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### Final Notes from Site Visit at Appalachian Power Company’s Mountaineer Plant

on September 11, 2008

EPA conducted a site visit at Appalachian Power Company’s Mo untaineer Plant (Mountaineer) located in New Haven, WV on Thursday, Se ptember 11, 2008 to learn about the operations at the plant, specifically the FG D wastewater treatment system.

These notes describe the information collected during the site visit and the pre-site visit phone call, which was held on August 8, 2008. Attached to this document are the following: (1) List of site visit participants; (2) Proposed NPDES Water Balance Diagram for the Mountainee r Plant, dated 3 Dec 2007; (3) Process flow diagrams for the FGD unit and FGD wastewat er treatment system; (4) Presentation that the Mountaineer personnel gave during t he site visit;

Plant Overview

• The Mountaineer plant has one generating unit with a ne t capacity of 1,300 MW. The table below gives some general information ab out the one

unit.

• Mountaineer operates a recirculating cooling system with a cooling tower. The cooling tower blowdown is transferred to the wastewat er treatment ponds.

• Mountaineer operates a limestone forced oxidation FGD scrubb er system.

• Mountaineer burns a blend of eastern bituminous (1.2-7.5 pounds of sulfur per MMBTU electricity produced) and Powder River Basin (PRB ) coal. Mountaineer blends up to a maximum of 15 percent of PRB into the coal. Mountaineer stated that they perform the blending of the c oal on site.

• The blended Mountaineer coal has a sulfur content of 5.5-6 pe rcent sulfur, or 4.5 pounds of sulfur per MMBTU electricity produced.

• Mountaineer operates a sulfur trioxide mitigation system. Mountaineer injects trona into the flue gas upstream of the ESPs to control sulfur

trioxide emissions. Unit Installation

Date Capacity

(MW) Particulate

Control NOx Control SO 2 Control 1 September

1980 1,300 Cold-side

ESP SCR – May

2002 Wet FGD - February

2007Page 2 • Mountaineer is conducting a pilot test of several technol ogies for the treatment of mercury in the FGD purge stream.

• Mountaineer is working with Alstom on a pilot test for a carbon capture technology.

Coal Pile

• Mountaineer has four coal pile runoff ponds, one located at each corner of the coal pile. During the site visit, Mountaineer staff measured the temperature and pH of water in each of the coal pile run off ponds. The following table summarizes the data collected during the s ite visit.

Pond Level Temperature (°C) pH

Southwest Pond Full 23.1 3.5

Northwest Pond Drained 22.2 7.17

Northeast Pond Drained 23.6 7.29

Southeast Pond Drained 23.6 7.72

• Mountaineer stated that the runoff collected in the nort hwest, northeast, and southwest ponds are all transferred to the southeast pond before being pumped to the bottom ash ponds.

Ash Handling

• The Mountaineer plant has dry fly ash handling. The dry fly ash is pneumatically blown to silos for temporary storage. Mount aineer uses reclaim water to condition the fly ash prior to trucking it to the on-site

landfill.

• The Mountaineer plant has a wet bottom ash handling syst em. The wet bottom ash sluice is sent to the two bottom ash ponds. Process wastewater from pyrite transport, fly ash silo sumps, limestone pile, gypsum pile, and the coal pile are also sent to the bottom ash ponds. Mountaineer only operates one bottom ash pond at a time; therefore, whil e one is in service,

the other is out of service.

• The overflow from the bottom ash ponds is transferred to one of two wastewater treatment ponds. Each bottom ash pond has i ts own wastewater treatment pond; therefore, like the bottom ash ponds, only one wastewater treatment pond is operating at a time. In a ddition to overflow from the bottom ash ponds, the treatment ponds also rece ive cooling tower blowdown, landfill runoff, and low volume wastes.

• The wastewater treatment ponds overflow to a single re claim water pond. Some of the overflow from the reclaim water pond is recycled for plantPage 3 operations and the rest is sent to the clearwater pon d, which discharges to

the Ohio River.

SCR System

• Mountaineer operates a SCR system directly after the b oilers. The SCR is located prior to the air preheater and ESPs because the system is operated at a temperature of 600-800°F. Mountaineer stated that a minimum temperature of 620°F is needed for the SCR reaction to initia te.

• Mountaineer does not store ammonia on site. Instead, Mounta ineer stores urea and hydrolyzes the urea to obtain ammonia gas. Mountai neer stated that 1 pound of urea is hydrolyzed to 0.56 pounds of ammonia.

• Ammonia is injected into the flue gas upstream just prior to the flue gas entering the SCR.

• The Mountaineer SCR system has three levels of plate catalysts. There are four injection points in each level.

• Mountaineer stated that ammonia slip happens when the cataly st becomes depleted. Additionally, Mountaineer stated that issues mix ing the ammonia into the flue gas can lead to ammonia slip. Mounta ineer has monitors to measure ammonia slip; however, the monitors can only measure the ammonia at the specific monitoring location in the SCR and does not account for the entire system. Typical ammonia slip is 2-2.5 ppm.

• Mountaineer stated that the SCR typically achieves a NO x removal efficiency greater than 90 percent.

• Mountaineer stated that the catalysts are sent off sit e to be regenerated. For Mountaineer, the catalysts have a lifespan of 3 to 8 years before requiring regeneration. However, plant personnel expect that lifespan to decrease now that the SCR will be operating year round.

FGD System

• Mountaineer operates a wet limestone forced oxidation FG D scrubber on the one generating unit. The FGD system consists of t wo modules made with 2205 stainless steel alloy. The FGD scrubber was insta lled in February 2007.

• The FGD system achieves a 98 percent removal of SO 2 from the flue gas.

• Mountaineer stated that they unload 1,500 tons of limestone per hour from barges. The limestone pile on site contains approximat ely 15,000 tons of

limestone.Page 4 • The limestone is ground in two ball mills which reduce th e size of the limestone to 95 percent passing 325 mesh. Each of the ball m ills processes 90 tons of limestone per hour. Mountaineer sta ted that they are able to hold 226,000 gallons of limestone slurry reagent. The li mestone slurry is approximately 25 percent solids.

• The FGD scrubber modules have six spray levels and each level has a designated recirculation pump. Mountaineer stated that t hey are currently operating four of the six recirculation pumps. Mountaine er stated that the number of pumps needed depends on the sulfur content of the coal. Each recirculation pump recirculates the FGD scrubber slurry at a flow rate of 76,075 gpm.

• The Mountaineer FGD scrubber modules have two blowdown pumps that continuously blow down the FGD scrubber slurry at 2,182 gpm. Mountaineer stated that the blowdown pumps are operating con tinuously,

but the flow is recirculated when a blowdown isn’t nece ssary.

• Mountaineer stated that they do not use any additives in th e FGD system because many additives are byproducts of other industries and th e availability of these additives are dependent on industry shifts. Additives are typically added to enhance the alkalinity of the syst em.

• Mountaineer stated that the gas flow rate within each mo dule is 2,600,500 acfm. The upward velocity of this gas is 10 feet per second a nd the average mass transfer contact time is 1-1.5 seconds. The flue gas approach temperature is approximately 350°F. The temperature within the scrubber is approximately 128°F, which is the adiabatic saturation temperature at the pressure within the absorber.

• Mountaineer stated that the liquid to gas (L/G) ratio is 120 gallons/1000 acfm. The L/G ratio for limestone forced oxidation syste ms is higher than that of AEP’s Gavin power plant, which has a L/G ratio of 28-32. Gavin is a magnesium-enhanced chemistry that operates at a gr eater alkalininty than the limestone forced oxidation process and so require s less L/G.

The SO 2 removal rate is dependent upon how fast SO 2 can be absorbed into the liquid phase. The low alkalinity of limeston e chemistry thus makes absorption the rate-limiting factor. Higher alkali nity systems (i.e., AEP’s Gavin plant) are not rate-limited by the absorptio n of SO 2 and thus can operate at lower L/Gs. As a result, higher L/G r atios are needed for

limestone-based chemistries.

• Mountaineer stated that the mist eliminators are layers of “Z” shaped packing that provide areas for water droplets to collect, nucleate, and fall back into the FDG scrubber. The plant washes the mist eliminators with fresh water to prevent plugging.Page 5 • Mountaineer typically blows down the FGD slurry from scrubbe r modules when the percent solids in the modules reaches 17 percen t. The blowdown is operated until the percent solids is reduced to approxima tely 14 percent.

The maximum allowable solids content in the scrubber is 20 percent.

• Mountaineer stated that the size of the gypsum crystals is affected greatly by residence time, and degree of agitation.

• Mountaineer stated that the design chlorides concentratio n in the scrubber is a maximum of 12,000 ppm. The scrubber purge is generated 24 hours per day, 5 days per week. The flow rate is typically 270 gpm , which can increase to 350 gpm. The purge contains 5,000-6,000 ppm chlorides.

• The blowdown from the FGD scrubber is sent to one of thr ee sets of hydroclones. The underflow from the hydroclones contains 58 percent
solids.

• Mountaineer transfers the hydroclone underflow to one of three vacuum

belt filters. The vacuum belt filters handle 83 tons o f gypsum per hour and dry the gypsum to approximately 10 percent moisture content. Mountaineer does not wash the gypsum on the vacuum belt f ilter.

• Mountaineer estimated that the final gypsum product has a chlorides concentration of 10,000 ppm.

• The overflow from the hydroclones, which contains five pe rcent solids, is either returned to the FGD scrubber or transferred to a pur ge tank and sent to the FGD wastewater treatment system.

• The filtrate from the vacuum belt filter is recycled back to the FGD scrubber system.

• The Mountaineer plant does not sell any of the gypsum pr oduced. All of the gypsum is landfilled. Mountaineer stated that a sma ll amount of water is added to the gypsum product at the landfill for handling an d landfilling.

• In addition, off-specification gypsum produced at the Mit chell plant (located in Moundsville, WV) is transferred to Mountainee r for disposal.

• The landfill where the gypsum solids are sent has a “No free liquid” requirement, which means that the gypsum must not conta in any water that easily flows off of the solids.

• Plant personnel stated that there is no market for th e Mountaineer gypsum because the plant is too far away from major highways.Page 6

Mountaineer FGD Wastewater Treatment System

• The overflow from the hydroclone is sent to the purge tan k and then

transferred to the Mountaineer FGD wastewater treatment system. Mountaineer stated that the design flow rate from the pur ge tank is 350

gpm.

• Mountaineer stated that a portion of the FGD wastewate r has to be purged from the system because otherwise chlorides would build up in the system and the metallurgy of the system cannot handle the high chlorides concentrations. Mountaineer stated the goal of the FGD wastewater treatment system is to remove solids and control the pH of the FGD wastewater before discharging to the Ohio River.

• From the purge tank, the FGD wastewater is transferred t o one of two desaturation tanks, each 11,800 gallons, where lime is added to increase the pH from approximately 5.6 to 8.2.

• The overflow from the desaturation tanks is transferre d to the primary clarifiers. Each desaturation tank has a designated prim ary clarifier. Each

clarifier is 30 feet in diameter. As the wastewater flows to the primary clarifier, an anionic polymer (GE 1125) is added to the wastewa ter. The primary clarifiers are designed to remove 95% of the sol ids present in the

wastewater.

• The underflow from the primary clarifiers is transferr ed to a sludge tank for temporary storage and then sent through a filter pres s for dewatering. The filter press cake is sent to a landfill.

• The overflow from the two primary clarifiers are com bined and transferred to the equalization tank. The filtrate from the filter press is also transferred to the equalization tank.

• From the equalization tank, the wastewater undergoes ironcoprecipitation and coagulation. The wastewater is tran sferred to the ferric chloride mix tank. Mountaineer stated that they no longer add ferric chloride to this tank. Instead they add a cationic polymer ( GE 1195).

• The overflow from the ferric chloride mix tank is split and enters two secondary clarifiers, each 30 feet in diameter, where an anionic polymer is added (GE 1125). The underflow from the secondary clarifie rs is recycled back to the primary clarifiers. The overflow from the two secondary clarifiers are combined and transferred to a 15,000 gallon eff luent storage

tank.

• From the effluent storage tank, the FGD wastewater is t ransferred to the clearwater pond and then discharged to the Ohio River.Page 7 • Mountaineer stated that this system is operated 24 hours a da y, 5 days a week. The typical flow rate of the purge stream is 270 gall ons per minute and can be as high as 350 gallons per minute.

• Mountaineer stated that the chlorides levels in the effl uent of the FGD wastewater treatment system range between 5,000 to 6,000 ppm.

• Mountaineer stated that they regularly monitor the FGD w astewater effluent for TSS and pH. However, the Mountaineer plant does not have a NPDES permit for the effluent from the FGD wastewater treatment system, since it discharges into the plant’s pond comple x which does have an NPDES permit.

Landfill

• Mountaineer stated that its fly ash is compacted and tran sported to its

landfill.

• An underground collection system directs the runoff and le achate from the fly ash to the leachate collection pond. The leachate collection pond also receives leachate from the FGD gypsum pile.

• Mountaineer estimated that a combined total of 3,500 tons of f ly ash and gypsum are generated every day.

• The overflow from the leachate collection pond flows into the wastewater ponds.

• Uncontrolled runoff from this landfill flows to a stor m outfall.

CO 2 Capture Project

• [CBI information has been removed from this document.]

Mountaineer FGD Wastewater Treatment Pilot Testing

• [CBI information has been removed from this document.]Page 8Table 1. Site Visit AttendeesNameOrganization (Representing)TelephoneE-mailRandy Brown Appalachian Power Company - Mountaineer (304) 882-4024 rlbrown4@aep.comDave HallAppalachian Power Company - Mountaineer(304) 882-4071 drhall@aep.comJ.L. PerryAppalachian Power Company - Mountaineer(304) 882-4106 jlperry@aep.comCharlie PowellAppalachian Power Company - Mountaineer(304) 882-4100 capowell@aep.comGreg PriceAppalachian Power Company - Mountaineer(304) 882-4020 gkprice@aep.comBrian SherrickAppalachian Power Company - Mountaineer(614) 716-1923 bdsherrick@aep.comDavid ThompsonAppalachian Power Company - Mountaineer(304) 882-4023 rdthompson1@aep.comPaul CreeAmerican Electric Power(614) 716-1845 ptcree@aep.comTom HartAmerican Electric Power(614) 716-3260 tomlhart@aep.comAmanda JanasovAmerican Electric Power(614) 716-3751 agjanasov@aep.comTim LohnerAmerican Electric Power(614) 716-1255 twlohner@aep.comMark O’BrienAmerican Electric Power(614) 716-1852 mobrien@aep.comBrent WattsAmerican Electric Power(304) 882-4115 mbwatts@aep.comDonna Hill Southern Company. (205) 257-5234 dbhill@southernco.comJosh Hall EPA/Office of Water (202) 566-1002 hall.josh@epa.govRon Jordan EPA/Office of Water (202) 566-1003 jordan.ronald@epa.govDeb Bartram ERG (Contractor to EPA) (703) 633-1669 deborah.bartram@erg.comPage 9Kurt Blohm ERG (Contractor to EPA) (703) 633-1675 kurtis.blohm@erg.comT.J. Finseth ERG (Contractor to EPA) (703) 994-7130 thomas.finseth@erg.com