Draft Notes from Site Visit at Duke Energy’s M ia mi 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

,

s pecifically 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 th ese notes

, identifies the site visit participants. The presentation that the Duke Energy personnel gave during
the site visit is provided as Attachment 1 to these notes and includes a FGD system process flow diagram, a simpli fi ed flow diagram of the FGD wastewater treatment system

, and detailed view of the DensaDeg® clarifier

. A mo re detailed process flow diagram of the FGD wastewater treatment system and a n aerial view of the plant are provided as Attachment s 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. Unit s 7 and 8

, which began operation in 1975 and 1978, respectively, each
have a generating capacit y of 550 megawatts (MW). All three units are operated
as bas eload units. The table below contains 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 Bu rners None

7 1975 550 ESP (cold

side) Selective Catalytic Reduction (SCR) ( 2003 ) Wet FGD installed
December 2007

8 1978 550 ESP (cold

side) SCR (2001) Wet FGD installed in April 2007

• Duke Energy is a partial owner of all the units at the plant. Miami F ort 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

con trol 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. Mi ami 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. P lantMay 27 , 2009 Page 2

personnel stated that more ammonia slip was not iced this year. Miami Fort is beginning to discuss the options for how to handle the SCR catalysts. Plant personnel explained that the y are considering the following options:

o I nstall a new layer of catalyst ;

o R egenerate a n existing layer of catalyst; or

o R eplace 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 bur ned . Sonic horns are continuously used to remove ash from the catalysts; however, during q uick 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?]

• Miami Fort burns e astern 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 fr om 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 emissio ns. The plant now injects 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 h andling 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 U nits 7 and 8

. Addi tionally, the plant has the capability to load rail cars from the Unit 7 silo.

• Miami Fort sells most of the ash to Ready M ix. Any fly ash that the plant cannot
sell is transferred to their landfill located 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.

• Miami Fort operates wet bottom ash h andling 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 pon d. The plant sluices pyrites separate ly to the ash pond to enable the plant to market some of theMay 27 , 2009 Page 3

bottom ash . Miami Fort previously had a contract with Home Depot to re use filtered bottom ash for cement board. The contract was dropped when the plant
switch ed 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 p olymer to the ash pond near where the sluice pipes deposit the ash to improve solids removals. The plant operates the first cell using a rim ditch stacking method. This approach entails using equipment to maintain channels for
the sluice water to mov e through the mass of ash solids collected in the pond. The plant removes the solids that settle out in the channels of the ash pond and stacks them in piles along the channels to allow the solids to dewater , while the water drains back into the pond.

• The plant hauls the dewatered ash from the 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, FGD gypsum wastes and FGD wastewater
treatment solids are tran sferred to the landfill. [QUESTION FOR MIAMI FORT: What gypsum is sent to the landfill (e.g., off

- specification, extra that can’t marketed)?]

• Miami Fort sends about 150,000 tons of ash to the pond per year . The plant
estimates that the water in the ash po nd 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 seco nd 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?] Miami Fort has the capabil ity to add carbon dioxide to the ash pond wastewater as it flows from Pond A to Pond B. [QUESTION FOR MIAMI FORT: Has the plant added carbon dioxide to the pond? When does the plant add carbon dioxide?]

• Miami Fort discharges the ash pond effluent to the O hio 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. T he 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 Rive r via a stormwater outfall. Plant personnel stated that the combined flow from all 38 drains is about two gpm.May 27 , 2009 Page 4

• Miami Fort has groundwater monitoring wells around the ash pond

. [QUESTION FOR MIAMI FORT: How many wells does the plant have? Are they upgradi ent 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 measure s background concentrations ?]

• 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

.

• Miami Fort maintains the solids concentration in the FGD system between 21 and 24 percent solids. According to plant staff, absorber chlorides are typically maintained at approximately 5,000

- 10,00 0 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 chlorides and solids concentrations in the
absorber. The FGD system operates at a pH of 5 S.U.

• The blowdown fo r 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 fu r ther dewatering.
The overflow from each primary hydrocycl one is transferred to its own secondary hydrocyclone

. The underflow from the secondary hydrocyclone s 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 hydrocyc lone s , 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 vacuum belt filter s, Miami Fort washes the gypsum with service water to reduce the chlorides in the gypsum to less than 10 0 ppm. The vacuum belt filter s 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?]May 27 , 2009 Page 5

• The filtr ate from the vacuum belt filters 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 i n one of the FGD systems? If used primarily in one FGD system, which FGD system is the reclaim tank water used?]

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

.

FGD Wastewater Treatment System

• 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 . F erric 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 scrubb er 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 th e sludge from the downstream clarifiers which provides seed crystals for gypsum
nucleation . The equalization tank also receives flush water from the recycle sludge lines, and wastewater from the wastewater treatment building sump, which
consists of filter press filtrate.

• From the equalization tank, the FGD w astewater 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 coagulation of the solids precipitated i n 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 tha t flow to two DensaDeg ® clarifier s

. The DensaDeg® clarifier has an initial reactor section, where p olymer is added for coagulation and flocculation to improve solids
removals. From the reactor section, the wastewater enters the clarification/thickening sec tion of the clarifier, 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 i s hauled off site for disposalMay 27 , 2009 Page 6

at a landfill. [QUESTION FOR MIAMI FORT: Is the wastewater treatment sludge sent to the same landfill as the ash?]

• 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 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.

• 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® 1689 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 effective in lowering mercury levels.

• Miami Fort is also pl anning to test a General 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 planne d slip stream flow rate?]

• 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 sampl ing episode.

• The plant stated that mercury data are available 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 .]

Information for Sampling

• EPA identified the FGD wastewater treatment system influent sampling point as the tap off the secondary hydrocyclone flowing to the equa lization tank.

• 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.May 27 , 2009 Page 7

There is p lenty of table and cooler storage space near the sample point in the FGD

wastewater treatment building

.

• Plant personnel stated that all EPA/ERG sampling personnel would be required to go through a 45 minute health and safety orientation prior t o 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.Table 1

. Site Visit Attendees

Name Organization (Representing) Telephone E

- mail

Pat Coyle Duke Energy 513

- 287

- 2268 pat.coy le@duke

- energy.com

Brian Huddleston Duke Energy 217

- 218

- 2985 huddlebj@muohio.edu

Joseph G. Potts Duke Energy 513

- 287

- 2609 joseph.potts@duke

- energy.com

Jim Stieritz Duke Energy 513

- 287

- 2269 jim.stieritz@duke

- energy.com

Tara Thomas Duke Energy 513

- 467

- 4 950 T ara.thomas @duke

- energy.com

JR Wood Duke Energy 513

- 467

- 4886 jr.wood@duke

- energy.com

Donna B. Hill Southern Company/UWAG 205

- 587

- 4846 dbhill@southernco.com

Jezebele Alicea US EPA 202

- 566

- 1755 alicea.jezebele@epa.gov

Ron Jordan US EPA 202

- 566

- 1003 j ordan.ronald@epa.gov

TJ Finseth ERG 703

- 633

- 1698 thomas.finseth@erg.com

Elizabeth Sabol ERG 703

- 633

- 1659 elizabeth.sabol@erg.com