Storm Water Energy Dissipator with limited length
Storm Water Energy Dissipator with limited length
(OP)
We've experienced contractor error which led to a 36" outlet pipe discharging out of a CRM wall (16' high) with way too steep of a slope. I originally designed a drop inlet structure before the wall (not constructed) which led to adequate exit velocity. The property line is 5' from the outside face of wall, limiting our ability to use common dissipator types. I was thinking of using an impact basin but turning it 90 degrees at the pipe outlet. The water (63 cfs, 20 fps) would slam into a wall and turn parallel the wall, thus giving baffle/riprap length as needed. I have no idea how to calculate the final velocity or the effect of the wall impact. Any advice or direction is much appreciated, (fyi I've got the FHWA HEC14 manual handy).
Thanks,
AnalyzingAlan
Thanks,
AnalyzingAlan





RE: Storm Water Energy Dissipator with limited length
There are some culvert roughing techniques in section 7-1 and 7-2 of HEC 14 that may be useful, or maybe convert the pipe to a broken back culvert design, but if the pipe is already installed it would just be easier to tear it out and build it to plan, than to install the roughness features, or change the slope.
RE: Storm Water Energy Dissipator with limited length
RE: Storm Water Energy Dissipator with limited length
That's worked for me in your scenario. Of course cross your Ts and dot your Is on structural and geotechnical issues.
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com
RE: Storm Water Energy Dissipator with limited length
RE: Storm Water Energy Dissipator with limited length
Thanks again everybody
RE: Storm Water Energy Dissipator with limited length
One thing I caution you on and that is the velocity leaving your site must be equal to or less than the velocity before your project began. This is a fundamental drainage If your materials are not CMP you will need to customize.
Please look me up if you need more help on the details