20231361 Ver 1_More Info Requested_20240108

Homewood, Sue
From: Homewood, Sue
Sent: Monday, January 8, 2024 10:30 AM
To: [e-mail]; Hales, Jason C.; [e-mail]
Cc: Thomas, Zachary T; Harmon, Richard G CIV SAW
Subject: Request for Additional Information for I-85 sewer improvement SGWASA - Granville
County - DWR#20231361
Follow Up Flag: Follow up
Flag Status: Flagged
0
DWR has reviewed the 401 application for the above noted project and requires additional information to complete our
review. Please respond to the items below within 30 days. The application will be considered "on hold" until DWR
receives a complete response.
1. Please provide either a Buffer Determination Letter issued by the DWR Raleigh Regional Office or USGS Topo
Maps and Published Soil Survey maps with the project limits clearly shown in order to document which features
within the project will be subject to the Neuse Buffer Rules.
2. As discussed in a meeting on January 5, 2023, please:
a. revise the plan sheets to clearly show where work is being conducted within an existing, maintained
utility corridor, existing transportation facility or any other location where the work will be conducted
within a location of an "existing use" as defined by the Neuse Buffer Rules.
b. For each buffer impact area, clearly indicate what line item within the Table of Uses is applicable
c. Clarify or revise the term "temporary impacts" for buffer purposes. The Neuse Buffer Rules do no
provide for "temporary impacts" in the Table of Uses.
d. Provide an updated buffer impact table that includes documentation of impacts requiring mitigation
e. Provide an updated mitigation total in accordance with "zonal multipliers" pursuant to 15A NCAC 2B
.0295
f. Provide an updated buffer mitigation SOA if necessary
3. Please note that all work must be done "in the dry'. Therefore, dewatering methods will be necessary to
temporarily dewater the stream channel during culvert installation and during utility line installation. Please
provide a construction sequence and dewatering details that show that dewatering is to be utilized at the site
and the sequence of construction events to be followed to ensure compliance with this condition. In addition,
please ensure that the location of the temporary impacts are shown on the construction drawings and clearly
indicated in the revised impact table.
4. Please provide a stream restoration detail for the utility line installation stream impact locations and a wetland
restoration detail for utility line installation wetland impact locations.
5. Standard 401 certification conditions require that: Any utility construction corridor that is parallel to a stream or
open water shall not be closer than 10 feet to the top of bank or ordinary high-water mark. It appears that this
project will not meet this condition at multiple locations. Please carefully review all locations and either revise
the design to meet this requirement or provide justification for why this condition cannot be met and what
measures are proposed to ensure water quality protection during construction. The Division cautions that
streams are dynamic and often move over time and locating sewer line parallel to a channel will likely create
future problems for the municipality.
6. Please provide justification for why the impacts to Ledge Creek cannot be avoided by use of other installation
methods (boring, etc)

7. Notwithstanding item 6 above: the Division has significant concerns regarding open cut installation methods in
large stream systems. It is staff's experience that open cut installation methods within large streams are
extremely difficult to construct and maintain in a manner that ensures compliance with water quality
standards. Please provide very specific construction details, including proposed dewatering methodology,
expectation of encountering rock and methodology for removal of rock, expected construction timeline, and
additional measures proposed to ensure water quality protection during construction.
8. For all proposed permanent culverts, please provide a plan and profile design drawing that clearly show that the
culvert will be installed to meet 401 standard 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. Notification, including supporting documentation such as a
location map of the culvert, geotechnical reports, photographs, etc. shall be provided to DWR a minimum of
30 calendar days prior to the installation of the culvert. If bedrock is discovered during construction, then
DWR shall be notified by phone or email within 24 hours of discovery.
Installation of culverts in wetlands shall ensure continuity of water movement and be designed to
adequately accommodate high water or flood conditions. When roadways, causeways, or other fill projects
are constructed across FEMA-designated floodways or wetlands, openings such as culverts or bridges shall
be provided to maintain the natural hydrology of the system as well as prevent constriction of the floodway
that may result in destabilization of streams or wetlands.
The establishment of native woody vegetation and other soft stream bank stabilization techniques shall be
used where practicable instead of rip -rap or other bank hardening methods.
9. It appears that the proposed culvert installation for the road access to the 1-85 Lift Station is not in alignment
with the natural channel. Please realign the culvert so that the inlet and outlet are in alignment with the existing
stream to the maximum extent possible.
Note that upon review of the response to the items listed above, additional requests for information may be necessary.
Thanks,
Sue Homewood (she/her/hers)
401 & Buffer Permitting Branch
Division of Water Resources

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