NC0000396_Request for Minor Modification_20210426

. - - 4' DUKE
Antonio D.Price,PE
� ENERGY® Plant General Manager
Asheville Combined Cycle Station
PROGRESS
FedEx tracking: 773483832087 Duke Energy Progress
ASVL PLT 146 Duke Energy Lane
Arden,NC 28704
File: 12520B
o: 828-650-0620
April 20, 2021 r 828-650-0701
[e-mail]
Dr. Sergei Chernikov,PhD
North Carolina Department of Environmental Quality RECEIVED
Division of Water Resources
1617 Mail Service Center AI'-? 2 6 2021
Raleigh,NC 27699-1617
NCDEQIDWRINPDES
Subject: Asheville Steam Electric Generating Plant
NPDES Permit NC0000396
Request for minor NPDES permit modification removing Outfalls OO1B and OO1D
Dear Dr. Chernikov:
The Asheville Steam Electric Generating Plant coal units retired in January of 2020 as planned and
concurrent to the new natural gas combined cycle station completing commissioning. Decommissioning
of the old units are well underway. A malfunction of the new oil water separator units, internal outfalls
001B and 001D,in February of 2020 has resulted in removing the equipment from normal service to
investigate and resolve conditions that may have caused the incident.
The investigation of the oil water separator malfunction revealed design criteria opportunities as well as
process improvements. Some exterior stormwater containments were diverted to the industrial
stormwater discharges and internal equipment drain piping was routed to the cooling water system.
During the engineering evaluation of the system,the preferred design change was to route the discharge
lines from the oil water separators to the side stream filter backwash sumps. This routing eliminates
internal outfalls 001B and 001D by recycling the flow back into the cooling water system and release
through existing internal outfalls 001A and 001C. Outfalls OOIA,001B,OO1C and OO1D contain the
same permit limits. This work was completed on April 19,2021 in accordance with the written
confirmation to proceed received from the North Carolinas Division of Water Resources.
1 A minor NPDES permit modification is therefore requested to remove internal outfalls 001B and 001D
from NPDES permit NC0000396. Enclosed are updated process flow diagrams for the system showing
this change.
Should you have questions or need additional information please contact Robert Wylie at 704 562-8258.
Sincerely,
i(iibtissr9
•fir
Antonio D. Price,P.E.
Asheville Plant Manager
Attachments
cc: Landon Davidson,DEQ,Asheville Regional Office
Teresa Williams,Duke Energy
Robert Wylie, Duke Energy

Former Coal Plant Operation
French Broad Make Up Consumptive
River L-oss
I
Y X Flue Gas
V
Ong '
g ng Clarifier
gene
Units 1 &2 S Lake Julian
> Condensers '' --> Outfall 002 Public
B Sewer
N Lake > Intake Circulating Water F System
Structure > to Heat Exchanger —> Ash Sump MSD
I U
YI
Diesel $ Y Y Y
Fire > Fire Preheater Ash Evaporation
Pump AA PProtection Cleaning Sluice in Boilers
e System Water Water IL
Y >D Chemical Metal
Service-Water Mender--supplied R Cleaning Waste
A water treatment G
fA1t)
Combustion M _�
-> ) 4- -
Turbine Site 1964 Y
> I=-ew-Vslame E Ash Pond > Rim Ditch 8, d
) {Duck Pond) o_r er ��` �
> Waste Sources X T ) Settling > River
A14 d - - -
A Outfall 001
'i
St Water '• n
# RetenRe-tent-ran ---- . Phys/Chem ndwa�er
Basin
,v Ba s+n WAS Ex Extraction
Coal Pile
Public Potable and Public Runoff Dam Seepage Attachment C Procecs Flow Diagram
Water —> Sanitary > Sewer Duko Energy Progrecs LLC
Shy Sir, Evaporation
Y
MSD
Fivaeemlae-County November-29-1-9

Post Coal plant shutdown Jan 2021
French Broad
Combined
River Intake ►and Simple Cycle
Structure Plant Note: Some process removed, no
Change in discharge
Make-up O Service location/characteristics
Water > Water
V
Settling N
Zone
E
Lined
Retention
D Pond
A
V
V Pre-Protection Combined
Lakest + Q and Simple Cycle
Julian Plant
V
Power
Block/Demo K
Industrial Storm EE
Water V
v
City of Onsite GG Secondary French Broad
Asheville v Physical/Chemical > Settling Basin
al r River
Public Water truck dust Outfall 001
water S A A
suppression
Potable C BB
and Contact SW and
Sanitary Interstitial water
Systems Evaporation < 1964 Ash Pond
FF
Public Sewer Segregated clean SW(potentially) Attachment A—Process Flow Diagram
System (MSD) I Duke Energy Progress,LLC
Groundwater
Dam Seepage Extraction Asheville Steam Electric Plant
Outfall 101 Buncombe County March 2021

S
Combined and Simple Cycle Combustion Turbine Plant
1 2 4 Ultrafiltration 8 10 16 25
Intake Backwash Strainer Service Water/Fire Service Equipment
Lake Structure >0 >0 > and ultrafiltration — > Water Tank ' Water Users > Drains Sump >
Julian skids
17 Existing Simple Cycle Existing Simple Cycle\ Existing
5 > Evap Cooling& J —Sto mwater Drains }—► Outfall
Makeup / and lift station /
002 to
3 38 38 Lako
Unit 07/08 Raw\ Standby RO/Demin Julian
> Water Supply > Trailers
9 12
Existing Unit 3 and 4 Simple 13 15 V 18
A Simple Cycle Cycle CTG Two-Pass Reverse Mixed-Bed Demineralized CTG NOx
Demineralized Water Water > Osmosis > Demineralizer > Water Tanks >I Injection >
Storage Tanks Injection
6 f
• Atmosphere < 14 D
Simple Cycle Evaporation 20
CTG Water Atmosphere <
Wash V - 22 19
> 11 21
> HRSG Blowdown HRSG
Transfer Truck Cooling Tower& >" Tank/Sump < F—
Basin
• A v
OF Backwash Sump - > < I 24 CTG Wash
(Shared) 45 I 24 V Water Transfer Truck
T 23 Sample
A 37 38 39 Panel 19
44
Unit 07/08
I (( Cooling Tower —'? t/ Unit 07/08 Unit 7/8 TB/
r X __ Oil Water Separator <
43 y Slowdown 001B
WiB drains sump
Sludge Side-stream Filter Side-Stream 001C a
— Thickener(1 per <— Filters(1 per -
Backwash Sump ---1 Filters ! Unit 05/06 Oil-Water Unit 5/6 TB
power block) (1 per power power block) X
Separator <-- drain sump
46 block) 0010
v 47 5 v v v 25
Unit 05/06
Filter Press Secondary
Cooling Tower(Shared) Blowdown > Waste Water Sump
(Shared) > Settling
Basin French Broad River
-
001A 26 Outfal 1001
•
Kxistins
Existing
Fuel Oil> Transfer Truck Fuel Oil
Oil-Water Area
Separator Stormwater
Existing Ash pond
LRB/WTS Attachment A-Process Flow Diagram
Duke Energy Progress,LLC
Asheville Steam Electric Plant
Buncombe County, March 2021