The project I am working on is in a campus setting and the neighboring site's excess runoff is discharged into a storm drain pipe that runs through our project's site. To save costs, we would like to utilize this existing pipe to help collect our runoff. Downstream we plan to connect this storm drain line into a new underground infiltration basin on site. This basin would be sized to infiltrate the correct amount of runoff from our project site. So in a black box scenario the volume infiltrated on site would be according to the LEED standards. However in reality, the infiltration basin would be filled initially with some of the neighboring site's runoff because of the shared line and eventually some of our site's runoff would flow freely off site if the basin gets filled. With LEED's emphasis on managing storm water on site, would this type of system disqualify it? The same amount of water will be infiltrated on site, just some of it will technically be from a neighboring site. Or will we need to run parallel pipes to keep the systems separate?
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Michael DeVuono
Regional Stormwater LeaderArcadis North America
LEEDuser Expert
187 thumbs up
January 10, 2018 - 1:01 pm
This isn't really a GI approach, since you are conveying the runoff away from the source. Scroll through the forums, another project with a similar approach was denied on this basis.
Now just from a hydraulic standpoint, it appears that you are designing a BMP that is inadequately sized to capture the receiving drainage area, causing later stages of your storm to overflow and bypass? I'd be more concerned with the downstream flooding impacts you may be causing than a LEED point.