NC0003468_Permit Application_20061031 (3)

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'EDuke Duke Energy Corporation
-ueigy® 526 South Church St
Charlotte, NC 28202
Mailing Address
PO Box 1006
Charlotte, NC- 28201 -1006
October 30, 2006
Mrs. Carolyn Bryant
State of North Carolina
Department of Environment and Natural Resources �1 OCT 3 1 2006 -
Division ofWater Quality
Point Source Branch i -
1617 Mail Service Center - DENR - WATER QUALITY _�
Raleigh, North Carolina 27699-1617' �olrir }OURrF e��- �_
Subject: Duke Energy Carolinas LLC — NPDES Permit Application
Dan River Stearn Station - #NC0003468
Dear Mrs. Bryant:
Duke Energy requests the subject permit be renewed and reissued The above
referenced permit expires April 30, 2007. As mandated by North Carolina
Administrative ,C.ode 15A NCAC 2H.01!05 (e); this permit application for renewal is
being submitted at,least 180 days prior to expiration of the current permit.
Please find enclosed 'in triplicate, the, renewal application, which includes the
following items:
EPA Form 1
EPA Form 2C
EPA Form 2E
EPA Form 2F
Site Map
Water Flow Diagram
Supplemental Information
Duke Energy requests notification that this application is complete.
Additionally, the attached report, ' "Assessment of Balanced and Indigenous
Populations in the Dan River near Dan River Steam Station, " - continues to indicate
recovery of aquatic populations and supports renewal of the current thermal
monitoring requirements for outfall #001. Duke Energy requests that all
temperature limits for outfall #001 be expressed solely in degrees Fahrenheit or
Celcius to eliminate ,confusion.
www duke - energy com

Duke Energy requests that the quarterly monitoring requirement for Total Iron at
outfall' #001 be removed. Comparison of outfall #001 and intake, results
demonstrate no iron contribution from the Condenser Cooling'Water System.
The following monitoring reductions at outfall , #002 are requested based on
historical monitoring data, which are attached The suggested methodology
changes are based on the Steam Effluent Guideline'in 40 ,CFR 423.12.
• Reduction of monitoring of Total Copper and Iron from monthly to quarterly.
• Reduction of Oil and Grease from quarterly to once /year.
• .Reduction of Total Suspended Solids from monthly to quarterly.
• Reduction of Total Nitrogen from quarterly to once /per year.
• Reduction of Total Phosphorous from quarterly to once /per year.
Thank you in advance for your assistance on this matter. Should you have
questions - regarding this application, please contact me at (704) 382 -4309.
Sincerely,
Allen Stowe
.Scientist, Water Management
Attachments
cc w_ /: Mr. David Russell - NCDENR Winston -Salem R.O.
Ms. Trish, MacPherson — NCDENR, Raleigh, N.C. (BIP Report,3 copies)

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D I S C F
DISCHARGE NO I S D U R C E
001
CONDENSER COOLING WATER
002
BASIN DISCHARGE
__ASH'
003
COMBUSTION TURBINE COOLING WATER
004
SETTLING POND OVERFLOW
005
UNIT °1 & ' °2 EQUIPMENT COOLING WATER
006
UNIT "3,EOUIPMENT COOLING WATER
007
DREDGE EQUIPMENT COOLING WATER
008
INTAKE OE -ICING DISCHARGE
009
CT COMPRESSOR FCOOLING, WATER
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D U K E P O W E R C I0 M P A, N Y
DAN RIVER STEAM STATION
L E G E N D
PLANT DRAINAGE
- - - -- DISCHARGE POINTS NPDES DISCHARGE POINTS

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' ,Gerieral Information
Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 2,of 24
Dan River (DR) Steam Station pumps water from the Dan River for condenser cooling and
service water requirements. The condenser cooling water is °once through, non- contact.
Service water is pumped to a settling pond to remove sand and silt before entering the
station. A schematic flow diagram of water use and discharges indicating typical (average)
flow, rates for individual waste streams at DR is attached. A brief discussion of each
discharge follows.
Discharge 001 - Condenser Cooling Water ('CCV1l)
The CCW system, -is a once through non- contact cooling water system that removes heat
rejected from the condensers and other selected heat exchangers. Each of the 3 DR units
has two condenser cooling pumps. The capacities of °these pumps are:
Unit 1 1 pump - 37,,600 GPM 2 pumps - 56,200 GPM
Unit 2 1 pump - 37',600 GPM 2 pumps - 56,200 GPM
Unit 3 1 pump - 54,000 GPM 2',pumps - ,82,000 GPM
The operational schedule for these pumps is dependent on the intake temperature and on
the unit load's. Depending on the electrical demand, pumps are operated to maximize
efficiency and to assure balanced and indigenous populations are maintained in the Dan
River.
Condenser cleaning is accomplished either mechanically by backwashing or by manually_
forcing metal scrapers through the tubes under- air pressure to remove mud and slime.
The condenser tubes are cleaned in this manner approximately once per year.
The intake screens are backwashed with raw water taken from the settling pond. The
combined flow rate from the pumps is 5000 gpm. 'These pumps are operated on an on /off
basis for a total operating time of 6 hours per day. Debris collected on the screens
consists mainly of twigs, leaves, and other material indigenous to the river and is flushed
back without adverse environmental consequences.

Dan River Stearn Station, Rockingham County
NPDES Permit No. NC0003468
Page 3 of 24
` ®ischarge 002 a Ash Basin
Storm Water
The DR ash basin accommodates flows'from the yard drainage sump, ash removal' lines,
and rainfall run- off'from the basin watershed area. The average rainfall run -off flows are
based on 44 inches of rain per year with 100% run -off from the pond surfaces and 50%
run -off from other areas. The average run -off for the, ash basin watershed area is 0.418
MGD.. The coal yard drainage drains to the yard sump and is then pumped to the ash
basin. The coal yard has an average run -off of 0.007 MGD. This run -off is based on 44
inches of rain per year with 506/6 run -off:
Fuel Oil Storage Run -Off:
DR ha& two large fuel oil storage tanks (each 500,000 gallons), with only one tank in
service at a time. Each tank is, surrounded by a dirt dike to 'Contain the contents, in
the event of an accidental rupture. Any stormwatercollected in the fuel' oil storage
tank containment area ,is verified to be free of oil prior to being pumped into a drain
that discharges into the Dan River. In addition to this precaution, two 20,000 gallon
oil trap tanks have been installed to collect any spilled oil before the runoff reaches
the river, including runoff from the fuel unloading area. Any storm water runoff and
any oil spillage around and 'inside of,the combustion turbine buildings are routed to
the oil trap tanks prior to release to the Dan River.
All oil storage facilities are presently covered under the Spill Prevention Control and
Countermeasure Plan.
Floor Drains
The powerhouse floor drains connect to sumps where the waste is then pumped to the ash
basin. These drains can receive inputs from spillage or leakage, floor wash water, as well
as flows from water,treatment processes. The following are examples of materials that are
stored inside the powerhouse:
sulfuric acid
ethylene glycol (recycled)
gasoline
oil, lube oil (recycled)
hydrazine
sodium hydroxide
asbestos
water treatment chemicals
sulfur
ammonium hydroxide
soda ash
industrial cleaning products

Dan River Steam Station; Rockingham County
NPDES Permit No. NC0003468
Page 4 of 24
Make -Up Water Process Wastes
The water treatment wastes are made up of sedimentation, filter backwash, demineralizer
regeneration wastes and boiler blowdown. Make -up water is fed to the boilers to generate
steam to turn the turbines. The current_ primary make -up water treatment system is
comprised of activated carbon filters, a reverse osmosis filter unit and a demineralizer with
two cells with water,supplied from the City of Eden. The back -up make -up water treatment
system consists of a clarifier, pressure filter, activated carbon filters, a reverse osmosis
filter unit and a demineralizer with two cells with water supplied' from the service water
system (Note: In the future, this, back -up system could be re- designated as the, primary
make -up water system):
Clarifier:
The clarifier utilizes a continuous feed of Nalco 8105 cationic water treatment
polymer, Calgon CA -25 clay and chlorine in order to maintain an average of 3 ppm,
30 ppm and ,3 ppm, respectively. The solids in the clarifier are desludged
continuously to the floor drains and then pumped to the ash basin.
Pressure 'Filters:
Two pressure filters used for removal of colloidal material are backwashed on an as
needed basis dependent upon, the level of solids in the intake water, but no more
than twice per week. The filter.medium, which is composed of gravel, sand, garnet
and' anthracite (coal), is replaced approximately once every ten years and 'is sluiced
to the ash basin.
Activated Carbon Filters:
'Two activated carbon filters remove organics ,and the chlorine that is injected in the
clarifier. These filters are backwashed approximately twice per month to the ash
basin. Approximately 80 ft 3, of activated carbon is replaced as required (typically
every two or three years) and the spent carbon is discharged to the ash, basin .

Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 5 of 24
Reverse Osmosis (RO) Unit:
The RO u6it is used to decrease the conductivity in the make -up water, thereby
increasing the efficiency of the demineralizers and reducing the amount of chemicals
needed for demineralizer regeneration. Sulfuric acid is injected continuously at a
rate of approximately 4 - 5' gal %day to control pH. During operation, the unit has a
continual .concentrate reject of 50 gal /min, which is discharged to ,the ash basin.
Small amounts of detergents are used approximately every three months to clean
the, RO unit per manufacturers recommendations.
Demineralizers:
Each, of,the two mixed bed ionic exchange demineralizer cells `has a capacity of ,90
gpm each, and one cell is regenerated, approximately every five days. A
regeneration demands 20 gallons of 66 Be' sulfuric acid (93 %), 80 gallons of 50%
sodium hydroxide, and approximately 11,000 gallons of water: The demineralizer
ion exchange resin is replaced approximately once every 5 to 8 years and the spent
resin (190 ft 3) is discharged to the ash basin. The quantities of'regeneration
chemicals that are specified by the manufacturer are such that they are effectively
neutralized prior to discharge.
Boiler Blowdown:
The total average blowdown for units 1, 2, and 3 is 2000 lbs. of steam per hour. The
boiler blowdown is allowed to flash back to steam in a flash tank so that the steam
can be recovered. Hydrazine is injected into the condensate system as an oxygen
scavenger. Most of the hydrazine is utilized and converted to ammonia and water
which is used for pH control. However, trace amounts oflhydrazine ( << 10 ppb) may
be found in the boiler blowdown which discharges to the floor drains and is pumped
to the ash basin. Ammonium hydroxide is used for pH control.

Dan River,Steam Station, Rockingham�County
NPDES Permit No. NC0003468
'Page 6 of 24
Boiler Cleaning
Boilers #1, #2 and 93, at DR are cleaned on an as needed basis, but no ,more than once
every three years. The wastes produced from a boiler cleaning are sluiced to the ash
basin. The chemicals and approximate amounts for each cleaning follow:
Chemical
*Ammonium Bifluoride
Ammonium Bicarbonate
*Ammonium Hydroxide, 260 Be'
Citric Acid
Copper complexer
*Hydrochloric Acid, 200 Be' (31:5 %)
Sodium Bromate
Sodium Carbonate
Sodium Hydroxide, 25%
Corrosion Inhibitors
Range of Amount used per Unit
1'000 Ibs - 1300 Ibs
1000 Ibs
800 gals - 900 gals
200 Ibs - 300 Ibs
1630 Ibs - 1770 Ibs
3400 gals - 4200 gals
550 Ibs
2200 'Ibs - 2600 Ibs
34,00 gals — 4200. gals
(as necessary)
These ,chemicals are present in amounts greater,than the reportable quantity as identified
under the Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA). If a spill of any these chemicals were to occur, in most cases, the spill would
be routed, to the ash basin for treatment._ These chemicals are being identified to qualify
for the spill reportability exemption provided under 40 CFR 117 and CERCLA.
The volume of diluted waste chemicals and water discharged from unit 1 or 2 during a
cleaning is approximately 340,000 gallons. The volume of diluted waste chemicals and
'water drained from Unit 3 is approximately, 275,000 gallons. Prior to the beginning of a
boiler chemical cleaning procedure; additional stoplogs are added to the ash basin
discharge structure to stop the discharge. This arrangement assures longer retention time
of the chemical wastes for proper treatment through, neutralization, chemical reaction, and
preei'pitation as documented in the- Ash Basin Equivalency Demonstration, (October 1976).
The discharge is held up, a minimum, of 96 ,hours following the first chemical drain and
additional pH and metals sampling is performed for three consecutive days once discharge
begins.
Sanitary Wastes
DR,uses municipal water for its sanitary and potable water needs. The estimated annual
average flow is 0.003 MGD, based on 70 permanent employees. The effluent from the
package aeration sewage treatment plant is discharged to the ash basin for secondary
treatment. No chemicals are added to the sanitary effluent prior to discharge to the ash
basin.

Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 7 of 24
Miscellaneous
Ash Disposal:
Electrostatic precipitators are used at DR for air pollution control. Sulfur'and
anhydrous ammonia is used, for flue gas treatment. Fly ash removed from the
precipitators and bottom ash removed from the boilers is sluiced to the ash basin.
Approximately 1.0 MGD of water are required for the ash removal from the
precipitators. In order to maintain adequate retention time in the ash basin, ash is
removed from the primary cell on an as needed basis, and the wet ash sludge is
deposited in the dry basin. Cover is then placed over the sludge and the area is,
reseeded. Excess water and' stormwater from the dry basin drain back to the ash
basin secondary cell.
Closed Cooling Systems:
Several plant cooling systems are recirculating systems and therefore require the
addition of microbiocides and corrosion inhibitors to prevent biofouling and piping
corrosion. While these are closed systems, they are drained on a non - routine basis,
as necessary for maintenance, to the turbine building, sump and pumped to the ash
basin.
Lab Wastes:
The chemistry lab on site performs a variety of water analyses and routine sample
collection. Therefore several chemicals are used 'in the lab in small quantities for
sample preservation, bottle rinsing, equipment calibration, analytical chemistry, etc.
The wastes are poured down the sink and discharge `into the building sump and then,
pumped to the ash basin.
Heat Exchanger Cleaning:
Heat exchangers are physically cleaned of mud fouling on an as needed basis.
Dredge 'Material:
Because silt settles constantly in front of the plant intakes, it is necessary to, dredge
routinely to assure a clear intake. In order to monitor the discharge of the return
water from the dredging activity, all dredge material (raw water and brown
micaceous silty sand) is pumped to the ash basin. Water quality standards can .then
be assured through routine TSS sampling of the ash basin. DR has 404 approval
from the Corps of Engineers for this activity.

Turbine, Non- destructive Testing:
Dan River°Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 8 of 24
Approximately once every 3 — 4 _years, one turbine is tested for cracks in the
generator shaft using an ultrasonic nondestructive test. During the process, one
hundred gallons, of demineralized water mixed with 1 gallon of corrosion' inhibitor is
used and discharged to the ash basin.
Chemical Additions to the Ash Basin
Small volumes of aluminium sulfate (alum), ferric sulfate, and miscellaneous
polymers are infrequently added directly to the ash basin to encourage coagulation
and flocculation, thus controlling suspended solids.
Discharge 003 - Combustion Turbine (CT) Cooling Water
DR has 3 oil/natural gas fired combustion turbines which are used to, provide electricity
during peak demand. These units use once through non - contact cooling water for the
turbine lube oil coolers at a maximum flow of 900 gpm (with all 3 units in operation) when
the CTs are in operation. The cooling water discharges to the settling pond. Due to the
fact that the 'CTs are only operated a few.days out of the year, normally there is .no flow
from this discharge.
Discharge 004 - Settling Pond Overflow
Water is withdrawn from the Dan, River and pumped to the settling pond'for use in the
plant. The settling pond is also fed by area drainage and Moir Branch Creek and has an
overflow discharge back to the river when pond levels get too high.
Discharge 005 & 006 - Equipment .Cooling Water
Once through non - contact cooling wat'er'is used to cool 'the following' equipment.
• Unit 1 & 2 preheaters and fans (005 discharges to the Dan River)
• Unit 3 preheaters and fans (006 discharges to�the settling pond).
No chemicals are added to these systems.

Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page' 9 of 24
Discharge 007 - Dredge Booster Pump Cooling Water
The intake of the plant is dredged twice per year on average to prevent the buildup of silt.
When this occurs, °a booster pump is necessary to facilitate, dredging. The booster pump
engine requires once through non - contact cooling water which has a maximum flow rate of
10 gpm. The booster pump is, adjacent to the river behind; the powerhouse and the, cooling'
water is discharged to a ditch which flows to the river. The dredge is operated
approximately 3 — 4 weeks annually.
Discharge 008 - Intake De4cing
During extremely cold weather, ice can, build up in the intake and make withdrawal of water
difficult. When this situation occurs, a portion of the warm�condenser cooling flow is'
diverted back to the intake to melt 'the -ice. However,; de-icing is done on a very limited
basis. The maximum flow is, 40,000 gpm when used. Because this discharge is used only
when the units are operating, the warm discharge is immediately pulled ,back;into the plant
through the CCW system. The Intake De -Icing System has not been operated in the last
thirteen years. When Unit #3 is operational; flow from the Unit #3 Lube Oil Cooler, is
discharged via this outfall.
Discharge 009 - Combustion Turbine Compressor Cooling
CT Unit 6C uses an air compressor that requires once through non - contact' cooling water.
The maximum flow when in operation is 14 gpm and discharges to a storm drain near the,
unit and eventually flows to the Dan River. CT Unit 6C is only operated a few days per
year. Typically'there is cooling water flow even when the CT is not in operation.

Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 10 of 24
Hazardous and Toxic Substances Table 2c- 3:
At DR Steam Station, the potential for toxic and hazardous substances being discharged is
very low. In reference to Item V -D of Form 2 -C, the substances identified under Table 2c -3
that may be in 'the ash basin discharge are as follows:
Asbestos, Stryrene, Cyclohexane, ,Xylene, EDTA, Acetaldehyde,
Naphthalene,Triethanolamine and also products such as commercial cleaners and
laboratory reagents may be ,purchased which contain very low levels of a substance found
in Table 2c -3. It is- not anticipated that these products will impact the ash basin's capacity
to comply with its toxicity limits, since their concentrations are extremely low.
40 CFR 117 and CERCLA Hazardous Substances:
The table below identifies hazardous substances located on -site that may be released to
the ash basin during a spill ,in quantities equal to or greater than the reportable quantity
(RQ) levels as referenced in 40 CFR 117; 302 and -355. This list is being provided in order
to qualify for the spill reportability exemption provided under 40 CFR 117 and the
Comprehensive Environmental Response Compensation and Liability Act ( CERCLA).
These values below represent the maximum quantities on -site that could be released at
one time and sent to the ash basin. They do not reflect quantities that are discharged
through typical use.
CHEMICAL AMOUNT SOURCE
Ibs
Dicofol 24 Pesticide storage.
Hydrazine 513 Power house
Sodium Hydroxide 9,538 Power house
Sulfuric Acid 19,333 Outside above ground tank
Xylene 308 Outside gasoline tank.
Dan River Steam Station ,Balanced Indigenous Population
Duke Energy's operating experience during the past five years under the thermal
limitations imposed in NPDES Permit No. #NC0003468 has ensured that the "thermal
component of the discharge assures the protection and propagation of shellfish, fish and
wildlife in and on the receiving body of water."

Dan, River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 11 of 24
Ash Basin Capacity
DAN RIVER STEAM STATION - Ash Basin Forecasting
Free Water Volume
Determination of Free Water Volume (FWV) FWV is the sum of,the runoff accumulated in the ash basm
which results from,a 10 -yr 24 -hr storm (must assume 100% runoff) + the maximum 24 -hr dry weather waste
stream (DWW) which discharges to the Ash Basin (refer,to Section A 9 - 'Special Condition of NPDES permit NC0003468).
I Estimate Runoff,to Ash Basin from 10 -yr 24 -hr Storm
1 Natural Drainage Area of Ash Basin = 1301 Acres
,Station Yard Area Pumped to Ash Basin = 17.0
Total = 1471 Acres
2. Precipitation from 10 -yr 24 -hr storm =
52
inches
3 Total Stormwater Runoff.to.Ash Basin =
63.74
Ac -ft
II Estimate Maximum 24 -hr Dry WeatherWaste Stream Discharging to Ash Basin
1 From station records, maximum recorded
Ash Basin discharge =
2. Convert max recorded Ash Basin discharge
discharge to units of Ac -ft
710 x10 ^6 gallons /'day
2397 Ac -ft
III Free Water Volume = Sum of (I.) and (II) above = 8771 Ac -ft
IV Estimate Quantity of Solids (Ash) to be Discharged to Ash Basin During Life of Permit
(Refer to PROSYM 1Q 2006 Update)
Note Use 1,2/31/2012 as permit's end date
Cumulative
Time Period
Actual / Pro-
jected Coal
Consumption
1000's tons
Actual /
Projected
Ash %
Estimated
Ash,
Production
1000's tons
Estimated
Ash
Production
Ac -ft
DWW &
Sohdsnto
Ash.Basm
Ac -ft
8/25/05'-
12/31/05
82.7
9.3
7.7
64
941
1/1/06.-
9/30/06
373.1
10.2
38 1
318
125.9
10/l/06-
12/31/06
114.2
12.0
13.7
114
1373
2007
610.5
133
80,9
67.5
2049
2008
6124
13.3
81 1
677
272.6
2009
5937
13 -3
78.7
657
3383
2010
673.1
13 3
892
745
412 ,7
2011
546.3
13.3
_ 724
604
473.2
2012
4832
1 133
640
534
5266

Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 12 of 24
Totals I 4,0892 I I 5257 4389
V Estimate Total Storage Volume Required =,Sum of (III ) and (IV) above:
Free Water Volume = 877 Ac -ft
Estimated Solids to Ash Basin = 438.9
Total= 1 527 Ac -ft
VI Results (Using date of most recent survey„ 8/25/05, as a reference).
Required Storage (thru 12/31/2012) =527 acre -ft.
Available, Storage in.Prnmary°and Secondary Cells of Ash Basin =4094 93.2 = °202 acre -ft.
(See attached stage - storage graphs for Dan River Ash Basin Primary and Secondary Cells )
A project involving the removal of approximately 350,000 cubic .yards of ash from the Primary Cell is planned`for 20064 2007.
350,000 cubic yards = 20 acre -ft.
'Therefore, projected storage °to be made available = 202 + 217 = 419 acre -ft. < required storage of 527,acre -ft.
,Accordingly, future periodic Ash Basin Capacity,cerhficathons will be required and addrtional'ash removal project(s) may be req
Sto rrn Wate r
3.1 Site Description
The site covers approximately 380 acres, most of which forms an undeveloped buffer
around the station. I'n the developed areas, the powerhouse and the plant yard behind the,
powerhouse cover about 2'/2 acres. The Units 1 and 2 switchyard and the Unit 3
switchyard cover a total of about 1'Y2 acres. The,re'is a 2Y acre material laydown area west
of the powerhouse. The station parking lot covers about 3/4 of an acre. The coal pile is
located north of the powerhouse and encompasses 3'/2 acres. The combustion tur'bi'ne
units (CT's) are located upgradient, behind the coal pile, and the total area for these units
'is about 3 acres. The, bulk fuel oil storage tanks and the earthen containment berms
around' them cover approximately 1 acre. The 3/4 acre fuel oil unloading area is located
along the plant access road. The primary and secondary ash settling basins have a
surface area of approximately 35 acres. About 20 acres are designated for dry ash
storage: There are approximately 2'/ miles of rail access and 13/4 miles of paved roadways
on -site.
The Soil Survey of Rockingham County, North Carolina lists soils at Dan River Steam
Station as loamy Udorthents Which is a da_ssification used for topography that has been
altered. Undisturbed soil in areas adjacent to the station indicate that the original site soils

Dan River Steam Station, Rockingham County
NPDES P_ ermit No. NC0003468
Page 13 of 24
along the riverfront were from the Chewacla and Congaree loam series while soils in
upgradient areas -were from the Mayodan sandy loam series. The Chewacla and
`Congaree series are classified as sandy clay 'loam typically found on floodplains. The
Mayodan series are a combination of red, yellow, and gray sandy clay loam, The site
topography is generally flat with rolling hills ,in' outlying, undeveloped areas.
In developed areas, runoff flows overland to ditches and catch basins which are connected
to a buried network of corrugated metal ,pipes (CMP). Rainfall runoff from the coal pile ,and
coal handling areas and portions of the plant yard and powerhouse roof`goes to the yard
sump which discharges to the ash basin. Storm water runoff from other areas of the site is
discharged to the Dan River. Rainfall runoff'from the switchyards, CT area, fuel oil tank
area, and fuel oil unloading area is routed through oil trap tanks prior to being discharged.
3.2 Facility Drainage and Inventory of Significant Materials and Controls
This section details the drainage basin characteristics of the site's storm water outfalls to
the Dan River. To provide a complete description of the storm water drainage system, the
yard sump system is also characterized'. Note the outfalls are not numbered consecutively
because some outfalls have, been abandoned or because ,the intermediate outfall numbers
were previously assigned to non- storm'water- outfalls.
A description of the drainage area, significant materials, and material control measures is
presented for each drainage basin. In addition to the significant materials particular -to
each drainage basin, herbicides are applied annually to selected areas throughout the Dan
River site to eliminate undesirable vegetation along railways, fuel oil ,and ash pipelines,, and
fences. Rip -rap areas at the ash basin dikes, river bank, settling pond, and ditches are
also sprayed. Herbicides are spot applied where required 'in parking areas, switchyards,
parts laydown areas, along walkways, and around various fixtures and buildings. All
,herbicides used at Dan River Stearn Station ,are, approved by the company as
environmentally safe and are applied in an environmentally safe manner and quantity.
Records are retained at the site which document,information such as: the areas treated,
the herbicide used and the amounts of herbicide used.
Storm Water'Outfalls
Characteristics for 14 individual outfalls are presented as follows.
o Storm Water Outfall 2 / NPDES 004
Discharge Structure: 36 inch ( ") diameter (�) CMP
Location: West of powerhouse from Service Water Settling Pond to Dan
River, outlet is submerged
Drainage Area: 147 acres on -site + — 600 acres off -site

Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 14 of 24
Area Description
This outfall conveys overflow from the Service Water Settling Pond. The Service Water
Settling Pond was formed by constructing an embankment across a small stream. The
pond has a surface area of 9 acres. On -site, the drainage basin for the pond is
undeveloped wooded areas, and there, are no paved or roofed areas. Off -site; the
drainage area for the Service Water Settling Pond includes undeveloped wooded areas
and some developed urban and residential areas., In addition to,the natural' stream flow
and storm water runoff, raw river water is pumped from the Dan River- to the Service Water
Settling Pond to provide service waterfor the station. Also, NPDES Discharges 003 and
006 are pumped to the Service Water Settling Pond; both are non - contact cooling water.
Overflow from the, Settling Pond to'the Dan River'is NPDES Discharge 004.
Significant Materials / Controls
Oil: On -site, fuel oil pipelines run aboveground through this drainage area.
• Storm Water Outfall 5 / NPDES 002a and 009
Discharge Structure: 2' Concrete Ditch
Location: In a ravine, east of powerhouse and west, of ash basin
Drainage Area: 1.3.4 acres ,
Control Structures: 20,000 gallon oil trap tank #4 for Units 1 and 2 switchyard -
22',0,00 gallon oil, trap tank #2 for Unit ,6C Combustion Turbine
Area, Description
Runoff from most of the Units 1 and 2 switchyard is processed through oil trap tank #4 and
discharged to Storm Water'Outfall 5. The Units 1 and 2 switchyard covers about 1 1/3
acres. Runoff from the Unit 6C CT area is processed through oil trap tank ° #2 and
discharged to this outfall. The portion -of the CT ,area within, this basin is about 1 2/3 acres.
A 500 foot portion of multiple, parallel rail lines passes through this drainage area, along
with; 500 feet of the paved plant access road. Approximately 20 percent of the drainage
area is paved or roofed. The basin includes open grassy areas between the CT area and
bulk fuel oil, tanks, between the CT's, and railroad tracks, between the switchyard and yard
sump, and a portion of the ash basin dike., Runoff from 'these areas is not routed through
the oil trap tanks.
Yard sump overflow could be conveyed to the Dan River by this outfall. Sump overflow is
NPDES permitted discharge 002a. Sump overflow is non - standard operation. Non- contact
cooling water from the Unit 6C air compressor is conveyed by this outfall, and this
discharge is NPDES permitted discharge 009. Other non -storm water discharges at this
outfall include seepage from the. toe drains at fhe ash basin embankments and
groundwater flow from a spring at the CT's.

Dan River Steam Station, Rockingham County
NPDES Permit No. NCO603468
Page 15 of "24
Significant Materials / Controls
Oil: Fuel' oil pipelines to CT Unit 6C run ,abovegrourfd through thi's area. The fuel oil return
'tank for the CT's has a maximum capacity of 500 gallons. The main lube oil tank for
CT Unit 6C has a maximum capacity of 1,500 gallons. The CT- Unit 6C transformer
contains 4,880 gallons of mineral, oil. All -runoff, from these source areas is processed
through oil trap tank #2 which has a capacity of 22,000 gallons.
Ash:
The yard sump transformer contains 156 gallons of mineral oil. A transformer
associated "with the new coal unloader contains 207 gallons of mineral, oil. Both of
these transformers are located on small concrete pads with low curbs. Neither of
these, tanks is located within the areas protected by oil trap tanks.
Switchgear `in the Units 1 and 2 switchyard contains about 86,500 gallons of mineral
oil, and 95 percent of the equipment is located within drainage area 5. The largest
volume contained by any single component is 7,800 gallons. There is an empty, out
of service, 16,0,00 gallon transfer tank adjacent to the switchyard. During transformer
maintenance, oil from the piece of equipment being worked on was drained to the
transfer tank and then transferred back after the maintenance was, complete. Now, an
8,000 gallon tanker truck is used to hold the oil during maintenance. Runoff from most
of the switchyard is processed through a 20,000 gallon oil trap tank, and runoff from-
the other small portion of the switchyard goes to the yard sump.
Ash pipelines run through this drainage,area, going to the ash basin.
Coal:
Coal is transported by rail lines through this area.
Wastewater:
Yard sump pipelines run through this drainage area, to the ash basin.
Laydown Area:
Spare equipment, parts, steel, iron, cable, and miscellaneous supplies are stored on
covered racks adjacent to the CT warehouse on the northeast side and on the
concrete pad on the northwest side. The equipment and supplies generally do not
contain liquids.

• Storm Water O
Discharge Structure:
Location:
Drainage Area:
Control Structures:
Dan River Steam Station, Rockingham County
NPDES Permit,No. NC0003468'
Page 16 of 24
utfall 7
44' Reinforced Concrete Pipe (RCP)
From CT area, beneath the ash basin, to Dan River
49,.9 acres onsite + roadway drainage from offsite
20,000 gallon oil trap tank #1 for Units 4C & 5C CT's
Earthen berms around bulk fuel oil tanks
Area Description
This culvert begins in a low lying area downgradient of the CT's and runs beneath the ash
basin to the Dan River. It was originally installed to pass flow from a.small stream beneath
the railroad tracks. Runoff from most of the Units 4C and 'SC CT area, the fuel' oil
unloading area, and the bulk fuel oil tank area is routed through oil trap tank #1 and then
discharged to the low lying area where the 4' RCP begins. The Units 4C and 5C CT's
cover about 1 1/3 acres: The bulk fuel oil tanks and the earthen berms-around them cover
approximately 1 acre, and the fuel oil unloading area contains about 3/4 of an acre. The
area also includes open grassy areas between the CT area and railroad tracks and
between the CT's and fuel oil tanks and fuel oil unloading area. A large portion of this
drainage area is an undeveloped tract north and east of the CT's. Runoff from the
undeveloped areas 4is 'routed to the low lying area Where'the 4' RCP begins, and it is not
processed through the oil trap tank. An 850 foot portion of multiple; parallel rail lines
,passes through this drainage area along with about mile (onsite) of the paved plant
access road. Roadway drainage from an offsite portion of the plant access road would,
flow to this outfall. Approximately 8 percent' of the drainage area is paved or roofed.
Non - storm water discharges at this outfall include seepage from the' toe drains at the .ash
basin embankments and flow from a small stream between the CT's and the plant access
road. These flows are not processed through the oil trap tank.
Significant Materials / Controls
Oil: Fuel oil pipelines run aboveground through this area. Inside'the purifier house, the CT
purifier tank contains 1,000 gallons of lube oil. The main lube oil tanks for CT Units
4C and 5C have ,a maximum capacity of 1,500 gallons each. The CT Units 4C and 5C
transformers each contain 5,463 and 4,473 gallons of mineral oil, respectively. All
runoff from these source areas is processed through oil trap tank #1 which has a
,capacity of 20,000 gallons.
The fuel oil bulk storage tanks are aboveground, galvanized steel cylinders
surrounded by earthen berms sufficient in height to contain a total spill plus rainfall.
Each. tank has a total tank capacity of 500,000 gallons. Only one tank is ever in
service at any given time, and the other is considered permanently closed. Whenever
tank inspections are required, oil from the in -use tank is transferred to the other tank.
There are catch basins inside 'the berms. 'The outlet for these catch basins has a

' Dan River Steam Station, Rockingham County
'NPDES Permit No. NC0003468
Page 17 of 24
valve which is normally closed. There is a manual siphon that can be used to drain
the accumulated rainfall from within the berms ,if there is significant standing water.
The water is inspected for the presence of oil prior to siphoning. Water drained from
within the berms is routed to oil trap tank #1.
In the 'fuel oil unloading area, fuel is transferred from an 8,000 gallon tanker truck to
the bulk storage tank via pipelines. DOT unloading procedures are followed. The fuel
oil unloading area is paved and surrounded by a concrete curb. 'The two unloading
bays are covered and, enclosed on three sides. Spill clean -up supplies are located
nearby. Runoff from the fuel oil unloading area is routed through,oil trap tank #1.
Coal: Coal is transported by rail lines through this area.
• Storm Water Outfail 8
Discharge Structure: 3' � RCP
Location :, From undeveloped area between dry ash storage area and
ash basins, beneath the ash basin, to Dan River
Drainage Area: 2.9 acres
Area Description
This outfall conveys runoff from an undeveloped area between the dry ash storage area
and the ash basins. This culvert begins in a low lying area downgradient of the dry ash
storage area and runs beneath the ash basin to the Dan River. An 850 foot portion of
multiple, parallel rail lines passes through this drainage area. There are no paved or
roofed areas in this drainage area.
Non -storm water discharges at this outfall include seepage from the toe drains at the ash
basin embankments and groundwater flow from a spring.
Significant Materials / Controls
Coal: Coal is transported by rail lines through this area.
• Storm Water Outfall 9
Discharge Structure: 12" ,� CMP
Location: West of the powerhouse, beside the, battery house
Drainage Area: 0.8 acres
Control Structure: 6,000 gallon oil trap tank #3
Area 'Description
This outfall conveys runoff from the Unit 3 switchyard and from the Unit 3 boiler and turbine
room roofs. The Unit °3 transformers are elevated above the yard area on a 4,400 ft2
concrete platform with drains that flow to the pipe network that feeds the oil trap tank #3.

Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 18 of 24
The Unit 3 roof covers about %2 acre, and the roof drainage.goes through the oil trap tank.
Approximately 75 percent of the drainage area is paved or roofed.
Significant Materials / Controls
Oil: The Unit 3 transformers contain a total of 18;362 gallons of mineral oil. The largest
volume contained by any single component is 4,960 gallons. There is an empty, out
.of service, 8,000 gallon transfer tank located adjacent to the switchyard. This tank
was formerly used to hold mineral oil drained from switchgear equipment during
transformer maintenance. Now, �an 8,000 gallon tanker truck is used to hold the oil
during maintenance. All runoff from these source areas it processed through a 6,000
gallon oil trap tank.
The fuel tank for the supplemental air compressor can hold 80 gallons of diesel fuel.
The supply tank for the compressor has a capacity of, 550 gallons. The supply tank is
a double -wall steel 'tank. 'Both the ,com,pressor, and the supply tank ,are located on a
curbed concrete pad at the front corner of the powerhouse. The catch basin inside
the curbed area is routed to oil trap tank #3.
Storm'Water Outfall 1'2 / NPDE9 007
Discharge Structure: 8" � CMP
Location: West of powerhouse,
booster°pump house
Drainage Area: 0.2 acres
between the battery house and the
Area Description
This outfall conveys runoff from a, small, flat area around the battery and booster pump
houses. T,he roofs of those buildings cover 600 ft2, so ,8 percent of the drainage area is
roofed.
NPDES discharge 007 is conveyed through this outfall. NPDES discharge 007 is non -
contact, cooling water from the booster pump engine for the intake dredge machine. The
intake is dredged annually for about 2 -3 weeks.
Significant Materials / Controls
There are no significant materials exposed to storm water within this area.
• Storm Water Outfall 14
Discharge Structure: 12" � CMP
„Location: West of powerhouse,
building and the storage racks
Drainage Area: 1.8 acres
between the maintenance storage

Dan RiveriSteam Station, Rockingham County
NPDES Perm_ it No. NC0003468
Page 19 of 24
Area Description
This outfall conveys runoff from the large laydown area west of the powerhouse and. from
areas adjacent to the oil storage house. The laydown area covers most of this drainage
basin. The laydown yard is extremely flat, and covered with gravel. The oil storage, house
sits atop an embankment, and a catch basin in front of the oil storage house drains to an
outlet at the base of t'he embankment. All other flow in this drainage area is overland to
ditches that lead to the outfall. About 15 percent of thi's drainage area is paved or roofed.
Significant Materials / Controls
Laydown Area:
Spare .equipment, parts, steel, iron, cable, and miscellaneous supplies are stored ,in a
large flat, gravel laydown yard west of the powerhouse. The equipment and supplies
generally do'not contain liquids.
Oil: Various types of new oil and lubricants are stored in 55- and 25- gallons drums under
cover `in the oil storage house. The total' amount of oil in the OR storage house is
approximately 3,500 gallons. The storage area is enclosed on three sides. The floor
is sloped to drain to a small trench at the back side of the shed. The trench drains to
a small sump with an estimated capacity of 200 gallons.
Chemicals:
Drums of new solvents and cleaners are stored under cover in the oil storage house.
The total amount of cleaners and solvents stored in the oil storage house is
approximately 300 gallons. The storage area is enclosed on three sides. The floor is
sloped to drain to a small trench, at the back side of the shed. The trench drains to a
small sump with an estimated capacity of 200 gallons.
Waste Storage and Collection Areas:
Various waste products and batteries are stored under cover in the oil storage house.
The storage area is enclosed on, three sides, and the floor, is,slo,ped to drain to a small
trench at the back- side of the shed. The trench drains to a small sump with an
estimated capacity of 200 gallons., Paint wastes and used solvents are stored
separately in Polyspill Pallet Cover containers adjacent to the. northeast corner of the
oil storage house.
® Storm Water Outfall 15 Discharge Structure: Three 6" � steel pipes
Location: West of powerhouse, beside the storage racks
Drainage Area: 0.8 ,acres
Area Description
This outfall conveys runoff from the large laydown area west of the powerhouse. The
la,ydown yard is� extremely flat and covered with gravel. All flow in this drainage area is
overland to a ditch that leads to the outfall. None of this drainage area 'i's paved or roofed.

Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 20 of 24
Significant Materials / Controls
Laydown Area:
Spare equipment, parts, steel, iron, cable, and miscellaneous supplies are stored in a
large flat, gravel laydown yard west of the powerhouse. The equipment and supplies
generally do ,not contain liquids.
• Storm Water Outfall 16
Discharge Structure: 4" � Steel Pipe
Location: Exterior Wall of Unit' 3 Screen Room
Drainage Area: 575 ft2
Area Description
This outfall conveys roof drainage from the western half of the Unit 3 screen room roof.
100 percent of the drainage area is roofed.
Significant' Materials / Controls
Significant materials are not stored on the roof.
• Storm Water Outfall 17
Discharge Structure: 4"" � Steel Pipe
Location: Exterior Wall of Unit 3 Screen Room
Drainage Area: .575 ft2
Area Description
This outfall conveys roof drainage from the, eastern half of the Unit 3 screen room' roof.
100 percent of the drainage area 'iS roofed.
Significant Materials / Controls
Significant materials are not stored on the roof.
• Storm Water Outfall 1'8
Discharge Structure: 4" � Steel Pipe
Location: Exterior Wall of Old Chlorinating Room
Drainage Area: 600 ft2
Area Description
This outfall conveys roof drainage from the roof of the chlorinating room. 100 percent of
the drainage area is roofed.
Significant Materials,/ Controls
Significant materials are not stored on the roof.

Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 21 ,of 24
• Storm Water Outfall 19
Discharge Structure: 4" � Steel Pipe
Location: Exterior Wall of Units 1 and 2 Screen Room
Drainage Area: 750 ft2
Area Description
This outfall conveys roof drainage from the western half of the, Units 1 and 2 screen room
roof. 100 percent,of,the drainage area is roofed.
Significant Materials / Controls
Significant materials are not stored on the roof.
Storm Water Outfall 20
Di's_ charge Structure: 4" � Steel Pipe
Location: Exterior Wall of Units 1 and 2 Screen Room
Drainage Area: 750 ft2
Area Description
This outfall conveys roof drainage from the eastern half of the, Units 1 and 2 screen room
roof. 1'00 percent of the drainage area is roofed.
Significant Materials / Controls
Significant materials are not stored on the roof.
s Storm Water- Outfalt 211 NPDES'005
Discharge Structure: 8" � Steel Pipe
Location: Exterior Wall of Units 1 and 2 Turbine Room
Drainage Area: 0.3 acres
Area Description
This outfall conveys roof drainage from the Units 1 and 2 turbine room roof. 100 percent of
this drainage area is roofed.
NPDES discharge 005 is non- contact cooling water from the Units 1 and 2 ,fans and
preheaters, and it is discharged through Storm Water'Outfall 21.
Significant Materials / Controls
Significant materials are not stored on the roof.
Yard Sump
The yard holding basin 'is located northeast of the Units 1 and 2 switchyard. The drainage
area for the yard sump is about 11.9 acres. Effluent from the yard holding sump is pumped
to the ash basin. Overflow from the yard sump could reach' the Dan River via, Storm Water
Outfall 5. Overflow from the yard sump is permitted as NPDES discharge 002A. Overflow
from the yard sump is not standard operating procedure.

Dan River Steam Station, Rockingham County
NPDES Permit,No. NC0003468
Page 22 of 24
Area Description
Industrial wastewater from the powerhouse and coal handling sumps flows to the yard
sump. 'Storm water runoff from, a portion of the powerhouse roof, a portion of the Units 1
and 2 switchyard, the plant yard, the parking lot, and the coal pile and coal handling
facilities goes to the yard sump. The total roofed area in this drainage basin 'is 3/ acres
and includes the Units 1 and 2 boiler room roof, the warehouse roof, the tractor shed, and
the roofs of'the coal handling facilities. The station parking lot covers about 3/4 of an acre,
between the railroad tracks and the Units 1 and 2 switchyard. Approximately % mile of the
plant access road passes through, this drainage area. About 20 percent of this drainage
basin is paved or roofed. The coal pile encompasses 30 percent of this drainage area. A
1,250 foot portion of multiple, parallel rail lines passes through this drainage area.
'Significant Materials / Controls
Oil: The 11 transformers for the precipitators contain a 'total of 1,806 gallons of mineral oil.
The maximum oil content of any single, component is 176 gallons. These transformers
are located overhead, and a spill would fall to the roof and /or pavement. A
transformer at the old coal handling facility contains 400 gallons, of mineral oil. A
transformer at the dozer maintenance shed contains 220 gallons of mineral oil.
Used oil is stored in a 1,,200 gallon steel tank located west of the coal sampling
building. The tank is surrounded by a concrete dike about 2 feet tall. Rainfall that
accumulates inside the dike can be drained by opening ,a valve that drains to a catch
basin which leads to the yard sump. The valve is normally closed. When the used oil
tank is full, the product is removed from site by tanker truck.
Drums of new and 'used oil in the dozer maintenance shed contain a total of
approximately 440 gallons of product. Drainage from the tractor shed and from the
concrete pad at the tractor shed fuel oil dispenser is routed to a 1,000 gallon oil trap
tank that discharges onto the coal pile.
A fuel oil dispenser for the locomotives is located at, the northwest corner of the coal
sampling building. A fuel oil line runs overhead from this dispenser to the dozer
refueling area inside the coal pile retaining wall.
Laydown Area:
Spare equipment, parts, steel, iron, cable, and miscellaneous supplies are stored in
racks 'under cover outside the locomotive shelter. The supplies generally do not
contain liquids.

Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 23 of 24
Gasoline:
There is ,a 500 - gallon aboveground, carbon steel ,gasoline tent tank and dispenser
across from the warehouse. The tank is completely enclosed within a steel tent
enclosure, and any leaks would be self contained., The enclosure can be drained by
opening a valve,, and that valve remains closed at any'other time. The tank is filled by
a 1,500 .gallon tanker truck. Cleanup supplies are located nearby.
Wastewater, Plant wastewater from 'equipment discharges, floor drains, sumps, etc. is
routed to the yard sump. This wastewater may include oil, chemical, and hazardous
waste spills.
Parking:
There ',is a,-% acre parking lot between the railroad tracks and the Units 1 and 2
switchyard.
Coal: Coal dust is present along the railroad tracks and coal handling areas.
Chemicals:
There is a 5,000 gallon tank of sulfuric acid, located in the northwest corner of the,
parking lot. The tank is surrounded by a concrete dike.
3.3 Identification of Non -Storm Water Discharges
Non -storm water discharge is conveyed through Storm Water Outfalls 2, 5, 7, 8, 12, and
21. The non -storm water discharge at Storm Water Outfall 2 is NPDES discharge 004„
and the non -storm water discharge consists of raw river water pumped from the Dan River
to the settling pond for use as station service water, stream flow from the branch that feeds
the pond, and NPDES discharges 003 and 006 to the Service Water Settling Pond. The
non -storm water discharge at Storm Water Outfall 5 consists of NPDES discharges 002A
and 009, seepage from the toe drains at the ash basin dikes, and flow from a groundwater
spring at the CT's. Non -storm water discharge at Storm Water Outfall 7 includes seepage
from the toe drains at the ash basin dikes and flow from a small stream between the CT's
and the plant access road. Non -storm water discharge at Storm Water Outfall 8 includes
Seepage from the toe drains at the ash basin dikes and flow from a ,groundwater spring
between the ash basins and the dry ash storage project. The non -storm water discharge
at Storm Water Outfall 12 is NPDES discharge 007. The non -storm water discharge at
Strom Water Outfall 21 is NPDES discharge 005.
Visual assessments for non -storm water discharges have also been conducted. Each
outfall was observed for outflow after a period of at least 3 (three) days of dry weather.

Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 24 of'24
3.4 'Monitoring and Sampling Data
There are 14 storm water outfalls at Dan River Steam Station. Monitoring all of the storm
water outfalls at Dan River Steam Station should not be necessary since many of the
outfalls convey storm water from areas of substantially identical activities and materials.
There are seven land use categories: roof drainage, switchyards, plant yard, open grass -
or wooded undeveloped areas, material laydown areas, the combustion turbine area, and
the fuel oil tank, area and fuel oil unloading area. Most drainage areas have more than one
land use. Storm Water Outfalls 5 and 9 are recommended for sampling. Samples from
these outfalls should be characteristic of all the land uses, significant materials, and
activities. Drainage areas and, thus, outflows vary among the outfalls.
Storm water samples have been collected and analyzed for Storm Water Outfalls SWO05
and SW009.

.;.
�.� , z _ _ ..,a..
,•,

GROUNDWATER MONITORING, WELL CONSTRUCTION, AND SAMPLING
1. The permittee shall conduct groundwater monitoring as may be required to determine
the compliance of'this�NPDES permitted facility with the current groundwater Standards
found under 15A NCAC 2'L.0200.
2 `WELL CONSTRUCTION. Within 1,20 days, of permit issuance, monitoring wells, as
proposed on the Attachment, shall' be installed to monitor�groundwater quality:
a Monitoring wells shall be constructed in accordance with 15A NCAC 02C 0108
(Standards of Construction for Wells Other than Water Supply) and any other
jurisdictional laws and regulations pertaining to well construction. The genera;
locations for all monitoring wells are indicated on,Attachment XX.
'b. The Winston-:Salem Regional Office, telephone number (336) 771 -5000 shall
approve,the location of new monitoring wells prior to installation The regional
office, shall be notified at least 48 hours prior, to the construction of any
monitoring well and such notification to the Aquifer Protection Section's
regional supervisor shall be made from 8:00 a m until 5:00 p.m. on Monday
through Friday, excluding State Holidays
C. Within-60 days of completion of the monitoring wells, the Permittee shall
submit two original copies of a -site map 'with a- scale no greater than 1 -inch
equals 500 feet. At a minimum, the map shall, 'include, the following
Information:
i The location and identity of each monitoring well.
Ii The location of mayor components of the waste disposal system.
iii. The 'location of property boundaries Within 500 feet of, the disposal
areas.
iv The latitude and longitude of the established horizontal control
monument.
V. The elevation of the, top of the well casing '(i.e., measuring point)
relative to a common datum
vi. The depth of water below the measuring point at the time the
measuring point is established
vii The location of compliance and review boundaries
.viii. The date the map is,prepared and /or revised.
ix Topographic contours in no more than'ten (10) foot intervals
d The above information should be overlaid on the most recent, aerial',photograph
taken of'the site Control monuments shall be. installed in such a manner and
made of such materials that the monument will not be destroyed due to
activities taking place on the property. The map and any supporting
documentation shall be sent to the Division of Water Quality, Aquifer Protection
'Section, 1636 Mail Service Center, Raleigh, NC 27649,1636
e `The well(s) must be constructed by a North Carolina, Certified Well, Contractor,
the property owner, or the property lessee according to General Statutes 87-
98.4. If the construction is not performed by a certified well contractor, the
property owner or lessee, provided they.are a natural person, must physically
perform the actual well construction activities
f The ,monitoring wells shall 'be regularly maintained Such maintenance shall
include ensuring that the well caps are `rust -free and locked at all times, the
outer casing is upright and undamaged; and the well does, not serve as a conduit
for contamination
NPDES Well Construction and Groundwater Monitoring Page 1 of 4 12/20/2010

3. GROUNDWATER SAMPLING. Monitoring wells shall ,be sampled after construction and
thereafter at the frequencies and for the parameters as specified in the Attachment All
mapping, well construction forms, well abandonment forms and monitoring data shall
refer�to the permit number and the well nomenclature as provided on the Attachment.
a. Per 15A NCAC 02H 0800, a Division certified laboratory shall conduct all
laboratory analyses for the required effluent, ,groundwater,or surface water
parameters
bi The measurement ofwater levels shall 'be made priorto purging,the wells. The
depth to water in ,,each well ,shall be,rmeasured, from the surveyed point- on the
top of the casing:' The;measurement of pH shall be, made after purging and prior
to sampling for the remaining,parameters-
c. The measuring points (top of well casing) of all monitoring wells shall be
surveyed to provide the relative elevation of the, measuring point for each
monitoring well The measuring points (top of casing) of all monitoring wells
shall be; surveyed relative to avcommon datum.
d. For initial sampling of monitoring, wells, the, Permittee.shall submit a Compliance
Monitoring Form (,GW -59), and a Well Construction Record Form (GW -1) listing
this permit number and the appropriate monitoring well identification number.
Initial Compliance Monitoring Forms (GW -59) without copies of the Well
Construction Record Forms (GW -1) are deemed incomplete, and may `be
returned to -the Permittee without °being processed.
e. Two copies of the monitoring well sampling; and analysis results shall be
- submitted on a Compliance Monitoring Form (GW -59), along with attached
copies of laboratory analyses, on or before the, last working day of the month
following the sampling month. The Compliance Monitoring Form (GW =59) shall
include this permit number, the appropriate well identification number, and one
GW -59a certification form shall be submitted with each set of sampling "results:
All information shall,be submitted to,the following address:
Division of Water-Quality
Information Processing, Unit,
1617 Mail Service Center
Raleigh, North Carolina 27699 -1617
f. For monitoring wells inside the compliance boundary (for list, see attached
groundwater monitoring clan).
(i) These wells shall ,be sampled for the same parameters and at the same
frequency as required by the attached groundwater monitoring plan
(ii) The sampling data shall be submitted to the Winston -Salem Regional
Office at the following address:
Division of Water Quality
Aquifer Protection Section
Attn: APS Supervisor
585 Waughtown Street
Winston - Salem, NC 27107 -2241
N,RDES Well Construction,and Groundwater`Monrtonng Page 2 of 4 12/20/2010

(iii) If a parameter exceeds the groundwater quality standards for two
consecutive sampling periods, predictive calculations shall be made
from the referenced well to a point at the nearest compliance boundary
in order to demonstrate compliance within the current groundwater
standards This demonstration shall be submitted to the Winston -Salem
Regional Office at the above address.
(iv) After the first demonstration of compliance is made for a parameter„
the Winston -Salem Regional Office shall determine the method and
frequency of'future demonstrations of compliance for that parameter.
4. COMPLIANCE BOUNDAWY The compliance boundary for the disposal system shall be
specified in accordance with 15A NCAC 02L .0107(a). This disposal system was
individually permitted prior to December 30, 1983; therefore, the compliance boundary
is established at either 500'feet from the effluent disposal area, or at the property
boundary, whichever is closest to the effluent disposal area. An exceedance of
groundwater standards'at or beyond the compliance boundary'is subject to remediation
action accordmg,to 15A NCAC�021_ .0106(c) as well as enforcement actions in accordance
with North, Carolina General Statute 143=215.6A through 143,215.6C.
NPDES Well Construction and Groundwater Monitoring Page 3 of 4 12/20/2010

ATTACHMENT — GROUNDWATER MONITORING PLAN
Permit Number: Ne0003468 Version 1.0
WELL
NOMENCLATURE
PARAMETER DESCRIPTION
FREQUENCY
Monitoring Wells: *MW-
9D, *MW -10D, *MW -11D
MW-,20S, MW -20D, MW-
21S,,MW -21D, MW -235,
MW -23D
Antimony
Chloride
Manganese
Sulfate
March, June,
September
Arsenic
Chromium',
Mercury'
TDS
Barium,
Copper
Nickel
Thalhum
Boron
Iron
Nitrate
Water °Level
Cadmium
Lead
PH
Zinc
Selenium
Note 1 For locations of monitoring wells, see attached map
Note 2 Monitoring revisions may be considered, as applicable, if there -are no significant detections prior to pemut
renewal
Note 3 Monitoring wells inside the compliance boundary are indicated with an asterisk Please�see paragraph 3(0
of the Groundwater Monitoring, Well Construction, and' Sampling section for monitoring submittal instructions.
NPDES Well Construction and Groundwater Monrtormc, Page 4�of 4 12/20/2010

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Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 19 of 24
Area Description
This outfall conveys runoff from the large laydown area west of�the powerhouse and from
areas adjacent to the oil storage house. The laydown area covers most of this drainage
basin. The laydown yard is extremely flat and covered with gravel. The oil storage house
sits atop an embankment, and a catch basin in front of the oil storage house drains to an
outlet at the base of the embankment. ,All other flow in 'this drainage area 'is overland' to .
ditches that lead to the outfall. About 15 percent of this drainage area is paved or roofed.
Significant Materials / Controls
Laydown Area:
Spare equipment, parts, steel, iron; cable, and miscellaneous supplies are stored in a
large flat, gravel laydown yard west of the powerhouse. The equipment and supplies
generally do not contain liquids.
Oil: Various types of new oil and lubricants are stored 'in 55- and 25- gallons drums under
cover in the oil storage house. The total amount of oil in the oil storage house is
approximately 3,500 gallons. The storage area is enclosed on three sides. The floor
is sloped to drain to a small trench at the back side of the shed. The trench drains to
a small sump with an estimated capacity of 200 gallons.
Chemicals:
Drums of new solvents and cleaners are stored under cover in the oil storage house.
The total amount of cleaners and solvents stored in the oil storage house is
approximately 300 gallons. The storage area is enclosed on three sides. The floor is
sloped to drain to a small trench, at the back side of the shed. The trench drains to a,
small sump with ,an estimated capacity of 200 gallons.
Waste Storage and Collection Areas:
Various waste products and batteries are stored under cover in the oil storage house.
The storage area is enclosed on three sides, and the floor'is sloped to drain to a small
trench at; the back side of the shed. The 'trench drains to a small sump with an
estimated capacity of 1200 gallons. Paint wastes and used solvents are stored
separately in Polyspill Pallet Cover containers adjacent to the northeast corner of the
oil storage house.
• Storm Water Outfall 1r5
Discharge Structure: Three 6" � steel pipes
Location: West of powerhouse, beside the storage racks
Drainage Area: 0.8 acres
Area 'Description
This outfall conveys runoff from the large laydown area west of the powerhouse. The
laydown yard is extremely flat and covered with gravel. All flow in this drainage area is
overland to a ditch that leads, to the outfall. None of this drainage area is paved, or roofed.

, ' s V
Dan River'Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 20 of 24
Significant Materials,/ Controls
Laydown Area:
Spare equipment, parts, steel, iron, cable, and miscellaneous supplies are stored in a,
large flat, gravel laydown yard West of the powerhouse. The equipment and supplies
generally do not contain liquids. '
Storm Water Outfall 16
Discharge Structure:, 4" � Steel Pipe
Location: Exterior W'a'll of Unft 3 Screen Room
Drainage Area: 575 ft2
Area Description
This outfall conveys roof drainage from the western half of the Unit 3 screen room roof.
1,00 percent of the drainage area is roofed.
Sign ificant_Materials / Controls
Significant materials are not, stored on the roof.
® Storm Water Outfall 17
Discharge Structure: 4" 0 Steel Pipe
Location: Exterior Wall of Unit 3 Screen Room
Drainage Area: 575 ft2
Area Description
This outfall conveys roof drainage from the eastern half of the Unit 3 screen room roof.
100 percent of the drainage area is roofed.
Significant Material's / Controls
Significant materials are not stored on the roof.
• Storm Water Outfall 18
Discharge Structure: 4" ,Steel Pipe
Location: Exterior Wall ,of Old Chlorinating Room
Drainage Area: 600 ft2
Area Description
This outfall' conveys roof drainage from the `roof of the chlorinating room. 100 percent of
the drainage area is roofed.
Significant Materials / Controls
Significant materials are not stored on the roof.

Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 21 of 24
• Storm Water Outfall ,19
Discharge. Structure: 4" � Steel Pipe
Location: Exterior Wall of Units 1 and 2 Screen Room
Drainage Area: 750 ft2
,Area Description
This outfall conveys roof drainage from the western half of the Units 1 and 2 screen room
roof. 100 percent of the drainage area is roofed.
Significant Materials./ Control's
Significant materials are not stored on the roof.
• Storm Water Outfall 20
Discharge Structure: 4" 0 Steel Pipe
Location: Exterior Wail of Units 1 and 2 Screen Room
Drainage Area: 750 ft2
Area Description
This outfall conveys roof drainage from the eastern half of the Units 1 and 2 screen room
roof. 100 percent of the drainage area is roofed.
Significant Materials / Controls
Significant material's are not stored, on the roof.
• Storm Water Outfall 21 / NPDES 005
Discharge Structure`: B" � Steel Pipe
Location: Exterior Wall of Units 1, and 2 Turbine Room
Drainage Area: 0.3 acres
Area Description
Thi's outfall conveys roof drainage from the Units 1 and 2 turbine room roof. 100 percent of
this drainage area is roofed.
NPDES discharge 005 is non - contact cooling water from the Units 1 and 2 fans and
preheaters, and it is discharged through Storm Water Outfall 21.
Significant Materials / Controls
Significant materials are not stored on the roof.
Yard Sump
Tho yard holding basin is located northeast of the Units '1 and 2 switchyard. The drainage
area for the yard sump is about 11.9 acres. Effluerit'from the yard holding sump is pumped
to the ash basin. Overflow from the yard sump could reach the Dan River via Storm Water
Outfall 5. Overflow from the yard sump is permitted as NPDES discharge 002A. Overflow
from the yard sump is not standard operating procedure.

'4• ,
Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 22 of 24
Area Description
,Industrial wastewater from the powerhouse ,and coal handling sumps flows to the yard
sump. Storm water runoff from a portion of the powerhouse roof, a portion of the Units 1
and 2 switchyard, the plant yard, the parking lot, and -the coal pile and coal handling
facilities goes, to ;the yard sump. The total roofed area, in this drainage basin is 3/ acres
and includes the Units 1 and 2 boiler room roof, the warehouse roof, the tractor shed, and
the roofs of the coal handling facilities. The station parking lot covers about 3/, of an acre
between the railroad' tracks and the Units 1 and 2 switchyard. Approximately' /4 mile of the
plant access road passes through this drainage area. About 20 percent of this drainage
basin is paved or roofed. The coal pile encompasses 30 percent of this drainage area. A
1,250 foot portion of multiple, parallel rail lines passes through this drainage area.
Significant Materials / Controls
Oil-- The 11 transformers for the precipitators contain a total of 1,806 gallons of mineral oil.
The maximum oil content of any single component is 176 gallons. These transformers
are located overhead, and a spill would fall to the roof and /or pavement. A
transformer at the old coal handling facility contains 400 gallons of mineral oil. A
transformer at the dozer maintenance shed contains 220 gallons, of mineral oil.
Used oil is stored in a, 1,200 gallon steel tank located west of the coal sampling
building. The tank is surrounded by a concrete dike about 2 feet tall. Rainfall that
accumulates inside -the dike can be drained by opening a valve that drains to a catch
basin which leads to the yard sump. The valve is normally - closed. When the used oil
tank is full, th-e product is removed from site by tanker truck.
Drums of new and used oil in the dozer maintenance shed contain a total of
approximately 440 gallons of product. Drainage ,from the tractor shed and from the
concrete pad at the tractor shed fuel oil dispenser is routed to a 1,000 gallon oil trap
,tank'that discharges, onto the coal pile.
A fuel oil dispenser for the locomotives 'is located, at the northwest corner of the coal
sampling building. A fuel oil line runs overhead. from `this dispenser to the dozer
refueling area inside the coal pile retaining wall.
Laydown Area:
Spare equipment, parts, steel, iron, cable, and miscellaneous supplies are stored in
racks under cover outside the locomotive shelter. The supplies generally do not
contain liquids.

+ Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 23 of 24
Gasoline: ;
There is a 500 - gallon aboveground, carbon steel gasoline tent tank and dispenser
'across from the warehouse. The tank is completely enclosed within a steel tent
,enclosure, and any leaks would be self contained. The enclosure can be- drained by
opening a valve, and that valve remains closed at any other time. The tank is filled by
a 1,500 gallon tanker truck. Clean up supplies are Located nearby.
Wastewater: Plant wastewater from equipment discharges, floor drains, sumps, etc. is
routed 'to-the yard sump. This wastewater may 'include' oil, chemical, and hazardous
waste spills.
Parking:
There is a 3/4 acre parking .lot between the railroad tracks and the Units 1 and 2
switchyard.
Coal: Coal dust is present along the railroad tracks and coal handling areas.
Chemicals:
There is a 5,,000 gallon tank of sulfuric acid located in the northwest corner of the
parking lot. The tank is surrounded by a concrete dike.
3.3 Identification of Non -Storm Water Discharges
Non -storm water, discharge,is conveyed through Storm Water Outfalls 2, 5,, 7, 8', 12, and
21. 'The non -storm water discharge at Storm Water Outfall 2 is NPDES discharge 004,
and the non -storm water discharge consists of raw river,water pumped from the Dan River,
to the settling pond ,for use as station service water, stream flow from the branch that feeds
the pond, and NPDES discharges 003 and 006 to the Service Water Settling Pond. The
non -storm water discharge at Storm Water Outfall 5 consists of NPDES discharges 002A
and 009, seepage from the toe drains at the ash basin dikes; and flow from a groundwater
spring at the CT's. Non -storm water discharge at Storm Water Outfall 7 includes seepage
from the toe drains at the ash basin dikes. and flow from a small stream between the CT's
and the plant access road. `Non -storm water discharge at Storm Water Outfall 8 includes
seepage from the toe drains at the ash basin dikes and flow from, a groundw,ater.spring
between the ash basins and the dry ash storage project. The non -storm water discharge
at Storm, Water Outfall 12 is NPDES discharge 007. The non -storm water discharge at
Strom Water Outfall 21 is NPDES discharge 005.
Visual assessments for non -storm water discharges have also been conducted. Each
outfall was observed for outflow after a period of at least 3 (three,) days of dry'weather.

.1 . ♦ . .
3.4' Monitoring and Sampling Data
Dan River Steam Station, Rockingham County
NPDES Permit No. NC0003468
Page 24 of 24
There are 14 storm water outfalls at Dan River Steam Station. Monitoring all of the storm
water outfalls at Dan River Steam Station should not be necessary since many of the
outfalls convey storm water from areas of substantially identical activities and materials.
There are seven land use categories: roof drainage, switchyards, plant yard, open grass
or wooded undeveloped areas, material laydown areas, the combustion turbine area, and
the fuel oil tank area and fuel oil unloading area. Most drainage areas have more than one
land use. Storm Water Outfalls 5 and 9 are recommended for sampling. Samples from
these outfalls should be characteristic of all the land uses, significant materials, and
activities. Drainage areas and, thus, outflows vary among the outfalls.
Storm water samples have been collected and analyzed for Storm Water Outfalls SW005
and SW009.

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