In California, we are required to intercept and infiltrate storm water as part of the Water Quality BMP.
When it comes to tracts, we have choice of taking up a lot(s) ($) or placing a BMP in each lot.
An underground system is an "inspection concern" and a "maintenance headache". At least one City has changed their policy, to no more individual underground BMPs in single family lots---there needs to be an HOA created for maintenance of the BMP in a central location, etc.
Several cities have required only above ground BMPs or (Basins, surface bmps).
What ever you decide, whether for storm water or water quality, keep it simple and there should be fewer complications.
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Wendell Iwatsuru
Madole & Associates, Inc.
Rancho Cucamonga CA
(909)230-8798
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Original Message:
Sent: 04-17-2019 11:03
From: Garret Duhon
Subject: Submerged Storm System in Residential Application
We are currently designing a single family development with a connected detention basin system where the individual storm outfalls are all submerged (below static water surface elevation). One of the sections currently under design is experiencing an underground utility conflict that can be resolved by having several pipe lengths upstream of the outfall submerged. Personally, this is something I have been taught to avoid but I have no actual basis (practice or reference) for why or why not this situation should be avoided.
I was hoping for some insight as to whether anyone has experienced issues with this type of situation. Obviously, this results in greater potential for sediment in the system but any thoughts other than that would be appreciated.
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Garret Duhon,P.E.
Houston, TX
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