NC0004979_SOC WQ S17-009_20200423

c.(' DUKE James Wells
Vice President
ENERGY® Environmental,Health and Safety
Programs&Environmental Sciences
526 South Church Street
Charlotte,NC 28202
[phone]
April 23, 2020
Via Overnight Mail RECEIVED
MAY 01 2020
Corey Basinger
Mooresville Regional Office Regional Supervisor NCDEQ/DWR/NPDES
North Carolina Department of Environmental Quality
Division of Water Resources
Water Resources -Water Quality Regional Operations
610 East Center Avenue, Suite 301
Mooresville, NC 28115
Bob Sledge
North Carolina Department of Environmental Quality
Water Quality Permitting Program
Division of Water Resources
1617 Mail Service Center
Raleigh, NC 27699-1617
Subject: Report Under Special Order by Consent - EMC SOC WQ S 17-009
Duke Energy Carolina, LLC-Allen Steam Station
NPDES Permit NC0004979
Quarterly Progress Report for 1st Quarter 2020
Dear Messrs. Basinger and Sledge:
On behalf of Duke Energy Carolinas, LLC (DEC), I am submitting to you the Allen Steam Station
Progress Report summarizing the work and activities undertaken with respect to closure of coal
ash surface impoundments as required by the Allen Steam Station NPDES Permit NC0004979
Special Order by Consent (SOC), SOC No. S 17-009 Section 2.c.2).
As required by the SOC, 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 fine and imprisonment for knowing violations.

Messrs. Basinger and Sledge
April 23, 2020
Page 2
Please direct any questions concerning the Allen Steam Station NPDES Permit NC0004979 SOC
No. S 17-009 to Robert Wylie at [phone].
Sincerely,
gWitAi
ame Vice resident, Environment, Health & Safety-
Programs and Environmental Sciences
Duke Energy
CC: Richard Baker, Duke Energy
Robert Wylie, Duke Energy
Elizabeth Glenn, Duke Energy
Randy Gantt, Duke Energy
George Hamrick, Duke Energy
Paul Draovitch, Duke Energy
Matt Hanchey, Duke Energy
Randy Hart, Duke Energy

•
NPDES PERMIT NC0004979
SPECIAL ORDER BY CONSENT EMC SOC S17-009
QUARTERLY PROGRESS REPORT
ALLEN STEAM STATION
APRIL 23, 2020

Background and Summary
On April 18, 2018, Duke Energy Carolinas, LLC (DEC) and the North Carolina Environmental Management
Commission entered into a Special Order by Consent-EMC SOC S17-009 (SOC) applicable to the Allen Steam
Station (Allen). This report is submitted in accordance with Section 2.c.2) of the SOC. In compliance with
Section 2.c.2),this report summarizes the work and activities undertaken with respect to decanting work and
closure of coal ash surface impoundments at Allen.The quarterly reports are due no later than the last day of
January, April,July,and October for the duration of the SOC,once the decanting process has begun.
Allen Steam Station is located in Belmont, NC,along the west shore of Lake Wylie. Lake Wylie is a man-made
reservoir created by the impoundment of the Catawba River. Allen is a five-unit, 1140 megawatts, coal-fired
generating facility. The Allen Station began commercial operation in 1957 with Units 1 and 2. Unit 3 began
operation in 1959, Unit 4 in 1960, and Unit 5 in 1961.
Allen historically wet sluiced coal combustion residual(CCR) products into two surface impoundments located
on the property. These surface impoundments are known as the Retired Ash Basin (also referred to as the
Inactive Ash Basin)and the Active Ash Basin, which are impounded by the following dams:
• Retired Ash Basin (GASTO-016)
• Active Ash Basin(GASTO-061)
The ash basins at Allen cover approximately 293 acres with a current ash inventory of approximately 19.4
million tons of ash, as of January 2020, which is inclusive of the Active Ash Basin, Retired Ash Basin, Retired
Ash Basin Landfill,and the Distribution of Residual Solids facilities.
The Retired Ash Basin received CCR products from initial operation in 1957 until 1973,when it reached capacity
and was retired. Allen then commissioned the Active Ash Basin and began wet sluicing CCR products into this
new basin. In 2009,Allen replaced its fly ash wet sluicing operation with a dry ash handling system and began
placing dry fly ash into a landfill constructed over a portion of the Retired Ash Basin (Permit No.36-12). Allen
ceased wet sluicing of bottom ash in February 2019 when the dry bottom ash system became operational. The
Active Ash Basin was removed from service in February 2019 upon the completion of dry bottom ash handling
and diversion of all other wastewater flow to a newly lined retention basin.
Decanting Status
In compliance with this SOC, Duke Energy initiated design and procurement efforts inQ3 2018 for a decanting
water treatment system at Allen. Wastewater flows were removed from the basin on February 9,2019. Duke
Energy provided advanced notice for the projected start date of decanting to NCDEQ on January 24, 2019, as
required by the NPDES Permit,and written notification for the Initiation of Decanting,per the SOC,on February
14, 2019. Pumping in order to decant the Active Ash Basin began on June 5, 2019. Decanting continued
through March 31, 2020, bringing water elevation to approximately 619.9 feet. Decanting is scheduled to
complete in advance of the June 30, 2020 SOC deadline.
Allen:2