20210224 Ver 1_NCDWR Response letter_Westpoint_12-16-21_20211216

Environmental Consultants,
8412 Falls of Meuse Road, SulLe 104, Raleigh, NC 27615 • Phone: [phone]
s andec.com
December 16, 2021
S&EC Project #13706.W13
NC DWR, 401 & Buffer Permitting Unit
Attn: Paul Wojoski
1617 Mail Service Center
Raleigh, NC 27699-1617
Re: Request for Additional Information
Westpoint
AID#SAW-2006-40196; DWR #20210224
Durham, Durham County, NC
Dear Mr. Wojoski:
The purpose of this letter is to respond to a Request for More Information letter dated November
16, 2021 from the NC Division of Water Resources (NCDWR). The original questions/requests
from the November 16, 2021 letter are below and are followed by responses.
Additional Information Requested:
Your application states that "cofferdams and a pump around will be used" during of the
construction of the road crossing in Impact A. (See Section E: Impact Justification and
Mitigation, 1b) However, no temporary stream impacts are requested in Section D of the
application. Please provide more details or an exhibit on the cofferdams and a pump around
design and clarify if there are temporary impacts associated with it. [15A NCAC 02H
.0502(c)]
The culvert design has been refined to include the headwalls and the associated
grading. Per the project engineer, the initial impact maps and submittal included a
conservative culvert layout that had headwalls located at the toe of the fill slope. This
was a conservative overestimate of impacts since the culvert would not be installed
to the toe of the slope. When the headwalls were fully designed and graded in, the
cofferdam would fit within the previous approved disturbed area. Please note that the
updated impact exhibits now include temporary stream impacts identified and
quantified, the coffer dam shown, and permanent -no permanent loss stream impacts
identified and quantified for the riprap dissipator Please see updated electronic Pre -
Construction Notification (ePCN) application, updated Grading Plan and updated
Impact Area A.
Please note that the wetland impacts have increased at Impact Al. This increase is
due to the raised street grades. Per the project engineer, with the higher street the fill
slopes extend further into the wetlands. The street was raised to force the runoff
from the street into the proposed constructed stormwater wetland on the west side of
the stream. This change should result in increased peak flow control as well as
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additional nutrient reduction. Additional wetland mitigation has been proposed for
this change, please see updated ePCN application, updated Grading Plan, updated
Impact Area A and updated Statement of Availability (SOA) letter.
2. Your application states that "Impact A2 — Buffer Mitigation for Zone 1 only may be required."
(Section D: Proposed Impact Inventory, 6i). Please clarify how this impact is categorized in
the Table of Uses in 15A NCAC 02B .0714(11). Further please clarify the boundaries of
Impact A2 on the impact maps and provide the width of the permanent maintenance
corridor. [15A NCAC 02H .0502(c) and 15A NCAC 02B .0611(b)(2)].
The site plan has been modified to avoid this impact. Please see updated ePCN
application and updated Impact Area A.
3. On the impact map for Impact A, the proposed new sewer line turns north to connect with
the existing sewer line to the north of the proposed road crossing. Please provide more
details as to why the tie in was designed this way. It appears additional avoidance and
minimization of wetland impacts can be achieved by continuing the new sewer line straight
to tie into the existing sewer line. [15A NCAC 02H .0502(c)]
The sanitary sewer layout has been revised to now tie into the street rather than in the
wetland on the north side of the street. As a result, the wetland impacts have been
decreased. Please see updated ePCN application and updated Impact Area A.
4. On the impact map for Impact B, there is a label for "New Waterline" but no corresponding
water line on the map. Please clarify the label and if a "New Waterline" is being proposed
and if it has any buffer or stream impacts. [15A NCAC 02H .0502(c)]
The proposed water line extension has been included in the updated impact exhibit.
There are no proposed stream, wetland, or buffer impacts associated with this utility
line. Please see updated Impact Area B.
5. On the Overall Site Plan, Sheet Number CD-2.0, there appears to be an outlet for a
proposed stormwater wetland that goes through the buffer for Stream E on the west side of
the project and another outlet for a proposed stormwater wetland that goes through the
buffer for Stream A on the northeast side of the property. Please provide additional details
on these outfalls and how they meet dispersed flow as defined in 15A NCAC 02H .1002.
Further please clarify why these discharge points are proposed to be armored through the
buffer all the way to the stream banks. [15A NCAC 02B .0714(9)]
Per 15A NCAC 02B .0714(9)(a)(i), these impacts are "deemed allowable" activities.
Per the project engineer, these discharges are lined with riprap to prevent erosion
and slow velocities. Please see updated Grading plan with notes.
6. Please provide a copy of the Stormwater Management Plan for this project. [15A NCAC 02H
.0506(b)(1)]
Please see attached Stormwater Impact Analysis.
7. Public Hearing — The Director has determined that it is in the public's interest to hold a
public hearing to received comment and additional information on the proposed project. This
hearing must be held prior to taking final action on your application. The Division is in the
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process of scheduling the public hearing and will forward the details by separate letter. [15A
NCAC 02H .0503(f).
We anticipate that this will provide answers to the NCDWR's questions/concerns. If additional
information is needed, please do not hesitate to email me at cbrunick(a)sandec.com.
Sincerely,
Camden Brunick Digitally signed by Camden Brunick
Date: 2021.12.16 12:15:06-05'00'
Camden Brunick
Environmental Specialist
CC:
Jon Holtvedt-Terramor Homes (email)
April Norton-USACE (email)
Attachments:
1) Updated ePCN
2) Updated Overall Site Plan CD-2.0
3) Updated Grading Plan CD-3.1
4) Updated Impact Area A
5) Updated Impact Area B
6) Updated Culvert Crossing Profile
7) Updated Statement of Availability (SOA) letter
8) Stormwater Impact Analysis for Westpoint
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