It is our understanding that Section 438 is used only to define the 95th percentile and that there is no requirement to follow Section 438 in full. Please confirm this understanding.
Thank you,
Suzanne Johnson
Hensel Phelps
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Michael DeVuono
Regional Stormwater LeaderArcadis North America
LEEDuser Expert
187 thumbs up
April 29, 2014 - 8:37 am
Suzanne, EPA 438 will outline the procedures for data collection and the methodology to determine the 95th percentile storm for your project. You must follow this methodology.
Section 438 outlines a few options to replicate pre-development hydrology, which are in line with the v4 Reference Guide, specifically Option 1, to manage the 95th percentile storm.
Basically, determine the 95th percentile storm, apply that storm to the post-development condition, and manage that runoff volume on-site with some form of BMP.
Is there something specific you are not sure about with the credit or 438?