Notes from Site Visit at Ameren Corporation’s Duck Creek Energy Center on April 27, 2010

EPA conducted a site visit at the Ameren Corporation’s Duck Creek Energy Center (Duck Creek) located in Fulton County, IL on April 27, 2010 to learn about the operations at the plant, specifically to learn about the FGD operations and how they operated without the discharge of FGD wastewater. Table 1, located at the end of thes e notes, identifies the site visit participants. The water flow diagram discussed during the site visit is provided as Attachment 1 to these

notes.

These notes describe the information collected during the site visit and the pre-site visit phone call, which was held on April 8, 2010.

[QUESTION FOR DUCK CREEK: Please provide a copy of the presentation given to EPA during the site visit for inclusion in these notes.]

Plant Overview

• Ameren Corporation’s subsidiary, Ameren Energy Resources Generating Company, is comprised of two coal-fired power plants: Duck Creek (Canton, IL) and E.D. Edwards (Bartonvill e , IL).

• The Duck Creek plant operates one generating unit with a coal-fired cyclone boiler. The unit has a gross capacity of 465 MW and a net capacity of 430 MW. [ QUESTION FOR DUCK CREEK: Please confirm capacity values for the unit.]

• The unit was originally installed in 1976. In 2003, a selective catalytic reduction (SCR) system to control NOx emissions was added, followed by an upgrade to a low NOx burner in 2007. In March 2009, Duck Creek installed an electrostatic precipitator (ESP) to control particulate emissions and upgraded their flue gas desulfurization (FGD) system to a limestone, forced oxidation system to better

control SO 2 . The plant also installed a continuous emissions monitoring system at

this time. [QUESTION FOR DUCK CREEK: When was the FGD system initially installed?]

• The catalyst for the SCR is not regenerated on site. To date, the plant has changed one layer of catalyst in the system.

• The plant burns about 1 million tons of coal per year. Approximately 400,000

tons of coal and limestone is stored on s ite at any given time, with ditch collection for rainwater, which is transferre d to the cooling water reservoir.

• The system was designed to operate w ith 100 percent Illinoi s bituminous coal; however, the plant currently operates with a blend of Powder River Basin coal. The coal typically runs between 900 and 1,000 ppm SO 2 . The absorber is made of carbon steel with a flake glass lining. Comment [MJS1]: Provided on this CD.

Comment [MJS2]: These appear to be good numbers for capacity values.

Comment [MJS3]: The unit has operated with a FGD since initial operation. The former system was replaced with a forced oxidation FGD that was placed into service in March 2009.Page 2

FGD System

• The new FGD scrubber system is a Hitachi spray tower design, with forced air oxidation, which operates with a counter-current spray. The Hitachi design includes a continuous limestone slurry bl eed loop, which the plant stated allows higher SO 2 removal than a batch system. The system achieves 95% removal of

SO 2

.

• Duck Creek operates a horizontal wet ball mill to process the limestone. A new

mill was installed at the time the new scru bber system was installed. The old ball mill was also upgraded and is used as a backup system. Duck Creek uses water from their cooling pond to create a limestone slurry with about 30% solids.

• The FGD system has five spray levels, and the plant typically operates three to four levels at a time dependent on the SO 2 removal rate achieved.

• The pH of the system is 5.8 S.U., with a density of 70 pounds per cubic foot. The level in the system ranges from 18 to 22 percent.

• The FGD system is designed to operate up to a maximum chlorides level of 50,000 ppm; however, the plant currently operates at about 15,0001,500 ppm chlorides. [QUESTION FOR DUCK CREEK: Please confirm the chlorides level in the system is 15,000 ppm.]

• The system has a feed forward control system to trigger blowdown. The bleed stream is transferred to a tank, where it is mixed with reclaim water to dilute the stream to 2% solids. This dilution is to prevent plugging of solids in the two sets of 3-mile transfer lines to the gypsum management facility.

FGD Solids and Wastewater Treatment

• The FGD system is a closed loop system. Duck Creek uses water from the gypsum management facility to reduce freshwater make up water to the system, and ultimately blows down FGD wastewater to the closed loop system. The plant must manage the influx of rainwate r to maintain the water balance within the closed loop system

.

• The plant is not able to quantify the flow of blowdown because it is not measured.

• The gypsum management facility is comprised of a 30-acre pond in which the diluted bleed stream is fed to settle out the gypsum and the decant water is transferred to a reclaim pond which is ultimately returned to the FGD system. Gypsum can be stacked up to 100 feet high. The gypsum stack pond is lined with compacted clay, and a 60-ml HDPE and geotext i le double liner with integral leak

detection and leachate collection between the two HDPE liners . Duck Creek expects the lifespan of the pond will be 7 to 8 years, and will be expanded as

needed. Comment [MJS4]: Per plant analyses and the information request submitted to USEPA in September 2010, a good number for chloride concentration is 2,500ppm. Note that FGD chloride concentration is dependent upon the coal blend

combusted in the boiler.

Comment [MJS5]: Blowdown flow can be calculated using pump runtime and capacity.Page 3

• The reclaim pond is 10 acres with a volu me of 33 million gallons (water is approximately 20 feet deep). This pond receives the gypsum stack decant, stack runoff, and leachate from the gypsum stack. The leachate collection system has been operating since March 2009 and no leachate had yet been collected as of the time of the site visit. Dam safety measur es require that the reclaim pond also has four relief pipes for overflow to the cooling water pond.

• The gypsum stack pond is monitored using a series of 40 groundwater monitoring

wells.

Fly Ash Handling System

• The fly ash handling system was retrofitted in 2005 and 2006 to a dry ash (vacuum pump) handling system.

• The dry ash is transferred to the top of onsite silos, where the ash is separated using bag filters similar to a baghouse. Mixers at the bottom of the silos move the ash to the storage facilities. Duck Cree k uses fresh water to condition the ash. Although Duck Creek also has the ability to load ash dry (i.e., unconditioned), the dry unloading capabilities had not yet been used at the time of the site visit because none of the fly ash has been marketed/reused.

• Duck Creek personnel stated that ash from a mixture of PRB and bituminous coal is not as competitive as ash from 100% PRB. For another Ameren plant, their ash marketability was further reduced since they are adding activated carbon for mercury controls.

• The dry ash that will be disposed is transferred to the onsite landfill.

Bottom Ash Handling System

• The current bottom ash handling system began in 2008, and all bottom ash is beneficially reused in road construction.

• Bottom ash is sluiced from the boiler to one of two primary settling basins. The majority of the ash settles out in the pr imary basins, where it is pushed out and allowed to dewater. While one primary basin is being cleaned out, the other is used to treat the bottom ash sluice. The decant from the primary basins is transferred to one combined secondary equalization basin, where it then overflows continuously to the cooling water reservoir.

• The basins are lined with compacted clay, HPDE, and 8 inches of concrete.

• Duck Creek uses 2 MGD of bottom ash sluice water. The source for this water is treated service water from the cooling water reservoir.

• Duck Creek’s previous bottom ash handling system combined the bottom ash with low volume wash water and FGD solids, and placed this material in the oldPage 4

ash ponds. [QUESTION FOR DUCK CREEK: Was it bottom ash and sluice water, or just the bottom ash solids?]

Other Plant Wastewater

• The plant generates low volume waste fr om the water treatment system (0.5 MGD), the turbine room sump (0.3 MGD), and the boiler room sump (0.3 MGD).

This water is treated in the bottom ash basins.

• Runoff from the onsite landfill is transf erred to the cooling water reservoir, while

leachate from the onsite landfill is used for dust control and/or in the gypsum management facility.

Plant Outfalls

• Duck Creek has four outfalls:

• 001: Dam seepage collection;

• 002: Cooling pond overflow (elevation 565) for Duck Creek;

• 003: Intake screen backwash; and

• 004: Cooling pond overflow (elevation 562.5) for Illinois River.

• Outfall 004 is a new outfall to allow discharge to the Illinois River. Both the Illinois River reservoir makeup water Outfall 003 and Outfall 004 share a pipeline. The Illinois River reservoir makeup wa ter intake structure 003 intake

water was used to originally fill the cooling water pond, while 004 can be used to discharge to the river.

• Outfall 002 has not been used since 2004 as there have been no cooling water reservoir discharges via this outfall

.

Ash Ponds

• Duck Creek previously had three unlined ash ponds:

• Ponds 1 and 2: all wastewater was transferred to Pond 1 until full, then moved to Pond 2 (each pond had a 7-14 day turnover);

• Recycle Pond: this pond was built fo r surge capacity for the plant.

• At the time of the site visit, Pond 1 was mounded with ash, while Pond 2 had freestanding water. Duck Creek is actively involved in closing the ponds. They

are transferring bleeding the remaining water to the reservoir, which overflows to the river discharges via Outfalls 002 and 004

.

• Duck Creek conducted a study to look at the impact of the out of service pond discharges to the reservoir and the Illinois River. The out of service ash ponds are monitored using a series of 44 groundwater monitoring wells. A hydrogeologic report was delivered to the State of Illinois in March. [NOTE TO DUCK

CREEK : Please provide copy of report.] Comment [MJS6]: Bottom ash and sluice water was directed to the former ash pond system.

Comment [MJS7]: This report is not provided with this submittal as a subsequent evaluation was conducted after the water from the ponds was

transferred to the reservoir.Page 5

• The plant is currently evaluating different methods for closing the ponds, including “in place closure” (no removal of solids), with a cap and cover, installation of a storm water management system, and installation of groundwater monitoring.

• In Duck Creek’s 2004 permit package, the plant conducted a technology evaluation related to closing the ash ponds, including the cost and feasibility of treating the ash pond water, discharging to both Duck Creek and the Illinois River, and impact of boron and other pollutants on water quality. [ NOTE TO

DUCK CREEK : please provide copy of permit package.] Comment [MJS8]: Appropriate excerpts of this report are provided on the CD.Page 6Table 1. Site Visit AttendeesNameOrganization (Representing)TelephoneE-mailMichael BollingerAmeren314-554-3652 mfbollinger@ameren.comRoger FergusonAmeren314-825-9163 rferguson3@ameren.comJim Marshall Ameren 309-668-3804 jmarshall@ameren.comRich Phillips Ameren 314-609-5947 rphillips@ameren.comGreg Russell Ameren 309-668-3800 grussell2@ameren.comMichael Smallwood Ameren 314-554-4581 mjsmallwood@ameren.comSteve WhitworthAmeren314-554-4908 scwhitworth@ameren.comDonna HillUWAG205-257-5234 dbhill@southernco.comBill BuscherIllinois EPA217-785-4787 bill.buscher@illinois.govDarin LeCroneIllinois EPA217-782-0610 Darin.lecrone@illinois.govLeslie Lowry Illinois EPA 217-782-0610 leslie.lowry@illinois.govRon Jordan EPA/Office of Water 202-566-1003 jordan.ronald@epa.govBill Swietlik EPA/Office of Water 202-566-1129 swietlik.william@epa.govDeb Bartram ERG (Contractor to EPA) 703-633-1669 deborah.bartram@erg.comTJ Finseth ERG (Contractor to EPA)703-633-1698 thomas.finseth@erg.com