### Final Notes from Site Visit at
Louisville Gas & Elect ric Company’s Trimble County Station on December 10, 2008

EPA conducted a site visit at Louisville Gas & Electric Company’s Trimble County Station (Trimble County) located in Bedford, Ke ntucky on December 10, 2008 to learn about the operations at the plant, specifically the FGD wastewater handling system.

These notes describe the information collected du ring the site visit and the pre-site visit phone call, which was held on November 19, 2008. Att ached to this document are the following: (1) List of site visit participants; (2) Presentation that the Trimble County personnel gave during the site visit; (3) Labeled and unlabeled aerial photographs of the plant; (4) Plant water balance diagram; (5) Simplified plant overview process flow diagra ms for the current operation of generating unit 1 and the proposed operation of generating units 1 and 2; (6) Simplified process flow diagrams for the Unit 1 FGD system and the planned Unit 2 FGD system; and (7) Graph showing buildup of chlorides in the FGD reaction tank, followed by graph showing buildup of chlo rides in the ash pond.

Plant Overview

 Trimble County operates one coal-fired ge nerating unit at the power plant, which
is a baseload unit with a net generating capacity of 515 MW. A second unit is currently under construction at Trimbl e County, which is expected to begin commercial operation in June 2010. This second unit will have a net generating capacity of 760 MW. The table below contains some general information for the two generating units. A process flow diagram for the existing operation of Unit 1 and the proposed operation of Units 1 and 2 are included as attachments to this
memorandum.

Unit Installation
Date Capacity (MW) Particulate
Control NOx Control SO 2 Control 1 1990 566 ESP (cold-side) SCR , low-NOx
burners and
overfire air Wet FGD in original design (1990)

2 (planned) Expected
2010 810 ESP (cold-side) SCR , low-NOx
burners and
overfire air Wet FGD in original design (2010)

 The Unit 1 boiler is a subcritical boiler, which converts 33.5 percent of the energy in the coal to electricity. The planned Unit 2 boiler will be a supercritical boiler, which is expected to convert approximately 40 percent of the energy in the coal to electricity.Page 2

 Ultra supercritical boilers al so exist in the industry a nd these typically convert 50 percent of the energy in coal to electricity. Trimble C ounty stated that they do not expect any more subcriti cal boilers to be built.

 Trimble County burns eastern bituminous coal in Unit 1. The plant burns approximately 1.6 million tons of coal per year. The coal comes from the Illinois basin and is mostly mined in Kentucky, I ndiana, southern Ohio, West Virginia,
and Illinois. All of the coal is deliver ed via barge on the Ohio River.

 When Unit 2 begins operating, the unit will burn a mixture of 70 percent eastern bituminous and 30 percent Powder River Ba sin (PRB) coal. The PRB coal will
be used to lower the total sulfur content of the coal burned. The lower sulfur coal
is needed because Unit 2 has a stricter SO 2 emission limit (i.e., 3,263 tons
SO 2 /year for Unit 2 versus 4,822 tons SO 2 /year for Unit 1).

 Trimble County is currently bui lding a coal blending facil ity at the site to blend
the eastern bituminous and PRB coals. The blending facility will consist of a conveyer system with weight belt feeders.

 Trimble County occasionally burns a deslag ging coal which helps with slagging issues in the boiler. The deslagging coal is a “middlings” coal and is generally high ash (25-35%), lower sulfur (1%) , and low BTU (9,000-10,500 BTU) with a high ash fusion temperature. The coal is mined in Eastern Kentucky and West Virginia.

 The sulfur content of the coal used at Trimble County typically ranges from 5.5 to
6.5 lbs SO 2 /mmBTU, but Trimble County has recei ved some coal that is 7 lbs
SO 2 /mmBTU.

 Trimble County stated that the chlorine content of the coal is typically 300-700

ppm.

 The coal pile runoff is collected in a coal pile runoff pond that also receives limestone pile runoff. The overflow from the coal pile runoff pond is transferred
to the ash treatment basin.

 Prior to the site visit, Trimble County personnel collected four samples from the coal pile runoff pond and measured the pH and temperature. The table below presents the results of the measurements.

Date pH (S.U.) Temperature ( o C)
11/19/2008 7.92 7.7
11/26/2008 7.99 5.8
12/3/2008 7.88 4.3
12/8/2008 7.75 2.7

 Trimble County operates a SCR system on Unit 1. Prior to December 2008, Trimble County operated the SCR only duri ng the ozone season. Because of thePage 3

uncertainty of CAIR, Trimble County resu med operation of the SCR in December 2008 and plans to operate it year round.

 Trimble County uses the Ohio River as th e source for the power plant’s water. Trimble County operates a recirculating m echanical draft cooling tower for Unit 1. Trimble County Unit 1 used to utilize a natural draft hyperbolic cooling tower, but the tower wouldn’t have the capacity to handle the coolin g water for both Unit 1 and the new Unit 2. Therefore, Trimble County built a mechanical draft cooling tower, which is now used for the Unit 1 cooling water. Trimble County will use the natural draft hyperbolic cooling tower for Unit 2 when it begins operating.

 The cooling tower blowdown from Unit 1 is discharged directly to the Ohio River. The Unit 2 cooling tower blowdown w ill also be discharged directly to the
Ohio River.

 Trimble County also operates six co mbustion turbines, which each have a capacity of approximately 160 MW. The capacity of the combustion turbines changes with the seasons. The capacity is larger in the winter because the air is denser and therefore, more fuel can be burned efficiently with the same volume of air. In the summer, Trimble County can us e evaporative cooling water to cool the air at the intake, prior to the compressor, which causes the inlet air to become more dense, thereby allowing more fuel to be efficiently burned which results in an increase in capacity.

 Illinois Municipal Electric Agency ow ns 12.12 percent of the Trimble County coal-fired units and Indiana Municipal Power Agency owns 12.88 percent of the
coal-fired units. Louisville Gas & El ectric Company and Kentucky Utilities Company own the remaining 75 percent of the coal-fired units, 100% of the combustion turbines and manage all plant operations.

 The Trimble County plant is located on approximately 2,250 acres of land, including a 114-acre wildlife preserve.

 Trimble County employs approximately 125 workers.

Unit 1 FGD System (Current Operation)

 Trimble County operates a limestone, forced oxidation wet FGD scrubber on Unit 1. Process flow diagrams for the Unit 1 FGD system and the planned Unit 2 FGD system are included as an attachment to this memorandum.

 Trimble County uses large, horizontal ball mills to crush the limestone to the
correct size for use in the limestone slurr y. Water from the ash treatment basin is used to prepare the limestone slurry.

 Trimble County uses approximately 185,000 tons of limestone each year (dry basis). The limestone is deliver ed to the plant via barge.Page 4

 The Unit 1 FGD system began operating in 1990, when the plant began operating. The FGD system has four absorber modules . Each of the four modules has five recirculation pumps, each with a designate d elevation of spray header nozzles.
There are two reaction tanks for the f our modules (two modules per reaction tank).

 Trimble County has the capability of addi ng dibasic acid (DBA) or equivalent organic acid to the Unit 1 FGD system to increase the sulfur dioxide removal efficiency, but the plant has not used DB A in the system. Its use has never been required to meet permit compliance le vels. The new Unit 2 FGD system was designed to meet compliance requir ements without the use of DBA.

 Trimble County stated that when the FGD system was built for Unit 1, it was
considered a 3 rd -generation design capable of high removals with all pumps running but intended for compliance at lower removal levels with some equipment redundancy. Through equipment changes using the existing equipment installed on-site, the plant recen tly upgraded the system to optimize the
sulfur dioxide removal. The upgrade included the following:

o Optimizing the liquid to gas (L/G) ratio;

o Replacing some spray header nozzles with bidirectional spray nozzles;

o Inserting a ring between the spray leve ls which forces the flue gas up the middle of the scrubber and prevents gas sneakage up the module walls;

o Changing the angle at which the fl ue gas enters the scrubber; and

o Removing pluggage in the spray headers.

 The system upgrade improved the FGD equipment reliability by reducing spray nozzle pluggage and gas flow imbalances . This assures that sulfur dioxide removal efficiency can be reliably ac hieved at levels of 98 percent.

 Trimble County continuously runs the blowdown pumps for each of the FGD’s
two reaction tanks. Most of the tim e the blowdown is sent to a 3 rd Party gypsum marketer for shipment to a wallboard manufacturing plant. On the infrequent occasions when slurry is not sent to th e gypsum marketer, it is transferred to the
ash treatment basin. The solids in the reac tion tank are controlled to between 13 and 17 percent solids. Limestone slurry is added to the react ion tank to control the pH to between 5.5 and 5.8. To make up for the evaporativ e water loss in the
scrubber and to control the level in th e reaction tank, Trimble County adds water
from the ash treatment basin to the reaction tank.

 Trimble County stated that the Unit 1 FGD was designed for a maximum chlorides concentration of 5,000 ppm. Trim ble County stated that the chlorides in the FGD system have been building up becau se the plant is r ecycling all the FGD water and does not have a chlorides purge from the system. A graph presenting
the chlorides concentration in the Unit 1 r eaction tanks over time is included as an
attachment to this memorandum.

 Trimble County sells most of the gypsum th at is produced in the FGD process to a gypsum marketer who then provides it to a wallboard manufacturer. TrimblePage 5

County recently reached an agreement with the same gypsum marketer to provide
a wallboard manufacturer with at le ast 350,000 tons of gypsum per year for 20 years. For the wallboard manufacturer to accept the gypsum, the gypsum must contain a minimum of 93 percent gypsum solids. [CBI information has been removed from this document.]

 The blowdown from the scrubber is either tr ansferred directly to the ash treatment basin or to the hydroclone feed tank. Because the gypsum marketer does not take 100% of the gypsum produced by the Unit 1 FGD, the plant tr ansfers the amount the gypsum marketer will take to the hydroclones for dewatering. The quantity that is not used by the gypsum marketer is diverted to the ash treatment basin.

 The slurry in the hydroclone feed tank is transferred to the hydroclones. The overflow from the hydroclones is transfe rred to the ash treatment basin. The underflow from the hydroclones is transferre d to the vacuum belt filters. Trimble County washes the gypsum with service wate r as it is applied to the vacuum belt
filter to reduce the chlorides concentra tion in the gypsum. Trimble County also operates a steam heater box on the vacuum belt filter, which reduces the chlorides concentration and helps dry the gypsum.

 The gypsum from the vacuum belt filters is approximately 8.5 percent moisture. The gypsum is trucked from the plant to the wallboard manufacturer. Trimble County has typically produced approx imately 250,000 dry tons of gypsum per year. On average, they have been ab le to market approximately 230,000 tons per

year.

 The filtrate from the vacuum belt filters is transferred to the ash treatment basin.

 In the ash treatment basin, the FGD wastewaters are mixed with ash sluice, effluent from the coal and limestone p ile runoff ponds, pyritic mill reject sluice,
and low-volume wastewaters.

 Trimble County stated that the chlorides concentration in the ash treatment basin is gradually increasing and therefore, continued operat ion of the basin by current practices is unsustainable. The current chlorides concentratio n is approximately 2,500 ppm. A graph presenting the chloride s concentration in the ash treatment
basin over time is included as an attachment.

Ash Handling and Wastewater Treatment (Current Operation)

 Trimble County operates a cold-side electr ostatic precipitator (ESP) on Unit 1.

 Trimble County injects hydrated lime into th e Unit 1 flue gas before and after the
ESP to remove the sulfur trioxide from th e flue gas, which reduces the blue plume
from the stack. The sulfur trioxide is generated in the SCR when the catalyst
converts sulfur dioxide to sulfur trioxide . Trimble County adds the hydrated lime before and after the ESP to capture as mu ch of the sulfur trioxide as possible.Page 6

 Trimble County estimates that approximat ely 149,000 tons of fly ash is generated each year from operation of Unit 1. Tr imble County operates both a wet and dry fly ash handling system. The fly ash is handled dry when it is marketable. Typically, Trimble County is able to ma rket approximately 8,000 tons of fly ash per year because there isn’t always a buye r for the fly ash. Therefore, the plant typically operates the wet fly ash handling system, which sluices the fly ash to the
ash treatment basin.

 Trimble County estimates that approx imately 37,000 tons of bottom ash are generated each year from the operation of Unit 1. Trimble County operates a wet bottom ash handling system. The bottom ash sluice is transferred to the ash
treatment basin. A vendor classifies the bottom ash by size using a sieve operation and markets approximately 13,000 tons of the bottom ash per year.

 The ash treatment basin also receives FGD wastewaters, effluent from the coal and limestone pile runoff pond, pyritic mill reject sluice water, and other lowvolume wastewaters.

 All overflow from the ash treatment basin is recycled for use as either bottom/flyash sluice make-up water, FGD make-up water, or pyritic mill reject sluice makeup water. There is no discharge from the ash treatment basin.

 Because the FGD process has large evaporative losses, the FGD process consumes a large portio n of the water from the ash treatment basin.

 The ash treatment basin was originally 60 to 70 feet deep when it was built. Now,
the area where the ash enters the basin in only about 10 to 20 feet deep. The area where the wastewater leaves the pond is still about 60 feet deep. Trimble County expects that there are only a few years of capacity remaining in the ash treatment
basin.

 As a short-term solution to extend the lif etime of the basin, Trimble County plans to complete building up the sides of the ash pond as originally designed including:
vertical extension of the ex isting clay liner; engineered structural support using
on-site soils and as much be neficial reuse of excavated bottom ash as practical. Trimble County estimates that this will add at least a couple year s to the life of the pond.

 As a long-term solution for the disposal of ash and gypsum at the plant, Trimble County has plans to use two ravines near th e plant. The ravines may be used as either landfills or impoundments for the disposal of gypsum and ash. One of the ravines would be used exclusively fo r gypsum and the other would be used exclusively for ash, although these pl ans are subject to change.

Generating Unit #2 (Under Construction)

 Trimble County is currently constructing a new generating unit (Unit 2) that is planned to begin operation in May 2010. The unit will have a capacity of approximately 810 (gross) MW.Page 7

 As described previously, the unit will ha ve a supercritical boiler. Additionally, the unit will have a bottom ash handling syst em that operates with a drag chain.
The bottom ash will be collected in a tr ough of water at the bottom of the boiler and a drag chain will move across the trough and convey the ash out of the boiler to a collection point.

 Unit 2 will have a SCR and a cold-side ESP. Trimble County will add hydrated lime into the flue gas prior to the ESP to re move sulfur trioxide, but will not add it after the ESP. Instead, Trimble Count y will inject powdered activated carbon (PAC) into the flue gas after the ESP. The PAC will absorb some of the mercury in the flue gas. The flue gas will be sent through a fabric filter baghouse, which will capture the PAC and the mercury ab sorbed with it, reducing the plant’s mercury emissions.

 Trimble County stated that they had or iginally planned to only operate the baghouse for particulate control; however, because the fly ash captured in the baghouse would contain PAC a nd mercury, the fly ash would not be marketable. Therefore, Trimble County decided to add the ESP prior to the baghouse to allow for most of the fly ash to be marketed, if possible. The addition of the ESP also reduced the size of the baghouse required.

 Trimble County is currently revising the approach for handling fly ash and anticipates that both Unit 1 and 2 ultimate ly will operate dry fly ash systems. The system being considered at the time of the site visit, as represented by the attached process flow diagrams, is as follows:

 Both a wet and dry fly ash handling systems would be installed for the fly ash collected from the Unit 2 ESP. Similar to Unit 1, the dry handling system would be used if there is an opportunity to market the fly ash and the wet handling system will be used when marketing is not possible. The fly ash sluice would be transferred to the ash treatment basin. If handled dry, it would be placed in an on-site landfill.

 Fly ash collected from the Unit 2 baghouse would be handled wet. Because the fly ash collected in th e baghouse will contain PAC that has absorbed mercury, the fly ash will not be marketable. The fly ash sluice
would be transferred to the ash treatme nt basin. If handled dry, it would be placed in an on-site landfill.

 After passing through the fabric filter, the flue gas will be sent to a wet FGD scrubber system, which will be a limest one, forced oxidation system. The FGD system will have only one absorber module with five spray levels. The designed sulfur dioxide removal from the FGD system is 98.5 percent.

 After the FGD system, the flue gas will pass through a wet ESP (a separate ESP from the dry ESP located upstream of the baghouse). The wet ESP uses spray headers to remove the collected fine part iculate from the collection plates. The water stream from the wet ESP will be transferred to the FGD system. Service
water will be used as the source water for the wet ESP.Page 8

 Trimble County stated that the wet ESP is intended for sulfuric acid mist mitigation and it is possible it may also help with capturing mercury.

Future FGD System Operation (Units 1 & 2)

 When Unit 2 begins operating, Trimbl e County will also begin operating a gypsum storage pond. Trimble County will be relining the area next to the ash treatment basin, which was originally intended to collect emergency overflow from the treatment basin, for use as the gypsum storage pond.

 At the time of the site visit, Trimbl e County intended to use the ash treatment
basin as the source water for the limest one slurry, which feeds both of the FGD systems. However, the plant now plans to use service water as the source of makeup water.

 The blowdown from the Unit 1 and Unit 2 FG Ds will either be transferred to the hydroclone feed tank or directly to the gypsum storage pond, depending on how much gypsum can be marketed.

 The slurry (reaction tank bl owdown) from the hydroclone feed tank will be transferred to the hydroclones and the hydr oclone overflow will be recycled to Unit 2 as make-up water. None of the hydr oclone overflow is planned to be used as make up for Unit 1. Currently, the pl ant anticipates using service water for makeup. (At the time of the site visit, th e ash treatment basin was expected to be the makeup water source for Unit 1.)

 The hydroclone underflow will be transfe rred to the vacuum belt filters for dewatering. The filtrate from the vacuum belt filters will be transferred to the gypsum storage pond.

 Because of the issue with the increasing chlorides concentration in the Unit 1 reaction tanks, Trimble County will no longe r recycle all of the FGD wastewater. Instead, the effluent from the gypsum storage pond will be commingled with cooling tower blowdown and discharged to the Ohio River. This discharge will purge chlorides from the FGD system.

 None of the water entering the gypsum stor age pond will be recycled back to the FGD process.

 At the time of the site visit, Trimbl e County estimated that the gypsum storage pond effluent would have a flow rate of 1.7 MGD with both units operating. However, Trimble County has made a recent change in the plant water management design strategy. Trimble C ounty no longer plans to reuse the ash treatment basin water as make-up in the FGD systems. Trimble County is still evaluating the reconfiguration of the water management design, but the plant expects the flow rate from the gypsum st orage pond to be greater than 1.7 MGD for the following reasons:Page 9

 Increase in freshwater use for the two FGD systems (related to the decrease in recycled as h treatment basin water);

 Increase in evaporation losses (f or two FGDs instead of one);

 Addition of coal pile and limestone pile runoff to the gypsum pond; and

 Addition of new storm water ac cumulated in the gypsum pond.Page 10Site Visit AttendeesNameOrganization (Representing)TelephoneE-mailTom CrutcherLouisville Gas & Electric – TrimbleCounty(502) 627-6201 tom.crutcher@eon-us.comJohn KipferLouisville Gas & Electric – TrimbleCounty(502) 627-6212 john.kipfer@eon-us.comWesley MollLouisville Gas & Electric – TrimbleCounty(502) 627-6202 wesley.moll@eon-us.comMitch SlaughterLouisville Gas & Electric – TrimbleCounty(502) 627-6208 mitch.slaughter@eon-us.comSharon DodsonE.ON U.S.(502) 627-2940 sharon.dodson@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.com0.01000.02000.03000.04000.05000.06000.07000.0 07/22/91 07/13/92 07/12/93 08/15/94 08/14/95 08/19/96 10/13/97 11/09/98 05/24/99 08/30/99 11/30/99 03/14/00 06/05/00 08/28/00 01/15/01 04/23/01 07/23/01 07/22/02 07/14/03 08/09/04 06/20/05 12/13/05 02/27/06 05/22/06 08/21/06 11/13/06 02/12/07 05/14/07 08/09/07 12/24/07 03/17/08 09/03/08

Chloride Concentration (mg/L)A Rx Tk ClB Rx Tk Cl0500100015002000250030003500

0 7 / 2 2/91 0 1 / 1 5/92 0 7 / 1 3/92 0 1 / 1 1/93 0 7 / 1 2/93 0 2 / 0 7/94 0 8 / 1 5/94 0 2 / 0 6/95 0 8 / 1 4/95 0 2 / 1 2/96 0 8 / 1 9/96 0 4 / 0 8/97 1 0 / 1 3/97 0 5 / 0 4/98 1 1 / 0 9/98 0 4 / 1 3/99 0 5 / 2 4/99 0 7 / 1 9/99 0 8 / 3 0/99 1 0 / 1 9/99 1 1 / 3 0/99 1 / 2 5 / 2 00 0 3 / 1 4/00 0 4 / 2 8/00 0 6 / 0 5/00 0 7 / 1 8/00 0 8 / 2 8/00 1 1 / 2 7/00 0 1 / 1 5/01 0 2 / 2 6/01 0 6 / 1 1/01 0 2 / 1 1/02 0 8 / 1 3/02 0 2 / 1 8/03 0 9 / 1 5/03 0 4 / 0 5/04 1 1 / 2 2/04 0 5 / 1 6/05 1 2 / 1 9/05 0 5 / 0 8/06 1 1 / 1 3/06 0 5 / 1 4/07 0 1 / 0 7/08 0 9 / 1 8/08

Chloride Concentration (mg/L)