HomeMy WebLinkAboutWPO201800049 Certified Engineer's Report 2023-02-16SHIMP ENGINEERING, P.C.
Design Focused Engineering
February 16, 2023
John Anderson, P.E.
Civil Engineer II
Albemarle County
Dept. of Community Development
Re: Oak Hill Convenience Store
Certification of Stormwater Control Structure
Dear Mr. Anderson,
I hereby certify that the control structure (A2) for the underground stormwater detention system is acceptable
as constructed. In my professional judgement, the 10" 10-yr orifice does not require a debris cage due the
large size of the orifice that will pass most debris and the velocity that such a level of storm would be flowing.
The absence of a debris cage over the 10" orifice has no negative effect on the 10-yr peak flow rate release
from the detention system. Conditions where the 10" orifice may become completely clogged have been
evaluated using stormwater modeling software and it has been verified to not have any negative impact on the
release rate or detention water surface elevation. The model shows that even with a completely clogged 10"
10-yr orifice, the resulting runoff release and detention system water surface elevations have no negative effect.
The Energy Balance Equations is still met and the 10-yr runoff release rate is still below pre -development. Also,
the 100-yr water surface elevation is contained within the system. Please seethe as -built submission package
for further details.
If you have any questions, please do not hesitate to contact me via email at: Justin@shimp-engineering.com
or via phone at 434-227-5140.
Sincerely,
Justin Shimp, P.E.
Shimp Engineering, P.0