NC0004987_Modification_20210519

PERMIT No. NC0004987
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENTAL QUALITY
DIVISION OF WATER RESOURCES
PERMIT
TO DISCHARGE WASTEWATER UNDER THE
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM
In compliance with the provisions of North Carolina General Statute 143-215.1, other
lawful standards and regulations promulgated and adopted by the North Carolina
Environmental Management Commission, and the Federal Water Pollution Control Act,
as amended,
Duke Energy Carolinas, LLC
is hereby authorized to discharge wastewater from a facility located at
Marshall Steam Station
At the intersection of NC Highway 150 and NCSR 1841
Terrell
Catawba County
to receiving waters designated as the Catawba River (Lake Norman) in the Catawba River
Basin in accordance with effluent limitations, monitoring requirements, and other
applicable conditions set forth in Parts I, II, and III hereof.
This modification shall become effective June 1, 2021.
This permit modification and authorization to discharge shall expire at midnight on
September 30, 2021.
Signed this day May 18, 2021.
for
DocuSigned by:
Potytwf
FB19B61SDD2178...
D. Daniel Smith, Director
Division of Water Resources
By Authority of the Environmental Management Commission
Page 1 of 3

PERMIT No. NC0004987
SUPPLEMENT TO PERMIT COVER SHEET
All previous NPDES Permits issued to this facility, whether for operation or discharge are
hereby revoked, and as of this issuance, any previously issued permit bearing this number
is no longer effective. Therefore, the exclusive authority to operate and discharge from this
facility arises under the permit conditions, requirements, terms, and provisions included
herein.
Duke Energy Carolinas, LLC is hereby authorized to:
1. Continue to discharge:
• Outfall 001: once -through cooling water and intake screen backwash
• Outfall 002: treated wastewater (consisting of metal cleaning wastes, coal pile
runoff, ash transport water, storm water, low volume wastes, landfill
leachate, extracted groundwater from remediation activities, and FGD wet
scrubber wastewater) from the ash settling basin.
• Outfall 005. Upon completion of construction, discharge from the new lined
retention basin. Basin will accept wastes from holding basin (coal pile runoff),
ash transport water, various sumps, stormwater runoff, FGD wastewater,
bottom ash purge from the submerged flight conveyers (purge volume not to
exceed 10% of the water systems volume), and various low volume wastes
such as boiler blowdown, oily waste treatment, wastes/backwash from the
water treatment processes, plant area wash down water, equipment heat
exchanger water, landfill leachate, and ash transport water. Upon completion
of construction all waste streams previously discharged to the ash basin, will
be re-routed to the new retention basin. During the transition period,
wastewater from the ash pond can also be discharged (Outfall 002).
• Outfalls 002A and 002B: yard sump overflows.
• Outfall 007: the emergency spillway of the Ash Pond. The spillway is designed
for a flood greater than 100-year event. Sampling of this spillway is waived
due to unsafe conditions associated with sampling during an overflow event.
• Internal outfall 001 /001A. Yard sump (wastewater from the yard sump 2, the
yard sump 3, the fly ash silo yard sump, and stormwater) discharging to the
retention basin.
• Internal Outfall 003: non -contact cooling water from the induced draft fan
control house to the intake for cooling water pumps.
• Internal Outfall 006: treated FGD wet scrubber wastewater to the new lined
retention basin.
• Internal Outfall 010 from Holding Basin: coal pile runoff, and stormwater to
the retention basin.
From a facility located at Duke Energy's Marshall Steam Station at the
intersection of NC Highway 150 and NCSR 1841 in Terrell, Catawba County;
Page 2 of 3

PERMIT No. NC0004987
2. Discharge from said treatment works at the locations specified on the
attached map into the Catawba River (Lake Norman) which is classified WS-
IV and B CA waters in the Catawba River Basin.
Page 3 of 3