Site is located in western Wasington state. We are using the western Washignton Hyraulic model #3 to size the underground detention. The infiltration rate for the site is 50"/hour. Using the LEED volume calculation, which requires 90% of the average annual rainfall to be captured, requiring the underground detention to double in size. Becasue of the high infiltarion rate is it possible to use an alternative compliance method to show the LEED volume calculation is onerous as the water will infiltrate, and the size isn't necessary.
You rely on LEEDuser. Can we rely on you?
LEEDuser is supported by our premium members, not by advertisers.
Go premium for
Michael DeVuono
Regional Stormwater LeaderArcadis North America
LEEDuser Expert
187 thumbs up
May 15, 2012 - 10:44 am
You don't need to "store" any volume of water with this credit, you need to treat it.
Is 90% of your site not routed through the basin? If not, i would simply model your ground cover as a "pseudo-infiltration practice." Does 90% of your site hit areas with 50"/hr infiltration rate?
I would caution against using such a high number, unless that is something typically used in Washington. (I'm not familiar at all with the Left Coast). I would get laughed at around here if I tried to submit any kind of calc using 50"/hr.
Divjot Singh
LEED AP BD+C2 thumbs up
May 18, 2012 - 6:50 am
I might be wrong, but as I see, it seems that the intention of this credit is to minimize polluted storm runoff getting into stormwater lines. So if we minimize this runoff thats one strategy and the runoff which is still going into stormwater lines, it has to be treated to remove 80% of TSS and its second strategy.
We can store water for other purposes but polluted stormwater runoff should be prevented from entering municipal storm water lines, thats what I think.