NCS000546_Amended Application EPA Form 2F_20141024

EPA ID Number (copy from Item 1 of Form 1)
Please orint or tune in the unshaded areas gni NCO 0 04 979 Form Approved OMB No. 2040-0066
FORM
2F
NPDES
Approval expires 5-31-92
U.S. Environmental Protection Agency
Oto E PA pp Washington DC 20460
A lication for Permit to Discharge Storm Water
Discharges Associated with Industrial Activity
Paperwork Reduction Act Notice
Pubfic reporting burden for this application is estimated to average 26.6 hours per application, including time for reviewing instructions, searching existing data sources
gathering and maintaining the data needed, and completing and reviewing the collection of information Send comments regarding the burden estimate, any other aspect
of this collection of information, or suggestions for improving this form, including suggestions which may increase or reduce this burden to: Chief Information Policy
Branch, PM -223, U.S Environmental Protection Agency, 1200 Pennsylvania Avenue, NW, Washington, DC 20460, or Director, Office of Information and Regulatory
Affairs, Office of Management and Budget, Washington, DC 20503
(.Outfall Location
For each outfall, list the latitude and longitude of its location to the nearest 15 seconds and the name of the receiving water
A. Outfall Number D Receiving Water
(list) B Latitude C. Longitude (name)
See attached'
supplemental
information
II. Improvements
A Are you now required by any Federal, State, or local authority to meet any implementation schedule for the construction, upgrading or operation of wastewater
tr-atment equipment or pract ces or any other environmental programs which may affect the discharges described in this application? This includes, but is not limited
to permet conditions, administrative or enforcement orders, enforcement compliance schedule letters, stipulations, court orders, and grant or loan conditions.
2. Affected Outfalls 4 Final
of Conditions Compliance Date
1. Ide Agreements
Agreements Etc number source of discharge 3. Brief Description of Project a. req b prof
B You may attach additional sheets describing any additional water pollution (or other environmental projects which may affect your discharges) you now have under
way or which you plan. Indicate whether each program is now under way or planned, and indicate your actual or planned schedules for construction.
III. Site Drainage Map
Attach a site map showing topography (or indicating the outline of drainage areas served by the outfalls(s) covered in the application if a topographic map is unavailable)
depicting the facility including: each of its intake and discharge structures the drainage area of each storm water outfall; paved areas and buildings within the drainage
area of each stone water outfall, each known past or present areas used for outdoor storage.6f disposal of significant materials, each existing structural control measure
to reduce pollutants in storm water runoff, materials loading and access areas, areas wher pesticides, herbicides, soil conditioners and fertilizers are applied; each of
its hazardous waste treatment, storage or disposal units (including each area not required 10 have a RCRA permit which is used for accumulating hazardous waste
under 40 CFR 262.34); each well where fluids from the facility are injected underground, springs and other surface water bodies which received Morin water discharges
from the facility
" ^ ' —'. ate' "-4r t' -'Z) Page 1 of 3 Continue on Page 2

Continued from the Front
IV. Narrative Description of Pollutant Sources
A For each outfall, provide an estimate of the area (include units) of imperious surfaces (including paved areas and building roofs) drained to the outfall, and an estimate of the total surface area
drained by the outfall
Outfall
Area of Impervious Surface
Total Area Drained
Ouffall
Area of Impervious Surface
Total Area Drained
Number
(prowde units)
(provide unn)
Numb, -r
(provide units)
(provide units)
See attached supplemental
information
B. Provide a narrative description of significant mater.als that are currently or in the past three years have been treated, stored or disposed :n a manner to allow exposure
to storm water, method of treatment, storage, or disposal past and present materials management practices employed to minimize contact by these materials with
storm water runoff, materials loading and access areas, and the location, manner, and frequency in which pesticides, herbicides, soil conditioners, and fertilizers are
applied.
e ttach. d supplemental _-if o mat -on
C. For each outfall, provide the location and a description of existing structural and nonstructural control measures to reduce pollutants in storm water runoff and a
description of the treatment the storm water receives, including the schedule and type of maintenance for control and treatment measures and the ultimate disposal
of any solid or fluid wastes other than by discharge.
Outfall
List Codes from
Number
Treatment
Table 2F-1
attached supplemental informat.on
V. Nonstormwater Discharges
A. I certify under penalty of law hat the ouffall(s) covered by this application have been tested or evaluated for the presence of nonstormwater discharges, and that all
nonstormwater discharged from these outfall(s) are identified to either an accompanying Form 2C or From 2E application for the outfall.
Name and Official Title (type or print)
Signature
�
Date Signed
Eric Matthews - General Manager II
PC.*AZ
1Q/�/I4(
B. Provide a description of the method used, the date of any testing, and the onsite drainage points that were directly observed during a test.
Visual inspection was performed on August 28, 2014. Stormwater outfalls were inspected following a period of dry weather of at
least 72 hours duration. NPDES discharges of process water were excluded. Non-stormwater discharge flows were observed only at
SW014, SW015, and at one 10 :inch diameter CMP within the outfall group :or Drainage Area 13. The non-stormwater discharge
source at these three outfalls is believed to be groundwater.
VI. Significant Leaks or Spills
Provide existing information regarding the history of significant leaks or spills of toxic or hazardous pollutants at the facility in the last three years, inducing the
approximate date and location of the spill or leak, and the type and amount of material released.
Within tk•. :. three years there have been no si-;nificant spills or :elks of hazardous substances in excess of reportable
antitic +.north by Section 311 of the Clean Water Act or Section i02 of CERCLA.
EPA Form 3510-217 (1-92) Page 2 of 3 Continue on Page 3

Continued from Paae 2 1
EPA ID Number (copy from Item 1 of Form 1)
II. Discharge Information
A, B, C &D See instructions before proceeding. Complete one set of tables for each outfall. Annotate the outfall number in the space provided.
Table VII -A VII•H, VII -C are included on separate sheets numbers VII -1 and VII -2.
E Potential discharges not covered by analysis — is any toxic pollutant listed in table 2F-2, 2F-3, or 2F-4, a substance or a component of a substance which you
currently use or manufacture as an intermediate or final product or byproduct?
❑ Yes (list all such pollutants below) 0 No (go to Section IX)
VIII. Biological Toxicity Testing Data
Do you have any knowledge or reason to believe that any biological test to
acute or chronic toxicity has been made on any of your discharges or on a receiving water
relation to your discharge within the last 3 years? in
❑ Yes (list all such pollutants below) Q✓ No (go to Section IX)
IX. Contract Analysis Information
Were any of the analyses reported in Item VII performed by a contract laboratory or consulting firth?
© Yes (list the name, address, and telephone number of, and pollutant:,
No (go to Secfion X)
analyzed by, each such laboratory or firm below)
A. Name
S. Address
C. Area Code & Phone No
D. Pollutant Analyzed
Pace Analytical Services, Inc. 9800 Kincey Avenue, Suite 100 [phone]
Huntersville, NC 28078
X. Certification
I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance wth a : ystem designed to assure
that qualified personnel properly gather and evaluate the information submitted Based inquiry
on my 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.
A. Name & Official Title (Type OrPnnt)
B. Area Code and Phone No.
Eric Matthews - General Manager II
[phone]
C. Signature 0-44
D. Date Signed
%/!-5N
EPA Form 3510-2F (1-92) Page 3 of 3

EPA ID Number (copy from Item 1 of Form 1) Form Approved. OMB No. 2040-0086
VII. Discharge information (Continued from page 3 of Form 2F)
Mppruval expires
Part A — You must provide the results of at least one analysis for every pollutant in this table Complete one
table for each outfall. See instructions for add tional details.
Pollutant
and
CAS Number
(ifavailab/e)
Maximum Values
(include units)
Average Values
(include units)
Number
of
Storm
Events
Sampled
Sources of Pollutants
Grab Sample
Taken During
First 20
Minutes
Flow -Weighted
Composite
Grab Sample
Taken During
First 20
Minutes
Flow -Weighted
Composite
Oil and Grease
N/A
See attached supplemen
Biological Oxygen
Demand (BODS)
information
Chemical Oxygen
Demand (COD)
Total Suspended
Solids (TSS)
Total Nitrogen
Total Phosphorus
pH
Minimum
Maximum
Minimum
Maximum
Part B — List each pollutant that is limited in an effluent guideline which the facility is subject to or any pollutant listed in the facility's NPDES permit for its process
wastewater (if the facility is operating under an existing NPDES permit). Complete one table for each outfall. See the instructions for additional details and
requirements.
Max mum Values Average Values
(include units) (include units)
Pollutant Grab Sample Grab Sample
and Taken During Taken During
CAS Number First 20 Flow -Weighted First 20 Flow -Weighted
(if available) Minutes Composite Minutes Composite
Number
of
Storm
Events
Sampled Sources of Pollutants
See attached supplemental
information
�.... i jai u-cr t -yc/ Page VII -1 Continue on Reverse

Continued from the Front
Part C - List each pollutant shown in Table 2F-2, 2F-3, and 2F4 that you know or have reason to believe is present See the instructions for additional details and
requirements Complete one table for each outfall.
Maximum Values Average Values
(include units) (include units) Number
Pollutant Grab Sample Grab Sample of
and Taken During Taken During Storrs
CAS Number First 20 low, Weighted First 20 Flow -Weighted Events
(if available) Minutes Composite Mmute; Compo%ite Sampled Sources of Pollutants
See attached supplemental
information
Psrt D Provide data for the Aorrn event(s) which resulted in the max_mum values for the flow weighted composite sample.
1
Date of
Storm
Event
2.
Duration
of Storm Event
(in minutes)
3
Total rainfall
during storm event
(in niche:)
4
Number of hours between
beginning of storm measured
and end of previous
measurable rain event
5.
Maximum flow rate during
rain event
(gallons/minute or
specify units)
6
Total flow from
rain event
(gallons or specify unit:)
See
attached
supplemental
information
7. Provide a description of the method of flow measurement or estimate.
See accacnea suppiementai information
EPA Form 3510-2F (1-92) Page VII -2

ALLEN STEAM STATION
Stormwater Discharge Permit Application
Form 2F Supplemental Information
NPDES Permit #NC0004979

GENERAL SITE INFORMATION
Allen Steam Station is a fossil -fueled, electric generating plant located approximately four miles
southeast of Belmont, North Carolina, in Gaston County. The facility has five active coal-fired
generating units with a net generating capacity of 1,155 megawatts. Power production originally
began at the site in 1957. In addition to the generation units, the station includes a Flue Gas
Desulfurization (FGD) facility, a dry ash handling facility, an active ash settling basin, an ash
landfill, ash structural fills, a limestone unloading and stockpile operation, a gypsum stacker and
storage operation, a wastewater treatment plant, a 115 kV electrical switchyard, a 230 kV
electrical switchyard, a station transformer yard, a coal handling operation and storage yard,
and various storage and maintenance buildings.
The Allen Steam Station property encompasses approximately 953 contiguous acres along the
Catawba River in the headwaters of Lake Wylie. The station powerhouse and surrounding plant
yard, the coal pile, the switchyards, and associated material and equipment storage areas
encompass approximately 65 acres. The FGD facility, including the dry ash handling facility,
limestone unloading and stockpile operation, gypsum stacker and storage operation,
wastewater treatment plant, and all associated FGD construction laydown areas, and parking
areas encompass approximately 56 acres. The remaining property is comprised of active and
retired ash settling basins, an ash landfill, ash structural fills, and undeveloped areas. The site
contains approximately 5 miles of rail lines and approximately 2 miles of paved roadways. Coal
and limestone are shipped to the site via these rail lines.
The active ash settling basin has a surface area of approximately 176 acres and a total
watershed of approximately 300 acres. Ash is sluiced to the northern section of the basin and
discharged into one of three rotating cells. Approximately 64 acres that were previously
occupied by a retired ash settling basin are currently the site of an active ash landfill operation.
In developed areas of the property, runoff generally flows overland to ditches and catch basins
which are connected to a buried network of corrugated metal pipes (CMP). Concrete, cast iron
pipes (CIP), and high-density polyethylene (HDPE) pipes also serve as discharge structures. In
most areas, this collected runoff discharges into a system of sumps that pump to the ash
settling basin. Areas of the site where stormwater is collected by sumps include areas
surrounding the Powerhouse, the coal pile and coal handling areas, the FGD facility, the dry ash
handling facility, the limestone unloading area, the gypsum storage area, the wastewater
treatment system (WWTS), and the ash landfill.
Stormwater runoff from the station transformer yard and the 115 kV switchyard is routed through
oil trap tanks prior to being discharged. Stormwater runoff from all remaining areas of the site is
discharged directly to the Catawba River via overland flow or subsurface drain piping.
Allen Steam Station maintains an up-to-date Spill Prevention Control and Countermeasure
(SPCC) Plan in place in accordance with the U.S. Environmental Protection Agency (USEPA)
Oil Pollution Prevention Regulation 40 CFR Part 112.

NPDES PERMITTED DISCHARGES SUMMARY
Allen Steam Station has seven NPDES process water outfalls. The NPDES discharges are
summarized as follows:
NPDES Outfall 001 — Once -Through Cooling Water
This discharge is a once -through non -contact cooling water system that condenses steam from
the plant condensers. This discharge occurs at the station discharge canal.
NPDES Outfall 002 — Ash Settling Basin Discharge
This is the outflow from the ash settling basin. While most of the ash is conveyed to the dry ash
handling facility, some residual ash is sluiced to the ash settling basins. All of the station
stormwater collection sumps discharge to the ash settling basin. This includes runoff from the
coal pile and the plant yard, from the FGD facility, from the limestone and gypsum operations,
and from the ash landfill. The ash settling basin also receives discharges of industrial
wastewater from powerhouse equipment, effluent from the septic system, and process
wastewater from the wastewater treatment system.
NPDES Outfall 002a — Coal Yard Sump Overflow
Should the pumps in the Coal Yard Sump lose power, experience a mechanical failure, or
become inundated during a large storm event, the sump would overflow through a corrugated
metal pipe to the Catawba River. Overflow from this sump is not a normal occurrence.
NPDES Outfall 002b — Powerhouse Yard Sump Overflow
Should the pumps in the Powerhouse Yard Sump lose power, experience a mechanical failure,
or become inundated during a large storm event, the sump would overflow overland to the
Catawba River. Overflow from this sump is not a normal occurrence.
NPDES Outfall 003 — Miscellaneous Non -Contact Cooling Water
This is non -contact cooling water from miscellaneous plant equipment. This cooling water flows
through the north oil trap tank prior to being discharged through stormwater outfall SW012 into
the plant discharge canal. During a rainfall event, this discharge will co -mingle with SW012
stormwater discharge.
NPDES Outfall 004 — Miscellaneous Cooling and Wash Water
This discharge contains miscellaneous non -contact cooling water from plant equipment, vehicle
wash water, and intake screen backwash water. Raw river water is used to backwash the
condenser cooling water intake screens to remove debris. The debris typically consists of twigs,
leaves, and other materials indigenous to the river. This discharge occurs through stormwater
outfall SW011 and co -mingles with stormwater during a rainfall event.
NPDES Internal Outfall 005 — Internal Outfall from Wastewater Treatment System
This is an internal outfall from the wastewater treatment system (WWTS) to the ash settling
basin and is composed of treated FGD scrubber wastewater.
2

STORMWATER OUTFALLS AND DRAINAGE AREA DESCRIPTIONS
This section details drainage basin characteristics of 20 identified stormwater outfalls at Allen
Steam Station (two of these are identified as outfall groups) that discharge to surface waters.
The outfall locations and contributing drainage area delineations are shown on the
accompanying site plan. All identified stormwater outfalls discharge into the Catawba River in
the headwaters of Lake Wylie. Fourteen outfalls (including one outfall group) discharge in the
region of the plant intake structure. Six outfalls (including one outfall group) discharge into the
plant discharge canal.
A description of the contributing drainage area for each outfall is provided below. Included with
the description is the approximate location coordinates of the outfall, the amount of impervious
surface area within the drainage area, any significant materials and activities within the drainage
area, the type of discharge conveyance, and a description of any discharge control measures.
The yards' sump systems have also been characterized to provide a complete description of the
stormwater drainage system. Additional outfalls have been excluded because either they have
been abandoned or because they are not located within the vicinity of the station or any
industrial activity.
In addition to any significant materials particular to each drainage basin, herbicides are applied
to selected areas at Allen Steam Station to eliminate undesirable vegetation. Herbicides are
generally used along railways, ash pipelines, and the perimeter fence. Herbicides are also
applied, as needed, in the gravel parking lots, switchyard, and laydown areas. Herbicides are
sprayed around the fuel oil bulk storage tanks, yard sumps, transformers, trailers, and the intake
structure. All herbicides used at Allen Steam Station are approved by the company and
considered safe to the environment when used according to directions. Records are retained at
the facility documenting the areas treated, and the type and amount of herbicides used.
Certain stormwater outfall drainage areas share similarities regarding significant materials
and/or activities. Based on these similarities, stormwater discharges from certain groups of
outfalls can be represented by the discharge of a designated representative outfall within the
group.
Outfall SW001 and SW001A (Drainage Area 1)
Discharge Structures: 10 -inch -diameter CMP — SW001
12 -inch -diameter CIP — SW001A
Location: North of Station Intake
Coordinates: 350 11' 47.45" N 81 ° 00' 33.15" W
Drainage Area: 6 acres
Impervious Area: 0%
Area Description
The drainage area for SW001 and SW001A includes approximately 2,000 linear feet of rail lines
and undeveloped wooded areas upland of the railroad tracks. This drainage area also includes
approximately 345 feet of gravel road. There are no impervious surfaces in Drainage Area 1.
Stormwater runoff from a strip of wooded area east of the rail lines occurs as sheet flow to the
river.
Significant Materials
Coal and Limestone: Train cars carrying coal and limestone use the rail lines that pass through
Drainage Area 1.
3

Discharge Controls
None.
Outfall SW002 (Drainage Area 2)
Discharge Structure: 24 -inch -diameter CMP
Location: North of Station Intake
Coordinates: 350 11' 42.66" N 81 ° 00' 31.86" W
Drainage Area: 10.8 acres
Impervious Area: 2%
Area Description
The drainage area for SW002 is comprised of primarily upland wooded areas west of the rail
lines. The drainage area also includes a 2.5 -acre graveled FGD facility construction laydown
yard and approximately 1,000 feet of paved road. A stormwater detention basin is present
immediately down -gradient of the gravel laydown yard.
Significant Materials
Inert Materials: Various quantities of structural steel, cable, truck trailers, and other inert
materials may be stored on the gravel yard area at various times.
Discharge Controls
None.
Outfall SW003 (Drainage Area 3)
Discharge Structure: 18 -inch -diameter HDPE Pipe
Location: North of Station Intake
Coordinates: 350 11' 42.60" N 81 ° 00' 31.64" W
Drainage Area: 0.8 acre
Impervious Area: 0%
Area Description
The drainage area for SW003 is comprised entirely of a small flat area that includes
approximately 1,500 linear feet of rail lines.
Significant Materials
Coal and Limestone: Train cars carrying coal and limestone use the rail lines that pass through
Drainage Area 3.
Discharge Controls
None.
Outfall SW004 (Drainage Area 4)
Discharge Structure: 10 -inch -diameter CIP
Location: North of Station Intake
Coordinates: 350 11' 39.01" N 81° 00' 28.11" W
Drainage Area: 1.3 acres
Impervious Area: 0%
Area Description
4

The drainage area for SW004 is located east of the rail lines and north of the limestone
unloading area, and is comprised of a small, flat, graveled area with a vegetated berm forming
the northeastern boundary.
Significant Materials/ Controls
None.
Discharge Controls
None.
Outfall SW006 (Drainage Area 6)
Discharge Structure: 10 -inch -diameter CIP
Location: North of Station Intake
Coordinates: 350 11' 37.32" N 81 ° 00' 27.58" W
Drainage Area: 0.9 acre
Impervious Area: 0%
Area Description
The drainage area for SW006 is comprised entirely of a small flat graveled area east of the
limestone unloading area.
Significant Materials/ Controls
None.
Discharge Controls
None.
Outfall SW007 (Drainage Area 7)
Discharge Structure: 18 -inch -diameter CMP
Location: North of Station Intake
Coordinates: 350 11' 33.50" N 81 ° 00' 26.36" W
Drainage Area: 5 acres
Impervious Area: 2%
Area Description
The drainage area for SW007 is comprised of the vegetated embankment slope east of the
FGD facility, rail lines, and graveled yard areas adjacent to and extending south from the
limestone unloading building. The drainage area includes approximately 1,500 linear feet of rail
lines, 400 linear feet of gravel roadway, and 400 linear feet of limestone conveyor.
Significant Materials
Coal and Limestone: Train cars carrying coal and limestone use the rail lines that pass through
Drainage Area 7. Limestone is transferred via conveyor through the area
from the limestone unloading building to the limestone stockpile area.
Discharge Controls
None.
Outfall SW008 (Drainage Area 8)
Discharge Structure: 24 -inch -diameter CMP
Location: North of Station Intake
5

Coordinates:
Drainage Area:
Impervious Area
350 11' 30.03" N 81 ° 00' 26.85" W
4.1 acres
6%
Area Description
The drainage area for SW008 is comprised primarily of rail lines and a gravel storage yard
located south of the limestone stockpile area and south of the North Warehouse. The area
contains approximately 2,400 linear feet of rail lines and approximately 1,000 linear feet of
paved roadway. Drainage Area 8 also includes a small portion of the vegetated embankment
slope east of the FGD facility.
nificant Materials
Coal and Limestone: Train cars carrying coal and limestone use the rail lines that pass through
Drainage Area 8.
Inert Materials: Various quantities of structural steel, cable, spare equipment, and other
inert materials may be stored on the gravel storage yard area at various
times.
Discharge Controls
None.
Outfall SW009 (Drainage Area 9)
Discharge Structure: 3 -foot -wide Concrete Ditch
Location: North of Station Intake
Coordinates: 350 11' 26.67" N 81 ° 00' 28.90" W
Drainage Area: 0.6 acre
Impervious Area: 0%
Area Description
The drainage area for SW009 is comprised of rail lines immediately east of the Powerhouse and
a grassed embankment located between the rail lines and the intake structure. The area
contains approximately 940 linear feet of rail lines. The station debris and clam filter is located
within this drainage area. The backwash from this filter is designed to discharge through a pipe
directly to the Catawba River. Occasionally the filter backwash will overflow and flow overland to
a discharge point near the SW009 ditch outlet point; however, the overflow does not co -mingle
with the SW009 stormwater discharge.
Significant Materials
Coal and Limestone: Train cars carrying coal and limestone use the rail lines that pass through
Drainage Area 9.
Discharge Controls
None.
Outfall SW010 (Drainage Area 10)
Discharge Structure: 12 -inch -diameter CMP
Location: South of Station Intake
Coordinates: 350 11' 23.46" N 81 ° 00' 27.50" W
Drainage Area: 0.7 acre
Impervious Area: 0%
N

Area Description
The drainage area for SW010 is comprised of rail lines immediately east of the Powerhouse and
a grassed embankment located between the rail lines and the intake structure. The area
contains approximately 1,280 linear feet of rail lines.
Significant Materials
Coal and Limestone: Train cars carrying coal and limestone use the rail lines that pass through
Drainage Area 10.
Discharge Controls
None.
Outfall SW011 (Drainage Area 11)
Discharge Structure: 72 -inch -diameter CMP
Location: South of Station Intake
Coordinates: 350 11' 21.1" N 81° 00' 24.0" W
Drainage Area: 13.4 acres
Impervious Area: 50%
Area Description
The drainage area for SW011 is primarily comprised of developed areas south and southwest of
the station Powerhouse. The drainage area includes approximately 5.3 acres of impervious
areas comprised of roof drainage from portions of the Powerhouse, the Machine Shop, the
Service Building, the Lower Warehouse, the Air Compressor Building, and the Coal Unloading
Hopper Building; and from paved parking areas and the station access road. The drainage area
also includes approximately 3,100 linear feet of rail lines, approximately 1,600 linear feet of ash
sluice piping, and some minor vegetated areas. Included within Drainage Area 11 are six large
transformers located in the station transformer yard, and various types of electrical equipment
located in the station 11 5k switchyard. All equipment located in these areas is within curbed
gravel -surfaced containments with open drains that route stormwater into a 65,300 -gallon oil
trap tank located east of the switchyard. The discharge from this oil trap tank occurs through
Outfall SW011.
A 500 -gallon -capacity aboveground, carbon steel gasoline tent tank is located within the Outfall
SW011 drainage area. The tank is completely enclosed within a steel tent enclosure.
Uncontained tanker unloading by a 1,500 -gallon tanker truck occurs adjacent to this gasoline
tank. An air compressor containing 70 gallons of lube oil is located inside the Air Compressor
Building. Drainage Area 11 also includes a black start diesel generator unit located adjacent to
the Air Compressor Building. The generator is a self-contained unit. Uncontained tanker
unloading occurs adjacent to the generator unit.
The 65,300 -gallon oil trap tank processes stormwater from the contained areas of transformer
yard and the 115 kV switchyard only. All other stormwater within Drainage Area 11 discharges
directly through Outfall SW011. Stormwater discharged through Outfall SW011 is also co -
mingled with NPDES Outfall 004 that includes miscellaneous non -contact cooling water from
plant equipment, vehicle wash water, and intake screen backwash.
Significant Materials
Coal and Limestone: Train cars carrying coal and limestone use the rail lines that pass through
Drainage Area 11. Coal is handled inside the Coal Unloading Hopper
Building within Drainage Area 11.
7

Oil: Mineral oil is stored inside six large station transformers in the transformer yard and in
other smaller transformers and circuit breakers in the 115 kV switchyard. This equipment
is located within curbed gravel -filled containments with open drains that discharge into
the 65,500 -gallon oil trap tank. The largest of these transformers contains 9,715 gallons
of mineral oil, with the total quantity of mineral oil contained in all the electrical
equipment being approximately 68,000 gallons. Seventy gallons of lube oil is stored in
the air compressor located in the Air Compressor Building. Tanker unloading for the
black start diesel generator occurs adjacent to the generator unit.
Gasoline: Up to 500 gallons of gasoline is stored in the gasoline tent tank. The tank is
within integral containment. Tanker unloading operations are conducted
periodically at the 500 -gallon gasoline tent tank.
Inert Materials: Various quantities of structural steel, cable, spare equipment, and other
inert materials may be stored on a concrete laydown yard adjacent to the
Warehouse at various times.
Discharge Controls
A 65,300 -gallon oil trap tank is available for the oil -filled electrical equipment located in the
transformer yard and in the 115 kV switchyard.
Outfall SW012 (Drainage Area 12)
Discharge Structure: 36 -inch -diameter CMP
Location: Discharge Canal
Coordinates: 350 11' 23.22" N 81 ° 00' 43.53" W
Drainage Area: 12.4 acres
Impervious Area: 5%
Area Description
The drainage area for SW012 is primarily comprised of gravel -covered surfaces or vegetated
yard areas west of the station Powerhouse. The drainage area includes the remaining portions
of the transformer yard not included within Drainage Area 11, and the entire gravel -surfaced 230
kV switchyard. Ten large transformers are located within this portion of the transformer yard.
These transformers are located in a curbed gravel -surfaced containment that discharges
stormwater via subsurface drain piping into a 100,000 -gallon oil trap tank located between the
Powerhouse and the switchyard. The discharge from this oil trap tank occurs through Outfall
SW012. The 230 kV switchyard contains no oil -filled equipment. Stormwater runoff from the
switchyard discharges into the Outfall SW012 subsurface drainage system downstream of the
oil trap tank.
The drainage area also includes approximately 1,400 linear feet of out -of -service rail lines,
approximately 300 linear feet of paved road, approximately 800 linear feet of ash sluice piping,
and the vegetated southern embankment of the FGD facility yard. Ash haul trucks use the
section of the paved road that passes through the SW012 drainage area. The trucks are loaded
with ash at the dry ash handling facility located up -gradient from the drainage area. Stormwater
runoff from within the ash handling facility is directed into a sump that pumps to the ash settling
basin.
Stormwater discharged through Outfall SW012 is also co -mingled with NPDES Outfall 003 that
includes miscellaneous non -contact cooling water from plant equipment. The NPDES discharge
is routed through the oil trap tank prior to discharge through SW012. Stormwater runoff from
non oil -containing areas with Drainage Area 12 is not processed through the oil trap tank.
M

Significant Materials
Oil: Mineral oil is stored inside 10 large station transformers in the transformer yard. This
equipment is located within a curbed gravel -filled containment with open drains that
discharge into the 100,000 -gallon oil trap tank. The largest of these transformers
contains 16,000 gallons of mineral oil, with the total quantity of mineral oil contained in
all 10 transformers being approximately 77,000 gallons.
Ash: Flyash is transported through ash sluice piping and in ash haul trucks that are loaded at
the ash handling facility.
Discharge Controls
A 100,000 -gallon oil trap tank is available for the 10 transformers in the transformer yard.
Outfall Group SW013 (Drainage Area 13)
Discharge Structure: Thirteen 10 -inch -diameter CMPs
Location: Every 200 feet along the rail lines south of the coal yard
Coordinates: 350 10'55.61" N 81° 00' 21.06" W (Representative Outfall)
Drainage Area: 3.9 acres
Impervious Area: 0%
Area Description
The drainage area for Outfall Group SW013 is comprised of a narrow strip of land along the
Catawba River south of the coal yard, between the ash landfill and the river. The drainage area
is approximately 2,400 feet long and includes approximately 2,400 linear feet of gravel road and
approximately 7,500 linear feet of rail lines. The group contains 13 outfalls spaced
approximately 200 feet apart that drain the rail lines and the eastern vegetated slopes of the ash
landfill. These outfalls are located every 200 feet along the railroad tracks in front of the coal
composition products (CCP) landfill. The outfalls discharge onto the heavily wooded bank along
the rivers edge. One outfall is identified as accessible and recommended for sampling.
Significant Materials
Coal and Limestone: Train cars carrying coal and limestone use the rail lines that pass through
Drainage Area 13.
Discharge Controls
None.
Outfall SW015 (Drainage Area 15)
Discharge Structure: 36 -inch -diameter Reinforced Concrete Pipe (RCP)
Location: Between the ash landfill and the ash settling basin
Coordinates: 350 10'52.75" N 81° 00' 21.01" W
Drainage Area: 170 acres
Impervious Area: 0%
Area Description
The drainage area for SW015 encompasses a large area west of the ash landfill site. The area
includes a large soil borrow area; two ash structural fill areas; the eastern, western, and
southern vegetated embankments of the ash landfill; and approximately 1 mile of gravel and dirt
roads. Approximately 2,000 linear feet of gravel road within the drainage area is used by ash
haul trucks to transport ash from the dry ash handling facility to the ash landfill.
9

All stormwater runoff from the SW015 drainage area is collected within an elongated detention
pond system located along the southern boundary of the ash landfill. Collected stormwater
discharges through a riser/skimmer system to the Catawba River beneath the rail lines to the
east and through the drainage area of the SWO13 Group.
Significant Materials
Ash: Flyash is transported in ash haul trucks that pass through the area from the dry ash
handling facility.
Discharge Controls
None.
Outfall SW016 (Drainage Area 16)
Discharge Structure: 36 -inch -diameter CMP
Location: Discharge Canal
Coordinates: 350 11' 22.30" N 81 ° 00' 44.88" W
Drainage Area: 21.8 acres
Impervious Area: 2%
Area Description
The drainage area for SW016 encompasses primarily vegetated upland areas along the site
access road south of the discharge canal. The drainage area includes approximately 1,700 feet
of the site paved access road, and approximately 1,000 linear feet of the paved ash haul road.
Ash haul trucks use the ash haul road to transport ash from the dry ash handling facility to the
ash landfill. The drainage area also includes an additional 700 linear feet of paved road south of
the access road, approximately 1,000 linear feet of dirt roads north of the access road, and a
gravel -surfaced laydown and equipment parking area north of the access road.
Significant Materials
Ash: Flyash is transported in ash haul trucks that use the ash haul road.
Inert Materials: Various quantities of structural steel, cable, truck trailers, and other inert
materials may be stored on the gravel laydown yard area at various
times.
Discharge Controls
None.
Outfall SW018 (Drainage Area 18)
Discharge Structure: 48 -inch -diameter CMP
Location: Discharge Canal
Coordinates: 350 11' 24.96" N 81 ° 00' 48.03" W
Drainage Area: 91.6 acres (on-site)
Impervious Area: 1%
Area Description
The drainage area for SW018 encompasses a large area north of the plant discharge canal and
west of the FGD facility. The watershed for Drainage Area 18 also extends into a large area off-
site to the north of the Allen Steam Station property. This off-site watershed area is comprised
of woodlands and residential properties north of the station and east of Highway 273. A
perennial stream originating off-site flows through Drainage Area 18 to Outfall SW018.
10

The drainage area includes approximately 2,000 linear feet of paved access road from Highway
273 to the FGD facility, and approximately 250 linear feet of the paved ash haul road. Ash haul
trucks use the ash haul road to transport ash from the dry ash handling facility to the ash landfill.
Stormwater runoff from within the ash handling facility is directed into a sump that pumps to the
ash settling basin. Gypsum haul trucks use the FGD facility access road to transport gypsum
off-site from the FGD facility.
The area includes approximately 150 linear feet of ash sluice piping from the Powerhouse to the
ash handling facility, and the gravel -surfaced CT2 Tap switchyard located east of the ash
handling facility. Drainage Area 18 also includes a portion of an earth spoil area associated with
construction of the FGD facility, and gravel parking areas used for parking and storage during
construction of the FGD facility.
Significant Materials
Ash: Flyash is transported in ash haul trucks that use the short section of the ash haul road
that passes through Drainage Area 18.
Gypsum: Gypsum is transported in gypsum haul trucks along the FGD facility access road.
Discharge Controls
None.
Outfall SW019 (Drainage Area 19)
Discharge Structure: 48 -inch -diameter CMP
Location: Discharge Canal
Coordinates: 350 11' 24.64" N 81 ° 00' 52.90" W
Drainage Area: 32.8 acres
Impervious Area: 0%
Area Description
The drainage area for SW019 encompasses an undeveloped area located between the
discharge canal to the north and the plant access road to the south. An active soil borrow area
is located in the western end of the drainage area. All stormwater runoff from this borrow area is
directed to a sediment basin located northeast of the borrow area. The remaining portions of
this drainage area are grassed or wooded.
Significant Materials/ Controls
None.
Discharge Controls
None.
Outfall SW020 (Drainage Area 20)
Discharge Structure: 48 -inch -diameter Concrete Pipe (Inlet)
Location: Discharge Canal
Coordinates: 350 11' 31.14" N 81 ° 1' 20.02" W
Drainage Area: 15.7 acres
Impervious Area: 0%
Area Description
The drainage area for SW020 is comprised of upland areas west of Drainage Area 18 and
located on both sides of the paved FGD facility access road. Approximately 1,300 feet of paved
11

access road passes through the center of the drainage area. Gypsum haul trucks use the road
to transport gypsum off-site from the FGD facility.
Drainage Area 20 also includes a portion of an earth spoil area associated with construction of
the FGD facility, and a gravel parking area used for parking and storage during construction of
the FGD facility.
The outlet to the discharge canal was inaccessible and not located in the field. The 48 -inch -
diameter concrete inlet located north of the of the haul road is recommended for sampling.
Significant Materials/ Controls
Gypsum: Gypsum is transported in gypsum haul trucks along the FGD facility access road.
Discharge Controls
None.
12

REMAINING DRAINAGE AREA DESCRIPTIONS
This section describes additional non -industrial stormwater runoff areas at Allen Steam Station
that discharge into station sumps that pump to the ash settling basin. Also described is a
drainage area outfall that was not able to be located after an extensive field reconnaissance.
Drainage Area 5
Discharge Structure
Location:
Coordinates:
Drainage Area:
Impervious Area:
Sheet flow
North of Station
350 11' 39.1" N
4.5 acres
2%
Intake
81°00'28.1"W
Area Description
Drainage Area 5 is primarily comprised of a gravel laydown yard and vegetated slopes located
west and upland of the limestone unloading area. The gravel laydown yard comprises
approximately 3 acres. The drainage area also includes approximately 500 linear feet of paved
roadway. A stormwater outfall was believed to convey runoff from Drainage Area 5, however,
after an exhaustive search this outfall could not be located. Consequently Drainage Area 5
should be considered to discharge via sheet flow and should be removed from any permitting
requirements.
Significant Materials
Inert Materials: Various quantities of structural steel, cable, truck trailers, and other inert
materials may be stored on the gravel laydown yard area at various
times.
Discharge Controls
None.
Outfall SW014 (Drainage Area 14)
Discharge Structure: 36 -inch -diameter CMP
Location: Between the coal yard and the ash landfill
Coordinates: 350 11' 21.29" N 81 ° 00' 42.63" W
Drainage Area: 3.4 acres
Impervious Area: 0%
Area Description
The drainage area for SW014 is comprised of a narrow strip of land located between the coal
yard and the ash landfill. The drainage area is primarily wooded and includes approximately
1,000 linear feet of gravel road. Outfall SW014 (Drainage Area 14) should be removed from
any permitting requirements.
Significant Materials/ Controls
None.
Discharge Controls
None.
13

Outfall Group SW017 (Drainage Area 17)
Discharge Structure: Numerous 12 -inch -diameter CMPs
Location: Every 170 feet along both sides of the discharge canal
Coordinates: 350 11' 24.51" N 81° 00'46.59" W (Representative Outfall)
Drainage Area: 35.1 acres
Impervious Area: 0%
Area Description
The Outfall Group SW017 drainage area is comprised of a narrow strip of land on both side of
the plant discharge canal. The drainage area includes gravel access roads that run along both
sides of the entire length of the canal. The numerous SW017 stormwater outlets are spaced
approximately 170 feet apart along both sides of the discharge canal and direct runoff from
vegetated embankments along the canal, beneath the gravel roads, and into the canal. Outfall
Group SW017 should be removed from any permitting requirements.
Significant Materials/ Controls
None.
Discharge Controls
None
Powerhouse Yard Sump
The Powerhouse Yard Sump collects effluents and wastewater from the Unit 5 area inside the
Powerhouse, from a portion of the Powerhouse roof, and from yard areas east of the
Powerhouse. The sump is located northeast of the Powerhouse and has a contributing total
drainage area of 3.6 acres. The drainage area for the Powerhouse Yard Sump includes a
100,000 -gallon fuel oil storage tank within a secondary containment basin, an adjacent curbed
tanker truck unloading station. These containments drain to the sump through valved catch
basin inlets within the containments. The drainage area for the Powerhouse Yard Sump also
includes numerous small transformers for the Units 1-5 precipitators. The maximum mineral oil
content of any single transformer is 205 gallons.
The Powerhouse Yard Sump discharges into the Yard Drainage Sump (see below). Rarely
occurring emergency overflows for the Powerhouse Yard Sump will discharge onto the ground
and then flow overland easterly to the Catawba River. This overflow is permitted as NPDES
Outfall 002b.
Yard Drainage Sump
The Yard Drainage Sump receives all effluent from the Powerhouse Yard Sump (above). The
Yard Drainage Sump also collects effluents from the turbine room sumps and boiler room
sumps located inside the Powerhouse. These interior sumps essentially collect effluents from
various areas and equipment located in the Powerhouse. The sump is located east of the coal
yard and has a contributing total drainage area of 5.2 acres. The drainage area for the Yard
Drainage Sump includes portions of the Powerhouse roof, portions of the coal handling
operation, the Maintenance Garage roof, the Warehouse roof, approximately 1,300 linear feet of
rail lines, approximately 600 linear feet of ash sluice piping, and other miscellaneous buildings
and yard areas east of the coal yard.
The drainage area for the Yard Drainage Sump includes the remaining small transformers for
the Units 1-5 precipitators (the maximum mineral oil content of any single transformer is 205
gallons), two 270 -gallon -capacity transformers for sump operation, and two 196 -gallon -capacity
transformers associated with the coal handling operation.
14

Also located within the contributing drainage area for the Yard Drain Sump are several chemical
containers, petroleum containers, and fuel dispensers. A 200 -gallon -capacity kerosene tank is
located along an ash sluice trench with open drains to the sump. A 4,500 -gallon -capacity used
oil storage tank within a steel containment enclosure is located in the coal handling area. This
valved containment also drains to the ash trench and then to the sump. A nominal amount of
55 -gallon drums are stored adjacent to the warehouse, inside the Maintenance Garage, and
inside a tractor shed. Fuel oil dispensers are located adjacent to the Maintenance Garage. A
5,000 -gallon sulfuric acid tank is located adjacent to the Warehouse. The tank is maintained
within a concrete containment dike with open drains to the aforementioned ash sluice trench.
Miscellaneous drums of chemicals are stored inside a covered and locked shed adjacent to the
Warehouse. A hazardous waste satellite accumulation area for paints, solvents, and chemicals
is located in a covered area adjacent to the Maintenance Garage.
The Yard Drainage Sump discharges into the ash settling basin. Rarely occurring emergency
overflows for the Yard Drainage Sump will discharge into the Coal Yard Sump (see below).
Coal Yard Sump
The Coal Yard Sump collects effluent from the station septic system, and collects stormwater
runoff from the coal pile and from portions of the coal handling operation. The sump is located
east of the coal yard and has a contributing total drainage area of approximately 24 acres. Also
located within the drainage area for the Coal Yard Sump are two 270 -gallon -capacity
transformers for sump operation, and approximately 800 linear feet of rail lines.
The Coal Yard Sump discharges into the ash settling basin. Rarely occurring emergency
overflows for the Coal Yard Sump will discharge through a corrugated metal pipe to the
Catawba River. This overflow is permitted as NPDES Outfall 002a.
FGD Stormwater Sump
The FGD Stormwater Sump is located at the FGD facility and routes stormwater to the ash
settling basin from the FGD stormwater collection basin. The contributing drainage area for the
sump and the stormwater collection basin is approximately 26 acres. Included within this
drainage area are the FDG facility buildings, the gypsum stacker operation and storage pile, and
the wastewater treatment facility. Stormwater runoff from the dry ash handling facility and the
surrounding paved area is also routed to the stormwater collection basin. Effluent from the
wastewater treatment facility is discharged independently to ash settling basin as internal
NPDES Outfall 005.
The drainage area for the FGD Stormwater Sump also includes four large FGD transformers
within secondary containment basins. These containments drain through open drains to an
oil/water separator that discharges into the stormwater collection basin, and then into the FGD
Stormwater Sump.
Limestone Unloading Area Sump
The Limestone Unloading Area Sump has a contributing drainage area of approximately 6 acres
and is located at the limestone unloading operation. The sump drainage area receives
stormwater runoff from the roof of the limestone unloading building, from limestone hoppers and
conveyors, and from the surrounding gravel -surfaced area. Stormwater runoff is collected within
a trench at the eastern edge of the drainage area. This trench discharges into the Limestone
Unloading Area Sump that subsequently pumps to the ash setting basin.
15

Ash Landfill Sump
The Ash Landfill Sump collects all leachate from the lined ash landfill located south of the Coal
Yard and subsequently pumps to the ash settling basin. The landfill encompasses
approximately 64 acres.
IDENTIFICATION OF NON-STORMWATER DISCHARGES
A visual assessment for non-stormwater discharges was conducted on August 28, 2014. Each
outfall was observed for outflow after a period of at least 72 hours of dry weather. NPDES
discharges of process water were excluded. Non-stormwater discharge flows were observed at
SW014, SW015, and at one 10 -inch CMP within the outfall group for Drainage Area 13. The
identified 10 inch CMP was sampled as part of the site seep investigation (Seep Sample S-8).
The non-stormwater discharge source at these three locations is believed to be groundwater.
MONITORING AND SAMPLING
Stormwater samples were collected from Outfall SW008 and Outfall SW010 on August 12,
2014. The remaining outfalls at the station will be sampled in due course as qualifying rainfall
events occur. After an exhaustive search no outfall was found conveying runoff from Drainage
Area 5, consequently runoff from this area will be excluded from any future sampling efforts.
Outfall SW014 and Outfall Group SW017 will also be excluded as these drainage areas include
no industrial uses associated with the Allen Steam Station.
16