Rating System

LEED BD+C: New Construction, LEED O+M: Existing Buildings, LEED BD+C: Core and Shell, LEED BD+C: Schools

Rating System Version

v3 - LEED 2009, v3 - LEED 2008, v2 - Schools 2007, v2 - LEED 2.2, v2 - LEED 2.0

Inquiry

The existing imperviousness of the project\'s urban site is 74%, mostly due to surface asphalt parking lots. A portion of the stormwater runs offsite while the remainder is piped to drywells. The new development will have a net imperviousness of approximately 62%, most of which will be a building roof and pedestrian plaza. This represents a reduction of 17%. All of the stormwater runoff from the new development will be directed to new drywells dispersed around the site, recharging groundwater. Stormwater from the minimal remaining surface parking will be piped to a water quality swale and discharged into drywells. The intent of Credit 6 is to "Limit disruption of natural water flows by minimizing stormwater runoff, increasing on-site infiltration and reducing contaminates." Credit 6.1 addresses the first two of these intents, while Credit 6.2 addresses the third, reducing contaminates. Credit 6.1 states "if existing imperviousness is greater than 50%, implement a stormwater management plan that results in a 25% decrease in the rate or quantity of stormwater runoff." Although the net imperviousness of site surfaces will be reduced by only 17%, rather than the stated 25%, we feel this project will meet the intent of the credit because 100% of the stormwater will remain on-site and be directed to drywells, thus infiltrating and recharging ground water. Run-off leaving the site will be eliminated, impervious surface area will be significantly reduced and on-site water flows will more closely resemble the natural flows that existed before the existing surface parking lot was constructed. Do you agree that the proposed stormwater management meets the intent of Credit 6.1?