WQ0040985_Other Correspondence_20210408

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2G02Iron Gate Drive, Suit¢ 102 ]429 Ash-Liffie Riv¢c Road
Wilrnixig[on, NC 28412 Ash, NC 28420
(910) 343-9G53 (910) 28']-5900
(910) 343-9G04 Fax [phone] Fez
John S. Tur.atall, P.E_ J. Phillip Norris, P.H.
T. Jason Cluk, P.E. Joseph K Bland, P.E.
Thomas J. Schnitz, E.I.
April 8, 2021
Ms. Christyn L. Fertenbaug h, P.E., Environmental Engineer
NC DEQ
Division of Water Resources /Municipal Permitting Unit
1617 Mail Service Center
Raleigh, NC 27699-1617
Re: Response for Variance /Alternative Design Request Application (VADC 1D-14)
Trinity Landing
New Hanover County
N8.T Project No. 19040
Dear Ms_ Fertenbaugh:
Pursuant to your a -mail comments of April 7, 2021, please find below the original April 1. 2021
submittal letter with our responses below in red (Items #2, #3, and #5). No additional documents
or plans are needed or included in this response.
Enclosed electronically for your review and approval is one (1) original VADC 10-14 application,
one (1) set of plans, and one (1) set of specifications.
We have had multiple communications about this situation and proposed solution
Contractors are installing a 6" force main at the intersection of Burning Tree Road and Coronado
Drive in Wilmington, NC. We have an area where the force main crosses above an existing
waterline. Existing waterline depth is approximately 5-6 feet below existing grade. The plans
called for 20 feet of the existing waterline to be replaced with DIP and to install 20 feet of DIP
force main above centered at the crossing. However, when the contractor uncovered the
waterline they found ajoint /bend at the point where the crossing occurs. We believe we will
have the required 18" of separation. Note, the Cape Fear Public Utility Authority (CFPUA) does
not want us to go under the waterline to avoid maintenance on a 6" force main that would be 7-
8 feat deep. However, we cannot get centered on one full length of water pipe due to the location
of the joint /bend. We also have an existing storm drain adjacent to this crossing and are trying
to avoid impacting the whole intersection. Plus, neither NC DOT nor CFPUA want the force
main crossing through the intersection. We era trying to stay within the existing 10' PUE_
We have decided to leave the water main as it is undisturbed and cross with a full 20-foot section
of 6" DIP force main centered on the water main crossing. This determination was made after
many discussions with the State and CFPUA.
NCBELB Licenae C-3G41

Ms. Chnsryn Fartenbaugh, P.E. / NC DEQ Municipal Permitting Unit
APril 8, 202t
Pages 2
To address 'ISA NCAC '18C .0906 (f):
'1. Rationale for not being able to meet rule.
Answer: We believe we may have '18" of separation, however we will be over a
waterline joint /bend. Due to the bend created at joint, we do not want to
reach back into the street to cross. In addition, we have an existing storm
drain to cross in the vicinity. The other option is to add more bends and
length to the force main which we always like to avoid.
2. Ex[ent of Deviation.
Answer: We believe we will have very close to '18" of separation; however, we will
be over a waterline joint. Deviation would include making the force main
DIP. A 20-foot section of DIP force main will be centered over the crossing
of the undisturbed existing waterline.
3. Consideration of Pipe materials.
Answer: Propose to leave waterline as undisturbed PVC with joint in place and
change the pipe type of the force main to DIP.
4. Ability to provide adequate work space.
Answer: The proposed path and deviation is still within the ROW and '10' PUE
allowing for work space.
5. Rationale for determining [hat the deviation will not result in unreasonable risk to public
health.
Answer: The use of DIP force main centered over the waterline crossing minimizes
the risk.
All applicable /relevant plan sheets are attached. We are requesting your approval of this
solution as we have discussed. It is our understanding that you can review and provide approval
as of April '1'r, 202'I .
Please advise if any additional information is required. Thank you for your assistance on this
project.
Sincerely,
NORRIS S TUNSTALL
CONSULTING ENGINEERS, P_C.
T. Jaso Clark, P.E.
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