Full disclosure: I'm not a civil engineer but I have to try to explain the LEED requirements too them. In the case of this credit, I'm trying to figure out if I'm missing something major here. The online guide added an exclusion of protected natural areas from the calculations and recommends different calculations than the print guide. Both of these changes help significantly but the rest of the language still implies (and at least one reviewer has stated) that every drop of water that isn’t absorbed or pooled on site must be prevented from leaving (for design rainfall X). It seems that the only possible approach is to have the entire site slope inwards, or have a wall or trench run along the LPB to stop any water from running off the edges of the site. Discrepancies between the language and examples occur in online and in print. These examples focus only on hardscape and roof runoff, and ignore new and existing vegetated areas and any inconveniently sloped areas near the LEED Project Boundary where rainwater could leave the site. At least in SSc6.2 in v2009, you only had to treat 90% of all runoff, but I don't see the same flexibility in v4. There seems to be either a LEED subtext or professional design convention that I’m missing that ignores runoff from vegetated areas and the edges of a site, or the discussions and examples to date haven't met the LEED requirements. Can anyone point me in the right direction? I'm quite lost. Thank you, Daniel Hartsig
LEEDuser Basic Member
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