Final Notes from Site Visit 

at Kentucky Utilities Company’s Ghent Generating Station 

on December 9, 2008 

EPA conducted a site visit at Kentucky Utilities 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 participants. The presentation that the Ghent personnel 

gave during the site visit is provided as an attachment to this memorandum. Also included as 

attachments to this memorandum are a labeled aerial photo of the plant, overall process flow 

diagrams for the generating units, and a process 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 included as attachments to this memorandum. 

Unit 

Installation 

Date 

Capacity 

(MW) 

Particulate 

Control NOx Control SO2 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 following locations: the Illinois basin, western 

Pennsylvania, or eastern Ohio. Ghent currently 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 percent PRB and 50 percent eastern bituminous 

coal in the Unit 3 and 4 boilers on occasion. 
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 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 

SO2/mmBTU, but it can range from 4.0 to 6.9 lbs SO2/mmBTU. The low sulfur 

coal for the non-FGD Unit 2 ranges from 0.8 to 1.1 lbs SO2/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 receives limestone pile runoff. The other coal pile runoff 

pond receives backwash from a sand filtration 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 tower 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 attachment to this memorandum. 

 Ghent uses ball mills to crush the limestone to the correct size for use in the 

limestone slurry. Service water is used 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 barge. 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 spare). Each of the three modules has 
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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. Without 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 below). 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 systems 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 trays; 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 complete, Units 1, 3, and 4 will have new 

scrubbers, and Unit 2 will be scrubbed by the older scrubber. 

 Ghent continuously runs the blowdown pumps for each of the scrubber modules. 

Most of the time the blowdown is recycled back to the reaction tank in the 

module. For the current Unit 1 FGD system, the blowdown is intermittently 

directed to the gypsum transfer tanks based 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 solids 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 FGD scrubbers are designed 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; 
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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 wallboard manufacturer, Ghent only transfers 

the amount that they expect to sell to the hydroclones for dewatering. The 

remainder is sent to the gypsum impoundment, 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 dewatering. 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 transferred to the gypsum impoundment. 

The hydroclone overflow contains gypsum fines. These gypsum fines have more 

fluid-like physical properties than bulk-dewatered gypsum and concentrated 

deposits of the fines within the gypsum impoundment can compromise the 

impoundment structure. Recycling fines back to the FGD reaction tanks generally 

improves the process and gypsum crystallization properties. Ultimately, a portion 

of the recycle hydroclone overflow must be removed from the system to prevent 

inerts/unreactive fines from over-concentrating in the FGD system. Because of 

this issue, Ghent stated that they would prefer to transfer the gypsum fines to the 

ash treatment basins instead of the gypsum impoundment. 

 The underflow from the hydroclones is transferred to the vacuum belt filters. 

Ghent washes the gypsum with service water as it is applied to the vacuum belt 

filter to reduce the chlorides concentration 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, Ghent expects to produce 800,000 tons of 

gypsum per year. The wallboard manufacturer is currently expected to accept 

425,000 tons per year. Therefore, Ghent will 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 the two cells enters 
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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 approximately 80 percent of the FGD wastewater. 

Ghent purges approximately one million gallons per day of gypsum impoundment 

overflow to the ash treatment basin, which 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 hydroclone overflow back to the reaction 

tanks. Ghent thinks that this would improve the efficiency of the plant because 

they would be pumping a more concentrated 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 some 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 bottom 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 take over the operation of the 

gypsum impoundment. 

Ash Handling and Wastewater Treatment 

 Ghent operates hot-side electrostatic 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; therefore, there are few plants that operate 

hot-side ESPs. 

 Ghent stated that hot-side ESPs have issues with sodium depletion. The layer of 

ash that is closest to the electrode plates becomes depleted of the sodium ion, 

which causes the ash to be more electrically resistant and therefore, decreases the 

performance of the ESP. 

 Ghent stated that the advantages of operating 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 the 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 reduces blue plume from the stack and helps 

prevent sodium depletion in the hot-side ESPs. The sulfur trioxide is generated in 

the SCR when the catalyst present converts sulfur dioxide to sulfur trioxide. 

Trona is added before and after the ESP to capture as much of the sulfur trioxide 

as possible. 
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 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 440,000 tons of fly ash are generated each 

year from the operation of the four generating 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 acres and was originally about 40 feet 

deep. Ash treatment basin 2 was built in 1994; the basin covers approximately 

200 acres and was originally about 90 feet deep. Neither 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 waters. Ash treatment basin 1 is currently 

80 to 90 percent full with solids. Less than 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 initial 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 receives the cooling tower blowdown and 

miscellaneous low-volume wastewater from all four units. From ash treatment 

basin 1, the wastewater is transferred 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 plant’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) and then to ash treatment basin 1. Ghent 

stated that the filtration system is operated 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 ensure that the wastewater meets the plant’s 

TSS limits for the waste stream. 

 Ghent injects carbon dioxide into the polishing pond effluent and FGD 

wastewater to control the pH of the discharge. Ghent estimated that the pH of the 

wastewater prior to the carbon dioxide injection is 9.1 to 9.3 S.U. The carbon 

dioxide injection is essentially 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 handling, 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 that 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 current ash treatment basin. 

 
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 Table 1. Site Visit Attendees 

Name Organization (Representing) Telephone E-Jeff Joyce Kentucky Utilities Company – Ghent (502) 347-4001 jeff.joyce@eonDavid Valkouci Kentucky Utilities Company – Ghent (502) 347-4134 david.valkouci@Paul Wright Kentucky Utilities Company – Ghent (502) 347-4003 paul.wright@eoRoger Medina E.ON U.S. (502) 627-2997 roger.medina@Michael Winkler E.ON U.S. (502) 627-2338 michael.winkleDonna Hill UWAG (205) 257-5234 dbhill@southerJosh Hall EPA/Office of Water (202) 566-1002 hall.josh@epa.gRon Jordan EPA/Office of Water (202) 566-1003 jordan.ronald@T.J. Finseth ERG (Contractor to EPA) (703) 994-7130 thomas.finseth@