20190889 Ver 2_Diffuse Flow Approval_20191209

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ROY COOPER
Governor
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MICHAEL S.REGAN
Secretary
LINDA CULPEPPER NORTH CAROLINA
Director Environmental Quality
December 9, 2019
DWR#2019-0889 v2
Guilford County
Mr. Butch Shumate, Facilities Manager
City of Greensboro
Post Office Box 3136
Greensboro,North Carolina 27402
Subject: APPROVAL OF STORMWATER DIFFUSE FLOW PLAN
Greensboro Science Center(GSC)Zoo Expansion
Dear Mr. Shumate:
The Division of Water Resources (Division) recently reviewed the proposed stormwater diffuse
flow plan for the subject project as required by Individual 401 Water Quality Certification issued
by the Division on September 12, 2019. Submittal of this plan satisfies the stormwater condition
no. 3 of the 401 certification and is subject to the requirements below.
The Division approves the stormwater diffuse flow plan for the GSC Zoo Expansion consisting of
a level spreader-vegetated filter strip including all associated stormwater conveyances, inlet and
outlet structures,and grading and drainage patterns depicted on plan sheets dated August 22,2619,
which are incorporated by reference and are enforceable by the Division. Additional drainage that
are not shown on the plans may not be added in the future without appropriate stormwater
management or diffuse flow device(s) and approval from the Division. The following conditions
also apply [15A NCAC 02H .0506(b)(5)]:
a) The overall built-upon area (BUA) for the project shall be maintained at or below those
identified in the approved drawings. Any increases in BUA shall require the applicant to
submit and receive approval from the Division prior to any construction or modification of j
the current site.
b) All drainage discharge outfalls into a stream shall do so at a non-erosive velocity for the 10-
year storm(peak flow).
c) The approved diffuse flow plan shall be constructed and operational before any new
permanent building or other structure is occupied at the site.
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North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 1 1617 Mail Service Center I Raleigh.North Carolina 2 769 9-1617
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DWR#2019-0889 v2
d) The diffuse flow plan may not be modified without prior written authorization from the
Division.
e) Maintenance activities for diffuse flow device(s) shall be performed in accordance with the
notarized O&M agreements signed by Mr. Butch Shumate of the City of Greensboro on
October 31, 2019. The O&M agreement shall transfer with the sale of the land or transfer of
ownership/responsibility for the approved SMP. The Division shall be notified promptly of
every transfer.
f) The applicant and/or authorized agent shall provide a completed Certificate of Completion
form to the Division within thirty(30)days of project completion or as soon as possible if the
project has already been completed. This form is made available online at
https://edocs.deq.nc.gov/Forms/Certificate-of-Completion.
Please contact Chonticha McDaniel at [phone] or [e-mail] if you
have any questions or concerns regarding this matter.
Sincerely,
6c Haupt, Acting Supervisor
401 & Buffer Permitting Branch
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cc: Michael Westcott, PE—Westcott, Small &Associates(via email)
Tori Small, PE—Westcott, Small &Associates (via email)
DWR, Winston-Salem Regional Office
DWR 401 & Buffer Permitting Branch File
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