NCS000546_Minor Revision_20181116

Ail e,
4i) DUKE
/°P�' `` '�J "° '��- `� P e C rk * Allen Steam Station
ENERGY® 0 — 253 Plant Allen Road
Belmont, NC 28012
November 16, 2018
R 12//(1) 5j- (I
North Carolina Dept. of Environmental Quality
Division of Water Resources -Wastewater Complex Permitting Section
Attn: Ms. Julie Grzyb
1612 Mail Service Center
Raleigh, North Carolina 27699-1617
Subject: NPDES Stormwater Permit Minor Revision
Allen Steam Station Permit No. NCS000546
Gaston County
Dear Ms. Grzyb:
Duke Energy respectfully requests the inclusion of previously permitted stormwater outfall
SW015 to the Allen Steam Station industrial stormwater permit NCS000546. The following
narrative provides a timeline of SW015 and a justification for this request.
• On August 31, 2016, an update to the NPDES wastewater permit application was
submitted requesting that NC DEQ Division of Water Resources include the historically
permitted stormwater outfall SW015 and associated drainage area in the NC0004979
wastewater permit. This was requested because, at the time, this flow contained both
industrial stormwater and potentially, a wastewater contribution from ash basin seepage,
if any.
• In a July 2016 letter, Duke Energy requested the removal of SW015 from the Allen
industrial stormwater permit for future inclusion in the wastewater permit. NC DEMLR
approved this request on September 9, 2016.
• Subsequently, the contributing ash basin seepage flow to the SW015 drainage was
reconfigured to more permanently collect, pump, and return flow to the ash basin. The
potential ash basin seepage flow is not included in NPDES wastewater permit
NC0004979 and is currently being returned to the ash basin through a collection and
pumping system
• NPDES Wastewater Permit No. NC0004979 was received July 13, 2018 without the
inclusion of SW015.
• Stormwater outfall SW015 is a 36-inch reinforced concrete pipe (RCP) which discharges
to the Catawba River (Lake Wylie) and drains an approximately 163.6-acre area. The
drainage area runoff is from a large soil borrow area, as well as two ash structural fill
areas, and approximately one mile of gravel and dirt road. The coordinates of SW015
are 35° 10' 52" N by 81° 00' 21"W. The Active Ash Basin Emergency Spillway, WW007,
drains to the SW015 RCP, as demonstrated in the attached drainage area map.

Page 2
Due to the reconfiguration of the contributing wastewater source and the unaltered state of the
original SW015 drainage area, Duke Energy requests to reestablish the previously permitted
outfall SW015 in the subject permit. Copies of the illustration of the new configuration and a
drainage area map is included as attachments with this submittal.
If you have any questions, please contact Ms. Elizabeth Glenn [phone].
I certify, under penalty of law, that this document and all attachments were prepared under my
direction or supervision in accordance with a system designed to assure that qualified personnel
properly gather and evaluate the information submitted. Based on my inquiry of the person or
persons who manage the system, or those persons directly responsible for gathering the
information, the information submitted is, to the best of my knowledge and belief, true, accurate,
and complete. I am aware that there are significant penalties for submitting false information,
including the possibility of fines and imprisonment for knowing violations.
Sincerely,
L) , 4-
Terry W. Tuck
General Manager II
Allen Steam Station
Fossil/Hydro Operations - Carolinas Coal Generation
Cc: Mooresville Regional Office, DWR Wastewater Program
Sergei Chernikov - NCDEQ
Elizabeth Glenn
Randy Gantt
Tina Woodward

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_ DRAWN BY: CML DUKE ENERGY CAROLINAS, LLC
ALLEN STEAM STATION
DESIGNED BY: MECHANICAL
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STORMWATER POLLUTION
CHECKED BY: ELECTRICAL PREVENTION PLAN
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APPROVED BY: DATE:
HDR Engineering,Inc.of the Carolinas License Number:F-Out — SCAM arr..e/stt.no. CO
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DRAWN BY: CML DAULKELEENNERSOTYEACARMOsLITNASATioLLNC
A IUMYZ - DESIGNED BY: MECHANICAL
CHECKED BY: ELECTRICAL STORMWATER POLLUTION
PREVENTION PLAN
SITE PLAN
APPROVED BY: DATE:
,
NOR Engineering:Inc.of the Carolinas License Number:F.01113
SCALL INU.NLANEIT NO.
•
SHEET 2
440 S Chinch Strout Suite 1000 Charlotte,NC 213202.2075
PE SOL NO CATE itEvismoi ORB OWN CIWO•PPR AL MC MECO PROJECT NUMBEFt 0000:0101234104
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