Loading...
HomeMy WebLinkAboutAllen Steam Facility - Duke Energy (17)IkO Duke Energy. February 17, 2011 Mr. Bradley Bennett Division of Water Quality Stormwater Permitting Unit North Carolina Department of Environment and Natural Resources 1617 Mail Service Center Raleigh, NC 27699-1617 Subject: NPDES Stormwater Permit Application Allen Steam Station Dear Mr. Bennett: CORPORATE EHS SERVICES Duke Energy 526 South Church St. Charlotte, NC 28202 Mailing Address: EC13K / PO Box 1006 Charlotte, NC 28201-1006 ��r= lLgOWR O E 2 l 2011 DENR - WATER Branch Duke Energy requests a stormwater discharge permit for the Allen Steam Station located in Gaston County, North Carolina. Please find attached three sets of the following documents related to this permit request: a. EPA Form 1; b. EPA Form 2F; C. EPA Form 2F Supplemental Information; d. Available stormwater analytical data; e. DWQ ROS Request Form; f. ROS Form Supplemental Information; g. Site Location Map h. Site Stormwater Plan Drawing Numerous stormwater outfalls are located at the Allen Steam Station. The accompanying stormwater analytical data was obtained from samples collected at outfalls SWO08 and SWO15 during June 2009 and April 2009, respectively. Please contact me at Mark.McGary@duke-energy.com or at 704-634-7098 if you have any questions or need any additional information. Sincerely, Mark McGary, P.E. Environmental, Health & Safety www.duke-energy.com ALLEN STEAM STATION Stormwater Discharge Permit Application Form 2F Supplemental Information 0 r GENERAL SITE INFORMATION Allen Steam Station is a fossil -fueled, electric generation plant located approximately four miles southeast of Belmont, North Carolina in Gaston County The facility has five active coal-fired generation units with ,a net generating capacity of 1,155 megawatts Power production originally began �at the site in 1,957 In addition to the generation units, the station includes a Flue Gas Desulfurization (FGD) facility, a dry ash�handlirig 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 was occupied by a retired ash settling basin is currently the site of an active ash landfill operation - In developed areas, runoff generally flows overland to ditches and catch basins which are connected'to a buried network of corrugated metal` pipes (CMP) Inmost 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 The Allen Steam Station maintains an up-to-date Spill Prevention Control and Countermeasure (SPCC) Plan in,place in accordance,with the USEPA Oil Pollution Prevention Regulation 40 CFR Part 112 1 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 Coolinq Water This discharge is a once -through non -contact cooling water system which condenses steam from the plant condensers This discharge occurs at the station discharge canal NPDES Outfall 002 - Ash Settling Basin 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-minglewith SW,012 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 CCW intake screens to remove debris The debris is mainly 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 WWTS This is an internal outfall from the wastewater treatment system (WWTS) to the ash settling basin and is composed of treated FGD scrubber wastewater K STORMWATER OUTFALLS AND DRAINAGE AREA DESCRIPTIONS The Allen Steam Station has twenty identified stormwater outfalls (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) discharges in the region of the plant intake structure Six outfalls (including one outfall group) discharges 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 In addition to any significant materials particular to each drainage basin, herbicides are applied to selected areas ,at,the 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 (Drainage Area 1) Discharge Structure 10 inch diameter CMP Location North of Station Intake Coordinates 35011'46 2" N 81 000'33 4" W Drainage Area 6 0 acres Impervious Area 0% Area Description The drainage area for SW001 includes approximately 2000 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 3 Significant Materials Coal and Limestone Train cars carrying coal and limestone use the rail lines that pass through Drainage Area 1 Discharge Controls None Outfall SW002 (Drainage Area 2) Discharge Structure 24 inch diameter CMP Location North of Station Intake Coordinates 35011'42 0" N 81 000'32 6" 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 rad lines The drainage area also includes a 2 5 acre graveled FGD facility construction laydown yard and approximately 1000 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 Location North of Station Intake Coordinates 35°11'424 N 81°00'312"W Drainage Area 0 8 acres Impervious Area 0% Area Description The drainage area for 8W003 is comprised entirely of a small flat area that includes approximately 1500 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 4 Discharge Controls None Outfall SW004 (Drainage Area 4) Discharge Structure 10 inch diameter Cast Iron Pipe Location North of Station Intake Coordinates 35011'39 8",N 81 000'28 4" W Drainage Area 1 2 acres Impervious Area 0% Area Description The drainage area for SW004 is located east of`the `rail lines and north of the limestone unloading area, and is comprised of a smalfflat graveled area with a vegetated berm forming the northeastern boundary Significant Materials/ Controls None Discharge Controls None Outfall SW005 (Drainage Area 5) Discharge Structure 18 inch diameter CMP Location North of Station Intake Coordinates 35011'39 1" N 81°00'28 1" W Drainage Area 4 5 acres Impervious Area 2% Area Description The drainage area for SW005 is'primanly comprised of a gravel laydown yard and vegetated slopes located west and upland of the limestone unloading area The gavel laydown yard comprises approximately 3 acres The drainage area also includes approximately 500 linear feet of paved roadway 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 SW006 (Drainage Area 6) Discharge Structure: 10 inch diameter Cast Iron Pipe Location: North of Station Intake Coordinates: 35011'37.5" N 81 000'27.6" W Drainage Area: 0.9 acres 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: 35011'34.8" N 81°00'26.9" W Drainage Area: 5.1 acres Impervious Area: 2% Area Description (tet 5��.I t%_ �-c c vR��c�(i, , -e 4 S 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 1500 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. Discharae Controls None. M Outfall SWO08 (Drainage Area 8) Discharge Structure- 24 inch diameter CMP Location North of Station Intake Coordinates 35011'29 1°' N 81°00'27 0" W Drainage Area 4 1 acres Impervious Area 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 lineaffeet 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 Significant 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 SWO09 (Drainage Area 9) Discharge Structure 3 feet wide Concrete Ditch Location - North of Station Intake Coordinates 35011"26 9" N 81°00'28 0" W Drainage Area 0 6 acres Impervious Area 0% Area Description The drainage area for SWO09 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 SWO09 ditch outlet point, however the overflow does not co -mingle with the SWO09 stormwater discharge 7 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 SW01,0 (Drainage Area 10) Discharge Structure 24 inch diameter CMP Location- South of Station Intake Coordinates 351011'23 5" N 81 000'27-,5" W Drainage Area 0 7 acres Impervious Area 0% 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 Sou of Station Intake Coordinates 3-5011'2 N 81 000'24 0" W Drainage Area (50 3 1 acres Impervious Area 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, 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 n 2446 I�6 h 7 �idYivt T 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. The SW011 drainage area 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. I ` Significant Materials .La GT,� G �,L r M oti,rn O�yaw v Coal and Limestone: Train cars carrying coal and limestone use the rail lines that pass 1 (UJ through Drainage Area 11. Coal is handled inside the Coal WW Unloading Hopper Building within Drainage Area 11. Oil: Mineral oil is stored inside six large station transformers in the transformer yard J(01; 0.(A and in other smaller transformers and circuit breakers in the 115 kV switchyard. This equipment is located within curbed gravel -filled containments with open L . drains that discharge into the 63,500 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. 70 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 65,300 gallon oil trap tank for the oil -filled electrical equipment located in the transformer yard and in the 115 kV switchyard, 9 Outfall SWO12 (Drainage Area 12) Discharge Structure: 36 inch diameter CMF Location: Discharge Canal Coordinates: 35011122,,'1" N Drainage Area: X12.4 acres Impervious Area: 5 % Area Description 81 000'44.2" W �r o�X I�,�C�3-s`0) The drainage area for SWO12 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 SWO12. The 230 kV switchyard contains no oil -filled equipment. Stormwater runoff from the switchyard discharges into the Outfall SWO12 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 SWO12 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 SWO12 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 SWO12. Stormwater runoff from non oil -containing areas with Drainage Area 12 is not processed through the oil trap tank. o �. ; < <, c° c c T ; Significant Materials Oil: Mineral oil is stored inside ten 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 ten 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 100,000 gallon oil trap tank for the ten transformers in the transformer yard. 10 5 IVI �#to b � 0,7/1 IOW Outfall Group SW013 (Drainage Area 13) Discharge Structure Fourteen 10 inch diameter CMPs Location Every 200 feet along the rail lines south of the coal yard Coordinates 35°11'59 0" N 81 000'21 1" W (center of group) Drainage Area 4 acres Impervious Area 0% Area Description The drainage area for Outfall Group SW013, is comprised of 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 14 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 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 SW014 (Drainage Area 14) Discharge Structure 36 inch diameter CMP Location Between the coal yard and the ash landfill Coordinates 35°11'10 3" N 81°00'21 2" 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 1000 linear feet of gravel road , Significant Materials/ Controls None Discharge Controls None 11 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 35010'53 4" N 81°00'21 7" W Drainage -Area 170 acres Impervious Area 0% Area Description The drainage area for SAM 5 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 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 SW013 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 Location Coordinates Drainage Area Impervious Area Area Description 36 inch diameter CMP Discharge Canal 35011'22 1" N 81°00'44 2" W 22 acres 2% 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 lineaffeet of dirt roads north of the access road, and a gravel surfaced laydown and equipment parking area north of the access road 12 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 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 35011'26 3" N 81 °00'03 5" W (center of group) Drainage Area 35 1 acres, Impervious Area 0% Area Description The 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 SW0V stormwater outlets direct runoff from vegetated embankments along the canal, beneath the gravel roads, and into the canal Significant Materials/ Controls None Discharge Controls None Outfall SW018 (Drainage Area 18) Discharge Structure 48 inch diameter CMP Location Discharge canal Coordinates 35011'25 2" N 81 000'47 7" W Drainage Area 92 3 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 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 13 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 ypsum_haul trucks use the FGD facility access road to transport gypsum off-site-from=the=F_GD 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 35011'25 1" N 81°00'54 3" 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 14 Outfall SW020 (Drainage Area 20) Discharge Structure Location Coordinates Drainage Area Impervious Area Area Description 48 inch diameter CMP Discharge canal 35011'26 4" N 81 °00'09 6" W 15 7 acres 0% The drainage area for SW019 encompasses 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 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 Significant Materials/ Controls, Gypsum Gypsum is transported in gypsum haul trucks along the FGD facility access road Discharge Controls None 15 REMAINING DRAINAGE AREA DESCRIPTIONS The Allen Steam Station has several non-stormwater discharge drainage areas that discharge into station sumps that pump to the ash settling basin There are six primary station sumps described as follows 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 1'00,000 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 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 number of 55 gallon drums are stored adjacent to the 16 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 would discharge through a corrugated W�`T ,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 stormwate_lllection basin Effluent from the wastewater treatment facility,.i_s discharged independently to ash setting_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 afthe eastern edge of the drainage area 17 This trench discharges into the Limestone Unloading Area Sump that subsequently pumps to the ash setting basin 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 18