Draft Notes from Site Visit at Duke Energy’s Miami Fort Station on March 1, 2010

EPA conducted a site visit at Duke Energy’s Miami Fort Station (Miami Fort) located in North Bend, OH on Monday, March 1, 2010 to learn about the operations at the plant, specifically the flue gas desulfurization (FGD ) wastewater treatment system. These notes describe the information collected during the site visit. Table 1, located at the end of these notes, identifies the site visit participants. The presentation that the Duke Energy personnel gave during the site visit is provided as Attachment 1 to th ese notes and includes a FGD system process flow diagram, a simplified flow diagram of the FGD wastewater treatment system, and detailed view of the DensaDeg® clarifier. A more detailed process flow diagram of the FGD wastewater treatment system and an aerial view of the plant are provided as Attachments 2 and 3, respectively, to these notes.

Plant Overview

 Miami Fort operates three coal-fired steam electric generating units at the power plant. Unit 6, which began operation in 1960, has a generating capacity of 175 MW. Units 7 and 8, which began operation in 1975 and 1978, respectively, each have a generating capacity of 550 megawatts (MW). All three units are operated

as baseload units. The table below contai ns some general information regarding the three generating units.

Unit Installation

Date Gross Capacity

(MW) Particulate

Control NOx Control SO 2 Control

6 1960 175 Electrostatic Precipitator (ESP) (cold-side) Low-NOx Burners None

7 1975 550 ESP (coldside) Selective Catalytic Reduction (SCR) (2003) Wet FGD installed

December 2007

8 1978 550 ESP (coldside) SCR (2001) Wet FGD installed in April 2007

 Duke Energy is a partial owner of all the units at the plant. Miami Fort explained that a joint committee that meets regularly makes decisions regarding the units. It was also stated that both parties split the expenses and revenue of the units.

 Miami Fort retrofitted Units 7 and 8 in 2007 with FGD scrubber systems to control the sulfur dioxide (SO 2 ) releases from the plant. Unit 6 was not retrofitted with a scrubber system and Miami Fort does not have any plans for a retrofit.

 Miami Fort operates SCR systems on Units 7 and 8, installed in 2003 and 2001, respectively. Miami Fort runs the SCRs year round. The plant has not yet performed a catalyst regeneration on either of the SCRs. The plant takes samples of fly ash every day and measures the amount of ammonia present. PlantMay 27, 2009 Page 2

personnel stated that more ammonia slip was noticed this year. Miami Fort is beginning to discuss the options for how to handle the SCR catalysts. Plant personnel explained that they are considering the following options:

o Install a new layer of catalyst;

o Regenerate an existing layer of catalyst; or

o Replace an existing layer with a new layer of catalyst.

 Miami Fort stated that ash can build up on the catalysts in the SCR system, depending on the type of coal burned. Sonic horns are continuously used to remove ash from the catalysts; however, during quick outages, the plant uses a water spray to remove any remaining ash buildup. [QUESTION FOR MIAMI FORT: Is the above description accurate? Also, are pressure gauges used to activate either the sonic horns or an automatic wash cycle?] Sonic horns are used continuously based on a timer. We do no spray water to remove the ash buildup during outages. We do however, vacuum the ash. The pressure gauges exist to calculate a differential pressure (dP) across the catalyst, but that is not used to

activate sonic horns.

 Miami Fort burns eastern bituminous coal in all three units. Miami Fort stated that the coal is delivered by barge from several different mines. Miami Fort explained

that the source of the coal is a variable.

 Miami Fort stated that the sulfur content of the coal ranges from 2.5 to 7.5 pounds of sulfur per million BTU and that the chlorine content of the coal can range from 0.04 to 0.3 percent, depending on the source.

 Miami Fort previously had issues with blue plume from the stack, associated with sulfur trioxide emissions. The plant now in jects lime into the flue gas between the

air heater and the ESP to control the sulfur trioxide emissions.

 Miami Fort operates dry fly ash handling systems on Units 7 and 8 and a wet fly ash handling system on Unit 6. The dry fly ash handling systems on Units 7 and 8 are separate systems and the ash from each unit is stored in a separate silo. Wet fly ash from Unit 6 is sluiced to the plant’s ash pond.

 Miami Fort has both wet and dry fly ash loading capabilities for Units 7 and 8. Additionally, the plant has the capability to load rail cars from the Unit 7 silo.

 Miami Fort sells most of the ash to Ready Mix. Any fly ash that the plant cannot

sell is transferred to their landfill loca ted approximately three miles away, which is owned by Duke Energy. [QUESTION FOR MIAMI FORT: Is the landfill operated by Duke Energy?] Miami Fort stated that if the ammonia in the fly ash exceeds 100 ppm, the ash is not able to be sold and is transferred to the landfill.

JR/Jim ?

 Yes, it is the Lawrenceburg Road Ash Landfill Formatted: Font color: Red, Not Highlight

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 Miami Fort operates wet bottom ash ha ndling systems on all three units. A hydroveyor vacuum system sluices the bottom ash to the ash pond. Miami Fort uses cooling tower blowdown as the source for the hydroveyor water. The fly ash and bottom ash from Unit 6 are sluiced together to the ash pond. The plant sluices pyrites separately to the ash pond to en able the plant to ma rket some of the bottom ash. Miami Fort previously had a contract with Home Depot to reuse

filtered bottom ash for cement board. Th e contract was dropped when the plant switched to a higher density coal. Miami Fort is currently not selling any bottom

ash for reuse.

 Miami Fort operates an ash pond with two adjacent cells operated in series. The fly ash and bottom ash sluice streams are transferred to the first cell. Miami Fort adds polymer to the ash pond near where the sluice pipes deposit the ash to improve solids removals. The plant ope rates the first cell using a rim ditch stacking method. This approach entails using equipment to maintain channels for the sluice water to move through the mass of ash solids collected in the pond. The plant removes the solids that settle out in the channels of th e ash pond and stacks them in piles along the channels to allo w the solids to dewater, while the water drains back into the pond.

 The plant hauls the dewatered ash from th e pond to the landfill that is owned by Duke Energy for disposal. This ash is typically 18 percent moisture. Miami Fort stated that along with the fly ash, F GD gypsum wastes and FGD wastewater

treatment solids are transf erred to the landfill. [Q UESTION FOR MIAMI FORT: What gypsum is sent to the landfill (e.g., off-specification, extra that can’t marketed)?] All off-spec gypsum and waste water treatment sludge is sent to an

off-site landfill at our East Bend or Zimmer St atsion Landfills.(EBS or ZIM)

 Miami Fort sends about 150,000 tons of ash to the pond per year. The plant estimates that the water in the ash pond has a three day retention time. The pond

also receives the effluent from the FGD wastewater treatment system, which is transferred to the first cell (Pond A) after the stacking portion. The sumps from all three units are transferred directly to the second cell (Pond B). Coal pile runoff is also transferred to the ash pond, but it is collected in a smaller pond before being transferred to the ash pond. [QUESTION FOR MIAMI FORT: Is the coal pile runoff added to Pond A or Pond B?] JR?

 Ash Pond A receives the Coal Pile Runoff.

 Miami Fort has the capability to add carbon dioxide to the ash pond wastewater as it flows from Pond A to Pond B. [QUESTION FOR MIAMI FORT: Has the Formatted: Indent: Left: 0.5", Hanging: 0.5", Bulleted + Level: 1 + Aligned at: 0" + Tab after: 0.25" + Indent at: 0.25", Tab stops: 1",

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plant added carbon dioxide to the pond? When does the plant add carbon dioxide?] Lab checks the crossover pH (from pond A to pond B) daily. If pH>8.5, carbon dioxide is added.

 Miami Fort discharges the ash pond effluent to the Ohio River via Outfall 002. The ash pond effluent flow rate is approximately 13 MGD.

 Leachate from the ash pond is collected in a dike along the outer edge of Pond B. The ash pond has 38 different drains that collect leachate and transfer it to the dike. The dike also collects rainfall and runoff from the ash pond berms. The removal of leachate from the ash pond keeps the pond from building too much pressure and makes the pond more stable. The leachate flows along the dike and is discharged to the Ohio River via a st ormwater outfall. Plant personnel stated that the combined flow from all 38 drains is about two gpm.

 Miami Fort has groundwater monitoring wells around the ash pond. [QUESTION FOR MIAMI FORT: How many wells does the plant have? Are they upgradient or downgradient? What analytes are monitored and at what frequency. When were the wells installed and when did monitoring begin? Does the plant have a monitoring well that measures background concentrations?] JR/Jim?

 There are 7 monitoring wells adjacent to Ash Pond A and B. One well is for water level only. One well is upgradient MW-.1. The rest of the monitoring wells are downgradient. Water level, ph, Specific Conductance, As. Ba, Cd, Ca,Fe, Pb, Mg, Mn, K, Se Na, Alkalinity, Cl Sulfate, and TDS are measured semiannually. The wells were installed in 2008. There is no background well other

than MW-1.

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 Miami Fort was recently issued a new NPDES permit on July 1, 2009. Miami Fort will provide EPA with an electronic copy of the permit. [NOTE: Miami Fort sent EPA the new NPDES permit on March 5, 2010.]

FGD System

 Miami Fort operates two limestone forced oxidation FGD systems (one each on Units 7 and 8).

 The FGD systems have three spray levels; however, the plant typically only operates two of the spray levels at one time. The FGD systems are also equipped with dual flow trays.

 River water is used as the source of makeup water to the FGD system. The plant does not use organic acids in the FGD systems. Formatted: List Paragraph, No bullets or numbering, Tab stops: Not at 1"May 27, 2009 Page 5

 Miami Fort maintains the solids concentrat ion in the FGD system between 21 and 24 percent solids. According to plant staff, absorber chlorides are typically maintained at approximately 5,000-10,000 ppm. The FGD systems have a design maximum chlorides limit of 12,000 ppm. The plant blows down from the absorbers in batches, depending on the ch lorides and solids concentrations in the absorber. The FGD system operates at a pH of 5 S.U.

 The blowdown for each FGD system is transferred to its primary hydrocyclone. Each FGD system has a dedicated hydrocyclone. The gypsum from the each primary hydrocyclone is sent to its own vacuum belt filter for further dewatering. The overflow from each primary hydrocyclone is transferred to its own secondary hydrocyclone. The underflow from the secondary hydrocyclones is sent to the reclaim tank, which is shared between the two units, and reused in the FGD system as make-up water. The overflow from the secondary hydrocyclones, which contains between 2.5 and 3.0 percent suspended solids, is sent to the FGD
wastewater treatment system.

 As the gypsum slurry is applied to the v acuum belt filters, Miami Fort washes the gypsum with service water to reduce the ch lorides in the gypsum to less than 100 ppm. The vacuum belt filters dry the gypsum to a moisture content of approximately nine percent. The gypsum product produced at the plant is marketed. [QUESTION FOR MIAMI FORT: To what industries is the gypsum marketed?]

 Marketed to Lafarge (wallboard manufacturer) or agricultural (either off-spec or if Lafarge refuses product)

 The filtrate from the vacuum belt filter s is collected in the reclaim tank and transferred back to the FGD systems. [QUESTION FOR MIAMI FORT: Is the reclaim tank water reused in both FGD systems, or primarily in one of the FGD systems? If used primarily in one FGD system, which FGD system is the reclaim tank water used?]

 Each unit has its own reclaim tank.

 Miami Fort’s third party contractor, Sy nmat, operates the entire FGD system, including reagent preparation, gypsum dewatering and marketing, laboratory, and wastewater treatment and solids handling.

FGD Wastewater Treatment System Formatted: List Paragraph, No bullets or numbering, Tab stops: Not at 1"

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 The FGD wastewater treatment system, which was designed by Infilco Degremont, is a chemical precipitation system that uses hydroxide and sulfide precipitation to remove metals and suspended solids from the wastewater. Ferric chloride and polymer are also added to enhance pollutant removals. The maximum design flow rate for the system is 200 gpm, but the average flow rate into the FGD wastewater treatment system is 150 gpm.

 Secondary hydrocyclone overflow from the scrubber is transferred directly to the equalization tank. Miami Fort adds lime to the equalization tank to raise the pH of the wastewater from approximately 5 S.U. to between 8.4 and 8.6 S.U. To promote desaturation of the gypsum, Miami Fort recycles some of the sludge

from the downstream clarifiers which provides seed crystals for gypsum nucleation. The equalization tank also receives flush water from the recycle

 (We do not recycle sludge) sludge lines, and wastewat er from the wastewater treatment building sump, which cons ists of filter press filtrate.

 From the equalization tank, the FGD wastewater flows to the coagulation tank, where Miami Fort adds organosulfide and ferric chloride to the wastewater. The

ferric chloride is used to assist in the co agulation of the solids precipitated in the equalization tank, as well as promote iron coprecipitation of some residual metals in the wastewater. The organosulfide is added to precipitate residual metals as sulfide complexes.

 Flow from the coagulation tank splits into two parallel streams that flow to two DensaDeg® clarifiers. The DensaDeg® clarifier has an initial reactor section, where polymer is added for coagulation and flocculation to improve solids removals. From the reactor section, the wastewater enters the clarification/thickening section of the cl arifier, where the solids settle out of the wastewater. As discussed previously, some of the sludge from the two clarifiers is recycled back to the equalization tank to provide seed crystals for gypsum nucleation. The remainder of the sludge is transferred to the sludge holding tank and then processed through the filter presses. The filtrate from the filter presses is collected in the wastewater treatment building sump and recycled to the equalization tank. The sludge from the filter presses is hauled off site for disposal at a landfill. [QUESTION FOR MIAMI FORT: Is the wastewater treatment sludge sent to the same landfill as the ash?]

 No

 The clarified wastewater from the two DensaDeg® clarfiers is combined in the effluent tank. The wastewater is pumped to the ash pond and discharged via Formatted: Highlight

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Outfall 002. The transfers to the ash pond are based on level control within the effluent tank; therefore, the transfers are not continuous.

 If the effluent from the FGD wastewater treatment system does not meet system specifications and discharge limits, the FGD wastewater treatment system is stopped. The material within the system is treated until the effluent meets specifications and then is discharged.

 This is not a true statement. There are no specifications or discharge limits. We adjust chemical treatment but the FGD wastewater treatment is not stopped.

 Miami Fort is currently testing the use of Nalmet® 1689 as the organosulfide in the FGD wastewater treatment system instead of TMT 15®, which was used by the plant when the FGD wastewater treatment system began operation. The plant is testing the effectiveness of Nalmet® 1 689 by adjusting its feed rate, as well as the feed rates of the other FGD wastewater treatment additives (i.e., polymer, ferric chloride). Miami Fort personnel stated that the Nalmet® 1689 results look promising and that it has been ef fective in lowering mercury levels.

 We will be using the Nalmet® 1689 during the EPA sampling event. It is our current method of treatment. We will be op timizing feed rates in the next few weeks and hope to completely eliminate the Ferric Chloride.

 Miami Fort is also planning to test a Ge neral Electric organosulfide product in the summer using a slip stream. [QUESTION FOR MIAMI FORT: What GE organosulfide is being tested? From where in the FGD wastewater treatment system will the slip stream be pulled? What is the planned slip stream flow rate?] No formal plans have been developed. Just basic discussions.

 EPA stated that regardless of the testing being conducted in the FGD wastewater treatment system, EPA would like the plant to operate the FGD wastewater treatment system at stable operating conditions during EPA’s planned sampling episode.

 The plant stated that mercury data are av ailable for the inlet and outlet of the FGD wastewater treatment system, Outfalls 601 and 608, respectively. EPA stated that these data would be helpful to review. Plant personnel stated that the data would be sent electronically to EPA. [NOTE: Miami Fort sent EPA the data on March 5, 2010.]

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 EPA identified the FGD wastewater treatment system influent sampling point as the tap off the secondary hydrocyclone flowing to the equalization tank.

1. EPA identified the FGD wastewater treatment system effluent sampling point as a tap on the pump discharge off the effluent tank. Miami Fort stated that they could install a smaller hose barb on the tap to accommodate the sample collection. Looking at using a small tap off the effluent tank (drain line) to a sump to get continuous flow for the sampling event. Or they can pull a sample from the densadeg overflows which is continuous , gravity fed into the effluent tank.

 There is plenty of table and cooler storage space near the sample point in the FGD wastewater treatment building.

 Plant personnel stated that all EPA/ERG sa mpling personnel would be required to go through a 45 minute health and safety orientation prior to the sample

collection.

 Plant personnel also stated that there is a first responder team on site and ERG would have access to the team in case of emergency. Formatted: Font: HighlightTable 1. Site Visit AttendeesNameOrganization (Representing)TelephoneE-mailPat CoyleDuke Energy513-287-2268 pat.coyle@duke-energy.comBrian HuddlestonDuke Energy217-218-2985 huddlebj@muohio.eduJoseph G. PottsDuke Energy513-287-2609 joseph.potts@duke-energy.comJim StieritzDuke Energy513-287-2269 jim.stieritz@duke-energy.comTara ThomasDuke Energy513-467-4950 Tara.thomas@duke-energy.comJR Wood Duke Energy 513-467-4886 jr.wood@duke-energy.comDonna B. HillSouthern Company/UWAG205-587-4846 dbhill@southernco.comJezebele AliceaUS EPA202-566-1755 alicea.jezebele@epa.govRon JordanUS EPA202-566-1003 jordan.ronald@epa.govTJ FinsethERG703-633-1698 thomas.finseth@erg.comElizabeth SabolERG703-633-1659 elizabeth.sabol@erg.com