### Final Notes from Site Visit at Louisville Gas & El ectric 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, De cember 11, 2008 to learn about the operations at the plant, specifically the FGD wastewater handli ng system. Table 1, located at the end of this memorandum, identifies the site vi sit participants. The presentati on that the Cane Run 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 aeri al photo of the plant, an overall process flow diagram for the generating units, and a pro cess 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 generati ng 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 th e three generating units (Units 4 through 6). A process flow diagram for Units 4 th rough 6 is included as an attachment to this memorandum.

Unit Installation Date Capacity (MW) Particulate Control NOx Control SO 2 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 th e 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 SO 2 /mmBTU.Page 2

 Cane Run stated that based on 35 samples of coal since 2002, th e 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 co al pile runoff pond. From the coal pile runoff pond, the wastewater is transf erred to the ash treatment basin.

 Prior to the site visit, Ca ne 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 s ource of the power plant’s water. Cane Run operates a once-through cooling syst em for each of the three generating units. The once-through cooling water is di scharged 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 oxi dation 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 a ttachment 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 a dded to all three of the FGD systems to prevent calcium sulfite from oxi dizing 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 li me 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 ar e 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 lim e, creating calcium sulf ite in the reaction tank.

 The FGD systems blow down contin uously 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 ma inly 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 vibr atory screen is returned to the filter feed tank. The wet solids from the vibratory screen, containing 55- 65 percent moisture, are tr ansferred 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 dua l 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 module s, 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 re action tanks and the sulfur dioxide is transferred from the sodium to the lime, and the lime and sulfur dioxide react, creating calcium sulfite. The tran sfer 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 sy stem 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 th at 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 blow down is transferre d to the Unit 6 hydroclones. The purpose of this hydroc lone 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 feed s 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. Additiona lly, 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 th e 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, re ferred 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 approximate ly 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 en trained in the material because of water evaporation/reaction during the curing process.

 The water collected in the filtrate retu rn tank is either transferred to the Unit 5 thickener or sent to the reac tion tanks for the various scrubbers.Page 5

Only about five percent of the filtrat e return is transf erred 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 av erage input water flow (e.g., pump purge-seals, equipment washdowns or ma intenance, 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 thickene r is typically transferred to the clearwell, but it can also be sent to the Unit 5 sc rubber 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 basi n and discharged. Cane Run stated that they have attempted to mini mize 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 equi pment cooling water is also routed to the ash treatment basin via the clearwell.

 Cane Run used to operate two differe nt sludge processing systems. The Unit 4 and 5 solids were handled to gether and the Unit 6 solids were handled separately. Two years ago, th e 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 so lids 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 bene ficial uses for the bottom ash. When the plant does find reuse opportunities for th e 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 occas ional fly ash sluice, the ash treatment basin also receives pyrite slui ce 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 sy stem for the landfi ll because the poz-otec material has very low permeability and thus resists leaching. Cane Run stated that their primary focus is upon the runoff fr om 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 developi ng 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 7Table 1. Site Visit AttendeesNameOrganization (Representing)TelephoneE-mailMichael Hensley Louisville Gas & Electric –Cane Run (502) 449-8853 mike.hensley@eon-us.comAnthony OsborneLouisville Gas & Electric – Cane Run(502) 449-8815 anthony.osborne@eon-us.comKevin ShaughnessyLouisville Gas & Electric – Cane Run(502) 449-8878 kevin.shaughnessy@eon-us.comSteven TurnerLouisville Gas & Electric – Cane Run(502) 449-8801 steven.turner@eon-us.comRoger MedinaE.ON U.S.(502) 627-2997 roger.medina@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