CS-2009 SSc6.2: Stormwater Design—Quality Control

  • Credit language straight from USGBC

    Need to check up on the exact LEED credit language from the LEED Rating System on the fly? LEEDuser includes the verbatim language. Members get:

    • Easy access to the official LEED credit language with just a couple of clicks.
    • On the jobsite without your bulky LEED Reference Guide? Check up on the credit language details here.
    • Credit language content is used by permission of the U.S. Green Building Council.

4 Comments

0
0
Amanda Ross
Sep 27 2011
Member
13 Thumbs Up

Estimating credit acheivement

1) Does anyone know of any local/regional programs with the 80% standard in the Vancouver, BC area? Our project is located in Surrey, BC.

My civil engineer tells me that he knows of no local/regional stormwater programs that have adopted the 80% TSSTotal suspended solids (TSS) are particles that are too small or light to be removed from stormwater via gravity settling. Suspended solid concentrations are typically removed via filtration. removal standard. Therefore, we need to provide field measurements after the installation.

2) Does anyone know of any good tools to estimate stormwater TSS removal? We have mostly non-structural measures (a lot of green roofs). It would be very helpful to know if we're getting close to this point.

Thanks!

-Amanda

Log In to Reply
0
0
Hansong Sun
Apr 20 2010
Guest
72 Thumbs Up

How to determine the 90% of the average annual rainfall

Hello
I'm very confused by the methods determining the 90% of the average annual rainfall in SSS Credit 6.2 LEED guide.
In p103 of LEED guide, they said "For this credit, managing 90% of the average annual rainfall is equivalent to treating the runoff from the amounts listed in Table:
Watershed Rainfall per 24 Hours(ins)
Humid 1
Semiarid 0.75
Arid 0.5
I wondered Why the 90% of average rainfall is equivalent to treating the runoff of 1,0.75 and 0.5 (this is the quantity of 24 hours? not entire year?).

Thanks

1
2
0
Jean Marais b.i.g. Bechtold INGENIEURGESELLSCHAFT MBH Apr 20 2010 Member 2152 Thumbs Up

1) Intensity-Duration-Frequency (IDF) Charts. These charts show the relationship between the rainfall intensity (rate) and the corrisponding rainfall duration (minutes). This data is required for 1 and 2 year statistical return periods.
2) Depth-Duration-Frequency (DDF) Charts. These charts show the relationship between the rainfall depth (volume) and the corrisponding rainfall duration (minutes). This data is required for 1 and 2 year statistical return periods.
3) Volume of the 90% rainfall event, i.e. only 10% of rainfall events have a cummilative depth of more than this amount.
4) 90% Shortest Time between rainfall events, i.e. only 10% of rainfall events have between them a dry time less than this time.
5) Volume of yearly rainfall for "water shed" classification as per LEED.

in plain english this means that it is the volume of rain coming down for an entire rainfall 24 hour equivalent event AND the event is the one that statistically happens most of the time.

I think the reason the userguide wording is comfusing is because the statistical concepts are confusing and these calculations are usually done by an expert civil engineer. I also am not 100% certain of this area.

Links:
http://www.hydrocad.net/pdf/TR-55%20Chapter%203.pdf
http://www.bossintl.com/download/SoilCharacteristics.html
http://www.bossintl.com/download/RunoffCurveNumbers.html

also google
RUN-OFF VOLUME CALCULATION - TR-55 Method
Stromwater Retention Volume - Schueler's Simple Method
RUN-OFF RATE CALCULATION - Rational MethodA formula that can be used for calculating stormwater flow rates. Q = CIA, where C represents a coefficient for physical drainage area, I is the rainfall intensity, and A is area. The method is suitable for watersheds smaller than 300 acres in size.

2
2
0
Hansong Sun Apr 26 2010 Guest 72 Thumbs Up

Hello Jean,
Thanks very much for your detailed explanation. I think what you said is right.

Log In to Reply

Copyright 2012 – BuildingGreen, Inc.