Re_ _External_ Re_ Forbes Road Extension Gaston Co questions

Wanucha, Dave
From: Megan Bollero <[e-mail]>
Sent: Thursday, April 20, 2023 4:00 PM
To: Wanucha, Dave
Cc: Stygar, KRYSTYNKA B CIV USARMY CESAW (USA); Aliisa Harjuniemi
Subject: Re: [External] Re: Forbes Road Extension Gaston Co questions
Attachments: Derry Phase 1_C-423 Forbes Road Stream Crossing.pdf
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Hi Dave,
The engineers' responses are below in red, and I have also attached the PDF they reference for the profile section of the
arched pipes. Please let me know if you need anything else.
I mostly work with projects that are designed to NCDOT specifications of which typically (not
always) include riprap on both sides of the stream at the inlet and along the slopes leading to
the stream. If there are headwalls at the inlet, rip rap may not be necessary, but there would
likely be some stream impacts associated with headwall installations. So, what you are saying
is that the designers do not anticipate impacts to the stream at the inlet, other than temporary
impacts due to dewatering? No additional impacts to the stream are anticipated with the
installation of the headwall. Temporary impacts from dewatering are typical. And no
additional stream or bank stabilization at or adjacent to the inlet is necessary? No additional
impacts are anticipated. Contractor will simply cut the slope at headwall and work from
behind the proposed headwall location. We are trying to ensure that when the project is
completed, it will be stable in the future with no impacts to water quality.
I need some clarification on the proposed arched pipes 1 and 2. The design proposes a CMP
culvert 90' x 60" to carry the stream under the road. What are the arched pipes to be used
for? The two (2) pipe arches are proposed to carry the larger storm events and eliminate any
rise to the base flood elevation offsite. Please provide a picture or two that provide examples
of how the final installed proposed crossing should look. See profile section in the top left of
the attached PDF for a section depicting how this will look. Timmons Group does not have
examples of final installed products of a similar nature that could be referenced at this time.
1

Please provide the storm frequency the culvert is hydraulically designed to carry, including the
method used to estimate peak discharge. Culverts have been designed to carry the 100-year
event. A flood study was performed using HEC-RAS 6.3.1 steady state modeling. Flood study
documents can be provided upon request.
On Wed, Apr 19, 2023 at 10:33 AM Wanucha, Dave <[e-mail]> wrote:
Hi Megan,
Yes, that is what we were asking —have the designers forgotten to include impacts associated
with the inlet? I mostly work with projects that are designed to NCDOT specifications of
which typically (not always) include riprap on both sides of the stream at the inlet and along
the slopes leading to the stream. If there are headwalls at the inlet, rip rap may not be
necessary, but there would likely be some stream impacts associated with headwall
installations. So, what you are saying is that the designers do not anticipate impacts to the
stream at the inlet, other than temporary impacts due to dewatering? And no additional
stream or bank stabilization at or adjacent to the inlet is necessary? We are trying to ensure
that when the project is completed, it will be stable in the future with no impacts to water
quality.
I need some clarification on the proposed arched pipes 1 and 2. The design proposes a CMP
culvert 90' x 60" to carry the stream under the road. What are the arched pipes to be used
for? Please provide a picture or two that provide examples of how the final installed
proposed crossing should look.
Please provide the storm frequency the culvert is hydraulically designed to carry, including
the method used to estimate peak discharge.
Thanks, and let me know if you have any questions.
Dave W.
4

Dave Wanucha
Environmental Specialist 11
Transportation Permitting Branch for NCDOT Divisions 9 and 11
Division of Water Resources, Department of Environmental Quality
Office/Cell: [phone]
[e-mail]
D7 E
ki;
NORTH CAROLINA
Department of Environmental Cluality
Email correspondence to and from this address is subject to the North
Carolina Public Records Law and may be disclosed to third parties.
From: Megan Bollero <[e-mail]>
Sent: Wednesday, April 19, 2023 9:16 AM
To: Stygar, KRYSTYNKA B CIV USARMY CESAW (USA)<[e-mail]>; Wanucha, Dave
<[e-mail]>
Cc: Aliisa Harjuniemi <[e-mail]>
Subject: [External] Re: Forbes Road Extension Gaston Co questions
CAUTION: External email. Do not click links or open attachments unless verified. Report suspicious emails with the Report Message
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Hi Dave,
Just to clarify, you are asking if there is supposed to be rip rap at the inlet (highlighted area)? I reached out to the
engineer and he said in their designs they don't typically have rip rap at their inlets, and that is the case for this project.
Let me know if you need anything else.

Thanks,
Megan Bollero
On Tue, Apr 18, 2023 at 2:45 PM Stygar, KRYSTYNKA B CIV USARMY CESAW (USA)
<[e-mail]> wrote:
Dave,
Good catch, I agree, where are the additional impacts?
Krysta
From: Wanucha, Dave <[e-mail]>
Sent: Tuesday, April 18, 2023 11:54 AM
To: [e-mail]
Cc: Stygar, KRYSTYNKA B CIV USARMY CESAW (USA) <[e-mail]>
Subject: [Non-DoD Source] Forbes Road Extension Gaston Co questions
Hi Megan,
I'm not seeing rip -rap impacts at the inlet and slope of your culvert design. Will not the inlet
and stream banks be protected by riprap (per yellow highlights below)?

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5
Dave W.
Dave Wanucha
Environmental Specialist 11
Transportation Permitting Branch for NCDOT Divisions 9 and 11
Division of Water Resources, Department of Environmental Quality
Office/Cell: [phone]
[e-mail]
5

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pOtlYrll� ihEr[Ml Oud1RX
Erna# coffespondence to and from this address is subject to the North
Carolina Poblrc Records Law and may he dfsrJased to third parties -
Megan Bollero, PWS
Project Scientist
Carolina Wetland Services Inc.
550 E Westinghouse Boulevard
Charlotte, NC 28273
Cel I:(757)-576-6433
www.cws.net
Megan Bollero, PWS
Project Scientist
Carolina Wetland Services Inc.
550 E Westinghouse Boulevard
Charlotte, NC 28273
Cell:(757)-576-6433
www.rwS. nPt