NC0004987_Fact Sheet_20210519

DEQ/DWR
FACT SHEET FOR NPDES PERMIT DEVELOPMENT/Major Modification
NPDES No. NC0004987
Facility Information
Applicant/Facility Name:
Duke Energy — Marshall Steam Station
Applicant Address:
Water Management, Duke Energy, P.O. Box 1006, Charlotte, NC
28201
Facility Address:
8320 E. NC Highway 150, Terrell, NC 28682
Permitted Flow
Not Limited
Type of Waste:
100.0% Industrial
Facility/Permit Status:
Major Modification
County:
Catawba
Miscellaneous
Receiving Stream:
Lake Norman
Regional Office:
Mooresville
Stream Classification:
WS-IV & B CA
USGS Topo
Quad:
Lake Norman North
303(d) Listed?:
No
Permit Writer:
Sergei Chernikov, Ph.D.
Subbasin:
03-08-32
Date:
June 8, 2020
Drainage Area (mi2):
NA
Addillir
Summer 7Q10 (cfs)
Release (60 cfs)
Winter 7Q10 (cfs):
NA
1Q10 (cfs):
IWC (%):
23
SUMMARY
This permit is being modified to make the following changes:
1). Add the bottom ash purge to the list of the contributing sources of wastewater to the Lined Retention
Basin. Per updated 40 CFR 423.13 (k) (2) (i) (A), the discharge of pollutants in bottom ash transport water
from a properly installed, operated, and maintained bottom ash system is authorized to maintain system
water chemistry where installed equipment at the facility is unable to manage pH, corrosive substances,
substances or conditions causing scaling, or fine particulates to below levels which impact system
operation or maintenance.
2). To adjust the Technology Based Effluent Limits for Total Arsenic, Total Mercury, Total Selenium,
and Nitrate/nitrite as N for Internal Outfall 006 (FGD wastewater) in accordance with updated 40 CFR
423.13(g)(1)(i). Please see the table below for details.
Both changes are based on the October 13, 2020 update to the 40 CFR 423 (BAT).
Pollutant
Existing monthly average - daily
maximum limit
Modified monthly average - daily
maximum limit
Arsenic
8.0 µg/L — 11.0 µg/L
8.0 µg/L — 18.0 µg/L
Selenium
12.0 µg/L — 23.0 µg/L
29.0 µg/L — 70.0 µg/L
Mercury
356.0 µg/L — 788.0 µg/L
34.0 µg/L — 103.0 µg/L
Nitrate/Nitrite
4.4 mg/L — 17.0 mg/L
3.0 mg/L — 4.0 mg/L
3). The pH limit for FGD wastewater was eliminated (Internal Outfall 006) to correct an error.
NPDES Permit NC 0004987
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All the remaining terms and conditions of the permit remain unchanged.
PROPOSED SCHEDULE
Draft Permit to Public Notice:
Permit Scheduled to Issue:
February 9, 2021 (est.)
April 2, 2021 (est.)
STATE CONTACT
If you have any questions on any of the above information or on the attached permit, please contact
Sergei Chernikov at [phone] or [e-mail].
CHANGES IN THE FINAL MODIFICATION
The optimization requirement and the reopener clause were added for the FGD Effluent Page in
response to the SELC comments.
NPDES Permit NC 0004987
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