### Final Notes from Site Visit at Kentucky Utilities Company’s Ghent Generating Station on December 9, 2008

EPA conducted a site visit at Kentucky Utilitie s Company’s Ghent Generating Station (Ghent) located in Ghent, KY on Tuesday, December 9, 2008 to learn about the operations at the plant, specifically the FGD wastewater handling system. Table 1, located at the end of this memorandum, identifies the site visit participan ts. The presentation that the Ghent personnel gave during the site visit is provided as an at tachment to this memorandum. Also included as
attachments to this memorandum are a labeled ae rial photo of the plant, overall process flow diagrams for the generating units, and a pr ocess flow diagram for the FGD systems.

This memorandum describes the information collected during the site visit, as well as the pre-site visit phone call, which was held on November 19, 2008.

Plant Overview

 Ghent operates four coal-fired generating units at the power plant, which is a baseload plant with a net generating capacity of 1,918 MW. The table below contains some general information for each generating unit. Process flow diagrams for Units 1 through 4 are include d as attachments to this memorandum.

Unit Installation

Date Capacity (MW) Particulate
Control NOx Control SO 2 Control 1 1974 557 ESP (cold-side) SCR, low-NOx burner, and
overfire air Wet FGD installed (1994)

2 1977 556 ESP (hot-side) low-NOx burner
and overfire air Wet FGD under construction (2009) 3 1981 557 ESP (hot-side) SCR, low-NOx burner, and
overfire air Wet FGD installed (2007)

4 1984 556 ESP (hot-side) SCR, low-NOx burner, and
overfire air Wet FGD installed (2008)

 Ghent burns eastern bituminous coal in all four generating units. Most of the coal burned originates from one of the follo wing locations: the I llinois basin, western Pennsylvania, or eastern Ohio. Ghent curr ently uses a low-sulfur coal from West Virginia in Unit 2 because the generating unit does not operate a FGD system.

 Ghent has the capability of burning Powder River Basin (PRB) coal in Units 3 and 4 because the generating units operate large fire box boilers, which are bigger than tangential-fired boilers (operated on Units 1 and 2). Ghent stated that they previously burned a blend of 50 percen t PRB and 50 percent eastern bituminous
coal in the Unit 3 and 4 boilers on occasion.Page 2

 Ghent burns approximately 5.5 million tons of coal per year. All of the coal is delivered via barge on the Ohio River.

 The sulfur content of the high-sulfur coal used at Ghent is typically 5.6 to 5.7 lbs

SO 2 /mmBTU, but it can range from 4.0 to 6.9 lbs SO 2 /mmBTU. The low sulfur coal for the non-FGD Unit 2 ranges from 0.8 to 1.1 lbs SO 2 /mmBTU.

 Ghent stated that the chlorine content of the coal is typically 700 to 800 ppm.

 The coal pile runoff is collected into two coal pile runoff ponds. One of the coal pile runoff ponds also receive s limestone pile runoff. The other coal pile runoff pond receives backwash from a sand filtr ation system used to treat the ash
treatment basin overflow. The overflow from the coal pile runoff ponds is
transferred to ash treatment basin 1.

 Prior to the site visit, Ghent personnel collected two samples from each of the coal pile runoff ponds and measured the pH . The pH in the coal pile runoff pond that receives limestone pile runoff was 7.2 S.U. (average of two samples). The pH in the coal pile runoff pond that receives sand filter backwash was 6.4 S.U. (average of two samples).

 Ghent operates SCR systems on Units 1, 3, and 4. Prior to December 2008, Ghent operated the SCRs only during the ozone season. Because of the uncertainty of CAIR, Ghent resumed operation of the SCRs in December 2008 and has begun to operate them year round.

 Ghent uses the Ohio River as the source for the power plant’s water. Ghent operates a recirculating cooling towe r for each unit. The cooling tower blowdowns are discharged to the plant’s ash treatment basin prior to discharge.

 The Ghent plant is located on approximately 1,700 acres of land.

 Ghent employs 196 workers.

FGD System

 Ghent currently operates a limestone, forced oxidation wet FGD scrubber on each of the following units: Units 1, 3, and 4. A process flow diagram for the FGD systems is included as an a ttachment to this memorandum.

 Ghent uses ball mills to crush the limest one to the correct size for use in the limestone slurry. Service water is us ed to generate the limestone slurry.

 Ghent uses approximately 350,000 tons of limestone each year (dry basis). The limestone is delivered to the plant via ba rge. Ghent expects that the limestone usage will increase to approximately 500,000 dry tons in the near future.

 The Unit 1 FGD system began operating in 1994. The FGD system has three absorber modules (two operating and one sp are). Each of the three modules hasPage 3

one tray and three spray headers. One of the spray headers is located under the
tray.

 Ghent has the capability of adding DBA to the Unit 1 FGD system to increase the sulfur dioxide removal efficiency. W ithout the use of DBA, the FGD system achieves 90 percent removal of sulfur dioxide and with DBA, the FGD system can achieve 95 percent removal of sulfur dioxide. Ghent is not currently using DBA in the Unit 1 FGD system. The Unit 1 FGD system will soon be reconfigured to service Unit 2, while Unit 1 will be connected to a newly constructed FGD (additional information be low). An organic acid alternative to DBA is being considered and will be used in the reconfigured Unit 2 FGD if additional SO2 removal is necessary and cost-effective.

 Units 3 and 4 each have new FGD system s that were installed in 2007 and 2008, respectively. These FGD systems include only one absorber module each. Each module has five spray headers and no tray s; however, only four spray headers are typically operated at any one time. The removal efficiency for the scrubbers is approximately 98.5 percent; therefore, no additives are used in the system.

 In May 2009, Ghent plans to reconfigure the Unit 2 flue gas duct work so that Unit 2 will be scrubbed by the current Unit 1 scrubber. After that is completed, Unit 1 will be scrubbed by a new scrubber system, similar to the new Unit 3 and 4 scrubbers. After the change is comp lete, Units 1, 3, and 4 will have new scrubbers, and Unit 2 will be scrubbed by the older scrubber.

 Ghent continuously runs the blowdown pu mps for each of the scrubber modules. Most of the time the blowdown is recycl ed back to the reaction tank in the module. For the current Unit 1 FGD sy stem, the blowdown is intermittently directed to the gypsum transfer tanks ba sed on level control in the reaction tank. For the Unit 3 and 4 FGD systems, the blowdown is intermittently directed to the gypsum transfer tanks based on so lids control in the reaction tank.

 Each of the FGD systems operate at approximately 15 percent solids and the chlorides concentration ranges from 2,000 to 3,000 ppm.

 Ghent stated that the Unit 3 and 4 F GD scrubbers are desi gned for a maximum chlorides concentration of 15,000 ppm.

 Ghent sells some of the gypsum that is produced in the FGD process to a wallboard manufacturer in Carrollton, KY. To sell the gypsum to the wallboard plant, the gypsum must meet the following specifications:

o Solids: calcium sulfate dehydrate ≥ 90 percent;

o Calcium sulfite: ≤ 0.5 percent;

o Chlorides: ≤ 3,000 ppm;

o Fly ash: ≤ 1 percent;

o Silicon dioxide: ≤ 2.5 percent;

o Sodium: ≤ 400 ppm;

o Magnesium: ≤ 400 ppm;

o Potassium: ≤ 200 ppm;Page 4

o pH: 6.0 to 8.0 S.U.; and

o TDS in liquid: ≤ 3,100 ppm.

 The blowdown from each of the scrubbers is transferred to and commingled in gypsum transfer tanks. The plant operates two gypsum transfer tanks, each with a one million gallon capacity.

 From the gypsum transfer tanks, some of the gypsum slurry is transferred to hydroclones and some is sent to the gypsum impoundment. Because Ghent cannot sell all of the gypsum to the wall board manufacturer, Ghent only transfers the amount that they expect to sell to the hydroclones for dewatering. The remainder is sent to the gypsum impoundme nt, which is lined. At the time of the site visit, Ghent was transferring two- thirds of the gypsum slurry to the hydroclones five days a week for dewateri ng. Ghent stated that a month prior to the visit, they had been sending two- thirds of the gypsum slurry to the hydroclones seven days a week. The wallboard manufacturer has reduced production due to the downturn in the economy.

 The overflow from the hydroclones is tr ansferred to the gypsum impoundment. The hydroclone overflow contains gypsum fines. These gypsum fines have more fluid-like physical properties than bu lk-dewatered gypsum and concentrated deposits of the fines within the gypsum impoundment can compromise the impoundment structure. Recycling fines b ack to the FGD reaction tanks generally improves the process and gypsum crystal lization properties. Ultimately, a portion of the recycle hydroclone overflow must be removed from the system to prevent
inerts/unreactive fines from over-concentr ating in the FGD system. Because of this issue, Ghent stated that they would prefer to transfer th e gypsum fines to the
ash treatment basins instead of the gypsum impoundment.

 The underflow from the hydroclones is tran sferred to the vacuum belt filters. Ghent washes the gypsum with service wate r as it is applied to the vacuum belt
filter to reduce the chlorides concentrati on in the gypsum. Ghent also operates a
steam heater box on the vacuum belt filter which helps the wash water reduce the chlorides concentration and helps dry the gypsum.

 The gypsum from the vacuum belt filters is approximately eight percent moisture. The gypsum is trucked from the plant to the wallboard manufacturer. After all four FGD systems are operating, Ghen t expects to produce 800,000 tons of gypsum per year. The wallboard manufactur er is currently ex pected to accept 425,000 tons per year. Therefore, Ghent w ill only be able to sell approximately 53 percent of the gypsum produced.

 The filtrate from the vacuum belt filters is transferred to the gypsum impoundment.

 At the gypsum impoundment, the gypsum from the gypsum slurry settles out of
the wastewater to the bottom of the impoundment. The gypsum impoundment has two 40-acre cells and a reclaim pond. The overflow from th e two cells entersPage 5

the reclaim pond and is either recycled to the FGD systems or combined with the ash treatment basin overflow and discharged.

 Ghent stated that they recycle as much of the FGD wastewater as possible back to the FGD process, which is approximatel y 80 percent of the FGD wastewater. Ghent purges approximately one million gallons per day of gypsum impoundment overflow to the ash treatment basin, wh ich represents the FGD scrubber purge.

 Ghent stated that in the future, they plan to operate individual sets of hydroclones for each FGD system and recycle the hydr oclone overflow back to the reaction tanks. Ghent thinks that this would impr ove the efficiency of the plant because they would be pumping a more concentr ated slurry (i.e., less water) to the dewatering process. Additionally, it would reduce the rate of fines from building up in the gypsum impoundment. Ghent noted that such a recycle would cause the chlorides to build up within the FGD systems.

 In the past, Ghent has excavated so me of the gypsum from the gypsum impoundment and sold it to the wallboard manufacturer. The gypsum had to be washed to remove chlorides before they transported it.

 Ghent stated that they have a botto m drainage system underneath the gypsum impoundment cells. The leachate collected is transferred to the reclaim pond.

 Ghent stated that they have hired a contractor to ta ke over the ope ration of the gypsum impoundment.

Ash Handling and Wastewater Treatment

 Ghent operates hot-side elec trostatic precipitators (ESPs) on Units 2 through 4
and a cold-side ESP on Unit 1. Ghent stated that the hot-side ESPs have more operating issues than cold-side ESPs; theref ore, there are few plants that operate
hot-side ESPs.

 Ghent stated that hot-side ESPs have issu es with sodium depletion. The layer of ash that is closest to the electrode plat es becomes depleted of the sodium ion,
which causes the ash to be mo re electrically resistant a nd therefore, decreases the performance of the ESP.

 Ghent stated that the advantages of operat ing a hot-side ESP are that the fly ash is removed prior to the SCR, which improves the SCR performance, and that there are no plugging issues in the air heater.

 Ghent injects trona (sodium carbonate and bicarbonate) into th e Unit 3 and 4 flue gas before the ESP and after the air heater . Trona is added to remove the sulfur trioxide from the flue gas, which redu ces blue plume from the stack and helps prevent sodium depletion in th e hot-side ESPs. The sulfur trioxide is generated in the SCR when the catalyst present convert s sulfur dioxide to sulfur trioxide.
Trona is added before and after the ESP to capture as much of the sulfur trioxide as possible.Page 6

 Ghent injects hydrated lime into the Unit 1 flue gas before and after the ESP. The hydrated lime is used to remove the sulfur trioxide in the flue gas, similar to the
use of trona.

 Ghent does not inject trona or lime into the Unit 2 flue gas because Unit 2 does not have a SCR, so less sulfur trioxide is generated and mitigation is unnecessary.

 Ghent estimates that approximately 4 40,000 tons of fly ash are generated each year from the operation of the four gene rating units. Ghent operates wet fly ash handling systems on each unit, which sluice the fly ash to the ash treatment
basins.

 Ghent estimates that approximately 110,000 tons of bottom ash are generated in the boilers. Ghent operates wet bottom ash handling systems on each unit, which
sluice the bottom ash to the ash treatment basins.

 Ghent operates two ash treatment basins. Ash treatment basin 1 was built in 1970; the basin covers approximately 110 acr es and was originally about 40 feet deep. Ash treatment basin 2 was built in 1994; the basin co vers approximately 200 acres and was originally about 90 feet deep. Neith er of the ash treatment
basins are lined.

 Ash treatment basin 2 was built because ash treatment basin 1 didn’t have enough capacity to properly treat the ash sluice wate rs. Ash treatment basin 1 is currently 80 to 90 percent full with solids. Less th an 25 of the original 110 acres are still

water area.

 The fly and bottom ash sluice waters, as well as pyrite sluice water, are
transferred to ash treatment basin 2 for in itial settling. There are four influent pipes into ash treatment basin 2. Each pipe is designated for one generating unit and transfers the fly ash sluice, bottom ash sluice, and pyrite sluice for the unit. The pipes entering the pond are floated on top of the pond with floaters, which allow the plant to control where the pipes discharge into the basin. Ghent stated that they move the pipes about once a year to control the placement of the ash in the basin. From ash treatment basin 2, the water overflows to ash treatment basin 1, which is at a lower elevation than basin 2.

 Ash treatment basin 1 also receiv es the cooling tower blowdown and
miscellaneous low-volume wastewater from all four units. From ash treatment basin 1, the wastewater is tr ansferred to the polishing pond.

 From the polishing pond, some of the water is recycled for use as Unit 3 and 4 fly ash sluice, some of the water is discharged directly to the Ohio River, and some is transferred to a sand filtration system prior to being discharged to the Ohio River.

 Because Units 3 and 4 began operating around the time of the NSPS standards, Ghent’s permit requires that all of the pl ant’s source water for the Unit 3 and 4 fly
ash sluice come from the ash treatment basins.Page 7

 Ghent transfers approximately 50 percent of the water that is discharged from the polishing pond to the sand filtration system. The filtration system consists of four filters operated in parallel. The backwash from the filters is transferred to one of the coal pile runoff ponds (east basin) a nd then to ash treatment basin 1. Ghent stated that the filtration system is operate d almost all of the time. The effluent from the filtration system is recombined with the effluent from the polishing pond and some FGD wastewater and discharged to the Ohio River. Ghent stated that they operate the filtration system to ensu re that the wastewater meets the plant’s
TSS limits for the waste stream.

 Ghent injects carbon dioxide into th e polishing pond effluent and FGD wastewater to control the pH of the discha rge. Ghent estimated that the pH of the wastewater prior to the carbon dioxide in jection is 9.1 to 9.3 S.U. The carbon dioxide injection is essen tially continuous year round.

 Ghent estimates that ash treatment basin 2 will be filled in approximately five years. Ghent is currently evaluating options for ash handling once ash treatment basin 2 is full. One of the options is to build a new ash treatment basin. Another option is to convert to dry fly ash ha ndling, and use hydrobins for bottom ash and pyrites handling, transferring the solids to a landfill that would be built. Ghent stated that they have not made a decision at this time, but th at they will most likely build a new landfill. Ghent stated that the costs for the conversion of the fly ash system have not been finalized, but the bottom ash system will remain wet
and be stored in the cu rrent ash treatment basin.Page 8Table 1. Site Visit AttendeesNameOrganization (Representing)TelephoneE-mailJeff Joyce Kentucky Utilities Company – Ghent (502) 347-4001 jeff.joyce@eon-us.comDavid ValkouciKentucky Utilities Company – Ghent(502) 347-4134 david.valkouci@eon-us.comPaul WrightKentucky Utilities Company – Ghent(502) 347-4003 paul.wright@eon-us.comRoger MedinaE.ON U.S.(502) 627-2997 roger.medina@eon-us.comMichael WinklerE.ON U.S.(502) 627-2338 michael.winkler@eon-us.comDonna HillUWAG(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.govT.J. Finseth ERG (Contractor to EPA) (703) 994-7130 thomas.finseth@erg.com