20200427 Ver 1_2020 04 24 PCN Response to comments_20200424

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April 24, 2020
US Army Corps of Engineers
CE-SAW-RG-R
Attn: Lyle Phillips, Regulatory Specialist
3331 Heritage Trade Drive, Suite 105
Wake Forest, North Carolina 27587
RE: Structure 106 Improvements
Project ID: SAW-2020-00138
Dewberry Project No. 50085067

Dear Mr. Phillips:
Dewberry Engineers Inc. (Dewberry) received your email NWP Incomplete Application Notification
dated April 10, 2020. Dewberry has responded to all of the comments as noted below and is submitting
attachments for your records and approval.
Comments & Response:
1) Based on the information provided in the PCN it appears the proposed activities do not comply with
Regional Condition 4.1.3 for NWP 42. Discharges of dredged or fill material into waters of the United
States, including wetlands, within the mapped FEMA 100-year floodplain, resulting in permanent
above-grade fills are not authorized by this NWP. Based on the information provided in the PCN the
proposed project could potentially be permitted under NWP 14. Please update the PCN accordingly.
Response: PCN has been updated to NWP 14.
2) The project proposes to fill wetlands and streams for the construction of a greenway trail. The need
for such is not disputed, however it is unclear if the design has demonstrated avoidance and
minimization to the maximum extent practicable as required by NWP General Conditions 23(a) and
(b). Can you provide some additional information as to why impacts to wetlands and streams could
not be minimized or avoided? For example, it is not clear why the crossings could not be achieved
without impacts through the use of boardwalks. The proposed stream crossing takes place directly
above a confluence; could the greenway trail be constructed below the confluence resulting in one
stream crossing and therefore reducing stream impacts? Please provide additional information to this
effect, including updates to the PCN and Plans as necessary.
Response: The greenway alignment follows an existing City of Raleigh Sanitary Sewer Easement
and is within the City of Raleigh existing Right-of-Way for Ratchford Drive. Several different
alignments were proposed, however due to the 2.2:1 slope on the south side of the tributary,
requiring large retaining walls and large amounts of cut and fill. The chosen route follows the
existing sanitary access easement and along the existing gravel road (which is at 8.78% slope). One
of the crossings is located in this access easement. Because the greenway is located within the
easement, it needs to allow vehicles to drive on the crossing, therefore a causeway cannot be used.
The second crossing is within the sanitary sewer easement, located away from existing manholes
and the 12” gravity sewer pipes. No structures can be constructed on top of the existing sanitary
sewer pipe.
Lyle Phillips
Structure 106 Improvements
SAW-2020-00138
April 24, 2020
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3) In order to verify compliance of Regional Condition 3.6 and General Condition 2, please provide
profile views of each stream crossing shown along the proposed culvert. These profiles should show
the culvert, rip rap pad, slope of the culvert and existing stream bed. Also, please address whether the
rip rap placed in the streambed is to be keyed in/depressed into the stream bed such that the top of
the rip rap is no higher than the stream bed and the profile view should clearly show that. If above-
grade rip rap is proposed on the stream bed due to needed velocity dissipation, clearly describe this
in the PCN and show on the plans.
Response: The culverts are buried 1’ deep and the slope of the culverts follows the slope of the
stream bed. The riprap will be depressed into the stream bed, resulting in no permanent loss of
function.
4) In order to verify that the proposed activity complies with the terms of the Nationwide Permit (NWP)
a conceptual sketch is necessary. Sketches should contain sufficient detail to provide an illustrative
description of the proposed activity (e.g., a conceptual plan), but do not need to be detailed
engineering plans. Please provide a sketch of the impacts at the proposed stream crossings that
depict the proposed activities.
Response: See attached sketch.
5) Based on information provided in the PCN the proposed project will use coffer dams/impervious
dikes during culvert construction with pump arounds to ensure all work occurs in the dry. Will these
activities result in temporary stream impacts upstream and downstream of the proposed permanent
impacts? Please update the PCN and plans accordingly.
Response: There will be a small area of temporary impact due to the coffer dams and pump
around during construction. The amount has been updated.
6) It is unclear the impact type (permanent or temporary) for Wetland Impact Site #2. Typically grading
would result in an introduction of permanent fill. Is this impact for temporary construction and will
be restored to preexisting elevations (temporary impact) or grading for greenway that results in
permanent fill (permanent impacts). Please update the PCN and Plans accordingly.
Response: Hand clearing would be conducted outside the fill areas; therefore this is a temporary
impact.

7) Under Regional Condition 23 wetland losses of 1/10-acre or less and stream losses that require pre-
construction notification, the district engineer may determine on a case-by-case basis that
compensatory mitigation is required to ensure that the activity results in only minimal adverse
environmental effects. Since the proposed activities are part of the larger greenway system resulting
in cumulative impacts please provide a compensatory mitigation plan for the proposed project.
Mitigation for wetland and stream impacts that result in permanent loss is typically required at a two
to one mitigation to impact ratio, unless otherwise justified based on reduced aquatic function
(NCWAM or NCSAM evaluation).
Response: The proposed project involves the repair of an existing facility damaged in 2018 as a
result of Hurricane Matthew. The repair project results in no more than a minimal impact, will not
influence nearby land uses and no additional greenways are currently proposed in the vicinity. A
NCWAM and NCSAM evaluation was conducted on wetland WA and streams SA and SB and all
resources received a rating of low due to previous impacts on the resources. Due to the diminished
aquatic quality, no mitigation is proposed to the streams or wetlands. A copy of these forms will be
provided to the USACE. The NCWAM and NCSAM assessments demonstrate that these resources
have been previously impacted from the existing sewer easement and currently provide a reduced
aquatic function. Due to the reduced aquatic function these resources provide and when taken in
conjunction with the size of these resources, the applicant believes that compensatory mitigation is
not warranted.
Lyle Phillips
Structure 106 Improvements
SAW-2020-00138
April 24, 2020
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Should you have any questions or concerns, please feel free to contact me via phone [phone] or
e-mail ([e-mail]).
Sincerely,
Dewberry Engineers Inc.

Pamela A. Kistner, PE
Senior Project Manager
C: Stephanie Goss, Division of Water Resources
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