Rating System

LEED BD+C: New Construction

Rating System Version

v2 - LEED 2.2

Inquiry

It is unclear from the LEED NC 2.2 Reference Guide if the following scenario would qualify for credit for SSc6.2 - Stormwater Management, Quality Control. We are wondering if the following strategy is an acceptable approach. The project site is 0.75 acres and stormwater from a total of 0.68 acres will be treated. This means that all of the stormwater falling on 91% of the site will be diverted to filtration devices that will remove over 80% of the total suspended solids (TSS). The stormwater falling on the remaining 9% of the site will intercept sidewalks which, for code requirements, slope away from the building and thus will flow off-site into existing storm drains. Although the sidewalks are being constructed as part of the project and are to be included in the LEED boundary, the stormwater treatment for the sidewalks is managed by the City of Portland and outside the scope of the project. SSc6.2 - Stormwater Management, Quality Control requires that 80% of the TSS is removed for 90% of the average annual rainfall. If the stormwater treated on 91% of the site removes 80% of the average annual post-development TSS for the 0.75 inch rainfall event (project is in a semi-arid zone), will this credit be achieved? Can you please let us know if the stormwater treatment system, as described, is in compliance or if we have misinterpreted the credit language? It is unclear to us whether this strategy is compliant by the guidance for v2.2 provided under LEED NC v2.1 CIR ruling from 9/14/2006.