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











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                                                                                                                                             7
                                                                                                         HION                       W          T
                                  (Human Activities, Impacts and
                                                                  Alternatives


                                                                 By Walter 1. Priest, III



                      Introduction

                            Regardless of the nature of human activities, they               Dredging is one of the more frequently proposed
                      all impact the environment. These impacts are rarely              environmental modifications, There are basically two
                      all good or bad. Most often some aspects are beneficial           types of dredging, new work and maintenance dredg-
                      and some are deleterious. The question of whether the             ing. New work is usually the most environmentally
                      benefits exceed the detriments associated with some ac-           consequential because it involves areas that have not
                      tivity is always a matter of perspective. In the environ-         been previously impacted and retain most of their inher-
                      mental management arena, however, the critical                    ent natural values. On'the other hand, maintenance
                      concern is an accurate assessment of both sides of the            dredging is usually less damaging because the area has
>                     equation, the impacts as well as the benefits. In this            already been dredged and the value of the area compro-
                      way, and only this way, can rational and equitable deci-          mised to some degree. The method of dredging,
                      sions be made affecting both humans and their environ-            whether mechanical or hydraulic, can also influence the
                      ment.                                                             degree of impact. Mechanical dredging using a crane
                                 ssessment of any proposal can be divided into          and a bucket of some type is usually less damaging.
                            The a
                      five basic parts:                                                 Hydraulic dredging has the potential for more wide-
                            1. Description and purpose of project                       spread impacts because of the large quantities of water
                            2. Description of resources                                 used to move the dredged material. A bermed upland
                            3. Impacts on resources                                     placement area that effectively contains the dredged ma-
                            4. Analysis of alternatives                                 terial helps minimize the impacts of the dredging. Un-
                            5. Conclusions and recommendations.                         confined overboard placement can have much more
                                                                                        significant impacts because much larger areas are being
                      Description and Purpose of Project                                affected. The impacts of dredging sand are usually less
                            The assessment process must begin with a detailed           than those of dredging silt and clay because sand settles
                      description of the proposed activities. The project de-           quicker.
                      scription should accurately characterize the nature and                Filling to convert an aquatic habitat to upland also
                      extent of the proposed project so that its impacts can be         results in serious environmental consequences. The fac-
                      accurately assessed. The following are a number of rou-           tor of primary importance in assessing impacts is the
                      tinely encountered activities which can have profound             size of the area to be filled. Other important considera-
                      environmental impacts. Included with each activity are            tions are the quantity and nature of the fill material and
                      a number of concerns which can influence the degree of            its method of containment to prevent its discharge into
                      impact and need to be considered in evaluating the pro-           the waterway.
                      posal.                                                                 Shoreline defense structures such as bulkheads and
                                                                                        riprap can also be responsible for significant alterations








                  2


                  of aquatic habitats. The length of
                  the structure and its encroachment
                  into a waterway, particularly chan-
                  nelward of mean high water are the
                  most significant parameters in de-
                  termining the extent of the struc-
                  ture's impact. Also important ar
                                                         e
                  the size and type ofmaterial to be                                     471
                  used, lumber for bulkheads and
                  stone for riprap, and its suitability
                  to the conditions: at the project loca-        @t
                  tion. Filter cloth should be used be-
                  hind either type of structure to
                  prevent the leaching of the backfill
                  material through the structure and
                  into the waterway. Properly de-
                  signed return walls are also neces-            Whenever possible, shoreline defMse structures such as bulkheads should be
                  sary to prevent the structure from            placed landward of wetlands.
                  being. outflanked by the erosion of
                  adjacent areas.                                                            structures along adjacent shorelines is also a very impor-
                        Groins and jetties almost always precipitate rapid                   tant factor in assessing impacts.
                  responses along adjacent shorelines. The charac-                               This'is but a small sampling of the types of projects
                  teristics which have the most influence on these re-                       that could potentially be encountered. It is critically im-
                  sponses are the length of structures, their height and the                 portant that clear and accurate drawings be provided to
                  distance between the structures. Some design consid-                       describe any proposed projects. Without these draw-
                  erations such as bei@g low profile, spurs and T-heads                      ings the assessment of the impacts on the local environ-
                  can measurably reduce impacts and increase the effec-                      ment is extremely difficult, if not impossible.
                  tiveness of the structures. The proximity of similar                           A statement on the purpose of the proposed project
                                                                                             is also vitally important, par.ticularly when considering
                  Wetlands Program                           December 1993                   alternatives to the proposal. The extent of public and/or
                  College of William and Mary                                                private use of the proposed facility as-well as the per-
                  School of Marine Science                                 Program           ceived public and private need can become pivotal fac-
                  Virginia Institute of Marine Science                                       tors when framing alternatives to a proposal with
                  Gloucester Point, Virginia 23062
                                                                                             significant environmental ramifications. The question
                  Dr. Carl Hershner, Program Director                                        of water dependency (Is the project inherently depend-
                  Editors: Maryann Wohlgemuth                                                ent on its proximity to the waterway or not?) can also
                            Pam Mason                                                        become a critical factor in the decision-making process.
                  Published by: VIMS Publicat      ion Center
                                                                                             Description of Resources
                  "A publication of the Virginia Department of Environmental
                  Quality's Coastal Resources Management Program pursuant to                     The next step in the assessment process requires an
                  National Oceanic and Atmospheric Administration Award No.                  appraisal of the habitat types, directly and indirectly in-
                  NA27OZ0312-01."                                                            volved in or impacted by the proposal. This informa-
                                           'This paper is funded in part by a granV
                                                                                             tion can be derived from a site visit, resource
                                                               ent from the National
                                           -ooperative agreern                               .nventories or other sources. The description of the pro-
                                           Oceanic and Atmospheric Administration.
                     o
                     @4.             zo    The views expressed herein are those of           posed project derived above must then be applied to the
                                           the author and do not necessarily reflect         project locale and the nature and extent of the impacts
                                           the views of NOAA or any sub-agencies.
                                                                                             to the natural system. The following are representative
                                                   Printed'on recycled paper.                types of habitats that are important components of








                                                                                                                                                       3


                      aquatic systems and are typically afforded special pro-             vide important habitat for numerous fishes and shell-
                      tection.                                                            fish. They are also important indicators of the good
                           Wetlands are critical links between upland and                 water quality necessary to maintain the seagrass beds.
                      aquatic systems which are critical to maintaining pro-                   Sand dunes are located adjacent to relatively high
                      ductivity. Wetlands can either be tidal or non-tidal and            energy shorelines that have a sufficient supply'of sand.
                      can either be vegetated or non-vegetated depending on               The dunes act as a reservoir of sand that is available to
                      the hydrologic regime and the sediment type.                        modulate shoreline changes during storm events. They
                           Subtidal bottoms are those areas that are perma-               also provide protection against tidal flooding and wild-
                      nently inundated and occur channelward of mean low                  life habitat.
                      water.in tidal situations.                                               Shellflsh beds are productive areas of primarily
                           Seagrass beds are basically subtidal areas which               oysters and clams both natural and cultivated which
                      support the growth of submerged aquatic vegetation.                 merit consideration by virtue of their economic and/or
                      These areas are immensely productive areas which-pro-               ecological value.


                                                                  Riprap Revetment Construction

                           4-









                                                                                                                 Right





                         It le _4@









                                                     Wrong








                                                                                                              1          0

                                                                                                                                     A
                                                                                                                         M








                 4


                     Spawning areas are those areas of concentrated                  quent boat traffic by larger vessels may lead to in-
                 finfish spawning, primarily for anadromous fishes in                creased shoreline erosion from boat wakes. Impacts to
                 the freshwater reaches of the estuary. Also included are            water quality from boat discharges, accidental spills
                 important shellfish beds that produce above average re-             and overboard garbage are also a concern. Mainte-
                 cruitment.                                                          nance dredging can cause continuing disruptions to bio-
                     Threatened and endangered species habitats are                  logical communities and loss of productivity.
                 those areas of critical habitat considered necessary for                Flooding
                 the survival of the species of concern.
                                                                                         Many types of projects can alter the flow modulat-
                 Impacts on Resources                                                ing characteristics of wetlands and waterways.
                     The third step in the assessment process involves               Changes in channel cross-section increase or decrease
                 the detailed evaluation of -the potential for the proposed          tidal amplitudes by improving or restricting the flow of
                 project to impact any number of ecological and socio-               water. Filling of wetlands can    Ieliminate the flood buff-
                 economic values. The following is not intended to be a              ering capacity of these areas increasing both the height
                                                                                     and duration of floods. Stream channelization and di-
                 comprehensive list of potential impacts. It is designed             version projects can also produce similar problems by
                 to cover the most frequently encountered situations and             circumventing wetlands and increasing flow velocities.
                 to hopefully stimulate the imagination to consider less
                 routine circumstances.                                              All of these situations can lead to increased flooding po-
                                                                                     tential downstream of the project.
                     Navigation'Concerns                                                 Shoreline Erosion and Accretion
                     Often overlooked, the impacts of a project on navi-
                 gation.as well as the ecological impacts of a navigation                Shoreline defense structures and dredging can have
                 project should be considered.                                       pronounced effects on shoreline erosion and accretion.
                                                                                     Jetties, groins and similar structures'alter littoral cur-
                     The location and position of piers, groins and                  rents and drift-causing changes in scour and deposition
                 breakwaters can have an impact on navigation. This
                                                                                     patterns. A reach of shoreline currently enjoying pro-
                 may be of particular concern in areas of high volumes
                                                                                     tection due to sediment accretion may be negatively af-
                 of boat traffic or at the upper ends of tidal creeks where
                                                                                     fected by an updrift structure. Vertical walls reflect
                 turning space is'limited.
                                                                                     incident wave energy to adjacent shorelines increasing
                     Dredging for the purpose of providing navigation                erosion rates. Changes in inlet configuration can cause
                 can cause a variety of environmental impacts. More fre-
                                                                                                            increased scour in some places and
                                                                                                            increased shoaling in others that re7
                                                                                                            quires more frequent maintenance
                                                                                                            dredging. The removal of erosion
                                                                                                            buffering marshes by dredging and
                                                                                                            filling can also accelerate local 'ero-
                                                                                                            sion rates.

                                                                                                            Fish and Wildlife

                                                                                                                 Fish and wildlife resources
                                                                                                            generally receive the most severe
                                                                                                            impacts from construction activi-
                                                                                                            ties because the two are seldom
                                                                                                            compatible. The loss of wetlands
                                                                @,qf
                                                                                                            and subaqueous habitats are usu-
                                                                                                            ally of the greatest concern. These
                                                                                                                       vide much of the primary
                                                                                                            areas pro
                                                                                                            production which supports aquatic
                 The proper design and construction of a bulkhead include the use of tiebacks               food webs. They are also the pri-
                 andfilter cloth.








                                                                                                                                               5


                     mary habitats for forage fishes and invertebrates that               Wetland losses can also affect water quality by re-
                     contribute significantly to food webs. They also pro-            ducing the capacity for nutrient cycling within the
                     vide critical nursery areas for juveniles of commercially        water body. They are important sites of nutrient remin-
                     important finfish and shellfish. All of the above make           eralization which involves the conversion of nutrients
                     these areas important feeding, nesting and resting areas         from organic particulate to more available dissolved
                     for waterfowl, shorebirds and wading birds.                      forms. Wetlands can also act as a sink which can ab-
                          Dredging can impact fish and wildlife resources in          sorb pulses of nutrients and release them slowly over
                     a number of ways. Increased turbidity decreases light            time.
                     penetration reducing the photosynthetic ability of plank-           Canals, particularly long convoluted residential ca-
                     ton and SAV. It can also stress filter feeders by clog-          nals, which are dredged into uplands are very prone to
                     ging gills and interfering with feeding. Spawning areas          developing water quality problems. Their extreme
                     for anadromous fishes can be adversely impacted by in-           length makes it difficult for material introduced at the
                     creased turbidity which reduces egg hatching success             head to be flushed out of the canal. This leads to an ac-
                     and larval, survival. Benthic communities destroyed in           cumulation of both organic materials and nutrients
                     -dredged areas can be expected to repopulate the areas           which are washed into the canal from the adjacent up-
                     within one or two years depending on new water                   lands. As the organic material decays it requires oxy-
                     depths, substrate and food availability.                         gen for decomposition. This increases the biochemical
                          Rare or endangered species have very specific habi-         oxygen demand (BOD) in the water and reduces the
                     tat requirements with little tolerance for modification or       amount of dissolved oxygen available, particularly dur-
                     disturbance that may result from proposed construction           ing the summer when water temperatures are high.
                     activity or increased human usage of an area after the           Added to this problem is the abundance of nutrients
                     project has been completed.                                      also present in the canal. These nutrients stimulate the
                          Water Quality                                               growth and reproduction of phytoplankton until bloom
                          Water quality is very easily affected by a wide             conditions are eventually reached. This is not a prob-
                     range of construction related impacts. Dredging, for ex-         lem during the day when there is so much photosynthe-
                     ample, can cause significant increases in the turbidity of       sis that the dissolved oxygen levels become saturated.
                     a waterway, particularly a small creek. This increase in         The phytoplankton population continues to expand until
                                                                                      one night there are so many phytoplankters in the water
                     suspended material can reduce the level of dissolved             column that there is not enough oxygen dissolved in the
                     oxygen in the water column due to
                     increased biochemical oxygen de-
                     mand from the resuspension of or-
                     ganic sediments. This
                                                                                                                .6,6,
                     resuspension of bottom sediments                   A
                     can also increase the availability of
                     any contaminants present to filter
                     feeding organisms.
                          Marina construction and ancil-
                     lary upland development can im-                                  7
                     pact water quality as a result of
                     increased coliform bacteria levels
                     due to ineffective sewage disposal
                     including failing septic systems,
                                                                                                                   41@
                     boats and sewage treatment plants.
                     Also, non-point source inputs of
                     nutrients, sediment and other pol-
                     lutants from upland runoff can be       Access to navigable water should be achieved by piering across wetlands
                     very deleterious to water quality.      rather than dredgi ,ng andfilling.








                6


                water to support their respiration. By very early in the          National Register of Historical Properties is generally
                morning, before sunrise, the phytoplankton has respired           required as a minimum.
                all of the oxygen out of the water and there is none left             Recrea@ion
                for-the fishesand other animals in the canal. If these
                animals are unable to 1@ave the canal in time, the result             The recreational aspects of a particular project can
                is a massive fish kill caused by suffocation from the             play an important role in how a particular project is per-
                lack of dissolved oxygen in the water.                            ceived, particularly with regard to whether the public
                                                                                  benefits might surpass the public detriments. - The posi-
                    Water quality can also be markedly affected by                tive aspects can be developed, for example, by enhanc-
                point source discharges that might result from a pro-             ing existing recreational facilities that might improve
                posed construction activity. These discharges are con-            access to a waterwa  .y or create new recreational opportu-
                trolled by. the Virginia Pollutant Discharge Elimination
                System. When assessing the impacts of a particular pro-           nities. This-increases the number of people able to use
                ject, these secondary impacts must also be included as. a         a project and thereby increases its public benefit. The
                                                                                  negative aspects can be minimized by avoiding the deg-
                part of the overall impact of the project. Also included
                in this category of impacts is the potential for spills of        radation of existing recreational facilities and ensuring
                petroleum products or other hazardous materials.                  public access to pew recreational facilities.
                    Non-point sources of nutrients, pesticides, organic               Socioeconornics
                material and sediments from urban and agricultural run-               The socioeconornics of a project, by and large, re-
                off can also have significant impacts on water qualit   y.        ceives more attention and is afforded more'weight in
                    Aesthetics                                                    the decision-making process than it'generally deserves.
                    By far the most difficult factor to assess is aesthet-        The most often cited public benefit to be derived from a
                ics because everyone's aesthetic per  .ceptions are differ-       particular project is that it will increase the local tax
                ent. Generally, the replacement or removal of                     base. This means that the improvements made as a re-
                                                                                  sult of the proposal will increase the value of the prop-
                dilapidated or derelict structures and removing or cover-         erty and allow the locality to charge the owner more in      .
                ing e@isting solid fill or rubbish fills can be considered        taxes thereby increasing revenues. The issue that is usu-
                to improve the aesthetics of an area.  -Ho@v-ever, many           ally ignored is that these improvements almost always
                more construction projects will be viewed as detracting           require an increased level of local services such as
                from the natural beauty of an area. When the pristine at-         roads, utilities, schools, and police and firefighting serv-
                tributes of an area are radically changed, the aesthetic
                                                                                  ices. An objective analysis in many circumstances
                impacts are usually considered negative.
                    Archaeological and
                    Cultural

                    T@e archaeological and cul-
                tural.resources of a site can also be
                significantly impacted by proposed
                construction activity. Since these
                                                                                                           71
                resources are, for the most part, ir-,
                replaceable, a considerable amount
                of coordination with knowledge-                                                   N
                able persons is usually required.
                This can include several phases of
                field surveys depending on discov-
                eries on the site. Coordination
                with the State Historic Preserva-
                tion Office, the Virginia Historic
                Landmarks Commission and the
                                                          Dredging can often be avoided by the use of boat lifts in shallow areas.






                           Human Activities, Impacts And Alternatives
                                                            Exam Questions


                    1. List the five major parts of the assessment outline presented in the education module.


                             2.

                             3.

                             4.

                             5.


                    2. Describe the difference between maintenance and new work dredging.






                    3. Define the major resource areas susceptible to impact by human activities.






                    4. What kind of environmental impacts can occur as a result of increased navigational use of a waterway?






                    5.   Describe the flood buffering capabilities of wetlands.






                    6.   How do groins and jetties effect the littoral transport of sand along a shoreline?






                    7.   Describe some of the ways dredging can adversely effect fish and wildlife habitat.









                                                                                                          College of William and Mary
                                                                                                          School of Marine Science
                                                                                                          Virginia Institute of MarineScience
                                                                                                          Gloucester Point, Virginia 230623







             2


             8.  Describe the water quality degradation process which is often the result of the construction of long convoluted
                 dead-end canals.







             9.  What role does aesthetics play in the evaluation process?






             10. How are the potential impacts of a project on archaeological or cultural resources identified?






             I L What role do enhanced recreational opportunities.play in the assessment process?





             12. What is the most often citea.public benefit to be derived from a development proposal?





             13. What are-the hidden costs of development which must be shouldered by community resources?






             14. What are the fourmajor,parts of the analysis of alternatives?
                      1.

                      2.

                      3.

                      4.


             15. What are the three typesof recommendations that a staff can make regarding the disposition of a permit applica-
                 tions?



                       2.
                       3.








                                                                                                                                                     7


                      would probably show that the increased cost of services           avoided by using an alternative location. If the impacts
                      usually offsets the increased revenues.                           cannot be totally avoided, can they be significantly re-
                           Many times it will be argued that a proposed pro-            duced by using different methods of construction,
                      ject will stimulate.the local economy by creating jobs            changing the acces*s to the site, avoiding critical times
                      and increasing payrolls. When new industries, fisheries           of the year or employing best management practices.
                      or commerce are developed, they can stimulate the                 Alternative means of achieving the stated purpose
                      economy of an area. These economic gains also have                should also be considered.
                      their costs such as increased demands for potable water                If a significant reduction in impacts could not be
                      and wastewater treatment which must be factored into              achieved through avoidance, consideration should be
                      the overall equation along with their environmental               given to reducing the scope of the project to a level the
                      costs, for example, lower ground water levels, saltwater          site can support at an acceptable level of impact. This
                      intrusion, ecological impacts of additional impound-              can be accomplished in some circumstances -by the use
                      ments and the potential for water quality degradation             of previously disturbed areas to reduce the scope of pro-
                      from wastewater discharges.                                       ject impacts on undisturbed habitats. The use of areas
                           Local zoning and land use plans are also a factor in         of lesser ecological significance should also be consid-
                      determining the level and direction of economic                   ered where justified to avoid impacting the more
                      growth. These can and do become important factors in              ecologically important habitats.
                      siting facilities and designing developments that must                 When all of the impacts possible have been
                      comply with the requirements of local ordinances.                 avoided and the scope of the project cannot be reduced
                                                                                        any further and there is still a significant level of im-
                      Analysis of Alternatives                                          pact, consideration should be given to the restoration of
                           This portion of the process involves making the de-          adjacent areas which have been damaged by previous
                      termination of which impacts appear to be avoidable               activities.
                      and which appear unavoidable. It also includes the de-                 Only after all of the above have been considered
                      velopment of reasonable means to reduce the impacts               and implemented to the maximum extent possible
                      of the proposal and re-establish the values lost when             should compensation for the unavoidable losses be con-
                      possible.                                                         sidered as a viable alternative to reduce the level of im-
                           The first alternative which must be considered is            pact. This alternative should only be considered when
                      whether the impacts to important resources can Ye                 it has been determined unequivocally that the unavoid-
                                                                                                             able impacts are in the public inter-
                                                                                                             est and the public and private bene-
                                                                                                             fits clearl outweigh the public and
                                                                                                                       y
                                                                                                             private detriments.

                                                                                                             Conclusions and
                                                                                                             Recommendations
                                                                                                                   This is where the weighing of
                                                                                                             the p
                                                                                                                   ublic and private benefits ver-
                      __Mhmwwkn@                                                                             sus detriments occurs as well as the
                                                                                                             formulation of recornmendations to
                                                                                                             ensure that the benefits outweigh
                                                                                                             the detriments.
                                                                                                                   In making these decisions, ex-
                                                                                                             tenuating circumstances or any
                                                                                                             other relevant information either pro
                                                                                                             or con not mentioned in the above
                      The proper design and construction of dredged material placement areas can
                      avoid many environmental impacts.






                                                                                                                          NOAA COASTAL SERVICES CTR LIBRARY


               8
                                                                                                                          3 6668 14111864 8

               paragraphs that might affect recom-
               mendations need to be addressed.
                    Recommendations should also
               be made for additions, deletions or
               modifications to the proposal, in-
               cluding any reasonable alterna-
               tives, necessary to make the
               project environmentally acceptable.,
                    Upon completion of this proc-
               ess, a recommendation should be
               developed which either recom-
               mends approval as proposed or
               puts well defined and readily deter-
               minable conditions or limits on the
               project so that the.benefits out-
               weigh the detriments and approval
               can be recommended. If a project         Whenever possible, shoreline defense strat   -egies should be designed to include
               cannot be sufficiently conditioned       the whole -reach of a shoreline to hei@ avoid the impacts oi isolated individual
               then the recommendation should           structures.
               be for denial.





               Ref@rences

               Allen, K. 0. and J. W. Hardy. 1980. Impacts of naviga-           Mulvihill, E. L., C. A. Fransico, J. B  Glad, K. B. Kas-
                    tional dredging an fish and wildlife: a literature re-           ter, and R. E. Wilson.  '1980. Biological impacts of
                    view. U.S. Fish & Wildlife Service. Offi@e of                    minor shoreline structures on the coastal environ@
                    Biological Services. FWS/OBS-80/07.                              ment: state of the art review. U.S. Fish and Wildlife
               Clark, J. R. 197.4. Coastal Ecosystems: Ecological Con-               Service, Biological Services Program. FWS/OBS-
                    siderations for Management of the Coastal Zone.                  77/51. 2 vol.
                    The Conservation Foundation, Washington, D.C.                Sail a,,S. B. 1980. Estuarine fishery resources and
                    178 pp-                                                          physical estuarine modifications: Some sugges-
               Clark, John R. 1983. Coastal Ecosystem Management.                    tions for impact assessment. Hamilton, P. and Mac-
                    The Conservation Foundation. R. E. Krieger Pub-                  Donald K. B. Eds. Estuarine Processes. Plenum
                    lishing Co. Malabar, FL. 928 pp.                                 Publishing Corp. New York, NY. p. 603-629.
               Daiber, F, C. 1986. Conservation of Tidal Marshes.               Schroeder, W. L. 1977. Dredging in Estuaries: A
                    Van Nostrand Reinhold Co., Inc., New York; NY.                   guide for review of environmental impact state-
                    341 pp.                                                          ments. Oregon State University, Coruall.is,   Oregon.
               Morton, J. W. 1977. Ecological effects of dredging and                2 Vol s.
                    dredge spoil disposal: a literature review. U.S.
                    Fish &Wildlife Service. Washingt6n,D.C. Tech-
                    nical Paper 94.