### Notes from Site Visit at Domini on Resources’ Clover Power Station on October 24, 2008

EPA conducted a site visit at Dominion Resour ces’ and Old Dominion Electric Cooperatives’ Clover Power Station (Clover) located in Clover, VA on Friday, October 24, 2008 to learn about the operations at the plant, specifically the F GD wastewater handling syst em. Table 1, located at the end of this memorandum, identifies the site visit participants. The presentation that the Clover personnel gave during the site visit is pr ovided as an attachment to this memorandum.

Also included as attachments to this memo randum are a flow diagram of the gas cleaning system, an overall plant wastewat er flow diagram, process flow diagrams for the FGD systems, a diagram of the baghouse operation, and a diagra m of the plant’s surface water outfall plan.

This memorandum describes the information collected during the site visit and the pre-site visit phone call, which was held on October 1, 2008.

Plant Overview

 Clover operates two generating units at the power plant, which is a baseload plant with a net generating capacity of 860 MW . The table below contains some general information for each generating unit. A pr ocess flow diagram of the basic gas cleaning system arrangement is included as an attachment to this memorandum.

Unit Installation

Date Net Capacity

(MW) Particulate

Control NOx Control SO 2 Control 1 1995 430 (net) Baghouses SNCR

installed 2003 Wet FGD in original design (1995) 2 1996 430 (net) Baghouses SNCR

installed 2003 Wet FGD in original design (1996)

 Clover burns eastern bituminous coal in bot h generating units. Most of the coal

used at Clover comes from mines in Virginia, but some is delivered from Kentucky. Clover consumes approximately 90 rail cars per day of coal.

 Clover personnel stated that the sulfur cont ent of the coal typi cally ranges from 1.0 to 1.3 percent sulfur. Cl over personnel stated that th e limit for the coal burned in the boilers is 1.7 percent sulfur on a per shipment basis and 1.3 percent sulfur

on an annual basis.

 Clover personnel provided data from an anal ysis of the coal bu rned in the boilers in July of 2004 that showed the chlorine content of the coal ranged from 0.03 to 0.1 percent chlorine on a dry weight basis.

 Clover operates SNCRs on both generating uni ts. The SNCR process consists of injecting urea directly into the boiler. Pr ior to injection, Clover adds dry urea to water to make an aqueous solution of urea. Clover stated that they may switch from receiving dry urea to receiving a queous urea. Clover that costs are thePage 2

driving factor for making the change because , at times, it is more cost effective to purchase aqueous urea inst ead of dry urea.

 Clover only injects the urea during a porti on of the ozone seas on (i.e., the SNCRs are not operated the entire ozone seas on). Clover operates the SNCR to meet emission limits or system targets. Additionally, Clover may operate the SNCR

when the cost emissions credits make the operation cost effective. Clover stated that the SNCR process achieves approxi mately 25 percent reduction of NOx.

 Both generating units have baghouses, wh ich achieve approximately 99.9 percent removal of fly ash and other particulates.

 Clover personnel stated that th e plant uses oil in the bo ilers primarily during start up. Clover additionally uses oil for stabi lization while the boile rs are operating at

a low load. Oil is used for flame stabilizat ion while taking coal mills in and out of service typically at loads of 400 MW or less.

 The baghouses must be bypassed during star t-up while burning oil. Clover is allowed, by permit, 30 minutes to place the baghouse into service once the first

coal feed commences.

 Clover uses the Roanoke River as the sour ce for the power plant’s water. Clover

withdraws water from the Roanoke River and pumps it to the raw water storage pond, which has a capacity of 310 million gallons. Clover maintains the raw water storage pond at capacity to ensure th at the plant will have a water source if

the river level decreases. Clover stat ed that the raw water storage pond has enough capacity to keep the plant running fo r approximately 22 days. An overall process flow diagram is included as an attachment to this memorandum.

 Clover treats the water from the raw water storage pond using clarifiers. Most of

the clarified water is transferred to the cooling tower as makeup water for the 9-10 MGD that evaporates. The remainder of the clarified water is transferred to a demineralizer/reverse osmosis system fo r further purificatio n and use as boiler make up or service water.

 Clover transfers its cooling tower blowdown to the holding pond. Cooling tower blowdown accounts for approximately 90 to 95 percent of the flow to the holding pond. The holding pond also receives water fr om the following sources: sewage treatment plant, oil/water separato r, plant drains, boiler blowdown, and

neutralization basin.

 Some of the effluent from the holding pond is reused in the FGD scrubber as make up water. The remainder of th e effluent from the holding pond is discharged to the Roanoke River.

 Clover operates a combined coal and limestone pile runoff pond. This pond collects runoff from the coal storage ar ea as well as the limestone pile and scrubber sludge storage area. The pond discharges directly to the Roanoke River;Page 3

however, Clover can transfer the pond’s cont ents to the emergency sludge storage ponds if necessary for reuse in the scrubber system.

 Clover occasionally adds sodium hydroxide to the coal and limestone pile runoff pond and pumps the water from one end of the pond to the other end to neutralize the pH in the pond. In addition, Clover may add bags of soda ash to the inlet of the pond if there is an excessi ve amount of rainfall. Cl over stated that the pH in the pond on the Monday prior to the vi sit (October 20, 2008) was 2.57 S.U.

 Clover operates a neutralization basin whic h receives wastewaters from chemical cleaning operations, reverse osmosis reje ct, and demineralizer regeneration

wastes. The wastewater from the neutraliz ation basin is typically transferred to the emergency sludge storage ponds but can be discharged to the holding pond if

desired. Acid or caustic can be adde d to the neutralization basin prior to discharge if necessary.

 Clover operates two emergency sludge st orage ponds. The ponds are used to

store solids in the case of an emergency such as a scrubber failure, in which case,

the scrubber contents could be transfe rred to the emergency sludge storage ponds. Clover stated that they can use the ponds to allow for additiona l settling/treatment of the coal/limestone pile runoff, if ne eded. Additionally, Clover transfers the

waste from the neutralization basin to th e ponds. Clover uses the water from the emergency storage ponds as make up for the FGD scrubber process. There is approximately 1 mgd evaporative loss from the FGD system, and additional water is removed from the system along with the gypsum sent to landfill.

 The Clover plant is located on 1,800 acres of land, 500 acres of which are managed wetlands.

 Clover employs approximately 140 workers.

FGD System

 Clover operates limestone forced ox idation wet FGD scrubbers on both generating units. Each generating unit ha s three individual ab sorber vessels, two that are in operation and one spare. Each of the FGD scrubber systems were installed at the time the generating units were initially built, 1995 for Unit 1 and 1996 for Unit 2. Process flow diagrams for the Unit 1 and 2 FGD systems are

included as attachments to this memorandum.

 Clover uses ball mills to crush the limest one to the correct size for use in the limestone slurry. Clover uses approxim ately 7,500 tons of limestone each month.

 The limestone slurry from the ball mills is approximately 50 to 55 weight percent solids and is transferred to hydroclones to remove the limestone particles that are too large, which are transferred back to the ball mill for additional processing. The overflow from the hydroclones is transf erred to the limestone slurry storage tank and is approximately 30 to 35 weight percent solids.Page 4

 Clover has had foaming issues in the sc rubbers; therefore, Clover continuously adds a defoaming agent to the discharge pi pe of the limestone slurry storage tank

that feeds the reac tion tanks of the FGD scrubbers.

 Each of the scrubbers at Clover has four spray levels, each operated by a separate recirculation pump. However, Clover typi cally only operates si x or seven of the spray levels for each generating unit at one ti me (i.e., three spray levels in each of the two operating absorber vessels, or thre e spray levels in one absorber vessel and four spray levels in the other absorb er vessel). Clover occasionally rotates which spray levels are used with in the various ab sorber vessels.

 The Clover FGD scrubbers typically achie ve an average of approximately 96 percent removal of sulfur dioxide from the flue gas. Clover’s permit limit requires a 94 percent removal. Clover adds adipic acid to th e scrubbers daily to improve the efficiency of the system. Cl over personnel stated that the contractor

that installed the FGD scr ubber system used adipic ac id during the testing phase of the system and it worked well. Ther efore, Clover chose to continue using adipic acid in the system.

 Clover operates the FGD scrubbers at a pH of 5.4 to 5.5. The scrubber operates

with a constant solids concentration of 13 weight percent. The chlorides concentration in each of the scrubbers ranges from 20,000 to 40,000 ppm. The FGD system piping is either constructed of stainless st eel or is rubber lined to prevent corrosion.

 The blowdown from the scrubbers is contro lled by the level in the scrubbers and is essentially continuous. The blowdown is not controlled by a pump, but rather, by gravity. A small pipe is located at the bottom of the reaction tank which extends from the scrubber, turns upwar d, and extends approximately 25 feet along the outside of the scrubber vessel. The pi pe then angles downward and is directed to the nearby waste slurry sump. This configuration causes a blowdown from the

scrubber at all times when the level in th e scrubber is above the top point of the blowdown pipe.

 The blowdown in the waste slurry sump is pumped to the th ickener feed tanks,

which also receives water from the ho lding pond and filtrate from the vacuum filters. The water from the holding pond is make-up water for the FGD scrubber system, which is treated in thickeners pr ior to being sent to the system. Clover operates two thickeners in parallel, each with a capacity of two million gallons.

 The overflow from the thickeners is tran sferred to the reclaim tank. From the reclaim tank, the water is used in the li mestone preparation process, used for conditioning the fly ash/FGD solids prior to disposal, or returned directly to the

scrubber.

 The underflow from the thickeners, which is approximately 35 weight percent solids, is pumped to the filter feed tanks. From the filter feed tanks, the thickener

underflow is sent to the vacuum drum f ilters that dewater the solids. The FGD solids from the vacuum drum filters, which are primarily gypsum, contain 15 toPage 5

18 percent moisture and are conveyed to a pug mill where they are mixed with dry fly ash and water.

 The filtrate from the vacuum drum filter is transferred to the waste treatment area sump then to either the thickeners or to the emergency sludge storage ponds.

 Clover has the capability of processing just fly ash, just FGD solids, or a combination of the two in the pug mills. Typically, fly ash and gypsum are processed together. If just fly ash is being processed, Clover adds water from the reclaim tanks to the pug mill to bring the fly ash to 20 percent moisture. If just FGD solids are being processed, Clover ma y add water from the reclaim tanks to the pug mill if necessary to bring the moisture content to 20 percent. Clover

stated that the additional water is needed to achieve the correct compaction of the

material in the landfill.

 Clover personnel stated that they have th e capability to add lime to the pug mill,

but have never done so because it is not n ecessary to aid in proper stabilization of

the material in the landfill.

 Clover personnel stated that when they st art processing the solids in the pug mill, they typically start with just fly ash and water, and then they slowly add the FGD solids to the mixture. From the pug mill, the processed solids are conveyed

outside to the stack out area.

 Clover personnel stated that they typically operate the vacuum drum filters and the pug mill during the night shift. Clover f ills up the filter feed tanks and the fly ash silos during the day shif t and then processes the materials during the night shift. In the morning, the solids that were sent to the stack out area are trucked to

the landfill.

 Clover personnel stated that the gypsum produced is not marketable partially because of the chlorides level present in the gypsum. Clover personnel also stated that because of the location of the plant, the transportation co sts for hauling the gypsum would be greater than sales from the gypsum.

Ash Handling and Wastewater Treatment

 Clover operates a dry bottom ash handling system, specifically a submerged bottom ash scraper/conveyor. At the bo ttom of each boiler is a collection trough

that contains a water bath. The holdi ng pond provides water for the water bath. The bottom ash generated in the boiler is collected in the trough and Clover operates a drag chain that moves across the trough and drags the ash out of the

boiler. At the end of the boiler, the conveyor chain reaches an incline which acts to dewater the bottom ash by gravity draini ng the water as the ash moves upward. The bottom ash is then dumped onto a nother conveyor which transports the bottom ash outside and dumps it onto a stor age area. Any water that drains off the bottom ash in the storage area is collect ed in a sump and transferred back to the boiler bottom ash collection trough or to the FGD absorbers. Clover personnel stated that the consumptive water use for the bottom ash system is low.Page 6

The solids that accumulate in the sump ar e removed via a jet pump back to the bottom ash pit. The bulk of the water that accumulates in this sump is transferred to the scrubber system and is re-used as reclaim water or can be sent to the emergency sludge storage ponds.

 Clover transports the bottom ash, along with mill rejects/pyrites, by truck to the on-site landfill for disposal. Clover estimated that they generate 50,000 tons of bottom ash per year.

 Clover operates a dry fly ash handling syst em. Clover uses baghouses to remove the particulates from the flue gas. Th e flue gas enters the baghouse compartment and is forced upward into the bottom of the bags. The flue gas passes through the bags fabric filter, which removes particulates in the gas. The filtered flue gas then exits out the top of the baghouse comp artment. A diagram presenting the operation of the baghouses is included as an attachment to this memorandum.

 After a few hours of operation, the fly ash collected in the baghouses can generate enough back pressure to burst the bags or restrict flow through the bags. Therefore, every few hours, Clover reverses the flow in the baghouse compartment forcing clean air to travel from the outside of the bags to the inside,

which causes the dust cake to crack and fa ll into the hopper below. The fly ash is collected at the bottom of the baghouse compartment in a hopper and pneumatically transferred to the fly ash s ilos. Clover stated that the bag cleaning process takes approximately 10 minutes for each compartment.

 The bags used in the baghouse are about 40 feet long. Each of the generating units has 32 baghouse compartments and each compartment holds 288 bags, for a total of 9,216 bags per generating unit.

 As discussed in the FGD System section, the fly ash is processed in a pug mill

with water and FGD solids and then transf erred to the on-site landfill for disposal.

Clover Landfills

 Clover is currently operating St age III of the on-site landf ill. Stage I and Stage II were filled, capped, and closed in 2003. Additionally, Phase 1 of the Stage III landfill is filled, capped, and closed. Clove r estimates that they have enough onsite landfill space to last for the life of the station. Clove r stated that they estimate the life of the plant to be 40-50 years and they estimate 55-60 years of landfill

space.

The leachate from Stage I and Stage II is piped directly to the Stage III leachate collection ponds. Therefore, the stormw ater runoff sediment pond located in the Stage I and Stage II landfill area contain only stormwater and no leachate. The stormwater runoff pond is batch discharg ed on an as needed basis, based on rainfall accumulations, directly to the Black Walnut Creek.Page 7

 Clover operates four concrete leachate colle ction basins associated with the Stage

III landfill. These collection basins al so receive some stormwater runoff from Stage III as well as the leach ate from Stage I and Stage II. The leachate collection basins are discharged directly to the Ro anoke River; however, the discharge is not continuous. Clover stated that they typi cally batch discharge to the river for several days each month. Clover monitors the discharge for pH, total suspended solids, and flow rate.

 Clover also operates several stormwater runoff sediment ponds in the Stage III landfill area. Like the Stage I and Stage II stormwater runoff sediment pond, the Stage III stormwater runoff sediment ponds discharge directly to the Black

Walnut Creek.

 Clover also operates five other stormwat er runoff drainage areas that are not

associated with the landfill area and discha rge directly to the Black Walnut Creek.

 A diagram of the Clover’s surface water outf all plan is included as an attachment

to this memorandum.Page 8Table 1. Site Visit AttendeesNameOrganization (Representing)TelephoneE-mailTim Hamlet Dominion Resources(434) 454-2150 tim.hamlet@dom.comWilliam GwynnDominion Resources(434) 454-2026 william.gwynn@dom.comKen RollerDominion Resources(804) 273-3494 kenneth.roller@dom.comOula ShehabDominion Resources(804) 273-2697 oula.k.shehab-dandan@dom.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.comAttachment

CLOVER PRESENTATIONClover Power StationWelcometo theHow It All StartedA brief history of the Clover Power Station♣In 1989, Old Dominion ElectricCooperative and Dominion team up toconstruct Clover Power Station♣In February 1992 Construction Commences♣Unit #1 began commercial operations in thefall of 1995 and Unit #2 in the spring of1996.How It All Works♣Coal is delivered by train from Virginia mines♣Clover consumes approximately 90 rail cars ofcoal per day when the units are at full capacity.♣Fuel oil is used for start-up then we switch to coalto heat the water to steam to drive the turbine andgenerator♣Each of our two units produces approximately 430Net MW of electricity which is enough to powerapproximately 100,000 homes.Keeping It CleanOne of our major concerns is the impact that we haveon the environmentOver $400 million of the $1.2 billion plant costs was spent onequipment to ensure that this station maintains compliance withits regulatory permitsTwo major pollution control measures used at Clover are thebaghouses and wet limestone scrubbersIn addition, an SNCR may be used during the ozone season andbeyondThe BaghouseThe Baghouse♣The baghouse acts as a filter that removes the ashfrom the flue gas before entering the scrubbersystem♣This very efficient process takes 99.9% of theash out of the flue gas♣The ash is transported to a silo then to the pug millwhere it is mixed with the scrubber byproduct andwater before being placed in our on-site landfillThe Scrubber♣The scrubber removes the sulfur dioxide that is producedas a result of burning coal♣This is done by mixing the hot flue gas with a slurry oflimestone and water♣Our typical removal rate is approximately 96% althoughthe permit limit is 94%♣Adipic acid is also used to improve removal efficiency♣Forced oxidation air is supplied to all of the vessels toassist in forming a sulfate product instead of sulfite whichis easier to dewater♣Refer to scrubber process diagramSelective Non-Catalytic Reduction• Dry Urea is made intoan aqueous solutionand injected into thefurnace for NOxReduction.• Results in anapproximately 25%reduction.This is the basic overview of the stationWastewater Treatment Systems♣All oil tank secondary containmentsand floor drains that have thepotential for receiving oil spillsdrain through oil/water separators♣All bulk chemical tank secondary containments drain to lift stationsthen to the neutralization basin♣All sanitary wastes are routed tothe on-site sanitary treatment plant♣Cooling tower and boiler blowdown,sanitary waste treatment plant,oil/water separators and neutralization basin discharge to the holdingpond before release to the Roanoke River.♣Limestone storage pile, the coalpile and coal combustion byproductstackout areas drain to the coal/limestone pile runoff pond beforerelease to the Roanoke River♣The landfill wastewater treatmentsystem consists of 4 leachatecollection basins and 7 stormwaterrunoff sediment ponds. Leachate ispumped to river through a 2.34 mileforcemain and the sediment pondsdischarge to Black Walnut Creek.♣5 stormwater runoff discharges inaddition to the 7 landfill ponds♣Refer to wastewater process diagramSome interesting facts about theClover Power StationThe power station withdraws water from the river and pumps itto the raw water storage pond. Fromthere, it is clarified and thebulk of which is routed to the cooling towers as make-up for theapproximately 9-10 MGD they evaporateThe remainder is routed to the water treatment plant for furtherpurification and used throughout the plant in various systemsincluding boiler water make-up, service/fire waterThe scrubber receives its water needs from the holding pond aswell as the 2 emergency sludgestorage ponds and accounts forapproximately 1 MGD of evaporative losses through the stacksSome other interesting factsabout the Clover Power StationThe Clover Power Station employsapproximately 140 workers, is base loadedand remains in operation year roundThe station is located on 1800 acres of landof which approximately 500 acres aremanaged wetlandsWe have an on-site landfill with the currentcell occupying approximately 30 acres.Tour Reminders♣Please remain with your tour guide at alltimes♣Feel free to take pictures and ask questionsbut please refrain from including employeesin photos.Attachment

CLOVER PROCESS FLOW DIAGRAMS