A consensus process conducted by a 29-member panel of planning, design, development and environmental experts has identified 22 specific principles for more environmentally sensitive, economically viable, and locally appropriate development. These principles, found in Better Site Design published by The Center for Watershed Protection, provides local planners, engineers, developers and officials guidelines they can use in designing new buildings and communities.
Residential Street and Parking Lot Principles
- Design residential streets for the minimum required pavement width needed to support travel lanes; on-street parking; and emergency, maintenance, and service vehicle access. These widths should be based on traffic volumes.
- Reduce the total length of residential streets by examining alternative street layouts to determine the best option for increasing the number of homes per unit length.
- Whenever possible, residential street right-of-way widths should reflect the minimum required to accommodate the travel-way, the sidewalk, and vegetated open channels. Utilities and storm drains should be located within the pavement section of the right-of-way wherever feasible.
- Minimize the number of residential street cul-de-sacs and incorporated landscape areas to reduce their impervious cover. The radius of cul-de-sacs should be the minimum required to accommodate emergency and maintenance vehicles. Alternative turnarounds should be considered.
- Where density, topography, soils and slope permit, vegetated open channels should be used in the street right-of-way to convey and treat storm water runoff.
- The required parking ratio governing a particular land use activity should be enforced as both a maximum and a minimum in order to curb excess parking space construction. Existing parking ratios should be reviewed for conformance taking into account local and national experience to see if lower ratios are warranted and feasible.
- Parking codes should be revised to lower parking requirements where mass transit is available or enforcement shared parking arrangements are made.
- Reduce the overall imperviousness associated with parking lots by providing compact car spaces, minimizing stall dimensions, incorporating efficient parking lanes and using pervious materials in spillover parking areas.
- Provide meaningful incentives to encourage structured and shared parking to make it more economically viable.
- Wherever possible, provide stormwater treatment for parking lot runoff using bioretention areas, filter strips and/or other practices that can be integrated into required landscaping areas and traffic islands.
Lot Development Principles
- Advocate open space development that incorporates smaller lot sizes to minimize total impervious area, reduce total construction costs, conserve natural areas, provide community recreational space and promote watershed protection.
- Relax side yard setbacks and allow narrower frontages and reduce total length in the community and overall site imperviousness. Relax front setback requirements to minimize driveway lengths and reduce overall lot imperviousness.
- Promote more flexible design standards for residential subdivision sidewalks. Where practical, consider locating sidewalks on only one side of the street and providing common walkways linking pedestrian areas.
- Reduce overall lot imperviousness by promoting alternative driveway surfaces and shared driveways that connect two or more homes together.
- Clearly specify how community open space will be managed and designate a legal entity responsible for managing both natural and recreational open space.
- Direct rooftop runoff to pervious areas such as yards, open channels, or vegetated areas and avoid routing rooftop runoff to the roadway and the stormwater conveyance system.
Conservation of Natural Area Principles
- Create a variable width, naturally vegetated buffer system along streams that also encompasses critical environmental features such as the 100-year floodplain, steep slopes and freshwater wetlands.
- The riparian stream buffer should be preserved or restored with native vegetation that can be maintained throughout the delineation, plan view, construction and occupancy stages of development.
- Wherever practical, manage community open space, street right-of-way, parking lot islands and other landscape areas to promote natural vegetation.
- Conserve trees and other vegetation at each site by planting incentives and flexibility in the form of density compensation, buffer averaging, property tax reduction, stormwater credits and open space development should be encouraged to promote conservation of stream buffers, forests, meadows and other areas of environmental value. In addition, off-site mitigation consistent with locally adopted watershed plans should be encouraged.
- New stormwater outfalls should not discharge unmanaged stormwater into jurisdictional wetlands or sensitive areas.
Adapting the Principles
Planning, design, development and environmental experts offer these guidelines to city, township and county officials as they adapt the model development principles to achieve better development.
- It should be clearly recognized that the principles must be adapted to reflect the unique characteristics of each community. Further, not all principles will apply to every development or community.
- The principles are offered as a benchmark to guide better land development. Communities should consider the principles as they assess current zoning, parking, street and subdivision codes.
- The principles should be used as part of a flexible, locally-adopted strategy for better site planning.
- The principles should be considered together with the larger economic and environmental goals and put forth in comprehensive growth management, resource protection, or watershed management plans.
- Where possible, infill and redevelopment should be encouraged to reduce new impervious cover in the landscape.
- These principles primarily apply to residential and commercial forms of developments, but can be adapted, with some modifications, to other types of development.
- Clearing and grading of forests and native vegetation at a site should be limited to the minimum amount needed to build lots, allow access and provide fire protection. A fixed portion of any community open space should be managed as protected green space in a consolidated manner.