Human activities, impacts and alternatives Self-taught education unit

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

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U it
I z
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

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

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

Right

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Wrong

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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.

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.

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. 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

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.

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

2.
3.

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

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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.