Draft Notes from Site Visit at RRI Energy ’s Keystone Generating Station on February 1, 2010

EPA conducted a site visit at RRI Energy ’s Keystone Generating Station ( Keystone) located in Shelocta, P A on February 1, 2010 to learn about the operations at the plant , specific ally 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 RRI Energy personnel gave during the site visit is provided as Attachment 1 to these notes. A dditionally, an overall water balance diagram for the plant (Attachment 2) , a proce ss flow diagram for the FGD system (Attachment 3) , process flow diagrams for the FGD wastewater treatment system (Attachment 4) , the design engineer’s report for the FGD wastewater treatment system (Attachment 5) , and an excerpt from the plant’s permit

pro viding the internal outfall and final outfall limitations for the FGD wastewater treatment system (Attachment 6) are provided as attachments to th e site visit notes.

Plant Overview

**•** Keystone operates two coal

- fired generating units at the power plant . Units 1 and 2, which began operation in 1967 and 1968, respectively, each have a gross generating capacity of 900 megawatts (MW). The total net generating capacity for the plant is of 1

, 700 MW. Both generating units are operated as baseload

units. Th e t able below contains some g eneral information for the two generating

units.

Unit Installation

Date Gross Capacity

(MW) Particulate

Control NOx Control SO 2 Control

1 1967 90 0 Electrostatic Precipitator ( ESP ) Low NOx Burners (1994), Selective Catalytic Reduction (SCR) (2003) Wet FGD installed

in Sept ember 2009

2 1968 90 0 ESP Low NOx Burners (1995), SCR (2003) Wet FGD installed

in Nov ember 2009
[QUESTION FOR KEYSTONE: Are the ESPs hot

- side or cold

- side?] Electrostatic precipitators are cold

- side after the air heater.

**•** Keystone recently retrofitted the two units with FGD scrubber system s to control the sulfur dioxide (SO 2 ) releases from the plant. The FGD systems were installed in September 2009 (Unit 1) and November 2009 (Unit 2). The wet FGD

scrubbe rs are designed to achieve greater than XX 98 percent removal of SO 2 from the flue gas. [QUESTION FOR KEYSTONE: What is the design SO 2 percent removal and what is the actual SO 2 percent removal? Design SO 2 percent removal is 98%; actual SO2 removal is 75% using two (2) spray

levels

. ] . With the recent addition of the FGD scrubber system, Keystone also installed an FGD wastewater treatment system to control the discharges of the wastewater generated during t he operation of the FGD scrubbers.**•** Keystone operates electrostatic precipitator ( ESPs ) to control fly ash and particulate emissions from the plant. Keystone also operates selective catalytic

r eduction ( SCR ) systems to control nitrogen oxide (NOx) emissio ns from the plant. In January 2009, the plant began operating the SCRs year round. Additionally, the boilers are operated with low

- NOx burners.

**•** Plum Creek and Crooked Creek supply the plant with water

.

**•** Coal arrives by train and truck. Keystone burns on ly eastern bituminous coal (mostly from Pennsylvania). Around f ive million tons of coal is burned per year. The plant receives coal from several dozen sources. The coal has a sulfur content

of 1.2 to 2.2 pounds of sulfur per million BTU

. Keystone states that the coal content varies greatly with the supplier. Over the last couple of months the sulfur

content has been 1 .5 to 1. 7 pounds of sulfur per million BTU

. Keystone’s five year business plan is to buy the cheapest coal as long as the sulfur content is less

than 2 to 2.25 pounds per million BTU

.

**•** When necessary (not routinely), K eystone takes feeder samples of coal and tests for BTU, chloride, sulfur, ash content, moisture, carbon, hydrogen, and nitrogen. Keystone does not test for metals unless there is a specific reason to do so.

**•** Keystone has no plans to install activated carbon technologies or any other flue

gas mercury controls. However, the plant has done some testing on mercury control systems for both units.

**•** The plant has no sulfur trioxi de controls except for the benefits from the FGD
system.

**•** Keystone operates dry f ly ash handl ing systems. The fly ash handling systems were installed when the plant began initial operation. The dry fly ash is
transpor ted to silos pneumatically

. After the silos

, it is conditioned and transported to the on

- site ash site. Keystone is looking to sell fly ash for beneficial reuse, but has no current contracts. Keystone state d that they are having difficulty marketing the fly ash due to the plant location.

**•** Keystone operates wet b ottom ash handl ing systems

. The plant sluices the b ottom ash to hydrobins

. The dewatered bottom ash is transported to the ash site. The hydrobin overflow is transported to the as h settling pond s

. The plant operates three ash settling ponds ; eac h is about half an acre

. From the ash settling ponds,

the wastewater travels to a thermal cooling pond, which covers approximately

seven acres. The ash wastewater is then transferred through the lagoon and finally discharges to Cro o ked Creek.

**•** Keystone combines f ly ash and bottom ash at the ash site (i.e., landfill )

. The landfill is lined and has a leachate collection system. The leachate collectionsystem produces a continuous waste stream. The flow of the east valley lan dfill

leachate is 100 gpm. [ QUESTION FOR KEYSTONE : What is the flow of the west valley landfill leachate ? In 2010, the flow of the leachate for the West Valley landfill was 42 gallons per minute (gpm) and has not significantly changed.

**•** The Keystone plant is located on approximately 1

, 000 acres in Armstrong County, Pennsylvania. Keystone has approximately 200 employees.

Main Plant Wastewater Treatment System

**•** Keystone operates a main plant wastewater treatment system that treats leachate

from the a sh site, contact storm water, coal pile runoff, bottom ash sluice water, wastewater from the sewage treatment plant, and plant drain wastewater.

**•** The t reatment system consists of conventional pH neutralization, flocculation, clarification, and/or extended aeration.

**•** The effluent from the treatment system is discharged to Crooked Creek via outfall

003.

Flue Gas Desulfurization System

**•** The plant operates two forced oxidation wet FGD systems (one per unit). Each

FGD absorber has five spray levels with a d ual flow tray system and a two stage

mist eliminator.

**•** Keystone uses a limestone slurry as the sorbent for the sulfur dioxide absorption. The limestone is delivered to the plant via truck and rail. Keystone uses ball mills onsite to pulverize the limest one. From the ball mills, the slurry is transferred to hydrocyclone s to collect limestone particles that are too large for use in the FGD system. The underflow from the hydrocyclone s is returned to the ball mill for additional processing. The overflow f rom the hydrocyclone s, which is approximately 25 to 30 percent limestone, is transferred to a storage tank prior to being fed to the FGD system.

**•** The fresh limestone slurry is fed to the reaction tank of the FGD system and the recycle pumps pump the slurry to the various levels of the FGD absorb er . Both absorbers have five spray levels. The slurry is pressurized and sprayed downward

into the absorber through spray nozzles

. As the slurry falls downward and the flue gas flows counter

- current to the slurry, the spray droplets of the limestone slurry contact the flue gas and absorb the sulfur dioxide, which reacts with the limestone particles and produces calcium sulfite . Additio nally, the dual flow tray generates a layer of sorbent slurry in the absorber that the flue gas must pass through, which provides additional contact time for the reactions to occur. The sorbent slurry passes through the tray and flow s downward in the abso rber until itreaches the reaction tank

. Keystone bubbles air through the reaction tank to oxidize the calcium sulfite to calcium sulfate (i.e., gypsum).

**•** Keystone does not use and does not have the capability to add any a dditives in the FGD system

.

**•** Keystone intermittently blows down the gypsum slurry from the reaction tank to

control the chlorides concentration in the absorbers

. The chlorides concentration

in the absorb ers is maintained between 18 ,000 and 2 0,000 ppm, with a design

maximum chlorides concentration of 25 ,000 ppm. The typical percent solids

within the absorber is 40 to 60 percent

.

**•** Keystone transfers the blowdown from the absorber to the gypsum dewatering operations. The blowdown is first transferred to the primary hydrocyclone s where the solid gypsum is separated from the water by centrifugal force. The solid gypsum is forced outward to the walls of the hydrocyclone s and falls downward, while the water exits the top of the hydrocyclone s. The gypsum from the primary hydrocyclone s is transferred to the filter feed tank, which is then transferred to the

vacuum belt filters. Keystone washes the gypsum with service water as it is applied to the vacuum belt filter to reduce the chlorides in the gypsum. The filtrate from the vacuum belt filter is transferred to the purge tank and then transferred to the FGD wastewater treatment system.

**•** Keystone generates around 2,000 tons of gypsum a day. The gypsum that is generated contains less than 120 ppm of chlo rides and less than 10 percent moisture. Keystone is attempting to market the gypsum; however, they do not have any current contracts to sell the gypsum. Therefore, the plant is transferring all the g ypsum to the on

- site ash site for disposal

. [ QUESTION FOR

KEYSTONE : What is the capacity of the landfill with gypsum and without gypsum? From the perspective of EPA’s site visit in 2010, if 100% of the

gypsum was placed in the landfill, the expected lives of Stages III and IV

would be 2015 and 2028 respectiv ely . If none of the gypsum produced is placed in the landfill, then the expected life of Stages III and IV would be 2020 and 2046 respectively

. ]

**•** Keystone monitors the solids level and chlorides level in the primary hydrocyclone o verflow because if the c hloride or solids level is low, the plant

sends the overflow back to the absorber. [QUESTION FOR KEYSTONE: At what chloride and solids concentrations does the plant transfer the primary hydrocyclone overflow back to the absorber? The primary hydrocyclone

overflow is transferred back to the absorber when the concentration of

chlorides is measured at 14,000 mg/L or the concentration of solids is

18%. Otherwise, the primary hydrocyclone overflow is transferred to the secondary hydrocyclone feed tank and the n pumped to the secondary hydrocyclone s.**•** The underflow from the secondary hydrocyclone s is returned to the absorber. The

o verflow from the secondary hydrocyclone s is transferred to a purge tank, which

also receives the filtrate from the vacuum belt filte r. The wastewater in the purge tank is intermittently transferred to the FGD wastewater treatment system

.

FGD Wastewater Treatment System

**•** A block flow diagram and more detailed process flow diagrams of the FGD
wastewater treatment system are provided as Attachment 4 to these notes.

**•** The wastewater from the purge tank, which includes both secondary hydrocyclone overflow and filtrate from the vacuum belt filters, is transferred to the equalization tank of t he FGD wastewater treatment s yste m . The equalization

tank also receives the filter press filtrate, gravity filter backwash, polishing filter

backwash , and off

- specification recycle . The FGD wastewater treatment system only treats wastewater from the FGD process. It was designed by Siemens and

consists of gypsum desupersaturation, metal sequestration, clarification, pH adjustment, and filtration.

**•** The plant began sending wastewater to the FGD wastewater treatment system in September 2009 , which was three to four weeks after the first FGD system began operation

. At the time of the site visit, the plant was still in the process of optimizing the system.

**•** The f low rate through the wastewater treatment system depends on the amount of

wastewater recirc ulated through the system. The avera ge 24

- hour flow rate is approximately 260 gpm. Keystone personnel attempt to keep the flow through the system constant by staggering the blowdown from the scrubbers. However, the flow can range from 400

- 450 gpm if both scrubbers are blowing down to zero

g pm if neither is operating

. The design flow rate for the treatment system is 450

gpm.

**•** Overflow from the secondary hydrocyclone s enters into the wastewater treatment system and is first sent to the equ a li zation tank. This overflow has a solids level

of a round 2 percent

. There is a sampl e point immediately upstream of the equalization tank. The equalization tank also receives water from the filtrate sump and effluent from the FGD wastewater treatment system, which the plant recirculates to maintain a steady flow of wastewater through the system

.

**•** T he wastewater then flows into the desaturation tank where the pH is adjusted

from 6 .0

- 7 .0 to 8.0

- 8.5 with the addition of a lime slurry

. The plant receives dry lime and slakes the lime on site, to generate 10% of lime slurry. The plant adds

lime to the desaturation tank to form metal hydroxides , which precipitate out of

solution

. The pH is optimal at this range because a h igher pH would cause magnesium hydroxide to precipitate.**•** After the desaturation tank, t he wastewater flows by gravity in to the heavy metals

reaction tank where Keystone adds o rganosulfide (TMT

- 15) to the wastewater

. The organosulfide is added to precipi tate residual metals as sulfide complexes.

**•** From the heavy metals reaction tank, the wastewater flows to the flow splitter tank where Keystone adds ferric chloride to the wastewater. The ferric chloride is used to assist in the coagulation of the solids precipitated in the desaturation tank and the heavy metals reaction tank.

**•** After the flow splitter tank, the wastewater is directed to two clarifiers, and the plant adds polymer to the wastewater as it flows to the clarifier. The wastewater

is divided equ ally between the two clarifier s

. The clarifiers are solids contact clarifiers that contain a sludge bed that attracts the solids in the wastewater. A portion of the sludge from the clarifiers is recycled to the desaturation tank, while the majority is transferred to a sludge tank and then pumped to a filter press for dewatering

. The dewatered sludge is sent to the ash site. The filtrate from the filter press is transferred to the filtrate sump. Wastewater in the filtrate sump is

re turned to the equal ization tank.

**•** The overflow from the clarifier s flow by gravity to the heat exchanger feed tank

. The plant operates two heat exchangers in parallel. Before the wastewater goes through the heat exchangers

, Keystone adds hydrochloric acid and antiscalant to
the wastewater

. The heat exchangers lower the temperature of the wastewater

from 1 1 0°F to 85°F

. Keystone uses cooling water in the heat exchanger. According to plant personnel, the wastewater cooling is necessary to control scale

formation in the 16

- mile discharge pipeline.

**•** From the heat exchangers, the wastewater is transferred to three continuous

backwash gravity filters , using sand as the filter media, operating in parallel. The gravity filters main purpose is to reduce the level of total suspe nded solids (TSS)

in the wastewater

. The b ackwash from the gravity filters is transferred to the

filtrate sump , which is eventually returned to the equalization tank.

**•** After the sand filters, the wastewater flows by gravity to the effluent tank.

**•** After the effluent tank, t he wastewater flows through the polishing filters. Even though the FGD wastewater treatment system was originally designed so that the polishing filters could be bypassed

, Keystone plans to use the polishing filters full

time. Keyston e states that the polishing filters and gravity filters are necessary to keep the TSS level below the limit. ( The permit authority lowered Keystone’s limit on TSS in exchange for allowing the plant to discharge a higher

concentration of selenium. )

**•** Keyston e has a composite sam pler after the polishing filter in the discharge pump

house. Keystone typically runs its compliance monitoring composite samples on Monday and Tuesday. The gauge pressure in the pipe at the sample point isapproximately 156 psi. The flow of the effluent is much more consistent than the

influent flow. Keystone tries to maintain a relatively constant flow of 180

- 220

gpm. [ QUESTION FOR KEYSTONE : What is the residence time through the wastewater treatment system? Based on the Design En gineer’s Report, the residence time is calculated to be 9.9 hours based on the design flow of 450

gpm ]

**•** In the D e sign E n gineer’s R eport

, Attachment 5, Keystone provided the design

wast ewater influent characteristics and the projected monthly average discharge

levels for the treated wastewater. Keystone states that t he influent characteristics

are based on coal and limestone data

. However, the actual influent values can vary greatly from those in the table. T his ta ble give s an indication of what species the FGD wastewater treatment system is targeting and to what degree. According to this table, the wastewater treatment system targets the following pollutants: TSS, pH, total aluminum, total cadmium, chromium III, t otal cobalt, total copper, total and dissolved iron, total lead, total manganese, total mercury, total nickel,

and total zinc.

**•** The effluent from the FGD wastewater treatment system is regulated by Keystone’s NPDES permit (PA0002062) via internal outfall 1 01. Attachment 6 includes Keystone’s permit limitations for internal outfall 101. Additionally, Keystone is required to sample the influent for the following parameters: total and dissolved selenium, TSS , total dissolved solids, and pH.

**•** The treated FGD wastewater is discharge d to the Allegheny River via final o utfall

001. The plant was prohibited to discharge to Crooked Creek because they could

not meet the chloride limitations or the limitation s for other trace metals such as

selenium. Therefore, Keystone built a 16 mile pip eline so that they could discharge to the Allegheny River. Discharge from the FGD wastewater treatment system is the only wastewater at the plant that is discharged to the Allegheny

River. [ QUESTION FOR KEYSTONE : How much did this piping cost? The estimated cost for piping alone was 1.3 million dollars ($1,300,000) ]

**•** According to Keystone personnel, the plant has not had any performance problems with the FGD wastewater treatment system

.

Sampling Information

**•** Ke ystone stated that they are not allowed to schedu le planned outages from June 15 through August 30. Information on planned outages in September and October

is confidential business information (CBI) , but Keystone will provide this information upon request

, if EPA decides to sample at this location.

**•** When shipping packages to the plant, Keystone stated that Mark Jacklin should be the plant contact.**•** The nearest hospital to the plant is in Indiana. During the daylight shift there is a person on call at the plant to respond to medical emergencies.Table 2 . Site Visit Attendees

Name Organization (Representing) Telephone E

- mail

Sara Marie Baldi RRI Energy

- Water Quality Group 724

- 597

- 8633 smbaldi@rrienergy.com

Donna Hill So uthern Co mpany /UWAG 205

- 257

- 5234 dbhill@southernco.com

Mark Jacklin RRI Energy

- Keystone Tech Dept 724

- 354

- 5475 mjacklin@rrienergy.com

John Kosinski RRI Energy

- Keystone Tech FGD Not Provided Not Provided

Josh Hall Environmental Protection Agency (EPA) 202

- 566

- 1002 hall.josh@epa.gov

TJ Finseth Eastern Research Group (Contractor to EPA) 703

- 633

- 1698 thomas.finseth@erg.com

Becky Schwantes Eastern Research Group (Contractor to EPA 703

- 633

- 1715 becky.schwantes@erg.com

Roger Smith Siemens Water Not Provided Not Provided

James Krizner Siemens Water Not Provided Not Provided

Rod Berkebile RRI

- Keystone Not Provided Not Provided

Note: RRI Energy request ed that all questions be submitted to Sara Marie Baldi and Mark Jack lin ; therefore, RRI Energy did not provide

c ontact information for the other site visit attendees

.