Rating System

LEED BD+C: New Construction, LEED BD+C: Core and Shell

Rating System Version

v2 - LEED 2.2, v2 - LEED 2.0

Inquiry

We are inquiring about the applicability of a 10 story office building in SE, DC, registered under LEED NCv2.1 to meet the criteria for SSc6.2. A small percentage of the run-off will not be treated. In light of the fact that the requirements for the percentage of the run-off to be treated has changed from 100% to 90% from LEED NCv2.1 to v2.2, will the following qualify? The total site area is 22,312 SF and the building, with exception of a small area (approx 1100 SF, 5% of the site) to the north is built to the lot line. All the roof drains are directed into a sand filter and storm water management vault on the 1st and 2nd parking level, respectively. The water is then to be re-used within the building in the cooling towers. The site area which is not being directed into the storm water filtration is in a public alley at the north-west side of the site, and mostly occupied by grating over the garage exhaust and transformer vault. Due to the fact that it is a public alley, trying to re-grade to capture this run-off is not an option. This area is sloped away from the building and the water will not be treated before it runs into the alley or is pumped out from the transformer vaults into the public system. The sand filter is sized to capture and treat the first 1/2" of runoff from the site area draining to it. The water quality volume provided was the larger of the two calculated volumes for water quality and water quantity (1/2" Quality vs. Quantity volume difference between the 15 year post-development storm and 15 year pre-development storm). The industry standard for a sand filter meets the 80/40 removal requirement for TSS/ Total Phosphorus when sized for the first 1/2". Once again, in summary all the storm water with the exception of approximately 5% will be treated and reused on site. Will this be eligible for a credit under LEED NCv2.1 in light of the fact that it would be applicable under the changes made in LEED NCv2.2?