HomeMy WebLinkAboutWPO201800049 Plan - As-built 2023-02-16SHIMP ENGINEERING, P.C.
Design Focused Engineering
February 16, 2023
Mr. John Anderson
County of Albemarle
401 McIntire Rd
Charlottesville, VA 22902
RE: Oak Hill Convenience Store
As -Built Comment Response #2
WPO-201800049
Mr. Anderson,
Thank you for your review of the As -Built Plans for Oak Hill Convenience Store. We have revised the
plans per your most recent comments emailed on January 24, 2023. Please find below a detailed
response to each comment.
1.) Please furnish video/still photos of weir plate in MH Str. A2.
Still photos of the weir plate in MH Str. A2 have been provide and includes a photo of the
installed 1-yr orifice trash rack Please see as -built submission package.
2.) Please prepare and seal letter to address particular as -built condition of control structure.
(10" 10-yr orifice has no trash rack.)
A signed and sealed letter has been provided certifying the stormwater detention system
control structure as it is constructed (with no trash rack over the 10" 10-yr orifice). Please
see as -built submission package for letter.
3.) We recommend model the 10-yr storm event as if 10" orifice did not exist to mimic complete
obstruction to ensure no negative effect.
A HydroCAD model has been provided that analyzes the system with no 10" 10-yr orifice
to evaluate effects of a completed clogged 10" 10-yr orifice. 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 Equation is
still met. The 10-yr flowrate is still below pre -development and the 100-yr water surface
elevation is contained within the system. Please see as -built submission package for this
HydroCAD model report and a summary of the stormwater analysis.
Regards,
Michael Chandler
Shimp Engineering, P.C.
912 E. High Sr. Charlottesville, VA 22902 1434.227.5140 1 shimp-engineering.com