, perhaps

             causing groundwater "peaks" that were not present before the canals were built.

                     5.     Better calibration results were obtained at Faka Union No. 5 when a higher value

             for deep fraction (DEEPFR) was used. DEEPFR represents the fraction of groundwater lost to

             the deep aquifer but also could represent groundwater lost to wellfield pumpage. This indicates

             that the City of Naples wellfield located between Weirs No. 5 and 4 is reducing groundwater

             outflow from the surficial aquifer north of Faka Union Weir No. 5.



































                                                            23









                           VL DEVELOPNMNT OF ALTERNATTVE RESrORATION PLANS




             A.      CRHIRIA FOR PLAN DEVELOPNENT

                     Alternative structural measures to modify the existing water management system of

             SGGE were evaluated on the ability to meet the following study objectives:

                     1.     Wetland hydroperiod restoration,

                     2.     Surface water sheetflow restoration,

                     3.     Replacement of concentrated shock load discharges to estuaries with distributed

                            sheetflow

                     4.     Improved water storage and aquifer recharge,

                     5.     Enhanced surface water deliveries to Fakahatchee Strand,

                     6.     Reduction of over-drainage of Fakahatchee Strand,

                     7.     Reduction of over-drainage of Panther Refuge lands,

                     8.     Maintenance of existing flood protection for areas north of 1-75.

             In addition to evaluating the effectiveness of each alternative to accomplish the stated objectives

             of the project, the economic feasibility and the hydrologic and hydraulic impacts were evaluated.

                     In order to quantify the system's response with respect to the hydrologic and hydraulic

             evaluation of the alternatives, various model outputs were analyzed. The various storage zones

             (upper zone soil, lower zone soil and groundwater storage) were analyzed. Also considered

             were the runoff volumes at Faka Union Weir No. 1 and over the entire basin. The base

             conditions to which the alternatives were compared was the current system for which the model

             is calibrated. A 23-year simulation was run (1970-1992) for both the base conditions and the

             alternatives.






                                                             24









              a      IDENTIFICATION OF ALTERNATIVES

                     Within the purview of the developed hydrologic-hydraulic model three alternative

              restoration measures were formulated to accomplish the stated objectives of the project.

                     1)      Alternative 1: Diversion Structure Plan. This alternative considers the present

              interim plan proposed by the Big Cypress Basin to be implemented in FY 1995. This is a partial

              plan, and not expected to achieve the full range of objectives identified for the SGGE restoration

              project. It includes a flow diversion structure with three 48-inch gated culverts located

              approximately one mile north of Faka Union Weir No. 1 (see Figure 7). The culverts will divert

              approximately 50 percent of the existing base flow to a spreader channel. The dissipated flows

              will be conveyed through public lands owned by the Fakahatchee Strand State Preserve (Florida

              Department of Environmental Protection) to distribute through the bridges under U. S. 41. These

              diverted flows will be dissipated and filtered through wet prairies as sheetflows to the Faka

              Union Bay.

                     2)      Alternative 2: S12reader Channel and Canal/ Road Removal Plan. This alternative

              (as shown in Figure 8) considers a spreader channel immediately below 1-75 extending from the

              western boundary of the SGGE study area near the western boundary of the Fakahatchee Strand

              State Preserve. This plan also considers removal of all roads and canals south of Alligator

              Alley. This alternative is intended to provide insight to predevelopment conditions had there

              been no development south of the Alley, although canal and roads will continue to exist north

              of the alley. Major system response information for SGGE such as runoff volumes and rates and

              relative soil storages were examined. Evaluation of northern Golden Gate Estates runoff was

              part of the output analyzed in this alternative.

                     3)      Alternative 3: SRreader Channel, Canal Blocks and Selected Road Removal Plan.

              This alternative has several elements. It includes two spreader channels with pump stations,


                                                              25











                                                                                         N

                                                 PROPOSED STRUCTURE                    N.T.S.

                                                         E)QS`nNG ROAD


                                                                     DUS11NG SWALE
                                  z



                                  z
                                                    SHEET FLOW
                                                    DfVERSION
                                                    AREA
                                       Li
                                        L


                             WEIR 2


                                                  TAMLAMI














                 LEGEND

             CANAL


             ROAD

             SWALE




                                                 v@     PL&L
                                                        RA.L        SOUMM COLIMM "TE MATES
             SOUTH FLORIDA WAIER                                      NrM MOMMMON PL4N
             MANAGEMENT DISTRICT                                    Conceptual Plan of
                                                     -MM Im Sri"    Alternative One

                                                                     FIWRE
                                                "as" 1                     7         Sm PLM


                                                      26















                                                          14




                           LIAITM 11

                                                                                          N


                                                                 Spreader
                                                                 Channel



                           "M CANAL


                                                        T T  T





                        SGGE Boundary




                                                                                          >












                                                                                          CA

                                  .. ....... L - - - - - - -

                                  -4
                                  >
                                  --4



                                  >                                                       -4
                                    C"                                                    >











                                               17
                                               m


                FIGURE 8. Conceptual Plan of Alternative Two

                                                    27








             removal of selected roads, canal plugs, and drainage improvements to Miller Boulevard for

             better exchanges of flow under the road (see Figure 9).

             a)     Spreader Channels

                    The first or main spreader channel would extend eastward from Everglades Boulevard

             to approximately one and one-half miles east of Merritt Canal. The inflow to this canal would

             be discharge from the Faka Union Canal and the north Merritt Canal. The spreader would be

             located just down from the proposed weir structure on the Merritt Canal which is approximately

             200 feet south of 1-75 (see Figure 10). The Faka Union Canal would be widened before

             discharging into the spreader to reduce the velocities in the canal before reaching the spreader.

                    The purpose of the spreader channel is twofold. First, it must take flow from the two

             north-south canals (Faka Union and Merritt) and spread this flow in an east-west direction.

             Secondly, it must allow discharge to the south onto the land surface. If only the first purpose

             was important, a channel cross-section similar to the current GAC canals could be used.

             However, raising the water surface elevation in the spreader channel high enough to allow

             overtopping and discharge onto the land surface (average elevation 11.5 feet NGVD), would

             compromise flood protection for the upstream portions of the Faka Union Canal. Two possible

             configurations for the spreader channel that would maintain flood protection north of 1-75 are

             proposed:

                    1)     The cross-section of the spreader channel would be similar to the existing GAC

             canals. The main goal of the canal would be to convey the flows in an east-west direction. The

             canal stages both in the Faka Union Canal and in the spreader channel would be maintained to

             prevent flooding north of 1-75. The water in the spreader channel would then be pumped from

             the spreader onto the land surface as shown in Figure 11.




                                                           28








                                                                                N



                            1-75


                                                                                               N
                            MIL  ER#2ï¿½ft-   h
                                             w   w 'kB               BLOCK
                                          +
                 MILLER
                 SPREADER                                                       MAIN
                 WITH PUMP          BLO'                                        FAKA
                 STATIONS                                                       UNION
                                                                                SPREADER
                                                                                WITH
                                                                                PUMP
        DRAINAGE                                                                STATIONS
        IMPROVEMENTS







                                                        LOCK







                                                    BLOCK
                                                                                    BLOCK
                                  'BLOCK
             sl

















                                                                         T.nrw






                                                             -BLOCK


                                                    BLOCK
   0,-
   000,


   011,
              mm

   00, >
   /   =                                                      FAKA UNION #1
       Pq m
                                                              @BLO





                                                         KT










                    FIGURE 9. Conceptual Plan of Alternative Three


                                                  29




















                                                               FAKA NION CANAL



                                                                                                                                                               NORTH











                                                                                                                                      -200'
                                                                                     --BERM (NORTH) 4.5'

                                                                                                                                                      RUCTURE
                                                                                                                                                  ""T
                                                                                                                                                is

          C)
                                                                            III ill 11 11 11 1U."Ill       mill 11111 '111 lie"Ill III                    it 1111111 (111 iif In 111W III III III




                                                         BLOCK _1@                            LOW BERM (S[L.TH) 2.5'                                         BLOCK
                                                                                                   WITH MULTIP-1 OPENINGS
                                                                   f

                                                               vt  L



                                                               IA



                                         BLOCK                              UNION CANAL                                                               MERRIT CANAL

                                                                                                                          BLOCK


                                                 CONCEPTUAL PLAN OF SPREADER CHANNEL AND
                                                                                                                                       2@1'



                                                                                                                                     .. .. .. ..















                                                           CANAL/SWALE BLOCKS                                           PLAN VIEW
                                                                                                                                                      NOT TO SCALE



                                                                                           FIGURE 10





















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                                                                                                                                                                                               If I I               III Ili W III If          I III Of I
                                                                                                                                                                                               AIMP 1.1,11-111-11L JILI11                         1.11LAIL
                                                                                                                                          C-o-not            Spre4der leghs


                                                                                                                                          SPREADER CHANNEL ("R(ISS-SECIIIIN


                                                                                                                                                            FIGURE 11
                                                                                                                                                                                     f                                    I   if     III,
                                                                                                                                                                                                                 at         1         11       11    1









                      The exact number and location of the pumps would be limited by the economic

               feasibility. However a minimum of three locations have been identified for the Faka Union

               Spreader and two locations for the Miller Spreader which correspond to the headwaters of major

               flowways and are shown in Figure 12. The first is just east of Everglades Boulevard, the second

               is near Desoto Boulevard and the third is near the Merritt canal. The pump stations for the

               Miller Spreader would be located on each side of the canal. There would be the flexibility to

               direct more or less flow into any desired flowway through the operation of the pumps.

                      2)      The second configuration for the spreader channel is shown in Figure 13.

                      This plan requires an installation of a canal block that allows two water surface elevations

               to be maintained on either side of the spreader channel. The water surface elevation would be

               "stepped up" by pumping into the spreader channel and the water would then flow by gravity

               onto the land surface. The low berm on the downstream side would have several openings (i.e.

               notches or culvert pipes) that could be evenly spaced or alternatively spaced to allow more

               discharge into the headwaters of the flowways (see Figure 14). The purpose of the low berm

               would be to force the water movement in an east-west direction and allow greater spreading

               capability and possibly prevent a situation where the majority of the water is discharged at or

               near the Faka Union Canal. The spreader channel would be a relatively wide and shallow canal

               with a berm on the north side to prevent water from escaping north. The canal outflow would

               distribute evenly over the entire area rather than at only the three places as in the first

               configuration. This second configuration would not allow the flexibility to direct more water

               into a particular flowway. Both configurations were represented in HSPF the same way. Further

               explanation on incorporating the effect of the alternatives in the model is explained in the next

               section.







                                                                 32










                                                                             N




                                           I  had -=i



                                                                         FAKA UNION
             MILLER SPREADER                                             SPREADER



















             MXWAFR7T..; vor         I




                                                   IL







                                NCH\
                                    AbW


      Cn






          son"
          Z   WN"                         A=
          (3






                             FIGURE 12. Pump Locations

                                                 33



































                                                  reyallred min







                                                                                               SPREADER CHANNEL




                                                           FAKA UNION CANAL


                                                                    SPREADER CIIANNEL CROSS-SECTION


                                                                             FIGURE 13




































                                                                   UPSTREAM BERM



                                                                                       D, WN STREAM BERM
                      4.0






                                       '-GROUND








                               D0Wl'4:S-rYZ1EAM IBEIRM     F7Rc)isq-r viEw


                                                                               NOT TO SCALE
                                                                                    ll@  [Ell





                                                 FIGURE 14





  40                  The second spreader channel would collect outflows from the Miner Canal and would
              extend from the western boundary of SGGE to Everglades Boulevard, approximately one and

              a quarter miles south of 1-75. Several upland areas exist just south of 1-75 within a mile of Miller

              Canal. Locating the spreader farther south would prevent water from circumventing the islands

              and backing up to the west. The alternative designs for the Miller spreader channel would be

              similar to the design for the main Faka Union spreader channel described above, but smaller to

              accommodated less flow.

              b)      Road Removal

                      Given that there are approximately 290 miles of roads in SGGE, their complete removal

              is not economically feasible. The major factors considered to select the segments of road for

              removal were: (a) roads that intercepted major flowways, (b) roads located at the north end

              of SGGE or closest to the spreader channels and (c) roads having the greatest environmental

              impact. The major flowways were determined using information from topographical maps, soils

              and vegetation maps, areal photographs, satellite images and field inspections. The roads

              crossing major flowways were considered top priority for removal. By removing roads at the

              north end first will ensure a flowway from the spreader channels and will prevent any backing

              up of water. As the water flows south, and farther from Interstate 75, the impact from any

              danuTting effect of roads is reduced. The paved roads in the SGGE area are wider and generally

              higher than the side dirt roads. Many of these dirt roads are overgrown with vegetation and

              are now merely a narrow path. Therefore, paved roads were considered to have a greater

              impact on the environment. Figure 9 shows the road segments selected for removal.

              C)      Canal Plugs

                      The canals in the SGGE have been responsible for the overall degradation of the

              hydrology and ecology of the area, much more so than the roads. Therefore, elimination of


                                                               36





  is         channelized flow south of 1-75 is suggested. With the removal of channelized flow south of 1-75,
             any spreader channels north of 41 or off of the Merritt or Prairie canals would be impractical due

             to lack of inflow into the spreader channel. Therefore, restoration elements of that type are not

             considered in this alternative. Several canal plugs are suggested and illustrated in Figure 15.

                     Plugs B5, B1 and A3 would be south of the spreader channels and prevent water from

             draining from the spreader directly into the canals. Since the canals are several miles long, they

             could provide some localized drainage, especially early in the wet season when canal stages are

             low. Therefore, the remaining canal blocks spaced at fairly regular intervals prevent any

             drainage from occurring. Plugs Al through A5 could be a first phase of restoration and B1

             through B6 could be constructed as additional land is acquired by the state. If funding permits,

             blocking the swales at the end where they enter the canals would prevent localized drainage.

             Additionally, the spoil banks on the sides of the canals, particularly near the south end of the

             canal system, need to be removed to allow flow across the canals.

             d)      Drainage Improvements

                     If Miller Boulevard were to become an evacuation route, several additional culverts or

             other cross-drainage facilities would need to be placed to provide adequate exchange of flow

             under the road. Everglades Boulevard, Stewart Boulevard and part of Lynch Boulevard remain

             intact for access to SGGE, however cross-drainage facilities would have to be improved for these

             roads. It is to be noted that during the wet season, under restored conditions, these roads may

             be under water.


             C_      HYDROLOGIC AND HYDRAULIC OdULATION OF ALTERNATIVES

                     The hydraulic configuration of the above three structural alternatives was formulated in

             the RCHRES module of the calibrated HSPF model of SGGE and their performance was

             simulated for the entire period of simulation. The detailed evaluation of alternatives are


                                                             37








                                                                                   N



                            1-75



                                                                        A3



                 MILLER
                                                                                  HA I
                 SPRE,UER
                                     B5                                           FAKA
                                                                                  UNION
                                                                                  SPREADER










                                                         B2









                                            1 -7

                                                     B
                                                                     A4                 Al
                                     B 6





















                                      Ann         off

                                                                 A5


                                                          B
                                m

                                                                              -4
          some                                                                m
                                                                              zi
                                                                              (A







                    FIGURE 15. Canal Plugs

                                                           38










             described below.

                    Alternative one was represented in HSPF by creating a new reach for the spreader

             channel and having this reach discharge into a land segment as a surface lateral inflow.

             However, because the receiving land area was too small an area, program complications

             prevented output analysis of this alternative as regards to the effects on soil storages, and

             hydroperiods of the overall basin.

                    The major model input to represent alternative two was changed by simulating the main

             spreader channel as a RCHRES and routing the outflow to a pervious land segment (PLS). As

             no further RCHRES was considered thereafter, the simulation for the downstream segments was

             performed only by the PERLND module. The runoff from the land segments was routed from

             one PLS to another, according to historical drainage patterns, as a surface, interflow and

             groundwater lateral inflows, until the runoff left the boundary of the basin.

                    The system representation was also changed to represent alternative three. Two new

             reaches were created to represent the spreader channels and these reaches discharged into the

             land segments directly to the south. The runoff from the land segments was then routed

             through historical drainage ways which were represented by newly created reaches as wide and

             shallow channels. The plugged canals were represented more like "ponds" in the model with

             interconnection occurring only when one pond overflows to another as water surface rises above

             the crest of the canal plugs.












                                                           39










                                     VIL EVALUATION OF ALTERNATIVE PLANS

              A.     HYDROLOGIC PERFORMANCE OF ALTERNATIVE ONE

                     Alternative one is a partial plan and does not achieve all the objectives of the project.

              The limited scope of this alternative provides a reduction in point source discharge of

              approximately 50 percent of the existing Faka Union Canal baseflow at the outlet. The sheetflow

              created would enhance the adjacent wetlands and reduce the freshwater shock loads to the

              estuary. However, due to program complications the specific relative changes in soil storages

              and hydroperiods over the entire basin could not be examined.

              B.     HYDROLOGIC PERFORMANCE OF ALTERNATIVE TWO

                     The overall water budget for alternatives two and three relative to the existing conditions

              is illustrated in Table 2.

                     The runoff is significantly reduced for alternatives two and three. Without the canals

              intercepting the shallow aquifer, groundwater does not contribute to runoff; hence overall runoff

              is reduced. The discharge at Faka Union Weir No. I is not applicable for alternative two because

              it is assumed no canals exist south of 1-75.


                     Figures 16 through 27 show the average daily soil storages in the upper and lower soil

              zones and active groundwater storages for existing and alternative two conditions for those land

              segments south of 1-75 for each month of the simulated period from January 1970 to December

              1992. Average daily upper zone soil storage increased by ten percent, lower zone by six percent

              and active groundwater storage increased 205 percent. The active groundwater storages for

              alternative two were extended annually for an average one to two-month period longer over the

              existing threshold conditions.






                                                              40












                                             TABLE 2


                                  SIMULATED WATER BUDGET FOR
                                      EXISTING CONDITIONS
                                AND ALTERNATIVES TWO AND THREE


                            Existing          Alternative      Alternative
                            Conditions        No. Two          No. Three


           Inflow


           Precipitation    59.72             59.01            59.90
           (in)



           Outflows


           Evaporation      36.74             37.65            38.16
           (in)

           Deep
           Percolation
           (in)             1.52              1.58             1.58

           Sheetflow
           Runoff (in)      0.06              0.13             0.11

           Runoff at
           Faka Union Weir
           No. 1 (in)       18.50             0                0.56

           Active
           Groundwater
           Flow (in)        2.97              19.84            19.84























                                               41





                                                                   Upper Zone Soil Storage (UZS)
                                                                               January 1970 - December 1975

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


                      1.5



                                                                                Current Cond.                Alt. #2 Cond.




                        1


               z





                     0.5                                                                              Vt






                        0       1 L-I-L-L I I  t. 1 -.11        LIA-LA-1-1-1-LL-1 LA-L-1 -I-LAA, 1-1 1 L t                    LF
                           Jan-70                   Jan-71                  Jan-72                   Jan-73                  Jan-74                   Jan-75
                                                                                          Time (Months)


                                                                                             JFIGUR.E 16
                                                                                               ------- ---- -----------------------------






                                          Upper Zone Soil Storage (UZS)
                                                 January 1976 - December 1981


             1.2


                1                                 Current Cond.    Alt. #2 Cond.


             0.8


         z
         U)  0.6
         N


             0.4



             0.2



               0
                 Jan-76         Jan-77         Jan-78         Jan-79         Jan-80         Jan-81
                                                       Time (Months)     i Lge
                                                                               UZtj
                                                                          19 (@
                                                                            81



















                                                         IFIGURE 17
                                                          -----------------------






                                          Upper Zone Soil Storage (UZS)
                                                 January 1982 - December 1987





                                                   Current Cond.     Alt. #2 Cond.

             0.8 -                            - ------- -------- -----



                               4
             0.6 -
         z



             0.4




             0.2




              0                                                      .1 LLA I 11-1-1-1 A- ---LI 1-t  LI LIJA
                 Jan-82         Jan-83         Jan-84          Jan-85        Jan-86         Jan-87
                                                       Time (Months)



                                                           IGURE 18

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






                                              Upper Zone Soil Storage (UZS)
                                                       January 1988 - December 1992

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






                                                     Current Cond.       Alt. #2 Cond.
               0.8




           --- 0.6
           z

           Cn

  Ln
               0.4 -




               0.2 -




                 0
                    Jan-88               Jan-89               Jan-90               Jan-91               Jan-92
                                                                Time (Months)




                                                                   FIGURE 19





                                        Lower Zone Soils Storage (LZS)
                                               January 1970 - December 1975





             12


                                               Current Cond.    Alt. #2 Cond.
             10



             8


         z
             6
         N


             4



             2



             0
               Jan-70        Jan-71         Jan-72        Jan-73        Jan-74        Jan-75
                                                                    @rage (!-Z@S)j
                                                                         5
                                                                    Orl 97L


                                                                      @:















                                                     Time (Months)

                                                       FIGURE 0





                                                          Lower Zone Soil Storage (LZS)
                                                                January 1976 - Decmber 1981

                  8



                                                                         Current Cond.            Alt. #2 Cond.

                                                                                                                   ----------------
                  6





                  4
             U)





                  2





                  0
                     Jan-76                Jan-77                Jan-78                Jan-79                Jan-80               Jan-81
                                                                              Time (Months)


                                                                                I FIGURE 211






                                          Lower Zone Soil Storage (LZS)
                                                 January 1982 - December 1987
                                                            -----------------



             8



                                                   Current Cond.    Alt. #2 Cond.


             6




         z
             4
         U)

  00




             2






             0
               Jan-82         Jan-83         Jan-84          Jan-85         Jan-86         Jan-87
                                                                      @
                                                                      raLe   (LZS)
                                                                      be 1987L]










                                                       Time (Months)


                                                         IFIGURE@j





                                                                      Lower Zone Soil Storage (LZS)
                                                                                  January 1988 - December 1992


                      8



                                                                              -Current Cond. - Alt. #2 Cond.

                                                                                                        --- --- -- - ------------- ---------- - - -------
                                                                                           - ---- ---------------------  -------- --------------
                      6





                      4





                      2





                      0
                          Jan-88                         Jan-89                          Jan-90                         Jan-91                          Jan-92
                                                                                             Time (Months)


                                                                                                IFIGURE13J







                                                                                                         Active Groundwater Storage (AGWS)
                                                                                                                            January 1970 - December 1975
                                                                                                       INVANAVAGUMVIOM                                -------------- - ---------


                                    6

                                                                                                                             - Current Cond. - Alt. #2 Cond.                                                                             Ii
                                                                                                                       - -------------                                 -------





                                    4
                          z    I

                          U)

                          0                                                                                                                          F
                          <         2



                                    0
                                         Jan-70                                  Jan-71                                   Jan-72                                  Jan-73                                  Jan-74                                   Jan-75
                                                                                                                                                     Time (Months)






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







                                Active Groundwater Storages (AGWS)
                                       January 1976 - December 1981


            5



                                            Current Cond.  Alt. #2 Cond.
            4



            3

         W


            2
         <


                                       IV  /A
            0
             Jan-76       Jan-77       Jan-78       Jan-79      Jan-80       Jan-81
                                               Time (Months)
                                                 FIGURE 25







                                                                  Active Groundwater Storage (AGWS)
                                                                                January 1982 - December 1987

                        5



                                                                                       Current Cond.                 Alt. #2 Cond.
                        4



                  Z     3                                                                            IN


    Ul                                                         A                                                                                             V


                        2








                        0                     LA-1 I I     I I I I    I I I I I I I  I   I                       L L,     I I I I
                            Jan-82                    Jan-83                    Jan-84                   Jan-85                    Jan-86                    Jan-87
                                      Lip, I I L I L W1,                I I, @L-, I @11\\  I A,,

                                                                                                 Time (Months)

                                                                                                     FIGURE 26







                         Active Groundwater Storage (AGWS)
                              January 1988 - Decembe r-1992

        5


                                Current Cond. Alt. #2 Cond.
        4                                  ------------




      Z 3

      U)


        2
      <




                                                            A


        0  -4-L I II                                    I    I
         Jan-88      Jan-89      Jan-90     Jan-91      Jan-92
                                   Time (Months)
                                             I Alk \      JA/
                                      41 111 1 A,,


                                    LIGUR





  40          C.     HYDROLOGIC PERFORMANCE OF ALTERNATIVE THREE
                     The overall water budget for alternative three relative to the existing conditions is also

              shown in Table 2. Similar to the results discussed for alternative two, without the canals to

              intercept the active groundwater outflow, runoff is significantly reduced.

                     Figures 28 through 39 show the average daily soil storages in the upper and lower soil

              zones and active groundwater storage for those land segments south of 1-75 under alternative

              three scenario for the entire period of simulation.         The relative increases in     soil and

              groundwater storage values are similar to that of alternative two. The upper zone soil storage

              increased by six percent, lower zone soil storage increased by four percent and active

              groundwater storage increased by 62 percent. The active groundwater storage under alternative

              three was extended average annually for approximately one month longer than existing

              conditions.


              D.     ECONOM[IC EVALUATION

                     A preliminary cost estimate analysis for structural implementation of the three

              alternatives are presented below. An economic benefit analysis under each alternative scenario

              has not been performed. The formulation of a recommended hydrologic restoration will,

              therefore, be based on the basis of least cost.

                     1)      ALTERNATIVE ONE

                     The estimated cost for the installation of an interim diversion structure with three 48-inch

              gated RCP culverts with a spreader channel as illustrated in Table 3 is $171,354. This is an

              interim plan for partial restoration of the hydrology of SGGE. The Big Cypress Basin Board has

              presently proposed to implement the project in FY 1995.






                                                              54





                                                       Upper Zone Soil Storage (UZS)
                                                                January 1970 - December 1975
                                                                                            --------- - ------------------------


                  1.5



                                                                 Current Cond.          Alt. #3 Cond.

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










            z


            N


                 0.5







                   0                                        1111.11 11111-1-LIII 11        1 1 1 1 1 1 1    A I I
                      Jan-70              Jan-71             Jan-72              Jan-73             Jan-74              Jan-75
                                                                        Time (Months)



                                                                           FIGURE






                                           Upper Zone Soil Storage (UZS)
                                                  January 1976 - December 1981


              1.2


                 1                                 Current Cond. - Alt. #3 Cond.

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




              0.8


          z
          cl) 0.6                                           A
          N


              0.4



              0.2



                 0
                  Ja
                    n-76         Jan-77         Jan-78         Jan-79         Jan-80         Jan-81
                                                         Time (Months)


                                                           [M @RE29





                   ,.Mob,



                                                                      Upper Zone Soil Storage (UZS)
                                                                                 January 1982 - December 1987


                      1.2



                                                                                   Current Cond.               Alt. #3 Cond.

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






                      0.8


                 z
                 W    0.6
                 N


                      0.4



                      0.2



                          0          1 1 1 1 1 1 1 1 1 1 1 -L-LLA-LI I I I I I I I I I I I I I I I I I  I    -LL I I I I I                  I I I I I I 1 -1   1 1 1 1 1 1 1 1
                            Jan-82                   Jan-83                  Jan-84                  Jan-85                   Jan-86                 Jan-87
                                                                                           Time (Months)
                                                                                                              tora       e    (UZS)
                                                                                                                       19
                                                                                                        '!@mbV
                                                                                                       D@          e

































                                                                                              FIGURE 30

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






                                                       Upper Zone Soil Storage (UZS)
                                                                 January 1988 - December 1992

                                                         -----------                               ------------------
                  1.2


                     1 -                                      Current Cond.           Alt. #3 Cond.                                      IN


                  0.8 -


             z

             I.-
             U)   0.6 -
   Ul
   00        N


                  0.4 -



                  0.2 -




                       Jan-88                   Jan-89                   Jan-90                  Jan-91                   Jan-92
                                                                            Time (Months)


                                                                              [FIGURE 3-1'





                                                                  Lower Zone Soils Storage (LZS)
                                                                               January 1970 - December 1975
                                                                                ----------






                       12



                       10
                                                                               Current Cond.               Alt. #3 Cond.

                                                                                  ------------------ - - ------------------------------------ - ---------------
                       8


                z
                1.-1   6
                Cf)



                       4



                       2



                       0
                           Jan-70                 Jan-71                 Jan-72                  Jan-73                 Jan-74                 Jan-75
                                                                                         Time (Months)



                                                                                             FIGURE 32





                                           Lower Zone Soil Storage (LZS)
                                               January    1-9-7-6--- Decmber 1981

               10



                                                  - Current Cond.      Alt. #3 Cond.
               8                              - ----------------- --------------



               6
          z


          U)
  CD
               4




               2




               0
                 Jan-76          Jan-77         Jan-78         Jan-79          Jan-80         Jan-81
                                                         Time (Months)



                                                           FIGURE 33





                                                    Lower Zone Soil Storage (LZS)
                                                            January 1982 - December 1987
                                                               -------- - ------- --------------



                 10



                                                             Current Cond.        Alt. #3 Cond.

                  8





                  6
            z

            U)
            "A    4


                  2





                  0
                    Jan-82            Jan-83            Jan-84            Jan-85           Jan-86            Jan-87
                                                                    Time (Months)



                                                                      [FIGURE 34





                                                       Lower Zone Soil Storage (LZS)
                                                                January 1988 - December 1992


                   10



                                                                Current Cond.          Alt. #3 Cond.

                                                                   ----------- ----- ------- ----
                   8




              C4
                   6
                                                                                             tv

                   4





                   2
                      Jan-88                  Jan-89                  Jan-90                 Jan-91                  Jan-92
                                                                                       !- #3 C@ond.








                                                                         Time (Months)



                                                                            FIGURE 35



                                                          0



                                        Active Groundwater Storage (AGWS)
                                                January 1970 - Decemb-e-r---- 1---- 9-7-5 --- --- - -------- ----------

              5


                                                - Current Cond.     Alt. #3 Cond.
              4                              - - - ---- - - ---------



              3

          W

          0   2
          <
                     It  I                      I
                       tjI
                                                   IA@

              0     1. 1 A. II I I I I
                Jan-70         Jan-71          Jan-72         Jan-73          Jan-74         Jan-75
                                                         Time (Months)



                                                            FIGURE-36-
                                                                                           II @V,  , I IA,, I 'I',







                                           Active Groundwater Storages (AGWS))
                                                     January 1976 - December 1981

                5


                4                                           Current Cond.       Alt#3 Cond.

                                                                     ---- - -----




                3

                             1 V                                                                     ItI
                2
            <







                0
                  Jan-76           Jan-77           Jan-78           Jan-79           Jan-80           Jan-81
                                                               Time (Months)


                                                                  FIGURE 37

                                                                            ----------







                                        Active Groundwater Storage (AGWS)
                                                January 1982 - December 1987

              5



                                                    Current Cond.     Alt#3 Cond.
              4




           Z  3

  CYN
  @-n


              2
           <






                                                                                                       V


              0
                 Jan-82         Jan-83          Jan-84         Jan-85          Jan-86          Jan-87
                                                          Time (Months)
                                                                                        I I I Nlilkill,

                                                             FIGURE 38







                                        Active Groundwater Storage (AGWS)
                                               January 1988 --December 1992         -----

             5


                                                  -Current Cond.     Alt#3 Cond.
             4                                 -------- -------------- ----------------- ------------ ----




             3
         U)                                    r i

             2
         <







             o
               Jan-88             Jan-89            Jan-90             Jan-91            Jan-92
                                                        Time (Months)
                                                   kit











                                                                TABLE 3


                                   PRELIMINARY COST ESTIMATE FOR ALTERNATIVE ONE


                                       DIVERSION STRUCTURE WITH THREE 48-INCH
                                           GATED CULVERT WITH SPREADER CHANNEL



                                                                                       Unit Cost
                                Item                               Quantity            INC Labor,                      Total
                                                                                     Equip & Material                  Cost

                A. MOBILIZATION/DEMOBILIZATION                     1                       L.S.                      $ 30AM


                B. STRUCTURE
                        1. Pipe Barrels                            360 LF                  115                         41,400
                        2.    Flap Gates                           3 each                  2,630                       7,e@O
                        3.    Sand Cement Endwalls                 40                      180                         7,2M
                        4.     Backfill
                                a. Pipe Bedding                    87 yd3                  is                          1,305
                                b. Backfill                        650 yd3                 6                           3,9M

                C. SITE      WORK
                        1.   Shell Base                            83 yd3                  10                             W3
                        2.   Site Grading                          I                       L.S.                        3,OM
                        3.   Sodding                               510 yd    3             3.50                        l'-M

                D.      DEWATERING
                        1. Cofferdam
                                a. Design                          1                       L.S.                        1,000
                                b. Install & Remove                15 tons                 1,100                       16,-EM
                        2. Equipment                               1                       3,500                       3,-EM
                        3. Excavation for Pipe                     520 yd    3             3                           1,5m
                        4. Excavation for Endwall                  150 yd'                 3                              49D
                        S. Clearing                                1                       L.S.                        5,00D

                E.      SPREADER CHANNEL                           16,818 yd     3         3                           W,453

                                                                                           Subtotal                    @j ro

                F.      CONTINGENCY @ 10%                                                                              15,578


                                                                                           TOTAL                     $171,:FA















                                                                    67









                   2)     ALTERNATIVE TWO

                   The preliminary cost estimate for implementation of a spreader channel and canal and

            road removal plan as identified under alternative two is illustrated in Table 4.

                   3)     ALTERNATIVE THREE

                   The preliminary cost estimates for implementation of alternative three restoration

            measures which involve construction of two spreader channels, removal of selected road

            segments and installation of eleven canal plugs are illustrated in Table 5.





































                                                       68












                                              TABLE 4


                         PRELIMINARY COST ESTIMATE FOR ALTERNATIVE TWO


                             SPREADER CHANNEL WITH REMOVAL OF ROADS
                                      AND FILLING OF CANALS


           A. FILLING THE CANALS
                                   Volume of Fill          Cost per          Total
                                   Required (cu. yd)       cu. yd            Cost
                 Miller Canal             1,694,308        $5          $   8,471,540
                 Faka Union Canal         2,525,072        $5          $  12,625,360
                 Merritt Canal            1,575,772        $5          $   7,878,860
                 Prairie Canal              870,320        $5          $   4,351,600
                                                           Subtotal    $ 33,327,3-

           B. SPREADER CHANNEL
                 Excavation 255,493 cu.yd X $3/cu. yd                  $     766,479
                 Clearing, Mobilization, Demolition,
                 Diversion Channel During Construction,      etc.
                 @ 30%                                                 $     229,944
                                                           Subtotal    $     996,U-3

           C. ROAD REMOVAL
                 $2500 per mile X 290 mi                               $     725,000

           D. PUMPS
                 Miller Canal
                   25 HP Axial Flow Pump (Installed)
                   @ $40,000/pump                                      $     120,000
                 Faka Union Canal
                   25 HP Axial Flow Pump (Installed)
                   @ $40,000/pump                                      $     360,000
                 Merritt
                   25 HP Axial Flow Pump (Installed)
                   @ $40,000/pump                                      $     160,000
                 Pumping Cost
                   Miller
                   (24cfs) x (4 mo) = 1,862 MG/yr x $5/MG =            $        9,308
                   Faka Union
                   (117cfs) x (4mo) = 9,076 MG/yr x $5/MG =            $       43,378
                   Merritt
                   (33cfs) x (4 mo) = 2,560 MG/yr x $5/MG =            $       12,800
                                                           Subtotal    $     Tug-, To

                                                           TOTAL       $  35,754,269












                                                 69











                                           TA13LE 5


                      PRELIMINARY COST ESTIMATE FOR ALTERNATIVE THREE

                       SPREADER CHANNEL-ROAD REMOVAL-CANAL PLUG PLAN


          A. CANAL PLUGS
                                 Volume of Fill         Cost per           Total
                                 Required (cu.yd)       cu.yd              Cost
                Plug Al                   742           $5               $  3,710
                Plug A2                   987           $5               $  4,935
                Plug A3               1,231             $5               $  6,155
                Plug A4               1,231             $5               $  6,155
                Plug A5               1,831             $5               $  9,155
                Plug Bl               2,076             $5               $ 10,380
                Plug B2               1,316             $5               $  6,580
                Plug B3               2,231             $5               $ 11,155
                Plug B4               1,658             $5               $  8,290
                Plug B5               2,231             $5               $ 11,155
                Plug B6               3,564             $5               $ 17,820
                                                             Subtotal    $_95,490
          B. SPREADER CHANNELS
                Miller Spreader
                  Excavation 12,457 cu. yd x $3/cu. yd                     37,371
                  Clearing, Mobilization, Demolition,
                  Diversion Channel During Construction,   etc.
                  @ 30%                                                  $ 11,211
                Faka Union Spreader
                  Excavation 185,448 cu. yd x $3/cu. yd                  $556,345
                  Clearing, Mobilization, Demolition,
                  Diversion Channel During Construction, etc.
                  @ 30%                                                  $166,903
                                                             Subtotal    $77-1-,830
          C. ROAD REMOVAL
                $2500 per mile X 114 mi                                  $285,000

          D. PUMPS
                Miller Canal
                  25 HP Axial Flow Pump (Installed)
                  @ $40,000/pump                                         $120,000
                Faka Union Canal
                  25 HP Axial Flow Pump (Installed)
                  @ $40,000/pump                                         $360,000
                Merritt
                  25 HP Axial Flow Pump (Installed)
                  @ $40,000/pump                                         $160,000
                Pumping Cost
                  Miller
                  (24cfs) x (4 mo) = 1,862 MG/yr x $5/MG =               $ 9,308
                  Faka Union
                  (117cfs) x (4mo) = 9,076 MG/yr x $5/MG =               $ 43,378
                  Merritt
                  (33cfs) x (4 mo) = 2,560 MG/yr x $5/MG =               $ 12,800
                                                        Subtotal         $705,486

                                                        TOTAL            $1,857,806
 0                                            70









                    4)     SUMMARY OF ECONOMIC EVALUATION

                    The first cost of implementing the alternative restoration measures are:

                    Alternative One       $ 171,354

                    Alternative Two       $35,754,269

                    Alternative Three     $1,857,806

                    The economic evaluation of the selected altematives was solely based on the preliminary

             estimates of the initial construction costs. Alternative one is an interim plan for partial

             hydrologic restoration of SGGE, primarily to reduce the voluminous point discharges of

             freshwater to the Faka Union Bay Estuary. The project does not involve acquisition of private

             lands except a small parcel of land for construction easement.

                    Alternative two was hydrologically evaluated to investigate the effect of a large scale

             restoration measure relative to the historic conditions rather than as an economically feasible

             alternative. It is apparent that the cost of implementing such a plan will be astronomical. A

             quantitative economic benefit analysis of each alternative was not performed at this time. The

             formulation of a recommended plan will therefore be based only on cost of implementation.




















                                                           71










             E.      HYDROLOGIC MAC`1r ASSESSWNT

                     Alternative one is only a partial restoration plan to take advantage of presently available

             public lands. It would rehydrate a small portion of SGGE- The sheetflow created will enhance

             the functioning of the adjacent wetlands during the dry season. Storm flows will continue to

             be discharged at the Faka Union outlet during the wet season. However, a reduction of up to

             250 cfs of freshwater discharge point loads to the Faka Union Bay will be achieved which will

             contribute towards enhancing the ecological health of the estuary. This alternative does not

             inundate privately owned land. There will be no impact on upstream flood stages.

                     For alternative two, there would be no adverse impact on the flood protection for the area

             north of 1-75 because the pumps will force the water south. The areas south of 1-75 would be

             seasonally flooded. The lower zone soil moisture storage levels show an average annual increase

             of one to two months in duration as the dry season approaches. This plan would preclude

             residential development south of 1-75, and necessitate complete public ownership of the lands

             in SGGE.


                     The hydrologic impacts of alternative three are similar to alternative two. The pumping

             stations would be required to maintain flood protection north of the alley. Large areas south

             of 1-75 would be seasonally flooded and therefore, would necessitate public ownership of those

             lands. For both alternative two and three, a low berm along the perimeter of the Port of the

             Islands complex will be necessary to prevent flooding from restored surface flows.












                                                             72





  is                                          VHL RECONMNDED PLAN
                    On the basis of the above hydrologic-hydraulic, and economic evaluations, and

             assessment of impacts of three alternative measures, the alternative three plan involving

             construction of two spreader channels, eleven canal blocks and removal of selected segments of

             roads is recommended for implementation of the restoration of SGGE. Alternative one is a

             partial restoration plan, and only accomplishes limited objectives of the project. Alternative two

             is not economically feasible. Alternative three would reestablish sheetflow and eliminate the

             point flow discharges through the Faka Union Canal and achieve the various objectives of the

             project.




































                                                             73










                                                  DC CONCLUSIONS

                    The previous studies by the Army COE and others on the feasibility of modifying the

             Faka Union Canal drainage basin for restoring the hydrology and ecology of the area were based

             on hydrologic-hydraulic analysis with event-based models. This study used a state of the art

             methodology to simulate the continuous process hydrology of SGGE for a 23-year period and

             to predict the behavior of the water table and its effect on soil storage and surface water flow
             under three alternative scenarios. Altho4 certain modifications to the model are needed to

             more closely simulate South Florida hydrology, the model provided a fair representation of the

             existing hydrologic conditions of SGGE.               I

                    The number of alternative restoration measures analyzed were limited due to the limited

             time frame available within the scope of the grant contract. More alternative measures will be

             considered and evaluated with the calibrated model to develop an economically and

             environmentally viable plan to restore the hydrology and ecology of this unique region of south

             Florida.






























                                                            74







0























                     APPENM A





0













40









         PERLND    pervious land module
         PETMAX    air temperature which signals a change in ET
                   calculation only used if snow is considered
         PETMIN    air temperature which signals a change in ET
                   calculation only used if snow is considered
         PLS       pervious land segment
         PREC      precipitation
         PWATER    Pervious Land-Water Budget Simulation
         RCHRES    Reach-Reservoir
         RFAVGM    Program that averages daily rainfall at selected stations
         RO        Runoff
         ROVOL     runoff volume
         SUPY      Water Supply
         SURS      surface storage at the start of the simulation (in)
         TAET      total simulated evapotranspiration
         UZS       upper zone soil storage at the start of the simulation
         UZSN      upper zone nominal soil storage (in)
         WMD       Watershed Data Management, program ANNIE file










                                                     BIBLIOGRAPHY


             AQUA TERRA Consultants et al, August 1994. Technical and Cost Prol2osal in ResRonse to RFP
                     No. C-5365 HSPF Modifications for Southern Florida Hydrology. Mountain View,
                     California.


             Bennett, Michael W., April 1992. Technical Publication 92-04, A Three-dimensional Finite
                     Difference Groundwater Flow Model of Western Collier Coun!X, Florida. Hydrogeology
                     Division. Department of Research and Evaluation. South Florida Water Management
                     District. West Palm Beach, Florida.

             Black, Crow and Eidsness, Inc., October 1974. Hydrologic Study of the G.A.C. Canal Network.
                     Gainsville, Florida. Project No. 449-73-53.

             Swayze, L. J. and B. F. McPherson, 1977. The Effect of the Faka Union Canal System on Water
                     Levels in the Fakahatchee Strand, Collier Counly, Floirda. Water Resources Investigation
                     77-61, USGS, U. S. Government Printing Office, 19 pp.

             Wan& Flora C. and Allen R. Overman, 1981. "Impacts of Surface Drainage on Ground Water
                     Hydraulics." Paper No. 80163 of the Water Resources Bulletin.