20230512 Ver 1_More Info Requested_20230509

Baker, Caroline D
From:Homewood, Sue
Sent:Tuesday, May 9, 2023 2:36 PM
To:[e-mail]
Cc:Phillips, George L CIV USARMY CESAW (USA)
Subject:Request for Additional Information for the Chatham-Randolph Megasite Sewer
System Ext Project - Chatham County - DWR#20230512
Alex,

I will be reviewing this project for DWR. I need additional information to finalize my review. Please provide a response
to the item listed below within 30 days of receipt of this email. The project will be considered on-hold until a complete
response is received.

1. The project proposes to install a double barrel culvert at Impact Site S1 for the purpose of a permanent lift
station access road. In order to ensure that the culvert design will comply with the standard DWR condition,
please provide plan and profile drawings for the culvert design. Please ensure that the culvert design meets the
following requirements or provides additional information and justification for any proposed deviation from this
condition.
“Culverts shall be designed and installed in such a manner that the original stream profiles are not altered and allow
for aquatic life movement during low flows. The dimension, pattern, and profile of the stream above and below a
pipe or culvert shall not be modified by widening the stream channel or by reducing the depth of the stream in
connection with the construction activity. The width, height, and gradient of a proposed culvert shall be such as to
pass the average historical low flow and spring flow without adversely altering flow velocity. If the width of the
culvert is wider than the stream channel, the culvert shall include multiple boxes/pipes, baffles, benches and/or sills
to maintain the natural width of the stream channel. If multiple culverts/pipes/barrels are used, low flows shall be
accommodated in one culvert/pipe and additional culverts/pipes shall be installed such that they receive only flows
above bankfull.
Placement of culverts and other structures in streams shall be below the elevation of the streambed by one foot for
all culverts with a diameter greater than 48 inches, and 20% of the culvert diameter for culverts having a diameter
less than or equal to 48 inches, to allow low flow passage of water and aquatic life. If the culvert outlet is submerged
within a pool or scour hole and designed to provide for aquatic passage, then culvert burial into the streambed is not
required.
For structures less than 72” in diameter/width, and topographic constraints indicate culvert slopes of greater than
2.5% culvert burial is not required, provided that all alternative options for flattening the slope have been
investigated and aquatic life movement/connectivity has been provided when possible (e.g. rock ladders, cross-
vanes, sills, baffles etc.). Notification, including supporting documentation to include a location map of the culvert,
culvert profile drawings, and slope calculations, shall be provided to DWR 30 calendar days prior to the installation of
the culvert.
When bedrock is present in culvert locations, culvert burial is not required, provided that there is sufficient
documentation of the presence of bedrock.”

Thanks,

Sue Homewood (she/her/hers)
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401 & Buffer Permitting Branch
Division of Water Resources
[e-mail]
336 813 1863 mobile
919-707-3679 office *new*

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