Somerset County Planning Division

"CREATING QUALITY COMMUNITIES TOGETHER"

Robert P. Bzik, AICP/PP
Director of Planning
Anthony V. McCracken, Sr., AICP/PP
 Assistant Director

20 Grove Street
P.O. Box 3000
Somerville, NJ 08876

LOW IMPACT DEVELOPMENT

What is Low Impact Development?

Low Impact Development is a new and emerging land planning and engineering approach with the goal of maintaining and enhancing the pre-development hydrologic character of urban and developing watersheds. It combines resource conservation and hydrologically designed site plan water pollution prevention measures to reduce development-related water quality impacts.

How does Low Impact Development Work ?

Generally, major land development alters the natural landscape by highly disturbing areas with large amounts of impervious cover and introducing non- native vegetation. Convention development uses stormwater management structural control measures to convey water away from developed areas. Usually these measures, such a detention basins or underground pipe storage, are designed to control peak runoff rate for a pre-determined storm events, say 2 and 10 year storms. To some degree, these approaches have worked but cannot account for the increased runoff from smaller and more frequent storms nor do they address the larger watershed functions of storage, ground water recharge and filtration.

Low Impact Development relies on non-structural approaches through a system of source controls and small scale decentralized water treatment practices, such as bioretention areas, bioretention within open space areas and grassed swales and streets without curb and gutters, to help maintain predevelopment hydrological conditions. Low Impact Development also incorporates natural site features (wetlands, open space, stream corridor buffers, mature forests) as design elements and encourages flexible design approaches to protecting environmental features. New state Department of Environmental Protection stormwater rules, N.J.A.C. 7.8-5.3,recently adopted require developers to pursue these options first before considering structural approaches.

What are the Benefits?

The Low Impact Development Center in Maryland has document the benefits of this approach for municipalities, developers and the environment including:

Municipalities

• Protecting regional flora and fauna
• Balancing growth needs with environmental protection
• Reducing future municipal infrastructure and utility maintenance
• Increasing public/private sector collaboration

Developers

• Reduce land clearing and grading costs
• Balance growth with environmental protection needs
• Reduce stormwater management costs
• Potentially increase lot yield
• Increase project marketability by maximizing open space and mature vegetation

Environment

• Preserve the integrity of ecological and biological systems
• Protect site and regional water quality by reducing sediment, nutrient and toxic loads to water bodies
• Reduce impacts to local terrestrial and aquatic plants and animals
• Preserve trees and natural vegetation

More information on Low Impact Development can be obtained from the Low Impact Development Center http://www.lowimpactdevelopment.org  or the New Jersey Department of Environmental Protection at http://www.njstormwater.org