Forum discussion
NC-2009 SSc6.1: Stormwater Design—Quantity Control
Hello,
Can I presume that the imperviousness of a site is less than 50% if the overall runoff coefficient is less than 0.5 ?
Apologies if the answer is obvious but I am not an export in this field.
Thanks,
LEEDuser is supported by our premium members, not by advertisers.
Go premium forTo post a comment, you need to register for a LEEDuser Basic membership (free) or login to your existing profile.
Why do the requirements focus on 1-year and 2-year, 24-hour storms?
How can green roofs count as a stormwater control measure?
I have 100-year data—how do I convert to 2-year?
Are there special considerations for international projects?
What performance threshold do I need to achieve for an Exemplary Performance point?
Jean Marais
b.i.g. Bechtold DesignBuilder Expert832 thumbs up
November 8, 2010 - 4:58 am
Yes.
It is generally the opinion that site "imperviousness" (fraction) = area weighted Run-off coefficient (also fraction) for the site.
J.W. Shin
17 thumbs up
February 13, 2011 - 2:14 am
Hi.
I have a little doubt of comment from Jean.
See the page 95, on BD+C Reference guide.
Rv(volumetric Runoff Coef.) = 0.05 + 0.009xI
(where, I = percentage of imperviousness)
Following the equation above,
when "I" is 100, Rv will be 0.95.
So, Rv and I are not equal, but propotional.
Petra Hajná
Sustainability ConsultantSkanska Czech Republic
189 thumbs up
December 8, 2011 - 9:40 am
I think Jean is right. Taking into acount the equation, you are actually considering the "I" value and doing a weighted average based on surface area. Hope my explanation is clear and correct.