NCS000572_Renewal Update_20200827

ifs, DUKE Dan River Combined Cycle
ENERGY
Duke Energy Carolinas
864 South Edgewood Road
Eden, NC 27288
August 19, 2020 RECEIVED
Annette Lucas AUG 2.71010
NCDEMLR Stormwater Program
1612 Mail Service Center DENR-LAND QUALITY
Raleigh, NC 27699-1612 STORMWATER PERMITTING
Subject: Duke Energy Carolinas, LLC
Dan River Combined Cycle Station
NPDES Stormwater Permit NCS000572
Permit Renewal Application - Update
Dear Ms. Lucas:
Duke Energy Carolinas,LLC(Duke Energy)hereby requests updates to the subject NPDES permit
renewal application submitted 11/12/2019 to make the following changes:
1. Decommissioning of the retired Dan River Steam Station, combustion turbines, and
remaining facilities was completed in 2017. Outfalls SW003,SW003A,SW003B,SW004,
SW005, SW006, and SWO11 were removed during the final grading of this area. These
outfalls were removed by letter dated 1/29/2017 from permit and monitoring requirements
by Winston Salem Regional Office. Duke Energy requests that these outfalls be removed
from the permit.
2. Based on a site visit on July 11, 2017 from the Winston Salem Regional Office, it was
determined that outfalls SW007,SW007A,and SW008 were not associated with industrial
activity and were removed by Winston Salem Regional office in letter dated 7/14/2017.
Duke Energy requests that these outfalls be removed from the permit.
3. With final grading of the site for ash basin closure the drainage area for SW009 will
decrease to 12.6 acres as outlined in Minor Modification Request dated 7/30/2020. This
drainage area includes stormwater from the combined cycle maintenance fabrication shop,
which is an enclosed building with concrete floors. The industrial activity within this area
consists of minimal material laydown. Duke Energy requests that this outfall be removed
from the permit due to lack of industrial activity.
4. Analytical monitoring requirements for stormwater outfall SW001 includes monitoring for
total nitrogen. The domestic wastewater treatment system was located within SW001
drainage area when the original stormwater permit application was submitted. This system
was removed and replaced with a non-discharge septic system in 2017. Duke Energy

requests that the requirement for analytical monitoring for total nitrogen at outfall SW001
be removed from the permit.
5. An updated analytical results spreadsheet is included in Attachment 1 — Summary of
Laboratory Analysis.
6. An updated drainage area map is attached that identifies the new drainage areas and outfall
locations post final grading—Figure 1 —Stormwater Drainage Map—Final Site Grading.
Should you have any questions or need additional information please feel free to contact Joyce
Dishmon at 336-623-0238 or [e-mail].
Sincerely,
Terry Tuck
GM II- Regulated Stations
Dan River Combined Cycle
Power Generating Carolinas East
Attachments
Stormwater Drainage Map—Final Site Grading.
Cc: Dana Newcomb, EHS Manager
Billy Milam, EHS Site Professional
Joyce Dishmon/filenet, EHS Permitting &Compliance

LEGEND j ,' R. I° t
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USGS NATIONAL
HYDROGRAPHY DATASET
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Cooralnates Mondoi nq Dra,nage Area Runolt Description
4 t ^ Outlalk 36 4888402N Water Boat Area Arca TableThatl 9 -nclWes ruwR hom the OanRver Conb rcd Cyck
J Y S W001 79.723289 W dB rid RCP to Se nq nd 18 B acres 80% 1 r va6 tle
tlf Pe Faa�l ry,tlre Jha 1IJ pa Non of Re coolirgt
svn Fta d, M pond t Etlgewootl Roaa
� t SW002fq $NPDES OUTFALL 00 ]96]17419]W
CONMBINED CYCLE R. sWoo9 36.487703N
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mkdkiweneYseeea rl tlaonentlb N gSaw Oa OacyrgM1e'IaakaW,ernnabc hukWieNrao'nss gevsrc,wtl,zRero hcroM1amglk e[r b5eP rDrckDsN.aarMnrtln t 2thelhe3 r o1al0sts0boe0 c-wg aakolbfdnn
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36.492143N 36�ncM1 RCP VNer Sae Accezz Road rto
�$ SW010 a wetland prior to discharge to nprep ]2A acres am 8 The anircge area 66.06 6,606 home kM dRA.
�►bing tl 9]i999]W harvelbDanR•r
� +'DUKE DAN RIVER COMBINED CYCLE STATION
ENERGY, STORMWATER DRAINAGE MAP-FINAL SITE GRADING
FIGURE 1

SUMMARY OF LABORATORY ANALYSES
INDUSTRIAL STORMWATER
APRIL 2016-March 2020
NPDES Stormwater Permit NCS000572
Dan River Combined Cycle Station
SW Outfall SW001
SW009
Sampling Date 27-Apr-16 7-Oct-16 2-Jan-17 14-Jul-17 23-Apr-18 11-Oct-18 25-Mar-19 14-Aug-19 23-Mar-20 7-Oct-16 2-Jan-17 14-Jul-17 23-Apr-18 11-Oct-18 25-Mar-19 14-Aug-19 23-Mar-20
Total Rainfall(inches) 0.2 0.4 0.9 0.46 0.28 5.7 0.2 0.3 0.3 0.4 0.9 0.46 0.28 5.7 0.2 0.3 0.3
pH(6-9) 7.31 7.18 7.47 7.03 7.42 7.1 7.5 8.1 7.3 7.31 7.53 7.32 7.59 7.65 7.6 7.2 7,02
TSS(100 mg/L) 6 <5 5.6 <5 <5 11 <5 32 6 25 150 57 17 6.8 <5 40 <2.6
Ag(0.0003 mg/L) N/A N/A N/A N/A N/A N/A N/A N/A N/A <0.0003 <0.0003 <0.0003 <0.0003 <0.0002 <0.0002 <0.0002 <0.0002
As(0.34 mg/L) N/A N/A N/A N/A N/A N/A N/A N/A N/A <0.001 0.00370 0.00122 0.00138 0.00112 0.00146 <0.001
Be(0.065 mg/L) N/A N/A N/A N/A N/A N/A N/A N/A N/A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
Cd(0.003 mg/L) N/A N/A N/A N/A N/A N/A N/A N/A N/A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
Cr(0.9 mg/L) N/A N/A N/A N/A N/A N/A N/A N/A N/A 0.00264 0.0218 0.00777 0.0017 0.0175 <0.001 0.00227 <0.001
Cu(0.010 mg/L) N/A N/A N/A N/A N/A N/A N/A N/A N/A 0.00293 0.0174 0.00497 0.00653 0.00233 0.00103 0.0036 0.00168
Hg(ng/I) N/A N/A N/A N/A N/A N/A N/A N/A N/A 9.17 142 11.1 4.52 2.04 7.89 2.7 1.12
Ni(0.335 mg/L) N/A N/A N/A N/A N/A N/A N/A N/A N/A 0.00446 0.0194 0.00568 0.00376 0.01 0.00267 0.00239 0.0131
Pb(0.075 mg/L) N/A N/A N/A N/A N/A N/A N/A N/A N/A 0.00174 0.0208 0.0021 <0.001 <0.001 <0.001 0.00108 <0.001
Sb(0.09 mg/L) N/A N/A N/A N/A N/A N/A N/A N/A N/A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
Se(0.056 mg/L) N/A N/A N/A N/A N/A N/A N/A N/A N/A <0.001 0.00495 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
TI(ug/I) N/A N/A N/A N/A N/A N/A N/A N/A N/A <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002
Zn(0.126 mg/L) N/A N/A N/A N/A N/A N/A N/A N/A N/A 0.017 0.130 0.012 0.012 0.010 <0.005 0.020 0.018
B(mg/I) N/A N/A N/A N/A N/A N/A N/A N/A N/A 0.052 0.305 0.138 0.166 0.128 0.082 0.086 0.084
T.Nitrogen(30 mg/L) 0.48 0.30 0.4 0.52 0.38 0.85 0.59 1.4 0.37 N/A N/A N/A N/A N/A N/A N/A N/A
O&G(15 mg/I) <4.0 <4.0 <4.0 <4.5 <4.4 <4.4 <5 <5 <5 <4.0 <4.0 <4.9 <4.2 <4.4 <5 <5 <5
PCB-1016 <0.40 <0.40 <0.40 N/A N/A N/A N/A N/A N/A <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40
PCB-1221(mg/I) <0.40 <0.40 <0.40 N/A N/A N/A N/A N/A N/A <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40
PCB-1232(mg/I) <0.40 <0.40 <0.40 N/A N/A N/A N/A N/A N/A <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40
PCB-1242(mg/I) <0.40 <0.40 <0.40 N/A N/A N/A N/A N/A N/A <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40
PCB-1248(mg/I) <0.40 <0.40 <0.40 N/A N/A N/A N/A N/A N/A <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40
PCB-1254(mg/I) <0.40 <0.40 <0.40 N/A N/A N/A N/A N/A N/A <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40
PCB-1260(mg/I) <0.40 <0.40 <0.40 N/A N/A N/A N/A N/A N/A <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40

SUMMARY OF LABORATORY ANALYSES
INDUSTRIAL STORMWATER
APRIL 2016 - March 2020
NPDES Stormwater Permit NCS000572
Dan River Combined Cycle Station
SW Outfall SW010
Sampling Date 11-Oct-18 26-Mar-19 16-Aug-19 23-Mar-20
Total Rainfall(inches) 5.7 0.2 1.2 107
pH (6-9) 7.5 7.5 7.5 7
TSS(100 mg/L) 21 <5 18 11
Ag(0.0003 mg/L) <0.0002 <0.0002 <0.0002 <0.0002
As(0.34 mg/L) 0.00154 <0.001 0.00361 <0.001
Be(0.065 mg/L) <0.001 <0.001 <0.001 <0.001
Cd(0.003 mg/L) <0.001 <0.001 <0.001 <0.001
Cr(0.9 mg/L) <0.001 <0.001 <0.001 0.00135
Cu (0.010 mg/L) 0.00306 0.00106 0.00167 0.00256
Hg(ng/I) 4.59 4.59 2.95 2.93
Ni(0.335 mg/L) 0.00221 <0.001 0.00102 0.00178
Pb(0.075 mg/L) <0.001 <0.001 <0.001 <0.001
Sb(0.09 mg/L) <0.001 <0.001 <0.001 <0.001
Se(0.056 mg/L) <0.001 <0.001 <0.001 <0.001
TI (ug/I) <0.0002 <0.0002 <0.0002 <0.0002
Zn(0.126 mg/L) 0.055 0.007 0.009 0.013
B(mg/I) 0.313 0.201 0.134 0.075
T.Nitrogen(30 mg/L) N/A N/A N/A N/A
O&G(15 mg/I) N/A N/A N/A N/A
PCB-1016 <0.40 <0.40 <0.40 <0.40
PCB-1221(mg/I) <0.40 <0.40 <0.40 <0.40
PCB-1232(mg/I) <0.40 <0.40 <0.40 <0.40
PCB-1242(mg/I) <0.40 <0.40 <0.40 <0.40
PCB-1248(mg/I) <0.40 <0.40 <0.40 <0.40
PCB-1254(mg/I) <0.40 <0.40 <0.40 <0.40
PCB-1260(mg/I) <0.40 <0.40 <0.40 <0.40