Franklin Medical Center – 20 Bed Expansion - 2018-12-07_Stormwater Comment Response

December 7, 2018

Corey Anen
North Carolina Department of Environmental Quality
512 N. Salisbury Street
1612 Mail Service Center
Raleigh, NC 27699-1612

RE: Franklin Medical Center – 20 Bed Addition
100 Hospital Drive
Louisburg, NC 27549

Corey,

Below are our responses to comments received on 12/03/18.

1. The wet pond drawdown calculations use an incorrect flow rate, resulting in a drain time
greater than 5 days.
Response: In the drainage report under “Wet Pond Calculations”, the calculation for the flow
through the orifice had a typo that caused the desired flowrate to be cut in half. The equation for
the flowrate has been revised and the formulas used to calculate the diameter of the orifice have
been provided more clearly. On Sheet C8.0, the outlet structure detail has been revised to reflect the
revised orifice diameter.

2. Please provide calculations showing that the inlet into the wet pond and the outlet from
the wet pond are designed to prevent erosion during peak flows from the 10-year storm.
Response: In the drainage report the calculations for the rip-rap apron into the forebay and out of the
pond have been provided. On Sheet C6.0, a rip-rap apron has been added to the inlet to the forebay
at structure A1. On Sheet C8.2, the dimensions of the rip-rap apron detail have been revised to reflect
the calculations.

3. Provide pdfs of all revisions, 2 hardcopies of revised plan sheets, and 1 hardcopy of other
documents. Pdfs must be uploaded using the form at:
https://edocs.deq.nc.gov/Forms/SW_Project_Submittal
Response: A pdf of all revisions has been upload to the above link and the requested hard copies are
will arrive by FedEx.

We believe that all comments have been addressed and ask for approval of these plans. If you have any
questions or need additional information please contact me.

Thanks.

Will Crunk
Crunk Engineering LLC
615-873-1795
[e-mail]