Site Design Credits

Site design credits act as an incentive to developers, designers, and builders to implement better site design and low impact development techniques that can reduce the volume of stormwater runoff, preserve natural areas, and minimize the pollutant loads from the site. Credits allow developers to reduce or eliminate requirements for Recharge, Water Quality, Channel Protection, and Flood Control in exchange for implementation of these non-structural site design elements.

The specific calculation of site design credits will vary between communities. The credit can be expressed as a volume, or a fraction representing, for example, the fraction of the water quality volume met by the credit. In all of the examples presented here, the credits are calculated as volumes that are based on the fraction of the total site area or site impervious area affected by the credit.

Channel protection and flood control credits are typically accounted for by adjusting hydrologic parameters. In the examples below, adjustments reflect the use of TR-55 (NRCS, 1986). Similar assumptions could be used to alter the rational method, or other hydrologic methodologies.

Specific design credits detailed in this section include the following:

• Environmentally Sensitive Development
• Stream Buffers and Filter Strips
• Open Channels
• Conservation of Natural Areas
• Reforestation
• Rooftop Disconnection
• Non-Rooftop Disconnection
• Green Rooftops