Final Notes from Site Visit at 

Louisville Gas & Electric Company’s Cane Run Station 

on December 11, 2008

EPA conducted a site visit at Louisville Gas & Electric Company’s Cane Run Station (Cane 

Run) located in Louisville, KY on Thursday, December 11, 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 Cane Run 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, an overall process flow 

diagram 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 17, 2008. 

Plant Overview 

 Cane Run operates three coal-fired generating units at the power plant, which is a 

baseload plant with a net generating capacity of 563 MW. The table below 

contains some general information for the three generating units (Units 4 through 

6). A process flow diagram for Units 4 through 6 is included as an attachment to 

this memorandum. 

Unit 

Installation 

Date 

Capacity 

(MW) 

Particulate 

Control NOx Control SO2 Control 

4 1962 164 ESP (cold-side) Low-NOx 

burners and 

overfire air 

Wet FGD installed 

in 1976 

5 1966 209 ESP (cold-side) Low-NOx 

burners 

Wet FGD installed 

in 1977 

6 1969 272 ESP (cold-side) Low-NOx 

burners and 

overfire air 

Wet FGD installed 

in 1978 

 Cane Run retired Units 1 through 3 in the early 1980s. Units 1 through 3 were 

never scrubbed. 

 Cane Run burns eastern bituminous coal in each of the currently operating units 

(Units 4 through 6). The plant burns approximately 1.6 million tons of high sulfur 

Illinois basin coal per year. The coal is mostly mined in Kentucky, Indiana, 

southern Ohio, West Virginia, and Illinois. All the coal is delivered to the plant 

via railroad. 

 The sulfur content of the coal used at Cane Run is typically 5.5 to 6.0 lbs 

SO2/mmBTU. 
Page 2 

 Cane Run stated that based on 35 samples of coal since 2002, the chloride content 

of the coal has averaged less than 1,000 ppm chlorides. Cane Run stated the 

maximum was 2,000 ppm chlorides. 

 The coal pile runoff is collected in the coal pile runoff pond. From the coal pile 

runoff pond, the wastewater is transferred to the ash treatment basin. 

 Prior to the site visit, Cane Run personnel collected four samples from the coal 

pile runoff pond and measured the pH. The table below presents the results of the 

measurements. 

Date pH (S.U.) 

11/19/2008 2.80 (no rain event) 

11/26/2008 2.81 (no rain event) 

12/4/2008 2.84 (no rain event) 

12/10/2008 2.95 (rain event occurred) 

 Cane Run does not operate SCRs or SNCRs on any of the generating units. 

 Cane Run uses the Ohio River as the source of the power plant’s water. Cane 

Run operates a once-through cooling system for each of the three generating 

units. The once-through cooling water is discharged directly to the Ohio River 

after use. 

 The Cane Run plant is located on approximately 500 acres of land. 

 Cane Run employs 123 full-time employees. 

FGD System 

 Cane Run operates a lime, inhibited oxidation wet FGD scrubber on each of the 

three generating units (Units 4 through 6). A process flow diagram for the FGD 

systems is included as an attachment to this memorandum. 

 The Unit 4 and 5 FGD systems use lime as the sorbent. The Unit 6 FGD system 

is a dual alkali system that uses both lime and soda ash, which is sodium 

carbonate. Emulsified sulfur is also added to all three of the FGD systems to 

prevent calcium sulfite from oxidizing to calcium sulfate. 

 Cane Run uses approximately 123,000 tons of lime each year (dry basis). The 

lime is delivered to the plant by truck. Cane Run slakes the lime in batches by the 

truckload. Each batch of slaked lime contains approximately 26,000 to 30,000 

gallons. Service water is used as the source for the lime slaking. 

 The FGD systems remove approximately 85-90 percent of the sulfur dioxide from 

the flue gas. 
Page 3 

 Unit 4 and Unit 5 FGD Systems 

 The Unit 4 and 5 FGD systems each have two absorber modules per 

system. The Unit 4 scrubber reaction tanks are located outside of the 

modules and the Unit 5 reaction tanks are located inside of the modules. 

Each module has two spray headers. 

 Sulfur dioxide is absorbed into the lime slurry in the absorber module and 

then reacts with the lime, creating calcium sulfite in the reaction tank. 

 The FGD systems blow down continuously to the filter feed tanks, 

controlling solids in the reaction tanks between 16 and 20 percent solids. 

The chlorides concentration in the scrubber is approximately 2,000 ppm. 

(Cane Run does not routinely sample FGD chlorides since there is a 

limited possibility of establishing a significant concentration) The Unit 4 

and 5 FGD systems are constructed mainly from 317 LM and C276 alloys. 

 From the filter feed tank, the FGD wastewater is transferred to 

hydroclones. The overflow from the hydroclones is transferred to the 

filtrate return tank. The underflow from the hydroclones, which is 

approximately 38 to 42 percent solids, is sent to a vibratory screen. 

 The excess water removed from the vibratory screen is returned to the 

filter feed tank. The wet solids from the vibratory screen, containing 55-

65 percent moisture, are transferred to the pug mill. 

 Unit 6 FGD System 

 The Unit 6 FGD system has two absorber modules, each of which have 

two trays and no spray headers. The reaction tanks are located outside of 

the modules. 

 The Unit 6 FGD system, which is a dual alkali system, referring to the use 

of both lime and soda ash (i.e., sodium), operates differently than the Unit 

4 and 5 FGD systems. The sorbent slurry fed to the Unit 6 absorber 

modules is a soda ash solution, which is a clear liquor that contains almost 

no suspended solids. Within the modules, the sulfur dioxide is absorbed 

by the sodium, which is more effective than lime at removing the sulfur 

dioxide from the flue gas. Then, from the bottom of the module, the 

sorbent slurry is transferred to the reaction tank. 

 The lime slurry is fed to the Unit 6 reaction tanks and the sulfur dioxide is 

transferred from the sodium to the lime, and the lime and sulfur dioxide 

react, creating calcium sulfite. The transfer of the sulfur dioxide from the 

sodium to the lime regenerates the sodium, which can be reused in the 

absorber module. 
Page 4 

 Cane Run stated that the Unit 6 FGD system uses less power than the Unit 

4 and 5 FGD systems because the use of sodium allows for a much lower 

liquid to gas ratio (L/G). For comparison, the L/G for the Unit 6 FGD 

system is 5 and the L/G for the Unit 4 and 5 FGD systems is 

approximately 60. Cane Run stated that the disadvantage of the Unit 6 

FGD system is that the soda ash is expensive and increases the operating 

cost of the system. Therefore, Cane Run tries to recover as much of the 

soda ash as possible. 

 There are two different wastewater streams from the system, both of 

which are continuous. The first blowdown is transferred to the Unit 6 

hydroclones. The purpose of this hydroclone set is to recycle sodium back 

to the Unit 6 FGD. The overflow from the hydroclones is returned to the 

reaction tanks and the underflow is mixed with the Unit 4 and 5 blowdown 

in the filter feed tank, which feeds common hydroclones, as described 

previously. 

 The second blowdown stream from the Unit 6 FGD system is transferred 

to a thickener. The thickener is used to generate the clear liquor that is 

used as the sorbent slurry. Additionally, the thickener removes the sulfite 

fines from the system. The sulfite fines are too small to be removed by the 

hydroclones. 

 The thickener overflow is transferred to a small tank where the soda ash is 

added and is then transferred to the FGD system. The underflow from the 

thickener, which is approximately 24 to 32 percent solids, is transferred to 

a vacuum drum filter. 

 The filtrate from the vacuum drum filter is transferred to the filtrate return 

tank. The solids from the vacuum drum filter, which contain 

approximately 45 to 50 percent moisture, are transferred to the pug mill. 

 Solids Handling and Clearwell Operations 

 Within the pug mill, the vacuum drum filter FGD solids and the vibratory 

screen FGD solids are mixed with dry lime and dry fly ash to create a 

concrete like material, referred to as poz-o-tec. 

 The poz-o-tec material from the process is approximately 65 to 70 percent 

solids. Cane Run allows the poz-o-tec to cure approximately two days and 

then transfers the poz-o-tec solids to the landfill. Within the landfill, the 

material dries and cures to become a completely solid material that likely 

retains only a small amount of water entrained in the material because of 

water evaporation/reaction during the curing process. 

 The water collected in the filtrate return tank is either transferred to the 

Unit 5 thickener or sent to the reaction tanks for the various scrubbers. 
Page 5 

Only about five percent of the filtrate return is transferred to the Unit 5 

thickener. 

 The Unit 5 thickener acts as a final solids control system for the 

intermittent stream that results when there is a positive (or excess) water 

balance on the FGD system. When the plant temporarily experiences 

equipment problems requiring above average input water flow (e.g., pump 

purge-seals, equipment washdowns or maintenance, etc.), then the liquid 

inventories may build beyond the normal water make-up needs for the 

FGD process. In these instances, Cane Run reduces the high tank levels 

by temporarily directing water to the Unit 5 thickener. 

 The overflow from the Unit 5 thickener is typically transferred to the 

clearwell, but it can also be sent to the Unit 5 scrubber reaction tanks. The 

Unit 5 thickener overflow is the point from which wastewater is purged 

from the FGD system. The underflow from the Unit 5 thickener is 

transferred to the Unit 6 scrubber reaction tanks. 

 From the clearwell, the water can be used as mist eliminator wash water 

for the Units 4 and 5 FGD systems, used for miscellaneous pump seals, or 

transferred to the ash treatment basin and discharged. Cane Run stated 

that they have attempted to minimize the amount of water that is 

transferred to the ash treatment basin. Additionally, Cane Run stated that 

less than 50 percent of the wastewater sent to the clearwell is transferred 

to the ash treatment basin. 

 The typical flow rate from the clearwell to the ash treatment basin is 

approximately 50 gpm, which represents the FGD scrubber purge stream. 

Additionally, site runoff and some equipment cooling water is also routed 

to the ash treatment basin via the clearwell. 

 Cane Run used to operate two different sludge processing systems. The 

Unit 4 and 5 solids were handled together and the Unit 6 solids were 

handled separately. Two years ago, the plant consolidated the process to 

only operate one sludge processing plant. 

Ash Handling and Wastewater Treatment 

 Cane Run operates cold-side electrostatic precipitators (ESPs) on each of the three 

units (Units 4 through 6). 

 Cane Run estimates that approximately 140,000 tons of fly ash are generated each 

year from the operation of all three units. Cane Run uses all of the fly ash 

generated to process the FGD solids into the poz-o-tec material. 

 The dry fly ash is pneumatically conveyed to fly ash silos, which then feed the 

pug mills for the FGD solids processing. 
Page 6 

 Cane Run has a wet fly ash sluicing system, but it is only used as a back up to the 

dry handling system. 

 Cane Run estimates that approximately 35,000 tons of bottom ash are generated 

each year from the operation of all three units. Cane Run operates wet bottom ash 

handling systems for each unit. All of the bottom ash sluice is transferred to the 

ash treatment basin. 

 Cane Run stated that they try to find beneficial uses for the bottom ash. When the 

plant does find reuse opportunities for the bottom ash, it is excavated from the 

basin, allowed to dry, and then transported to the reuse site. 

 In addition to bottom ash sluice and occasional fly ash sluice, the ash treatment 

basin also receives pyrite sluice and low-volume wastewaters. 

 Cane Run dredges the pyrites and bottom ash solids from the ash treatment basin 

and transports them to an on-site landfill. 

 The ash treatment basin covers 40 acres. Cane Run stated that the ash basin is 

running out of capacity and likely has only two more years of capacity remaining. 

Landfills 

 Cane Run operates an on-site landfill. The landfill receives the poz-o-tec 

material, as well as the bottom ash and pyrites that are dredged from the ash 

treatment basin. 

 The landfill is not lined, but Cane Run stated that the poz-o-tec material acts as its 

own liner. 

 Cane Run does not have an under drain system for the landfill because the poz-otec material has very low permeability and thus resists leaching. Cane Run stated 

that their primary focus is upon the runoff from the landfill which is collected in a 

pond and transferred to the ash treatment basin. 

 Cane Run stated that the current landfill will be at capacity by 2013; therefore, the 

plant is working on permitting and developing a new landfill, which they stated 

would be lined. 

 Cane Run stated that a portion of the planned area for the new landfill is located 

in the floodplain and has a creek that runs directly through it. Cane Run expects 

to landfill the materials on both sides of the creek; areas of the floodplain affected 

by the landfill will be mitigated. 
Page 7 

 Table 1. Site Visit Attendees 

Name Organization (Representing) Telephone E-Michael Hensley Louisville Gas & Electric – Cane Run (502) 449-8853 mike.hensley@Anthony Osborne Louisville Gas & Electric – Cane Run (502) 449-8815 anthony.osbornKevin Shaughnessy Louisville Gas & Electric – Cane Run (502) 449-8878 kevin.shaughneSteven Turner Louisville Gas & Electric – Cane Run (502) 449-8801 steven.turner@Roger Medina E.ON U.S. (502) 627-2997 roger.medina@Donna 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@