v     Conservation Site Design

v     Establishing and Maintaining Forested Riparian Buffers

v     Effective Stormwater Management

v     Urban Nutrient Management

v     Minimizing Shoreline Disturbances

Better site planning is the final key for ensuring that development is carried out in a manner that protects coastal environments.  The proximity of coastal development to vulnerable environmental features like oyster reefs, tidal wetlands, dunes and riparian forests, and the nearly immediate and unbuffered impact that development can have on coastal water quality may make effective coastal site planning more critical than site planning elsewhere.  In addition, several factors complicate coastal planning. 

• Impervious surfaces include the total of rooftops, roads, sidewalks, parking lots and any other hard surface and can be used as a measurable indicator to determine the effects of development on aquatic resources because the amount of imperviousness directly affects stormwater runoff and water quality.  Numerous scientific studies indicate that water quality diminishes measurably when as little as 10 percent of a watershed is converted to impervious surfaces.  As the amount of impervious surface in a region increases, the hydrology of the area is drastically altered, nonpoint source pollution degrades water quality, aquatic habitat is destroyed, and the aesthetic value of natural waterbodies are lost. 

• Non-point source pollution cannot be clearly linked to an obvious pollution sources (a point source) such as an effluent pipe or a smoke stack.  These pollutants can include nitrogen and phosphorus, organic carbons, petroleum hydrocarbons, metals such as copper, lead and zinc, pesticides, sediments and in areas without sewer systems, fecal coliform from septic systems.  Stormwater runoff can rapidly transport nonpoint source pollutants across impervious surfaces and directly into coastal waters without allowing for natural pollution removal that occurs when stormwater is filtered through leaf litter and soil mediums.     

·        The size of the watershed and the types of land uses draining into coastal embayments, estuaries or other coastal water bodies can buffer or intensify the impacts of coastal development on water quality and aquatic habitat.  For example, a small watershed dominated by residential and commercial land uses will have a much more substantial impact on a small embayment than a large watershed dominated by forested lands.  Increasing the amount of impervious surface in a watershed can result in substantially more fresh water runoff reaching small embayments, altering the salinity of these ecosystems and making the area less habitable for some species.

• Tidal flushing characteristics affect the length of time a pollutant, such a s nitrogen, stays in an estuary or embayment.  The physical characteristics of an embayment, such as channel depth, the width of the mouth opening and even the direction it faces where it enters a larger estuary can affect the amount of salt water that enters.  The shallowness and low volume typical of the less navigable reaches can contribute to longer residence times and, therefore, the likelihood of nutrient over-enrichment.  If freshwater inflow and tidal exchange is small, there will be a limited capacity to withstand pollution loads leading to the degradation of the water and the biological habitat dependent upon it.   

Over the next twenty years there will be a tremendous amount of development along Virginia’s coasts.  Better coastal site planning will ensure that when and where coastal development occurs, it will be done in a manner that identifies (through available mapping resources) and plans site development that protects coastal conservation areas, utilizes effective stormwater management techniques to protect water quality, maintains riparian buffers, addressees potential sources of nonpoint source pollution (like septic systems, lawn fertilizer, and pet waste), minimizes shoreline impacts from excessive shoreline armoring and numerous private water access structures.

Conservation Site Design

Conservation site design identifies important conservation areas at the earliest stages of site design.  By using all available mapping resources, including those being developed by state agencies like the Virginia departments of Conservation and Recreation and Forestry (see Table 4.1.1), and carefully assessing significant conservation areas during field visits, site design can better protect coastal resources.

Conservation site design (outlined in Table 4.1.2) requires the identification of primary and secondary conservation resources as the first step in site design.  By identifying conservation resources as early as possible in the design process, land developers can (1) accurately gage probable environmental regulatory requirements that will be required to develop the land, (2) identify potential “green infrastructure” design efficiencies that should be incorporated into the site design, and (3) more effectively design infrastructure installation based on the placement of principal structures rather than vice-versa.  Find more information on conservation site design

Establishing and Maintaining Forested Riparian Buffers

Vegetated riparian buffers are one of the most functionally beneficial and biologically diverse systems that also provide services of great economic and social value. Benefits derived from vegetated riparian buffers, especially forested buffers, include water quality enhancement, stormwater and floodwater management, stream bank and shoreline stabilization, water temperature modification, wildlife habitat protection, and absorption of airborne pollutants. These benefits can translate into increased quality of life and real savings for the community.

Riparian buffers are complex hydrologic and ecological areas that are transitional zones between the surface waters and the upland areas. Although initially thought of as agricultural best

management practices, or BMPs, their multifunctional abilities are becoming better appreciated. Traditionally, BMPs were primarily used to control the quantity and quality of stormwater runoff for erosion and sediment, but did not necessarily address issues related to the effects of infiltration and the quality of ground water. A buffer’s value lies not only in the ability to moderate erosion and sedimentation, but also in the ability to improve water quality in ground water and surface water runoff, increase the base flow of streams, and provide a biologically diverse habitat.

Buffers may also serve as attractions for tourists and community members, becoming greenways and recreation areas for hikers, birders, photographers, fishermen, picnickers and other outdoor enthusiasts. The influx of visitors to the community can spur an expansion of the local economy from tourism and accessory businesses. These corridors increase the aesthetic appearance of a community, enhance property values, and increase local tax revenues.

Effective Stormwater Management

v    Low Impact Development

v     Regional Stormwater Management Systems

v     Urban Forests

Effective stormwater management mitigates changes in local hydrology that results in concentrated flows of stormwater runoff that is higher in volume, velocity and contaminate loading than pre-development runoff.  Failure to adequately address stormwater runoff resulting from suburban and urban development can:

·        Change the geomorphology of a stream segment

·        Cause erosive forces on the banks and bank failure

·        Increase periods of flooding

·        Increase sedimentation and turbidity

·        Increase pollutant loading to receiving streams.

Most new development and redevelopment projects are now required to include storm water management systems.  Engineered conventional stormwater systems are designed to collect and convey stormwater runoff as quickly as possible from developed areas in order to protect life, property, and health.  When conventional systems are designed to protect water quality the stormwater is conveyed to large ponds where pollutants, including sediment, can settle out.  Although effective in managing stormwater runoff, conventional systems consume large amounts of land contributing to sprawl and increasing the cost of housing.  By managing stormwater runoff through Low Impact Development, regional stormwater systems and urban forest and open space protection, communities can protect water quality, reduce coastal sprawl and help maintain pre-development hydrology.

Low Impact Development

Low Impact Development (LID) uses decentralized stormwater management to reduce the need for large structural BMPs by reducing the amount of impervious surfaces on the site, managing stormwater at the source rather than at centralized collection points, and using “chains” of natural treatment systems to reduce stormwater quantities and pollutant loadings.

The use of LID stormwater management technology changes conventional site design by combining a hydrologically functional site design with pollution prevention measures that compensate for the impacts of land development.  A natural undeveloped landscape controls stormwater runoff by intercepting surface flow through the storage of water in channels and small depressions, infiltration in the soil and groundwater, uptake by vegetation, and evaporation. 

Water quality is maintained through the use of landscape features such as bio-retention basins or rain gardens and other landscaped areas that encourage infiltration.  Infiltration of the water allows the physical, biological and chemical capabilities of the soil to remove pollutants from the runoff.  This may be accomplished through absorption, transformation, immobilization, plant uptake or conversion.  Any number of landscape features can be used as a rain garden to help remove pollutants.  FIND MORE INFORMATION ON LOW IMPACT DEVELOPMENT (LINK=LID).

Regional Stormwater Management Systems

In some situations, allowing offsite treatment of stormwater runoff may prove more cost-effective and ensure better water quality than numerous small stormwater management systems that depend on homeowner maintenance.  Some localities use a pollution credit purchase programs that allow developers to forego installing stormwater management systems that protect water quality on-site.  Water quality protection then becomes the responsibility of the local government, which maintains larger regional stormwater best management practices. Regional stormwater management may allow for more innovative water quality protection practices that may be cost prohibitive at the parcel scale and serve a dual use in the community.  For example constructed wetlands that are designed to manage stormwater runoff for water quality may also help recharge groundwater aquifers, provide plant and animal habitat, and offer educational and recreational opportunities for community members.  

Urban Forests

Healthy and extensive urban forests can play a significant role in managing stormwater runoff.   Urban trees can intercept, and thus reduce, stormwater runoff reducing the total amount of water reaching structural best management practices. Tree leaves can store a large amount of rainwater that is evaporated into the atmosphere once the storm is over.  Tree roots help to create macropores that increase the amount of water urban soils can absorb during storms.  Trees also pump a tremendous amount of water from urban soils into the atmosphere through evapotranspiration.  Urban forestes can also play a critical in sequestering carbon (a significant greenhouse gas), mitigating air pollution, reducing the urban heat island effect and providing habitat. Although air pollution, inadequate protection and poor management are overwhelming many urban forests, they continue to provide substantial benefits to many communities, as demonstrated in Table 4.3. 

Urban Nutrient Management

v     Septic Systems

v    Lawn Care

v     Pet Care

Many everyday uses can contribute nonpoint source pollutants, like nitrogen and phosphorous, to local waterways.  Minimizing nitrogen polluting septic systems and educating landowners about appropriate lawn care and pet waste management can help protect coastal water quality.

Septic Systems

When properly functioning, conventional septic systems reduce pathogens and some nutrients by filtering effluent through the soil medium of the drainage field. However, studies show that even properly installed and maintained conventional septic systems remove less than 30% of the nitrogen from effluent. Unfortunately, septic systems are much more complicated and require more maintenance than many homeowners realize.  Improperly functioning and failing septic systems exacerbate the problem of subsurface water contamination that results from the fact that conventional septic systems are not designed to efficiently and effectively eliminate nitrogen from effluent.    Depending on the physical, chemical and biological characteristics of the soil, a large portion of nitrogen from septic systems may reach ground and/or surface waters, substantially contributing to the total nutrient load.

The most effective means of managing septic system pollution is to require new development to connect to municipal sewer.  Centralizing the management of wastewater treatment at municipal facilities allows for more regular maintenance and upgrading of necessary infrastructure by highly trained, professional staffs rather than thousands of individual landowners.  As a last resort local governments should require that all new and replacement septic systems in coastal areas incorporate denitrifying technology.    

Lawn Care

Lawn care products applied to residential lawns and golf courses also provide a significant amount of nutrients to groundwater and surface waters.  Rather than depending entirely upon buffers to remove nutrients, homeowners can take a pro-active approach, by reducing the size of their lawns and minimizing nutrient application.  Sound lawn care techniques, such as those advocated by the Alliance for the Chesapeake Bay’s Bayscapes program are necessary components to nutrient control.  Limiting fertilizer to only that necessary for proper lawn care, in the proper season, using Integrated Pest Management (IPM) techniques to minimize the use of pesticides and minimize herbicide use are measures that require the participation of individual homeowners, and residential lawn care specialists.  Homeowner associations and managers of public parks and golf courses and other open spaces should also be included in educational efforts.  FIND MORE INFORMATION ON BAYSCAPES.

Pet Care

Homeowner education should include pet waste management.  A large dog can contribute as much waste as a small child; however, pet waste often enters waterways untreated.  In the same way that septic effluent contributes an excess of nitrogen and bacteria to groundwater, pet waste can contribute to contamination of surface and groundwater.  The consistent removal and appropriate disposal of pet waste from lawns is one more tool in the reduction of over-enrichment of adjacent waters.

Minimizing Shoreline Disturbances

v     Shoreline Erosion Control Structures

v    Community vs. Private Piers and Docks

The installation of shoreline hardening and shoreline access structures often requires the elimination of habitat directly and indirectly. These structures may require grading or the removal of shoreland vegetation and marsh grasses leading to direct and indirect habitat losses on the project site and adjacent properties.

Shoreline Erosion Control Structures

Both natural and structural control techniques may be used to reduce shoreline erosion. Careful selection of the control technique is important to prevent exasperating erosion rates elsewhere. Most conventional structural erosion control methods tend to aggravate erosion downdrift. Furthermore, these structures ultimately fail. Therefore, it is best to reduce, to the extent possible, the need for structures through appropriate shoreland planning. If erosion control is essential, selecting the best-suited strategy for the particular problem and location requires a careful assessment of the existing conditions.

Should the anticipated wave energy at the shoreline and the tidal range indicate a need for a structural answer to shoreline erosion, site-specific design criteria should be applied to arrive at the appropriate control method.  Sound technical advice should be sought to decide which control method would cause the least amount of harm to adjacent aquatic and riparian features. 

The least obtrusive erosion control technique should be implemented with special consideration given to maintaining shoreline habitat.  Studies demonstrate the substantial impact some of the least obstructive shoreline hardening structures like rip-rap can have on the shoreline ecosystem when compared to establishing or enhancing tidal wetlands. 

Community vs. Private Piers and Docks

The cumulative impacts of the construction and operation of private piers and docks can result in substantial degradation of the shoreline and near shore waters. The shade created by docks may affect SAV beds and habitat quality for juvenile fish.  Docks, piers or other public boat access facilities may also contribute toxic chemicals directly to the water. Even small amounts of chemicals from wood treated with creosote or chromated-copper-arsenate can have toxic effects on shallow habitat organisms, since such high concentrations of chemicals are in the wood (HRPDC, 25).

Community facilities should be considered in order to reduce the cumulative impacts of numerous private docks and piers.  Community facilities concentrate the disturbance and pollutant loads in a manner that may be more easily and economically managed and mitigated. Appropriate densities for piers and docks should be based on a number of factors including aesthetics, public access, flushing characteristics of the waterbody and sensitivity of nearby aquatic habitat.    

Additional access to the shoreline by boats and other recreational vehicles causes another set of challenges to the shoreline’s health. Hard surfaces are usually required to facilitate vehicular access to boat ramps. The process of creating access damages woody buffers and destroys oyster and submerged aquatic vegetation beds.  Motorized boating activities in narrow shallow embayments can potentially harm both terrestrial and aquatic resources from increased wave forces and increased turbidity. This activity causes physical damage to submerged aquatic vegetation beds and the shoreline.

[1] These estimates were developed using American Forests’ Citygreen software and summarized in a “Rapid Ecosystem Analysis for 2001” for each city.  Analysises for many other communities throughout the Chesapeake Bay watershed are available at  www.americanforests.org/campaigns/ecological_services/. 

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