SW3220301_Response To Comments_20220519

Kevin E. Herring ENGINEERING
16101 Silver Road, Oakboro NC 28129, 980-621-0935, kevin@kevinherringengineering. com
May 11, 2022
Memo To: Jim Farkas
NCDEQ Stormwater
14
From: Kevin E. Herring PE h14
Reference: Revised Submittal of Mini Warehouse USA
3622 W. Hwy 74, Wingate NC
This shall serve as a response to comments provided via email dated 5/ 10/22.
General MDC 4
Rirrap calculations were originally provided in the erosion control section of calculations. However in review I noticed
that the calculations reflected a Q(10) of 8.3c€s. Previously updated SCM talcs actually has the Q(10) as 8.99efs. I have
updated the apron talcs to reflect this which had a minor change to the apron sizing. In addition to the included updated
riprap apron calculations i have revised plan sheet 7 to reflect the updated sizing.
Sand Filter MDC 2
I have revised the location of the riprap berm separating the sediment and sand chambers such that the chamber sizes are
equivalent. I have revised plan sheet 4 to reflect this as well as details on sheet 5 where the berm showed up. Calculation
sheets referring to the chamber sizing have been updated and included in this submittal.
Application. Section IV, 8
The percent impervious of the site has been updated to 64%. This matches changes to the Drainage Area section of the
Supplement EZ form as noted below.
Su lenient EZ Form
All changes made as requested and updated based on changes noted above. The Entire Site Drainage Area section is still
somewhat confusing as it relates to onsite vs offsite, After updating it still may not be correct. To clarify the overall
property site area is 84735sf outside of NCDOT R/W. 3910sf of NCDOT R/W flows into the site therefore I have
corrected the Total DA of the entire site to be 88645sf (84735+3910), The total BUA of the project is 56830sf which
includes all of the proposed impervious area of the site plus 3410sf of existing and proposed impervious area in NCDOT
R/W. The percent BUA of the entire site is then calculated as 64% (88645 / 56830). This number was updated in Section
IV, 8 of the SWU-101 Application. Please advise if this is still not correct.
Additional Recommendations
There have been no plan changes relative to reducing the side slopes of the bypass channels; however, I have expressed
that concern to the owner and advised to reduce the slopes as much as possible during construction.
In summary, in addition to the revised calculations and documents, the plan sheet revisions include
Sheet # 1 to reflect the revision date change,
Sheet # 4 to reflect the revised riprap berm location
Sheet # 5 to update details showing the riprap berm
Sheet # 7 to update the riprap apron data block.
Please advise if additional information is needed.
kh