NC0004979_Report_20191024

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DUKE OCT 2 9 2019 James Wells
`Vice President
ENERGY, WQI=iOS Environmental, Health and Safety
Programs & Environmental Sciences
MOORESVILLE REGIONAL OFFICE 526 South Church Street
Charlotte, NC 28202
[phone]
October 24, 2019
Via Overnight Mail
Corey Basinger
Mooresville Regional Office Regional Supervisor
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 3rd Quarter 2019
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
October 24, 2019
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,
Jamet Wells
Vice president, 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
OCTOBER 24, 2019

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 517-009 (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. The ash basins at Allen cover approximately 293 acres
with a current ash inventory of approximately 19.3 million tons of ash as of July 2019, which is inclusive of
the Active Ash Basin, Retired Ash Basin, Retired Ash Basin Landfill, and the Distribution of Residual Solids
facilities.
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 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 in Q3 2018 for a decanting
water treatment system at Allen. Purchase Orders were awarded in January 2019 for the WWTS pad and
electrical infrastructure installations, as well as a Purchase Order for the OEM water treatment
supplier. 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. Through September 30, 2019, approximately 12.4 feet have been decanted from an initial depth of 21
feet.
Allen: 1