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HomeMy WebLinkAboutNC0004987_Permit Application_20091102Duke CORPORATE EHS SERVICES Energy Duke Energy Corporation 526 South Church St. Charlotte, NC 28202 Mailing Address: EC13K / PO Box 1006 October 26, 2009 Charlotte, NC 28201 -1006 Mr. Charles H. Weaver, Jr. State of North Carolina rp" f WDDepartment of Environment and Natural Resourc '" µ Division of Water Quality NPDES Unit 1617 Mail Service Center n Raleigh, North Carolina 27699 -1617 . WATER aUAL1TY Subject: Duke Energy Carolinas, LLC — NPDEr`�r� )W69e, BMNCH Marshall Steam Station - #NC000498 Dear Mr. Weaver: Duke Energy Carolinas, LLC requests the subject permit be renewed and reissued. The above referenced permit expires April 30, 2010. As mandated by North Carolina Administrative Code 15A NCAC 2H.0105 (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 2F Site Maps Water Flow Diagram Supplemental Information Duke Power requests notification that this application is complete. Additionally, the attached report, "Assessment of Balanced and Indigenous Populations in Lake Norman Near Marshall Steam Station," continues to indicate the maintenance of a balanced indegnious populations. Therefore, this report supports renewal of the current thermal monitoring requirements of outfall #001. www.duke-energy.com The elimination of monitoring for the following parameters at outfalls #002 and #004 is requested based on historical monitoring data • Total Arsenic • Chloride • Total Mercury • Total Nickel 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 Water Management Attachments cc w/• Mr Robert Krebs - NCDENR Mooresville R O. Mr Jay Sauber — NCDENR, Raleigh, N C (BIP Report 3 copies) J Nokm. At 0 A- ti P. z. At W, -4-01 civ VA 7 71y. F NORMAN' Lege nd Duke Energy Property Boundary BACKGROUND DATA: USGS TOPOGRAPHIC QUAD, WAS OBTAINED FROM NGDOT GEOGRAPHICAL nmmmmmff7=== Kilometers INFORMAT ON (GIS) WEBSITE. THE PROPERTY DATA WAS OBTAINED FROM THE CATAWBA COUNTY IC NORTH CAROLINA GIS DEPARTMENT PLEASE NOTE THIS DATA IS FOR INFORMATIONAL PURPOSES ONLY. 0 0.5 1 Miles SCALE: ASSHOWN FIGURE LOCATION MAP DUKE ENERGY NO. DATE: 10-15-2009 Duke MARSHALL STEAM STATION PROJECT NO: Energy& MARSHALL STEAM STATION 1411-08-140 CATAWBA COUNTY, NORTH CAROLINA 1�__ Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Page 3 of 30 1.0 General Information Marshall Stearn Station (MSS) 'is located on NC Highway 150, six miles west of 1 -77 in Catawba County on Lake Norman near Terrell, North, Carolina. MSS consists of four coal -fired steam electric generating units. Units 1 and 2 can generate 380,000 kilowatts (net) of electricity each and units 3 and 4 have the capacity to generate 660,000 kilowatts (net) of electricity each. A brief discussion of the individual waste streams follows. 2.0 Outfall Information 2.1 Outfall 001- Condenser Cooling Water (CCW) Units 1 -4 The CCW system is a once through non - contact cooling water system, which condenses steam from the condensers and other selected heat exchangers. When MSS is operating at full power, it has a design capacity to pump 1463 MGD (1,016,000 GPM) of cooling water through a network ,of tubes that runs through the condenser and `selected, heat exchangers. The raw cooling water is returned to the lake No biocides or other chemicals are used in the condenser cooling water. Units 1 and 2 have two CCW pumps per unit and Units 3 and 4 have three CCW pumps per unit with the following maximum flow capacities: Unit No. 1--Pump GPM 1 126,000 2 126,000 3 150,000 4 1,50,000 Z--Pump GPM 190,000 190,000 253,000 253,000 3 -Pump GPM 31'8,000 318,000 The operational schedule'for these pumps is dependent on the intake water temperature and on the unit loads Depending on the electrical demand, pumps are operated to maximize MSS efficiency and to assure balanced and indigenous populations are maintained in Lake Norman. Each unit is on an independent system to avoid a system trip that would suddenly reduce the discharge flow at outfall 001. This practice leads to a higher reliability factor for the units and protection of aquatic life taking refuge in the discharge canal during cold weather. Flow recorded on the monthly Discharge Monitoring Reports is based on CCW pump run times. The condensers are mechanically cleaned. Normally, amertap balls are cleaning the, tubes on a continuous basis while the plant is operating Periodically, after the condenser is drained, metal scrapers, plastic scrapers or rubber plugs are forced through the tubes to rid them of scale or other deposits. The condenser tubes may also be tested for leaks, as needed. A leak test can be conducted in approximately two to three hours per unit with usually no more than six infections of tracer gas (i.e , sulfur hexaflouride, helium, etc) each within approximately a 30 second period and /or checked with fluorescent dye The dye is added to the condensate water and put on the outside of the condenser, tubes. During the test, if fluorescent water does leak into the tubes, this, discharge indicates a leak does exist ,in the condenser tubing. The'levels of gas or dye that might be discharged would be well below any levels of aquatic biological toxicity concerns If leaks are detected, then one method used to temporarily stop small leaks is to add sawdust to the CCW system, as previously approved by NCDENR. The sawdust is Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Page 4 of 30 added at amounts that will plug the leaks and not result in 'an environmental' impact. This is a temporary measure until the unit can come off -line so the leaks can be permanently repaired. 2.1:1 Intake Screen Washing Manually by Removing Screens The Intake screens (32 total) are washed on an as needed 'basis. Normally, the screens require washing once a month for a period of approximately 5 minutes per screen. The screens ,(1,0 ft x 20 ft) are stationary type and are removed for cleaning. A low- pressure pump supplies the raw water required for washing with a design capacity of 300 gpm. Therefore, the average flow of water used to backwash the screens is 0.002 MGD. Should it become necessary to backwash the screens on a continuous basis the maximum flow would be 0 43 MGD per screen The idebris collected on the screens consists of twigs, leaves, and other, material indigenous to Lake Norman and is removed and properly disposed. The intake screen backwash water drains, back to the station intake cove without any adverse environmental impact. 2.2 Outfall 002 - Ash Basin The ash basin at MSS accommodates flows from 'two yard - drain sumps, an ash removal system, low volume wastes and non -point source storm water. Low volume waste sources include, but are not limited to* wastewater from wet scrubber air pollution control systems, ion exchange water 'treatment system, water treatment evaporator blowdown, laboratory and sampling streams, boiler blowdown, floor drains, and recirculating house service water systems Total average Influent from these sources combined is ' approximately 8.3 MGD. At times, due to unit loads, rainfall, evaporation and seepage of ash basin ponds, the amount of effluent may be different than influent volumes 2.2.1 Yard -Drain Sumps The yard - drain sumps are concrete structures having four level controlled pumps each that direct wastewater from the powerhouse area to the ash basin. These pumps are operated on a rotating basis Usually two pumps are set so that one pump is primary and the other is backup. After a selected period the controls are changed so that different pumps are utilized The yard -drain sumps collect wastewater from many sources, such as, the filtered water system, turbine and boiler room sumps, miscellaneous equipment cooling water, foundation drainage, low volume wastes, and tunnel unwatering. The yard -drain sumps also collect some storm water runoff from the coal pile, rail access, and powerhouse roofs and ,pavement Ground water from,,a foundation drainage system under the track hopper is also intermittently discharged to 'the 'yard -drain sumps The combined average flow from all sources tied to the yard -drain sumps is approximately 2.43 MGD, which is pumped to the ash basin ,for physical and biological treatment 2.2.2 Turbine Room Sumps The turbine room sumps collect approximately 0.35 MGD of wastewater. This wastewater comes from non - contact cooling water (from Units 1 & 2 boiler feedpump turbine lube oil coolers) and floor drains. Floor drains contain boiler blowdown, leakage from seals, equipment cooling water, condensate from the feedwater system, low volume wastewater, boiler room sump overflow, emergency fire, fighting water., general mechanical maintenance activities, miscellaneous plant wastes and' area, washdown water Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Page 5 of 30 2.2.3 Boiler Room Sumps The average flow pumped from the boiler room sumps directly to the ash'basin is approximately 1.55 MGD The sources of Input to the boiler room sumps include the following 2.2.3.1 Water Treatment System The MSS make -up water treatment system is comprised of a clarifier, 'three gravity filters, two sets of activated carbon filters, a reverse osmosis system and two sets of demineralizers The. water treatment wastes consist of, floc and sedimentation, filter backwash, reverse osmosis concentrate reject and cleaning wastes, and demineralizer regeneration wastes. Water processed through this system is supplied to the boilers to generate steam to turn the turbines On occasion a vendor may be used with a mobile water treatment unit to augment the facility water treatment capacity. Any vendor will use traditional water treatment methods, chemicals, and disposal methods generally described below. This wastewater is drained to the boiler room sump, which ultimately discharges to the ash basin Clarifier, The clarifier utilizes typical water treatment chemicals such as, aluminum sulfate (alum), sodium hydroxide, and calcium hypochlorite for the primary treatment of raw water. The sedimentation wastes collected in the clarifier consists of solids that were suspended in the service water plus aluminum hydroxide precipitate formed as a result of adding aluminum sulfate (alum) and sodium hydroxide. The quantity of alum used per year is approximately 14,000 gallons. The total amount of caustic is roughly one quarter the amount of alum. The average volume of water required for desludging the clarifier is approximately 0.008 MGD. These sedimentation wastes along with dilute water treatment chemicals and by- products are piped to a floor drain which flows to the boiler room sumps where they are pumped to the ash basin via the yard' -drain sump Gravity Filters - There are three gravity filters composed of anthracite (coal) which follow the clarifier in the water treatment process. They are used for removal of colloidal material and are backwashed as necessary, dependent upon the level of solids in the water Normally, one of these filters is backwashed each day. Approximately 0.007 MGD of backwash water is required for each filter. This flow is discharged to the floor drains,to the boiler room sump, which pumps to the yard -drain sump The gravity filter medium is changed out on an as- needed basis with the spent filter media being landfilled Activated Carbon Filters: Two activated carbon filters remove organics and the chlorine that is injected into the clarifier. These filters are typically backwashed approximately once a ,week. The flow of water required to backwash one of these filters is 20,000 gallons per day. The wash water flows to the boiler room sump and is pumped to the yard - drain sump. Activated carbon is replaced on, an as needed basis with the spent carbon sluiced to the pyrite system Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Page 6 of 30 Reverse Osmosis System There is a two stage Reverse Osmosis (RO) system which processes approximately 535 gallons per minute of filtered water Approximately 400 gpm of permeate water is produced and flows to the permeate water storage tank. Approximately 135 gpm of concentrate water is produced which flows to the boiler room sump and ultimately the ash basin via the yard drain sump. Water from the permeate tank is pumped to the demineralizers as supply water. The RO system is cleaned approximately,twice per year using, a dilute low, pH cleaner (sulfonic acid /citric acid), biocide (Trisep Tristat 110), and a high pH cleaner (sodium hydroxide /sodium lauryl sulfate) Deminerahzers Demmeralizers at MSS consist of two sets of mixed -bed cells which supply make =up water to the, boilers and other closed systems. Normal plant operation requires that only one cell of each demineralizer set operate at any one time. Each cell has a capacity of, 22&gpm. Each cell is regenerated approximately every four weeks Each year MSS' will use an estimated 8,000 gallons of 50% caustic and 2,500 gallons 93% sulfuric acid for demineralizer regenerations. The dilute, acid and caustic are discharged from the cell simultaneously through the same header for neutralization purposes The regeneration wastes flow to the boiler room sumps where it is pumped to the ash basin via the yard -drain sump. The useful life of the resin varies and when replaced spent resin is sluiced to the ash basin 2.2.3.2 Miscellaneous Waste Streams • Closed system drainage, cleanings, testing containing corrosion inhibitors (Calgon CS), biocides (Calgon H -550 and H 7330), cleanings) (small heat exchangers), dispersant (polyacrylamide), wetting agent (sodium lauryl sulfate), detergent (tri- sodium phosphate), and leak testing (disodium fluorescing dye). • Turbine room sump overflow • Boiler seal water (trace oil and grease) • Miscellaneous system leakages (small leaks from pump packings and seals, valve seals, pipe connections) • Moisture separators on air compressor,precipitators • Floor wash water • Emergency fire, fighting, water • Pyrite (ash) removal system overflow • Low Volume Wastewater 2.2.3.3 Chemical makeup tanks and drums rinsate Intermittent rinse water containing small amounts of aluminum sulfate, sodium hydroxide, hydrazine, ammonium hydroxide. 17o date small closed system cleanings (e.g. heat exchangers) have not used these chemicals, reserved for future use. Marshall Steam Station, Catawba,County NPDES Permit No N00004987 Page Tof 30 2.2.3.4 Boiler blowdown, Primarily when units 1 & 2 startup and until water chemistry stabilizes the blowdown from these boilers is allowed to flash in a blowdown tank. During startup a significant portion of this blowdown steam is vented to the atmosphere. After water chemistry has stabilized, blowdown venting is minimal and condensate flow is small Trace amounts of hydrazine, ammonia, and silica oxide may be present in the condensate. The combined condensate flow from blowdown amounts to an average of approximately 0.002 'MGD. This flow is routed to the boiler room sump and then to the ash basin 2.2.3.5 Boiler Cleaning Boilers #1, #2, #3 and #4 at MSS are chemically cleaned on an as needed basis. Tube inspections are performed during outages, which indicate when cleaning needs scheduling Boilers #1 and #2 are controlled circulation boilers and boilers #3 and #4 are supercritical boilers. The'wastes produced from a boiler chemical cleaning are pumped to the ash basin Boilers #1 and #2 each have ,a water -side volume of 51;600 gallons. The volume of #3 and #4 boilers is 35,300 gallons each The total volume of dilute waste chemicals, including rinses, discharged from #1 or #2 boilers during ,a chemical cleaning is 580,000 gallons The total volume of dilute waste chemicals drained from #3 or #4 amounts to 320,000 gallons. This dilute wastewater is drained through temporary piping to permanent ash removal piping where flow goes to the ash basin The ,chemicals and approximate amounts for ,each cleaning are listed below CLEANING CHEMICALS AMOUNT USED PER UNIT 1St Step (Alkaline Boilouts - only after major boiler tube work) Boiler #1 or #2 Boiler #3 or #4 Soda Ash 4400 lb NA Trisodium Phosphate NA, 3000 lb Triton X -100 Detergent (0.05%) 25 gal 1B gal Antifoam Agent (0.025%) 13 gal 9 gal 2nd Step (Copper Removal Solution) Boiler #1 or #2 Boiler #3 or #4 Sodium Bromate 550 lb NA Ammonium Bicarbonate 1000 lb NA Ammonium Hydroxide 1000 gal NA (26 °Be') Sodium Sulfite 1;00 lb NA 3 d Step (Iron Removal Solution) Boiler #1 or #2 Boiler #3 or #4 Hydrochloric Acid (31 5 %) (20 °Be') 7100 gal 4800 gal Ammonium Bifluoride (0.5 %) 2150 lb 1500 lb Copper Complexer (0 75 %) 2300 lb NA Thiourea or equivalent Rodine 213 (acid inhibitor) Citric Acid 142 lb 400 lb 4th Step (Neutralization Solution) Boiler #1 or #2 Soda Ash Trisodium Phosphate 4400 lb NA Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Pagei8 oU30 96 lb 300 lb Boiler #3 or #4 NA 3000 lb Prior to a boiler cleaning the ash basin water level is lowered and additional stop logs are added to the ash basin discharge structure. This process assures longer retention time of the chemical wastes for proper treatment through dilution, neutralization, precipitation, and ion - exchange as documented in,the Ash Basin Equivalency Demonstration (October 1976) Alternately, the boiler may be cleaned using ethylenediaminetetraacetic acid (EDTA). If EDTA is used for cleaning, no waste water will be discharged to the ash basin, rather all cleaning wastewaters will either be evaporated in the boiler or collected and transported off -site for proper treatment and disposal. 2.2.4 Stormwater Runoff The ash basin collects /receives flows from the yard drainage basin, ash removal lines and rainfall run -off from the basin watershed area. Details of storm water the runoff that flows into the ash basin ,is described in section 4.3. 2.2.5 Induced Draft'Fan Motor Bearing Cooling Water Once through non - contact cooling water is supplied to eight induced draft (ID) fan motor bearings to remove excess heat. No chemicals are added to the once through raw lake water The rate of flow through the ID fan heat exchangers that discharges to the yard - drain sumps is approximately 0 08 MGD, which is pumped to the ash basin. 2.2.6 Track Hopper Sump The track hopper sump collects ground water from a foundation drain system underneath the track hopper. The flow is usually intermittent, however, the pump capacity is 100 gpm. On, a daily basis it is estimated that the run time is only 50% which would correspond to a flow of 0 07 MGD to the yard - drain sumps, which is pumped to the ash basin 2.2.7 CCW Tunnel- Unwatering, Sump In the event that maintenance activities are needed in the intake or discharge tunnels an unwatermg sump is provided to remove water from the tunnels. Raw water in the tunnels can be pumped to the yard -drain sumps that ultimately discharge to the ash basin 2.2.8 Turbine Non - Destructive Testing Bore sonic testing of turbine rotors is infrequent, once every 5 years. Demineralized water is mixed with a corrosion inhibitor, e.g. Immunol 1228, at a ratio of 100 parts water to 1 part inhibitor. The mixture is applied to the turbine rotors. The excess is drained and mixed with .low volume wastewater and discharged to the ash basin via the yard -drain sumps Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Page, 9,of 30 2.2:9 Ash Sluice MSS utilizes electrostatic precipitators as its air pollution control devices Under normal plant operations, the dry fly ash captured in these precipitators is collected in temporary storage silos for subsequent disposal in a permitted on -site structural fill orlor recycling in off -site ash utilization projects. If the system that collects the dry fly ash is not operating, the fly ash can be sluiced to the ash basin. Bottom ash from the boilers is. usually sluiced with water to a holding cell for recycling activities. Pyrites from the mills are sluiced with water to an ash basin settling -cell Approximately 3.21 MGD of fly /bottom ash and pyrite sluice is pumped through large steel pipes (ash lines) directly to the ash basin settling -cell. Once through non - contact cooling water from the coal pulverizing mill is discharged, to the bottom ash hopper and pumped to the ash basin. Electrostatic precipitators at MSS are normally cleaned by mechanically vibrating the wires and rapping the plates inside the precipitator. Before major precipitator work `is performed they are cleaned by a wash down The wash water is pumped to the ash basin from the yard -drain sump 2.2.10 Sanitary Waste A sanitary waste treatment system is operational and consists of an aerated basin that provides treatment with & 30 -day retention time and has a total volume of 587,000 gallons Effluent from the aerated basin is polished further through additional residence time in the ash basin The new system is designed for 6100 gpd (normal) and 13,500 gpd (outage). The powerhouse lift station was installed as ,a central collection point to receive all the sanitary waste from MSS and pump it to the aerated basin. The present lift stations serving the vendor facilities and Units 3 and 4 have been upgraded. The sanitary system accommodates wastewater flow from the following sources: • General plant sanitary wastewater • Vendor facilities sanitary wastewater • Laboratory drains (Small amounts of laboratory chemicals used to test wastewater' effluents and high purity boiler water, see the, following table for non - hazardous substance) Substance Quantity Location 2 -Pro anol 4 gal LabNVarehouse Glycerin, 4 gal LabNVarehouse Indigo carmine 0.3 lb Lab Dimeth laminobenzaldeh de 0 22 _I_bs. Lab Table values represents typical quantities on -site at any given time and do not necessarily reflect quantities discharged. 2.2.11 Ash Silo Storm Water Sump A new ash silo system has been constructed for dry handling of the ash. This system includes a sump for collection of rainfall runoff and washdown of the silo area, which is Marshall Steam Station, Catawba County NPDES Permit No NC0004687 Page 10 of 30 pumped to the ash basin This sump's drainage area is approximately 1 acre. Overall, this will be a minimal input to the ash basin 2.2.12 Wastewater from Recent Plant Additions 2.2.12.1 Selective Non - Catalytic Reduction (SNCR) As part of the compliance with the North Carolina Clean Air Initiative (NCCAIR), Marshall installed urea based "trim" Selective Non - Catalytic Reduction (SNCR) systems on units 1, 2, and 4,. The trim'SNCR systems are,expected'to reduce NOx emissions by approximately 20 %. SNCR systems operate by injecting urea liquor into the upper section of °the boiler where a chemical reaction occurs .to reduce the NOx to water and nitrogen. Some residual ammonia will be collected in the fly ash from ,the electrostatic precipitators. The majority of this ammonia will stay with the ash as it is handled dry but a small amount may be carried to the ash basin. However, the operation of the SNCR system is not expected to require, additional treatment capabilities to ensure compliance with NPDES permit limits Marshall units 1, 2, and 4 currently are using this technology to reduce NOx whereas unit 3 operates a Selective Catalytic .Reduction (SCR) system. 2.2.12.2 Selective Catalytic Reduction (SCR) As part, of the compliance with the North Carolina Clean Air Initiative (NCCAIR), Marshall has replaced unit 3's SNCR with a more efficient Selective Catalytic Reduction ,(SCR) system, capable of reducing NOx by approximately 90 %. This SCR utilizes a urea to ammonia (U2A) which converts the urea liquor into an ammonia gas, external to the boiler in a hydrolyzer. The hydrolyzer contains approximately 1,000 gallons of urea while in operation and periodic blowdowns occur to flush out sediment in the bottom of each hydrolzer. Small quantities of urea will be discharged into the ash basin, from the blowdown process Roughly, 10,gallons a week is discarded during the blowdown, process and is collected in the ash basin. Similar to the SNCR, the SCR will also result in small traces of ammonia in the fly ash that is collected from the electrostatic precipitators The majority of this ammonia will remain with the ash as it is handled dry but a small amount may be carried, to the ash basin. However, the operation of the SCR system is not expected to require additional treatment capabilities to ensure compliance with NPDES permit limits. 2.2.12.3 Flue Gas Desulfurization (FGD) The installation of a Wet Flue Gas Desulfurization (FGD) system was completed in 2006 at Marshall for Unit 4. The remaining units FGD systems were completed in 20,07. The FGD is an air pollution control system that removes S02 from the flue gas system. In a Wet Scrubber system the S02 component of the flue gas produced from the coal combustion process is removed by reaction with limestone -water slurry. The particular system used at Marshall will collect the flue gas after it passes through the electrostatic precipitator and route the gas into the lower end of a vertical tank As the gas rises through the tank to the outlet at the top, 'the gas passes through a spray header An atomized slurry of Marshall Steam Station, Catawba County NPDES Permit No NC0004487 Page 11 of 30 water and limestone droplets is continually sprayed through this header into the stream of flue gas The S02 in the flue, gas reacts with the calcium in the limestone and produces S03 The S03 slurry falls to the bottom of the tank where a stream of air is infected to oxidize the slurry to form gypsum, (CaSO4 H20). The gypsum slurry is drawn off the tank to a hydrocyclone and subsequently routed to a vacuum belt filter. The liquid waste from this process will be treated as wastewater in the constructed treatment wetlands. The effluent from the CTW discharges to the ,ash basin (via NPDES Internal Outfall 004). The FGD system requires a material handling system that. supplies limestone to the scrubber and a gypsum storage area for the gypsum removed from the process The limestone comes into,the site by rail ,and is stored in an area near the coal pile. It is then transferred to the FGD site via a covered conveyor. Runoff from the storage area is routed to the ash basin. The gypsum is routed from the FGD tank via a covered conveyor belt that carries'it to a storage pile. The runoff from this area is also routed to the ash basin The FGD system also requires a ,gypsum landfill. The FGD landfill is located west of the Marshall Ash Basin. The runoff and leachate from this landfill 'is ro,uted to the ash basin FGD residue material that, is not suitable for beneficial use as wallboard will be placed in the landfill. In addition to this material, material is periodically removed from the clarifier stage, of the wastewater treatment system and placed in the landfill. The landfill footprint contains, approximately 20.64 acres The FGD residue is conveyed to the landfill site by truck, where the material is spread and compacted The landfill began receiving FGD residue in the fall of 2006 The volumetric capacity of the landfill is 2.1'9 million yd Duke Energy is exploring other beneficial uses for the FGD residue (gypsum). If these options are determiried to be viable, the FGD residue meeting the material requirements for the beneficial uses will not be disposed in the landfill. 2.2.13 Wastewater from Future Plant Additions Construction of an industrial waste landfill is scheduled to begin in early 2010. Landfill operation is slated for late 2010. Fly ash, FGD gypsum and clarifier sludge will be disposed in this landfill. Landfill runoff and leachate will be routed to the ash basin for treatment 2.3 Outfalls 002A and 0028 - Yard -Drain Sump Emergency Overflow An overflow pipe that could direct flow from the sump to Lake Norman was included in the construction of the two yard sumps. This modification was performed to prevent submergence and damage of the pump motors within the sumps in the event that all, pumps failed or redundant power supply lines could not be restored in a timely manner. Outfall 002A has overflowed five -times between April 2007 and March 2009 Outfall 0028 has overflowed two times between April 2007 and March 2009. Observations and monitoring of effluent during these events have indicated no noticeable impact to water quality. No sanitary waste is routed through the yard -drain sumps 2.4 Outfall 003-- Unit 4 ID Fan Control House Cooling Water Marshall Steam Station, Catawba County NP-DES Permit No ;NC0004987 Page 12 of 30 Once through non - contact cooling water is supplied to the Unit 4 induced draft (ID) fan motor control -house equipment to remove excess heat No chemicals are added to the once through raw lake, water. The flow rate through the control equipment that discharges to Lake Norman is approximately 0.2 MGD 2.5 Internal Outfall 004 — Treated FGD Wet Scrubber Wastewater The wastewater from the FGD system is conveyed to the wastewater solids removal system, which discharges into the mixed equalization tank The wastewater contained in the equalization ,tank is conveyed to the flocculating clarifier which is utilized as the liquid /solids separation device Polymer may be injected to aid i'n `the settling process. Clarified effluent is conveyed to the Constructed Treatment Wetlands (CTW) supply tank Settled solids are removed from the clarifier by the operating sludge transfer pump and conveyed to the mixed sludge holding tank and dewatered by the filter presses. Dewatered cake from the filter presses is ultimately landfilled Filtrate from the dewatering process is conveyed to the equalization tank for reprocessing The CTW system receives wastewater from the clarifier unit where it enters, two equalization basins, each with a 24 -hour hydraulic retention time (HRT) for cooling, mixing, concentration equalization, and settling of solids. Water from the equalization basins is normally split into three equal flows, each entering a treatment train consisting of two 1.28 acre wetland cells (36 hour HRT), a 0 24 acre rock filter and a 1 67 acre final wetland cell (64 hour HRT). Total area of treatment is approximately 15 acres with a normal HRT of 8 days based on average projected flows. The CTW system will treat an average flow of 1.2 and a peak flow of 1 4 MGD 3.0 Additional Information FUEL AND OIL STORAGE TANKS The following above ground fuel and oil storage tanks are located at MSS- • two 500 gallon, • three 1,000 gallon, 2,000 gallon, • 5,000 gallon • two 500,000 gallon fuel -oil tanks, • 1000 gallon gasoline tank, • four 750 gallon lubricating -oil tanks; • 500 gallon hydraulic -oil tank, • 900 gallon used -oil tank, 0 8000 gallon used -oil tank (inside the powerhouse). At the_time of this application, only one of the 500,000 gallon fuel -oil tanks is in service. All above ground tanks at MSS have secondary containment provided that -is capable of containing the entire contents of the tank. Marshall Steam Station, Catawba County NPDES Permit No. NC0004987 Page 13 of 30 All oil storage facilities and oil filled equipment are presently covered under Spill Prevention Control and Countermeasure Plans (SPCC)2. 4.0 STORMWATER 4.1 Site Description The site covers 2,043 acres. The station includes a plant yard of 28 acres, a six acre switching station, and a coal storage yard of 36 acres. A 450 -acre portion of the headwaters of Holdsclaw Creek serves as an ash - settling basin with regulated outflow to Lake Norman. Marshall Steam Station has recently undergone a large amount of construction. The site has added a Flue Gas Desulfurization (FGD) system, a Selective Catalytic Reduction (SCR) system, a wetlands wastewater treatment plant, a limestone unloading /stacker system, a gypsum stacker, a FGD landfill and various storage and maintenance buildings. Approximately 80 acres northeast of the FGD landfill are being used to place flyash in a structural fill. A 58 acre retired ash landfill is located east of the ash basin. A new ash landfill is currently under construction. The site has a sanitary wastewater treatment lagoon and several construction spoil areas. There are approximately six miles of rail access and three miles of paved roadways on -site. Soils at Marshall Steam Station are typical of the region and are predominantly micaceous sandy silts and silty sands with some clayey sands in flatter areas. The topography is generally flat with rolling hills in outlying, undeveloped areas. In developed areas, runoff is collected by catch basins and conveyed through a buried network of corrugated metal pipes (CMP). The network was originally designed to route flow to several primary trunk lines, which discharged directly to Lake Norman. In 1976 runoff from most areas with significant materials and activities was routed through either the yard holding sumps or the oil trap tank. Effluent from the yard holding sumps is pumped to the ash basin. Storm water processed through the oil trap tank is discharged to Lake Norman. Storm water runoff from the FGD area enters yard drains and is then routed via gravity flow through subsurface piping to a storm water detention pond. This pond then discharges to the station transfer sump and then to Yard Sump No. 2. Yard sump No. 2 eventually discharges via the ash basin. Runoff from the FGD Landfill, the Beneficial Structural Fill Area, the Closed Ash Landfill, the Gypsum Stacker, the Limestone Stacker, the FGD Constructed Wetlands and the Bottom Ash Operations all eventually drain into the ash basin. Marshall Steam Station has 11 storm water discharges and six NPDES process water outfalls. Four of the NPDES outfalls also contain storm water. The storm water discharges are described in Section 4.3. The six NPDES discharges are described as follows: • NPDES Outfall #001 — Once - Through Cooling Water 2 SPCC Plan required by 40 CFR 112. Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Page 14 of 30� This discharge contains non- contact cooling water from plant equipment. NPDES Outfall #002 - Ash Settling Basin Discharge This discharge is the outflow from the ash - settling basin. Plant wastewater including ash sluicing, treated sewage, equipment discharge, and chemical waste goes to the ash basin. Runoff from'the coal pile, bottom ash operations, beneficial structural fill area and the closed ash landfill is routed to the ash basin via surface ditches Runoff from the plant yard is routed to the ash basin via the yard sumps Additionally, drainage from the newly constructed areas of the site such as FGD storm Water, FGD process water, treated via the constructed wetlands system, treated water from the VVVVTP, the FGD landfill and drainage from the gypsum and limestone radial stackers go to the ash basin. NPDES Outfall 002A = Yard ,Sump #1- Overflows If the yard sump were inundated during a large storm event or spill, or if the power failed, the overflow would be conveyed to Lake Norman through Outfall SW007. Overflow from the yard sump is not a normal occurrence. • NPDES Outfall 002B — Yard Sump #2 Overflows This outfall is the emergency overflow for yard sump #2. NPDES Outfall #003-- Non - contact Cooling Water from the Induced Draft Fan Control House This is air conditioning condensate from the heat exchanger for the Unit 4 ID Fans electronics. This outfall also conveys yard drainage and is dually listed as Outfall SWO09 in Section 2 2. • NPDES Internal Outfall #004 — Treated FGD Wet Scrubber Wastewater to Ash Settling Basin 4.2 Facility Drainage and Inventory of Significant Materials and Controls Based on pipe networks and site topography, the Marshall Steam Station site was divided into individual drainage basins as shown on the attached site drawings. This section details eleven storm water outfalls to Lake Norman To provide a complete description of the storm water drainage system, the yard sump system is also characterized. Additional outfalls have been excluded because either'they have been abandoned or because runoff is from a small,area, which does not contain significant materials. 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 to selected areas throughout Marshall Steam Station to eliminate undesirable�vegetation 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 Marshall Steam Station are approved by the company and considered safe to the environment when used according to directions. Records ,are retained at the site which document information such as: the areas treated, the herbicide used and the amounts of herbicide used Marshall Steam Station, Catawba County N'PDES Permit No N00004987 Page 15 of 30 Fl,yash is loaded and transported daily through the site New ash storage silos have been built to the west side of,the intake canal, north of the plant Marshall Steam Station, Catawba County NODES Permit No N00004987 Page 16 of 30 4.3 Stormwater OutfaR Drainage Areas ® Outfalls SWO01 through SW005, "Drainage Areas 1 -5 "- Miscellaneous Material Storage Area Discharge Structure Outfall SW001. 24 inch ( ") diameter () CMP Discharge Structure Outfall SW002. 2-18" ifi CMP's Discharge Structure Outfall SW003. 2 -18" � CMP's Discharge Structure Outfall SW004: 2 -18" � CMP's Discharge Structure Outfall SWO05: This outfall was abandoned in 2001 Location: Intake Cove Drainage Area 8.9 acres Area Description These four outfalls are located along the road adjacent to the rail lines, northeast of the ash silos. These outfalls are grouped together because they perform similar functions. This drainage area includes the slopes of the ash basin dike and the adjacent road. The embankment of the ash basin dike is sloped at a ratio of two horizontal to one vertical (2H:1V) and covers approximately 3`0 percent of the drainage area. The road is 0.6 miles long. About five percent of the drainage area is paved. These outfalls do not discharge directly into Lake Norman. Runoff from the slopes of the ash basin dike is conveyed under the haul road through these pipes. Then, discharge from these pipes plus surface runoff from the area east of the road flows to the intake canal. Including the area east of the haul road, the drainage area is 22 acres. Any rainfall run -off and /or truck washing operations, are collected in a local' sump and pumped to the ash basin The flyash loading area, flyash silos and truck washing areas are located within this drainage area Additionally, ash haul trucks are washed down in this area to remove excess ash and prevent scattering ash on site roads Significant Materials/ Controls Ash- None. Storage Miscellaneous supplies such ,as steel and cable are stored outdoors in a lay-down area within this basin a Outfall SW006, "Drainage Area 6" Discharge Structure* 1,8" �, CMP Location: Intake Canal Drainage Area: 14 acres Area Description This drainage area includes a portion of the plant yard and approximately 9,000 square feet (ft) of the roof of the warehouse A storage shed east of the warehouse with roof area of about 3,300 ft2 is also included. A concrete pad of approximately 1'2,500 ft2 was poured between the warehouse and storage shed; the pad is covered but not enclosed. Railway lines Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Page 17 of.30 pass through the area. The embankment leading to the coal pile is sloped at a 2H:1V ratio and covers 35 percent of the drainage area Approximately 40 percent of the drainage basin is roofed or paved. Significant Materials / Controls Oil- A two inch diameter, above grade, pipeline passes through this area and carries fuel oil from the 500 „000 gallon bulk storage tank to the tractor shed Ash: Piping and discharge from the ash silo area flow through this drainage area. Drainage from the ash silos flows through the area and ends up in yard sump # 2 Outfall SWO07 / NPDES Outfall 002A, "Drainage Area 7” Discharge Structure 60" � CMP Location, Intake Canal Drainage Area. 55 acres Area Description This drainage area Includes a portion of'the plant yard, the switchyard, the limestone stacking area, the limestone unloading area and some vegetated land. The plant yard contains �a two acre parking lot and 1/2 mile of paved roadway. Roof area from the office annex, service building, and warehouse totals 35,000 ftz. Four miles of railway access cross the area. Railway and other embankments cover about 13 acres with maximum slope being 1.5H-1V Approximately four percent of the drainage area is surfaced or roofed. Emergency overflow from yard sump #1 would be discharged at this outfalL, It should be noted that while the newly constructed limestone stacking area is located within this drainage area, drainage from this area is designed to flow into a detention pond which discharges into Yard Sump #1, Significant Materials / Controls Gas A 1,000 gallon, above - grade, gasoline tank is located in the yard area west of yard sump #1 The tank has Integral spill containment Oil. Transformers containing a total of 340 gallons of oil are located in the switchyard. Gypsum and Limestone The Limestone Unloading area Is located within this drainage area. Additionally, conveyors which transport limestone and gypsum are located within this drainage area. See details of yard sump #1 for emergency overflow discharge characteristics. Overflow from the yard sump is an NPDES permitted discharge. Sump overflow is not a normal occurrence. ® Outfall SW008, Discharge Structure: Location: Drainage,Area: "Drainage Area 8" 8 "RCMP Intake Canal 0.1 acres Area Description This drainage area includes portions of the plant yard access road Approximately 70 percent of this area is paved. Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Page 18 of 30 Significant Materials / Controls Significant materials are not'typically stored in this drainage area. • Outfall SWO09 / NPDES Outfall -003, "Drainage Area 9" Discharge Structure 36" � CMP Location. Intake Canal Drainage Area- 3 6 acres Area Description This drainage area includes a portion of the plant yard and about one acre of grassy, undeveloped land The powerhouse roof for Unit 4 covers 63,800 ft2. The roofs of various other structures such as the ID fan electronics building 'cover approximately 4000 ft2. In this area, the plant yard covers about 2 2 acres and contains ,600 ,feet of railways and ,600 feet of paved roadways. About 50 percent of the total drainage area is either paved or roofed. On the south and east sides of this basin, the plant yard is surrounded by embankments which slope towards the plant yard at 1 5H.1V,. Office trailers, equipment, and materials are stored temporarily in, this area during outages The building, which houses the electronic equipment that controls the Unit 4 variable speed, ID fans is located in this drainage area. The electronics must be air conditioned, and the non - contact drain water from the air conditioner heat exchanger is discharged at this outfall as NPDES permitted discharge #003. There are four transformers associated with the variable speed ID fans- These transformers are located within this,drainage basin, but,the containment pits beneath them drain to yard sump #2 Unit's 3 and 4 precipitators are located in this drainage area A transfer sump is located within this drainage area This sump accepts drainage from a storm water detention pond located south of this area and transfers this drainage into yard sump # 2 In the un,'likely event of an overflow from this, transfer sump, 'this storm water could enter drainage area 9 and be discharged via Outfall SW009. However, this sump has engineered controls in place (e.g high level alarms, float valves, etc ) which should minimize this threat Significant Materials / Controls Significant materials are not typically ,stoned in this drainage area Storage This area is used temporarily as a laydown area during outages • Outfall SWO10, "Drainage Area 10" Discharge Structure* 30" � GNIP Control Structure. 22,000 gallon oil trap tank Location: Discharge Canal Drainage Area: 11.7 acres Area Description This drainage basin includes a. portion of the plant yard and the fuel oil unloading area. The plant yard contains the Unit 4 transformers, hydrogen and nitrogen tanks, three 46,000 gallon urea tanks and two 500,000 gallon oil tanks. One of the oil tanks is closed and locked out. Embankments with maximum slope of 1.51-1:1V cover about 2.4 acres. There are Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Page 19 of 30 approximately 0 3 miles of paved roadway and 0 2 miles of railways. Ten percent of the area is paved. All yard drainage in this basin is processed through a 22,000 - gallon oil trap tank. Storm water passes through the tank and discharges to Lake Norman, and oil is contained within the trap tank. The oil trap tank is inspected periodically and cleaned out as needed. Significant Materials / Controls Oil. Two 500,000 gallon bulk storage fuel oil tanks are located in the southwest corner of the plant yard Currently,, only one of the tanks is, in service, the other is closed and locked out. The tanks are aboveground, galvanized steel cylinders and 'are surrounded ;by an, earthen berm sufficient in height to contain a total spill of'both tanks plus rainfall. Rainfall collected within the containment berm is inspected for the presence of oil before being drained through a manually operated siphon to the oil trap tank In the fuel oil unloading area, fuel oil is transferred from an 8,000 gallon tanker truck by aboveground pipeline to the 500,000 gallon oil tank. DOT unloading procedures are - followed. The unloading area encompasses about 0.9 acres and is, surrounded by a four inch berm Catch basins drain to a 12 inch CMP that is routed to the oil trap tank The Unit 4 main transformer and three smaller transformers located within this drainage area contain a total of 30,536 gallons of oil with 14,120 gallons in the Unit 4 transformer, 10,398 gallons for CT1, and 3,009 gallons each for 4T1 and 4T2 and 6,671 gallons for each SCR T3 and T4 The containment pits beneath the transformers drain to the oil trap tank The transformer yard is surrounded by a 4 inch concrete curb. Urea. Three 46,000 gallon urea ASTs have recently been installed within this drainage area and are located adjacent to the bulk fuel ASTs within the earthen'berm. • Outfall SW011, Discharge Structure - Location Drainage Area. Area Description This outfall conveys water The basin is basin Outfall SWO12, Discharge Structure. Location' Drainage Area: "Drainage Area 11" 24 "RCMP Discharge Canal 0.6 acres overflow from the raw water tank, which is used to store fire protection a small grassy area. There are no significant materials stored within this "Drainage Area, 12" 24" � CMP Discharge Canal 2 5 acres Area Description This outfall conveys sheet flow runoff from areas drainage area includes a gravel parking area significant materials stored within this_basin. immediately north and west of_the_FGD. This located north of the -FGD. There are no Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Page 20�of 30 4.4 Yard Sump Systems There are two yard holding sumps at Marshall Steam Station. • Yard Sump #1 Yard sump #1 is located west of the coal transfer house, and effluent is pumped to the ash basin. This yard sump collects runoff from two drainage basins, and the total drainage area is 8.8 acres Emergency overflow for yard sump #1 would go to NPDES Outfall 002A, which is also Outfall SW007. The drainage basins which discharge into this sump are defined as 1A and 1 B and are discussed below. Yard Sump'Drainage Area 1A: Drainage Area* 3,4 acres 'Area Description Drainage area 1A consists of the Drainage collected from a portion of the plant yard west of the powerhouse which contains the Units 1, °2„ and 3 transformers. From inside the powerhouse, the turbine room sumps and all equipment located in the western half of the building discharge effluent to this sump. Approximately 0.5 miles of railways and 0.25 miles of paved roadways cross the area Approximately 21 percent of the drainage area is paved or roofed. Significant Materials / Controls Oil: The Units 1, 2, and 3 transformer yards are located in this drainage area and contain a total of 82,011 gallons of oil. Oil contents are as follows - Unit 1 18,270 gallons 1T• 3;043 gallons CT 1 and 2: 10,395 gallons Unit 2 1.8,270 gallons 2T. 3,362 gallons Unit 3 22,920 gallons 3T1. 2,810 gallons 3T2. 2,941 gallons FGD T1. 8,490 gallons FGD T2 9,088 gallons The transformers have containment pits beneath them, which vary in depth up to 24 inches. The transformer yard is surrounded by a 4 inch concrete curb. Yard Sump Drainage Area 1 B: Drainage Area. 5 4 acres Area Description Drainage Area 1B is collected from a portion of the plant yard, which includes coal handling facilities, chemical storage, and compressible gas storage. The roofs of the coal handling facilities, storage sheds, and tractor shed cover approximately 20,000 ft2. The newly constructed limestone stacker discharges into a storm water detention pond which is engineered to discharge into Yard Sump 1 Embankments cover about 1.3 acres and are sloped 2H:1 V or Less Approximately 0.5 miles of railways and 0.25 miles of paved roadways cross the area. Approximately 35 percent of the drainage area is paved or roofed. Significant Materials / Controls Oil. A 1,000 gallon fuel oil -tank is located beside the tractor shed The tank sits on a concrete pad and is surrounded by a concrete berm, a drain valve controls discharge from the enclosure Both a tractor and a bulldozer refueling station are located beside the tractor Marshall Steam Station, Catawba County i0bES Permit No NC0004987 Page 21 of 30 shed. 2,000 gallons of oil and torque fluid are stored Inside the tractor shed' within a bermed area A 500 gallon tank of hydraulic fluid is located beside the coal dumper /crusher building Two small transformers, each containing 188 gallons of oil, are located near the switchgear house. A transformer located at the sump #1 control system contains 270 gallons of oil Chemicals: The chemical storage building contains sodium nitrate, ammonia, and hydrazine and has approximately 500 ft2 of floor space The concrete floor is sloped to floor drains which are routed to yard sump #1 Hazardous Waste, A 55 gallon drum is used to temporarily store paint waste in a satellite accumulation area. The drum 'is covered inside a cage Wastewater. Plant wastewater from equipment discharges, floor drains, sumps, etc is routed to yard sump #1 This wastewater may include oil, chemicals, and hazardous material spills. • Yard Sump #2 Yard sump #2 ,is located east of the service building and north of Stack. #1. The drainage area for this sump covers 39 2 acres This yard sump collects runoff from two drainage basins. The drainage basins which discharge into this sump are defined as 2A and 2B and are discussed below. Drainage Area 2A Drainage Area. 9 2 acres Area Description Drainage is collected from the plant yard east of the powerhouse and 161,000 ft2 of the powerhouse roof at Units 1, 2, and 3. From inside the powerhouse, boiler room sumps and all equipment located in the eastern half of the building discharge effluent to this sump. The plant yard includes the precipitators, smoke stacks, and ID fans Cooling water from the ID fans bearings for all four units is processed through this sump There are approximately 800 linear feet of paved roadway and 1,200 linear feet of railways in this area. The paved and roofed areas represent approximately 90 percent of the drainage area Effluent from yard sumps is pumped to the ash - settling basin. Emergency overflow would discharge at NPDES 0028. Significant Materials / Controls Oil: Transformers located atop the precipitators contain a total of 1'0,848 gallons of oil. The maximum reservoir size in any one transformer is 176 ;gallons. There are four transformers associated with the Unit 4 variable speed ID fans. These transformers are located within the drainage basin of outfall #SW009, but the containment pits beneath them drain to yard sump #2. The basins beneath the transformers are sufficiently deep to contain a total spill Two of`the transformers, each contain 401 gallons of oil, and the other two hold 364 gallons each The total amount of oil in these transformers is 1,530 gallons Marshall Steam Station, Catawba County NODES Permit No NC0004987 Page 22 of 30 A transformer located at the yard sump #2 control system contains 270 gallons of oil. There is a 900- gallon used oil tank located between Units 2 and 3 for Marshall Steam Station generated used oil Sulfuric Acid: A 5,000 gallon tank of sulfuric acid is located near the southeast corner of Unit 2. The tank has a concrete pit with drain valve, which is capable of complete containment. Ash* Waste ash is sluiced across the area to the ash basin. Within the plant yard, the pipelines are contained in concrete trenches; storm water that collects in the trenches drains to yard sump #2. Beyond the plant yard, ash lines pass overland. There is a small berm between the ash lines and the ash 'haul road to direct spills back to the concrete trench. Flyash is transferred from the plant to the ash silos now located on ash haul road through above grade pipelines. The two ash silos can each store 2861 tons of ash. The ash is transferred from the silos to trucks for transport to either off-site facilities or the on -site structural fill project Other facilities within the area, which collect, handle, or store ash include: baghouses, pumps, blowers, hoppers, ,and precipitators. Wastewater Plant wastewater from equipment discharges, floor drains, sumps, etc. is routed to yard sump #2 This wastewater may include oil, chemical, and hazardous material spills Cooling water from Units 1,, 2, 3,, and 4 ID fan bearings is discharged to this sump. Drainage Area 213 Drainage Area 30 acres Area Description Drainage area 2B includes the newly constructed FGD, the Wastewater Treatment Plant and ancillary parking areas that serve these areas. Catch basins located along the additional 2000 ft2 of roadway and parking lots within these areas route storm water into a detention pond located' at the southeastern corner of the drainage area. Discharge from this pond is ,pumped into the transfer sump (located in the adjacent Drainage Area 9) The storm 'water is then pumped from the transfer sump into Yard Sump 2 Effluent from yard sumps is pumped to the ash - settling basin Significant Materials-/ Controls Oil: Transformers located north of the switchgear building contain a total of 5,300 - gallons of oil The maximum reservoir size in each of the four transformers is 1,325,-gallons. A containment pad is located at the base of these transformers. ,An emergency quench pump fuel oil tank is located on the north end of the absorber building. This tank has a capacity of 100 gallons. This AST is located within containment The fill station for this AST is located at the tank Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Page 23 of 30 Wastewater Plant wastewater from equipment discharges, floor drains, sumps, etc. is routed to the 'WWTP located within this drainage area After treatment, this waste water is pumped via underground piping to the constructed wetlands treatment system and is eventually discharged via the ash basin This wastewater may include process water from the FGD as well as oils, chemicals, and hazardous material spills. Gypsum and Limestone. Overhead conveyors which transport limestone and gypsum are located within this drainage area However, these conveyors are covered and should not represent a significant threat to storm water Additionally„ areas where these conveyors cross roads or ponds are completely encapsulated to further ,minimize the threat of a release. 4.5 Other Drainage Areas "Drainage Area 13 "- Gypsum Radial Stacker Discharge Structure: Two 24" � CMP Location: Detention Pond Drainage Area. 6 acres Area Description This drainage area consists of sheet flow and piped runoff from the gypsum stacking area and soil borrow area. Gypsum Is a byproduct of the FGD area. It is transported by covered conveyors from the FGD site to the gypsum stacker area, where it is stacked in a radial fashion. The soil borrow area adjacent to the radial stacker also contributes to this drainage area The drainage from the soil borrow area consists of the portion closest to the road. Drainage from these areas is engineered to flow into a storm water detention pond, which discharges Into a finger of the ash basin Discharge from this finger eventually reaches the ash basin Significant Materials/ Controls Oil A 500 - gallon AST and a 5,000 - gallon AST containing fuel -oil are located within this drainage area These ASTs ,are situated within a plastic -lined containment basin with no drain. These ASTs are owned and operated by Southeastern Fly Ash (SEFA) Gypsum- Gypsum is stacked in the area until It is shipped off by trucks to the wallboard facility. The gypsum piles are contained on three sides by a berm to prevent storm water runoff to these areas The north side of the area is open to convey the storm water through roadside ditches Into two pipes which drain into a detention pond. "Drainage Area 14 "- Soil Borrow Area Discharge Structure, 24" � CMP Location: Detention Pond Drainage Area. 6 acres Area Description This drainage area conslsts of sheet flow from the soil borrow area. The drainage from the soil ,borrow area is ,limiited to the half farthest from the road. Drainage from this area is engineered Marshall Steam Station, Catawba County NPDES Permit No 'Nc6004987 Page�24 of 30 to flow Into a storm water detention pond which discharges Into a small creek. No significant materials are located within this drainage area "Drainage Area 15 "- FGD Landfill Discharge Structure Location Drainage Area. 24 "RCMP Finger of the Ash Basin 20 acres Area Description This drainage area is composed of the entire FGD landfill., Significant Materials / Controls Gypsum. Gypsum is one of the significant materials associated with the drainage area. Gypsum that cannot be sold and is not of quality is ,disposed of in this area. The surface water flow from the landfill will typically collect at the lower end of the cell and discharge Into the storm water collection pond located at the 'southern end of the landfill. From the storm water basin, the runoff is piped into a finger of the ash basin that eventually discharges Into the ash basin FGD Wastewater Treatment Sludge. The sludge scrapped from the bottom of the wastewater treatment facility `i's brought to the gypsum landfill This process is performed because the wastewater sludge is mixed with the, gypsum to form a more dense substance that will not be carried by the wind Other ,Materials in Landfill Include- asbestos, flyash, bottom ash, construction and demolition debris "Drainage Area 16" — Coal Pile Discharge Structure Surface Ditches Location: Discharges into Ash Basin Drainage Area 40 acres Area Description This drainage area 0s composed of the entire Coal Pile. Significant Materialsi/ Controls The coal pile is the only significant material' associated with the drainage area. The surface water flow from the coal pile accumulates into ditches which surround the coal pile area. These ditches channel storm water runoff into the ash basin. A berm, which surrounds the coal pile, ensures that drainage from this area remains confined. "Drainage Area 17" — Sanitary Wastewater Lagoon Discharge Structure. 6 " 0 line to surface trench. Location Discharges into Ash Basin Drainage Area- 4.5 acres Marshall Steam Station, Catawba County NPDES Permit No NC0004987 0age,25 of k Area Description This drainage area is composed of the sanitary wastewater treatment lagoon and surrounding land Significant Materials / Controls This lagoon accepts sanitary wastes from the entire plant and performs aeration treatment on this waste before it is discharged Into the ash basin. Significant Materials / Controls Sanitary wastewater would be the only significant material associated with the drainage area. "Drainage Area 18" — FGD Constructed Wetland Treatment System Discharge Structure. 18" HDPE Location. Discharges Into Ash Basin, Drainage Area: 40 acres Area Description: The constructed wetland treatment system (CWTS) is designed to treat wastewater from the Flue'Gas Desulfurizati'on solid removal wastewater treatment system (WWTP). The wastewater Is Initially treated by the WWTP and pumped to the wetland system. All the rainfall runoff from the CWTS area flows into the ash basin Significant Materials / Controls There are no significant materials The wastewater is contained in the treatment system "Drainage Area 19" — Bottom Ash Operation and Pyrite Operation Discharge 'Structure ;Surface Ditches Location Discharges Into Ash Basin Drainage Area 35 acres Area Description This,area encompasses operations which Involve the bottom ash operation -and recovery of coal from pyrites All storm water discharge,from this area is routed via ditches into the ash basin. Significant Materials / Controls Coal and the numerous entities recovered from the coal are processed and /or staged within this area Oil: Charah (vendor) has a 550 gallon oil storage tank located in this drainage area. BKF has a 500 gallon oil storage tank located in this drainage area. e "Drainage Area 20" - Closed Ash, Landfill Discharge Structure Surface Ditches Location. Discharges into Ash Basin Drainage Area. 58 acres Area Description, This landfill is capped and is no longer in use Marshall Steam Station, Catawba County ,NPDES Permit,No NC0004987 Page 26 of'30 Significant Materials / Controls. There are no significant materials • "Drainage Area 21 "- Beneficial Structural Fill Discharge Structure. Surface Ditches Location- Discharges into Ash Basin Drainage Area- 84 Acres Area Description- This area is presently being used as a beneficial structural fill area. Significant Materials /Controls: Fly ash: Fly ash is a significant material located within this area 5.0 Hazardous and Toxic Substances 5.1 Hazardous and Toxic Substances Table 2c -3 At MSS, 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 discharge are as follows: Marshall Steam Station Hazardous and Toxic Substances Table 5.1 Acetaldehyde Dodecylbenzenesulfonic Acid Nitric Acid Sodium Hydroxide Acetic Acid Ethylbenzene Phenol Sodium Hypochlorite Adipic Acid Ferrous Sulfate Phosphoric Acid Sodium Phosphate Diabasic Aluminum sulfate Formaldehyde Phosphorus Sodium Phosphate Tribasic Ammonia Hydrochloric Acid Potassium Bichromate Styrene Ammonium Chloride Hydrofluoric Acid Potassium Hydroxide Sulfuric acid Ammonium Hydroxide Hydrogen 'Sulfide Potassium Permanganate Toluene Antimony Trioxide Maleic Acid Pro ionic Acid Vanadium Pentoxide Asbestos Mercuric Nitrate P rethrins Vinyl Acetate Benzene Monoethylamine Sodium Dodec Ibenzenesulfonate Xylene (Mixed Isomers) Chlorine 'Na hthenic Acidalene Sodium Fluoride Zinc Chloride Cupric Nitrate C clohexane I Nickel Hydroxide During the course of the year products such as commercial cleaners and laboratory reagents may be purchased that can 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. Marshall Steam Station, Catawba County NPOES,Permit No NC0004987 Page 27 of 30 5.2 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 Substances listed are present 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 in 40 CFR 117 and the Comprehensive Environmental Response Compensation and Liability Act (CERCLA) Marshall Steam Station Hazardous Substances in Excess of RQ Table 5.2 SU8STANGE QUANTITY SOURCE Aluminum sulfate 40,987 Ibs Powe rho useMater'Treatment Ammonium hydroxide 3,317,lbs Powerhouse Benzene 167 Ibs Gasoline Tank Hydrazine* 4145 lbs. Powerhouse/Warehouse Methyl Tert-But I Ether 1,334 Ibs Gasoline Tank Naphthalene 41,700 Ibs Fuel Oil Tanks Sodium hydroxide 50,040 Ibs Powerhouse Sulfuric acid 6,738 Ibs Powerhouse X lene Mixed Isomers 42,992 Ibs Fuel Oil Tanks Values in Table 5 -2 represent maximum quantities usually on -site at any given time and do not necessarily reflect quantities discharged Various amounts of these substances may go to the ash basin for treatment due to use in site laboratories, small leaks, spills, or drainage from closed loop systems Treatment of these substances and their by- products is achieved by physical and biological activity in the ash basin *Listed in 40 CFR 302 4 - Table 302 4 List of Hazardous Substances and Reportable Quantities 6.0 Marshall Steam Station 316 Determination, 6.1 316(a) Determination Duke Energy's operating experience during `the past five years under the thermal limitations imposed in NPDES Permit No NC0004987 substantiates EPA's 316(a) determination for Marshall (May 1975) 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." This is supported by the enclosed report entitled, "Assessment of Balanced and Indigenous Populations in Lake Norman near Marshall Steam Station" In Duke's judgment the operating characteristics of the station have a minimal effect on the aquatic environment of Lake Norman The character of the thermal discharge has not changed since the original 316(a) determination. Accordingly, Duke Energy requests that the thermal limitations in the present permit be continued 6.2 Marshall Steam Station 316(b) Determination In conjunction with the rulemaking process for the new Phase II 316(b) rule pertaining to fish impingement and entrainment, historical data and permitting records were reviewed. Initial 316(a) and 316(b) studies associated with enactment of the Clean Water Act concluded that the location, construction capacity, and design of the cooling water intake of Marshall and other Duke Marshall SteamStation, Catawba County NPDES Permit No NC0004987 Page "28 o0b Energy steam stations were not detrimental to the aquatic ecosystem and minimize adverse environmental impacts. Both North Carolina and EPA regulators concurred in 1976 that 316(b) fish impingement and entrainment studies were no longer needed at that time. When the new Phase II 316(b) Rule (Rule) was issued, Duke Energy developed Proposals for Information Collection (PICs) and initiated approved 316(b) field studies at its applicable steam stations for the eventual development of Comprehension Demonstration Studies (CDSs) to be used to determine Rule compliance. When the Rule was remanded back to EPA for revision, CDSs were no longer applicable and state agencies were instructed to use Best Professional Judgment (BPJ) in the interim to determine 316(b) impacts or the lack thereof. Currently, Duke Energy is summarizing the results of the 316(b ) study at Marshall Steam Station and will be submitting an Impingement Characterization and Adverse Environmental ,Impact Report, BPJ Report, and 40 CFR, §122.21(r)(2), (3), and (5) Source Waterbody Physical Data, Cooling Water Intake Structure Data, and Cooling Water System Data. These reports should be ready for .submittal to the NCDENR in early 2010. Ash Basin Capacity Part I Section 15 of the existing NPDES permit for Marshall Steam Station requires the perr6ittee to provide and maintain at all times a minimum free water volume (between the top of the sediment level and the minimum discharge elevation) equivalent to the sum of the maximum 24 hour plant discharges plus all direct rainfall and all runoff flows to the pond resulting from a 10 year, 24 hour rainfall event, when using a runoff coefficient of 1 0. Determination of Wet Weather Detention Volume Wet Weather Detention Volume is, the sum of the runoff accumulated in the ash basin which results from a 10 -yr 24 -hr storm (assuming 100,% runoff) plus the maximum 24 -hr dry weather waste stream which discharges to the Ash Basin (refer to NPDES Permit NC0004961) Estimate Runoff to the Ash Basin from a 10- yr 24 -hr storm Natural Drainage Area of Ash Basin = 1180.0 Acres Station Yard Drainage Area Pumped to Ash Basin = 14.7 Acres Total = 1194 7 Acres 2 Precipitation from 10 -yr 24 -hr . storm= 5.0 Inches 3 Total Stormwater Runoff to Ash Basin= 497.79 Acre -feet j (Assuming 100% runoff) Estimated Maximum 24 -hr Dry Weather Waste Stream Discharging to Ash Basin: 1 Maximum recorded Ash Basin Discharge = 12,400,000 Gallons /day a l 2 Increase maximum daily disharge by 10 % for conservatism and convert units to acre -feet = Wet Weather Detention III Volume Sum of Parts I. and II. = Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Page 29 of 30 41.86 Acre -feet 539.65 Acre -feet Estimated Quantity of Solids (Ash) to, be discharged to Ash Basin through IV. December 31, '2015. Note: NPDES Permit expiration date is 2/28/10. Time Actual or % Ash Estimated Estimated Estimated Period Estimated 'Total Ash Ash Sent to Ash Coal Production Structural Fill 'Discharged Consumpti (1000's or Re -Used to Ash on (1000's tons) (1000's tons) basin tons) (1000's tons) ** 2009 5013.00 11 10% 55540 50010 -31 70 2010 501240 11.20% 561,90 505.60 -35.70 2011 5088.80 1180% 600.00 538.00 -5.00 2012 508340 11 10% 566,30 509.30 -10.10 2013 4954.40 1060% 52270 472.30 -16.60 2014 4929,00 10.60% 52000 470.00 -17.00 2015 5231 20 1060% 551 90 249.10 -12.20 Total 35312.20 1 77.00% 3878.20 3244.40 ' - 1,28.30 * Calculation assumes an in -place ash density of 55 lbs. per cubic foot ** Approximately 30;000 tons of ash are transferred from the ash basin to the on -site structural fill annually until 2011 Estimated Total Storage Volume Required V. through 2015• Wet Weather Detention Volume 539.6 Acre -feet Required Storage Volume Through 12/31/2015 = 1 539 6 Acre -feet J Marshall Steam Station, Catawba County NPDES Permit No NC0004987 Page 30�of 30 VI Results Ash Basin @ Pond Elevation 790' +0" 2006 Ash Removal Project (200,000 Tons) Estimated Solids to Basin Oct 2005 - Dec. 2008 Total 672.5 Acre -feet 103.0 Acre -feet 35.1 Acre -feet 740 4 Acre -feet Note Available Storage based on basin survey dated 8/25/2005 Available Storage > Required Storage Based on these calculations, there is sufficient capacity in the ash basin to provide the retention volume specified in the permit through the year 2015.