Notes from Site Visit at AEP’s John E. Amos Plant on November 4, 2014

EPA conducted a site visit at American Electric Power’s (AEP’s) John E. Amos Plant (Amos) located

in Winfield, WV on November 4, 2014 to learn about the operations and wastewater treatment at the plant

and to learn more about a pilot study conducted by AEP to evaluate treatment technologies for flue

gas desulfurization (FGD) wastewater. EPA and ERG also received information about AEP’s

Mountaineer plant during the visit and that information is provided at the end of these site visit

notes.

Site Visit Attendee List

Name

Organization

(Representing)

Telephone E-mail

Chuck Johnson AEP Amos 304-759-3414 cmjohnson2@aep.com

Paul Massie AEP Amos 304-759-3246 pjmassie@aep.com

RJ Roush AEP Amos 304-759-3473 rjroush@aep.com

Jon P. Webster AEP Amos 304-759-3246 jpwebster@aep.com

Dave Wickline AEP Amos 304-759-3200

Jason F. Baker AEPSC 614-200-1845 Jfbaker2@aep.com

Tom Hart AEPSC 614-716-3260 tomlhart@aep.com

Tim Lohner AEPSC 614-716-1255 twlohner@aep.com

Steve Wells AEP - WERS 614-716-2232 sfwells@aep.com

J.T. Massey-Norton AEP Geotechnical 614-716-2924 jtmasseynorton@aep.com

Chuck Cunningham AEP Mountaineer 304-882-4020 cwcunningham@aep.com

David Thompson AEP Mountaineer 304-882-4023 rdthompson1@aep.com

James Covington EPA 202-566-1034 covington.james@epa.gov

Phillip Flanders EPA 202-566-8323 flanders.phillip@epa.gov

Jessica Hall EPA 202-564-3376 hall.jessica@epa.gov

Ron Jordan EPA 202-566-1003 jordan.ronald@epa.gov

Anna Dimling ERG 703-633-1692 anna.dimling@erg.com

TJ Finseth ERG 703-633-1698 thomas.finseth@erg.com
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Plant Overview

 AEP’s Amos plant is a coal-fired power plant with three stand-alone steam turbine

generating units, and a total generating capacity of 2,932 MW. The units were brought

online in 1971 (SE Unit-1), 1972 (SE Unit-2), and 1973 (SE Unit-3). Table 1 contains

some general information on the three steam electric generating units at Amos.

Table 1. Amos Plant Summary

Unit Fuel

Capacity

(MW) Fly Ash Bottom Ash FGD

NOx

Control FGMC

1 Coal: Bituminous

Oil: No. 2 Fuel Oil

816 Dry conveyed Wet Handled Wet System SCR None

2 Coal: Bituminous

Oil: No. 2 Fuel Oil

816 Dry conveyed Wet Handled Wet System SCR None

3 Coal: Bituminous

Oil: No. 2 Fuel Oil

1300 DryConveyed Wet Handled Wet System SCR None

 On the day of the site visit, Unit 3 was not operating because of a tube leak.

 Amos uses No. 2 Fuel Oil in each of the three boilers during start-up periods and for load

stabilization. For example, when the plant is increasing or decreasing the load on a unit, fuel oil

may be used to help stabilize the unit loading during the transition if it requires a pulverizer to be

placed into service.

 Amos uses eastern bituminous coal from Ohio, West Virginia, Kentucky, and sometimes

Pennsylvania (Pittsburgh) and usually has 8-10 coal suppliers at any one time. At the time of the

site visit they indicated they were using approximately 9-12 coal suppliers. The coal fed into the

boilers is a blend of low sulfur and high sulfur coal and is around 3 to 4 lbs SO2/million Btu for

Units 1 and 2 and 4 to 4.5 lbs SO2/million Btu for SE Unit-3. The chlorine content of the coal

used at Amos is approximately 0.01 percent.

 The limestone and coal are mostly delivered by barge because it is more economically favorable. It

costs around $5 per ton of coal to deliver by barge and each barge can carry 5,000 – 15,000 tons of

coal; whereas, rail cars can only carry around 500 tons of coal and cost significantly more per ton.

FGD Systems

 All three generating units at Amos have limestone forced oxidation FGD systems. The FGD

systems were installed in the following timeframes:

• Unit 3: February 2009;

• Unit 2: February 2010; and

• Unit 1: January 2011.

 Units 1 and 2 are each serviced by one FGD absorber module, while Unit 3 is serviced by two

absorber modules. The Unit 1 and 2 absorber modules are larger than the individual Unit 3

absorber modules.

 Each FGD absorber is a Babcock & Wilcox (B&W) Tray/Spray Tower. The Unit 1, 2 and 3 FGD 

absorber modules each have two levels of trays in the design of the absorber to increase contact
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with the FGD limestone slurry resulting in increased mass transfer, 75 L/G, and decreased FGD 

slurry flow rate. Units 1 and 2 have 2-1/2 levels of interstitial sprays; Unit 3 has 2 full levels of

interstitial sprays.

 Amos operates three ball mills at the plant to generate the limestone slurry used in the FGD

systems. The plant targets a limestone slurry that is 30 percent solids. The limestone slurry is

dumped into the FGD absorber module reaction tank to control the pH of the slurry. A number of

variables establish sulfur dioxide removal, such as L/G, pH, vessel design, etc. Absorber slurry

density is control by blowdown rate. Reaction tank level is controlled by the addition of

reclaim/service water.

 Amos uses service water as mist eliminator wash water, which is sprayed on the mist eliminators

to keep them clean and falls into the FGD absorber module. Amos washes the mist eliminators for

approximately 10-15 minutes every hour.

 The absorber recycle pumps move the slurry from the reaction tank supplying it to the spray

headers near the top of the absorber modules. The plant intermittently blows down, or “bleeds the 

absorber”, some of the FGD slurry from the reaction tank to control the approximately 20%

density in the FGD system. The blowdown from the FGD systems is transferred to the bleed

tanks. Plant controls are set automatically to initiate blowdown when solids reach 21.5%. The 

blowdown will continue until the solids are lowered to 19.5%.

 Each absorber module has agitators located around the walls of the reaction tank. Oxidation air is

added in front of the agitators and mixed into the FGD slurry to oxidize the calcium sulfite to

calcium sulfate (i.e., gypsum). Amos personnel stated that the plant uses two to three times more

oxidation air than is theoretically needed to achieve full oxidation of the FGD material.

 Amos personnel stated that the FGD absorbers operate at an oxidation/reduction potential (ORP)

between 100 to 300 mV. Amos has been monitoring the ORP levels in the absorbers to try and

optimize mercury removal, selenium removal, improve gypsum quality, and decrease manganese

oxide scaling. Amos personnel noted that if the oxidation air feed is shut down it has a minimal

effect on the ORP in the absorber. AEP has not determined a distinct correlation between FGD 

operating conditions and ORP levels within the absorbers.

 The absorber slurry (~20% solids) is pumped from the bleed tanks two miles and up a 350 foot

elevation to the FGD dewatering system (specifically to the hydrocyclone feed tanks). Amos

personnel noted that this required 14 miles of FRP piping; more specifically a total of 7 supply and

return pipes that are two mile long each.

 The FGD slurry is then pumped through one of the three sets of hydrocyclones, which operate

around 35 psi. The underflow from the hydrocyclones is 50-55% solids. The hydrocyclones

operate 36 hours/day collectively (e.g., 24 hours for one set of hydrocyclones and 12 hours for

another set of hydrocyclones).

 The hydrocyclone overflow (3-5% solids) is pumped at an average flow rate of 400 gpm (800

gpm maximum design flow rate; 500 gpm average design flow rate) to the equalization tanks in

the chemical precipitation system. Amos runs two 100% capacity trains at all times.

 The underflow from the hydrocyclones is fed by gravity to one of the vacuum belt filters (Amos

maintains 3 vacuum belt filters). The vacuum belt filters dewater the gypsum material to a

moisture content around 10-15 % moisture. The dewatered gypsum is then conveyed out of the

building on a belt and deposited on the ground for truck transport to the FGD landfill.
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 Service water is used to wash the vacuum belts and is mixed with the filtrate from the vacuum

belt filters.

 The facility does not market their gypsum due to economic and logistic considerations. Major

cities and companies that could potentially utilize the Amos gypsum do not like the wallboard to 

be shipped by train or barge; however, those transportation methods are the best available

shipping methods from Amos.

FGD Wastewater Treatment (WWT) Design

 Amos previously used Lamella separators as the secondary clarification step in the FGD

wastewater treatment; however, the facility experienced a number of issues and could not

optimize the system. According to plant personnel, the FGD by-product was the consistency of 

jelly and the Lamella plates would get clogged and the Lamella clarifiers needed weekly

maintenance. Amos ended up dismantling the system and sending it to another plant for handling

coal ash.

 Amos started a project to replace the Lamella separators with secondary clarifiers in November

2011. The total cost for that project was around $4 million. That project had a long start-up period

due to the time required for determining the dosage rates, injection locations, polymer vendors, and 

water sources.

 The current FGD chemical precipitation system consists of the following equipment (see DCN

SE05645A1 for process flow diagram): 

o [Redacted]

o Sludge holding tank

 20 – 25 % solids

o Filter Presses (five)

 Batch process, about 2-4 batches per day

 +65% solids

 Replace filter cloths every 500 runs

 Wash every 12 runs and wash water is sent to wastewater collection sump and

back to the beginning the process

 Filter cake is discharged through bomb bay doors and trucked to a landfill

o Wastewater Collection Sump

 Pumped back to FGD absorbers

o Clear Water Sump

 Discharged via Outfall 003

 Dosage Rates for the FGD wastewater treatment system:

o [Redacted]

 AEP stated that General Electric (GE-Betz) still visits the plant every Monday to assist the plant

with the performance of the chemical feed systems.

 The facility did not indicate organosulfide as a chemical in their 2010 Steam Electric

Questionnaire. Amos indicated that they started to add organosulfide into the system around

November 2010. [Redacted]

 Amos monitors the FGD wastewater treatment system daily by observing the turbidity in the

primary and secondary clarifiers from grab samples and checking that the feed pumps are
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operating correctly. The facility indicated that they are looking into installing a continuous

sample monitoring system.

 The clarifiers are treated once a year for algae. Additionally, once every three years, the facility

drains the entire clarifier tank for a thorough cleaning.

FGD WWT Sampling Results

 The following AEP plants are associated with the data provided in the AEP presentation (DCN:

SE05645A1)

o Plant A – John E. Amos Plant

o Plant B – Cardinal

o Plant C – Conesville

o Plant D – Mitchell Plant

o Plant E – Mountaineer Plant

 AEP eliminated statistical errors and outliers from the graphs provided in the presentation. Data

used to create the graphs are a mix of monthly and weekly samples; however, samples were

usually taken about one time a month or once every two months. AEP indicated that the samples

were taken over the course of 2+ years.

 The data from the Conesville plant showed a significantly higher arsenic concentration in the FGD 

wastewater. AEP stated that the Conesville plant has an older particulate removal system (ESP) and

a larger portion of fly ash carries over into the wastewater treatment influent. Therefore, that

facility uses their jet bubbling reactor (JBR) also as a polishing device for the particulate control.

 Currently, Amos takes a composite sample at the beginning of the month for the Department of

Environmental Protection (DEP) at Outfall 003. The permit limit for mercury at Outfall 003 are an 

average monthly limit of 229 ppt and daily maximum limit of 624 ppt. Amos also has a report only

NPDES internal limit for the FGD wastewater (Outfall 203) that will be renewed in 2018. The 

NPDES requirements for Outfall 203 include monitoring once per month for the following 

parameters:

o Flow – 24 hour total;

o Nitrogen nitrate – 24 hour composite;

o Nitrogen nitrite – 24 hour composite;

o Total mercury – Grab;

o Total recoverable selenium – 24 hour composite; and

o Total recoverable arsenic – 24 hour composite.

 Amos uses a diffuser in the Kanawha River to establish a mixing zone at their Outfall 003.

Ash Handling

 AEP sluices bottom ash from Units 1, 2, and 3 to a pond system prior to discharge via Outfall

003.

 AEP previously sluiced the fly ash from Unit 3 to a fly ash pond and discharged the fly ash

transport water via Outfall 001; however, the system has been retrofitted to a dry system.

Although the Unit 3 fly ash is now dry handled and most of the wet system was dismantled, some

of the piping out to the fly ash pond still exists. Currently, no fly ash transport water is sluiced to

the pond and the facility is in the process of closing the fly ash pond permanently (a 4-5 year

project). Amos also indicated no additional workers were needed for retrofitting the wet fly ash 

system to a dry handling system.
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 All of the fly ash at Amos is dry handled and sent to silos (2 per unit) for temporary storage. Each 

silo [Redacted]. From the silo the fly ash is transferred to the pugmill for wetting and then trucked

to a landfill or marketed to concrete customers. The fly ash trucks are weighed to keep track of the 

amount that is landfilled versus the amount that is marketed. AEP noted that only a small amount is 

marketed for sale. Between 2013 and 2015 roughly [Redacted] was marketed. AEP noted that if the

fly ash has a high loss of ignition (LOI), which is an indicator of the carbon content, it is not

suitable for sale. In addition, Amos has found that dry loading and trucking the fly ash is difficult.

 Amos indicated that the fly ash lines, silos, and vacuum pumps have redundant components.

Each generating unit is serviced by two fly ash silos, with one silo normally operating and the 

other acting as a spare. Fly ash lines to each silo are the same, with a primary line and a backup.

There are five pumps in the vacuum system and the facility can operate the ash handling system

with only four without shutting down the system. See DCN SE05664A2 for a diagram of the fly 

ash and bottom ash handling systems.

Landfills and Pond Systems

 The bottom ash pond system consists of Bottom Ash Pond A, Bottom Ash Pond B, Recirculation

Pond, and Clear Water Pond. Approximately 12,600 gpm of water from the recirculation pond is 

reused as seal water for the boilers and water for the ash handling system. AEP adds polymer in both

Bottom Ash Pond A and B for coagulation and settling. Clear Water Pond receives all the

wastewater from the pond system and discharges via Outfall 003. AEP identified the small size of

the Clear Water Pond as a driving factor in the wastewater treatment improvements (e.g.

installation and updates to chemical precipitation system) because a shorter residence time leads to

less solids settling before discharge.

 Bottom Ash Pond A was out of service during the site visit and bottom ash was being excavated

from the pond to be transferred to the landfill or beneficially reused (i.e., used in roads and

chimney drain in landfill).AEP indicated that they anticipate Bottom Ash Pond A to be back in

service by early next year (January or February 2015). AEP also indicated that they close one of

the bottom ash ponds about every 6 months for excavation and all bottom ash transport water is

directed to the other operating pond during that time.

 AEP’s FGD landfill was evaluated in 2013 to assess the available space; it was determined that

19-20 years of space was still available. The FGD landfill contains FGD wastes, mostly in the

form of gypsum. The Quarrier landfill is located about four miles down the road from the FGD

landfill and contains bottom ash and fly ash solids. Leachate is collected from both landfills and

sent to Bottom Ash Ponds A and/or B.

FGD Wastewater Pilot Study

 Amos was looking for a polishing step that would aid in consistently meeting the proposed ELG

limits for mercury. The facility later decided to also focus on other pollutants such as selenium and 

nitrate-nitrite; therefore, they reached out to the Electric Power Research Institute (EPRI) and used 

vendors to test five technologies, four vendors on a small pilot scale basis (3-4 month and 7 month

studies). The studies evaluated treating the treated chloride effluent at a flow rate of 1-2 gpm per

process. Amos also wanted to gather information on installation, regeneration, maintenance

(O&M), and life cycle costs for the technologies.

 During the site visit, Amos facility personnel provided data from the pilot studies, but noted that

they do not own any of the pilot study data; EPRI, technology vendors and the jointly

sponsoring utilities own the data.
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 At the time of the site visit, Amos had not yet received a draft of the pilot studies from EPRI.

 Amos personnel indicated that it was their professional opinion that none of the technologies tested 

were ready to scale up to commercial operation. In addition, AEP personnel noted that the

technologies work at a low pH in the initial steps and need a higher pH for subsequent steps, which 

necessitates greater chemical use and increased costs. One of the technologies is designed to remove 

only dissolved constituents; given that the majority of the mercury in the FGD blowdown water is

in the non-dissolved form, this technology would be of little value in meeting limits based on total

mercury in this application. Amos stated that the best design they could consider is having a slip

stream polishing step where a smaller side stream is redirected and treated from the CP effluent to

bring down the pollutant averages in the effluent.

 Amos personnel noted that the ZVI technology (Liberty Hydro) had trouble with fines (colloidal

particles) that pass through the dewatering step. They experimented with different kinds of filters

but found that they plugged up and did not function. Amos personnel also noted that the ZVI

technology had issues with nitrates/nitrites affecting the efficiency of the system.

Mountaineer Plant Information

 AEP’s Mountaineer Plant, located in New Haven, WV, is a coal-fired power plant with

one stand-alone steam turbine generating unit, and a total generating capacity of 1,300

MW. Table 2 contains some general information on the steam electric generating unit at

Mountaineer. AEP reported that the unit operated 341 days in 2009.

Table 2. Mountaineer Plant Summary

Unit Fuel

Capacity

(MW) Fly Ash Bottom Ash FGD

NOx

Control FGMC

1 Coal: Bituminous

Oil: No. 2 Fuel Oil

1300 Dry conveyed Wet Handled Wet System SCR None

 EPA conducted a site visit at the Mountaineer plant in New Haven, WV, see DCN SE02070 for

the site visit notes. Since that site visit, AEP has installed an ABMet biological treatment system

which began operating in November of 2011, to further treat the FGD wastewater prior to

discharge (FGD wastewater treatment previously consisted of only chemical precipitation

treatment). In addition to receiving the FGD wastewater after the chemical precipitation system,

the ABMet system also treats the combustion residual leachate that is generated at the plant.

 The lined leachate surge pond was designed to hold two consecutive 25-year rain events and

represented about 33 percent of the cost of the ABMet system (which includes piping and pumps

from the pond to the treatment system). AEP indicated that the logistics, lining, issues (problems

with liner floating), fencing (deer falling in and unable to get out), dual pumps (for redundancy),

controls/blending, and piping were all issues they addressed in the design of the pond. The pond

has a capacity of around 5 million gallons and is blended into the FGD treatment system after the 

CP system and before the ABMet system at a ratio between 50/50 and 60/40 for FGD CP

Effluent/Leachate pond water.

 AEP constructed the ABMet system over an approximate one year time period. In addition, the

commissioning period was on the order of a couple months.

 The physical / chemical system consists of the following equipment:
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o Desaturation tanks (with lime and organosulfide addition)

 Note: The Mountaineer treatment system has an opposite order of treatment

system than that at Amos since the desaturation tank is before the equalization

tank; however the order of the chemical addition remains the same.

o Primary clarifier (with primary polymer addition)

 Only the sludge from the primary clarifier is sent to a sludge feed tank located

upstream of the filter presses; the sludge from the secondary clarifier is sent back

to the beginning of the system (desaturation tanks) to be removed in the primary

clarifier.

o Equalization tank (with organosulfide addition)

o Ferric Mix Tanks (these tanks are out of service and bypassed; the facility does not add

ferric chloride any longer)

o Secondary Clarifier (with secondary polymer addition)

o Sludge Feed Tank

o Filter Presses (2)

 Larger than the filter presses at Amos

o Effluent Storage Feed Tank

 The influent to the biological treatment system is made up of about 50 percent CP effluent and 50

percent leachate with a design flow rate of around 600 gpm and an average flow rate of 500

GPM. The ORP of the comingled influent is around 200 – 300 mV (aim for 150 – 200 mV), the

TSS is about 200ppm, and the pH is around 8-8.4 S.U. (adjusted to 7-7.5 S.U. using sulfuric

acid).

 The ABMet biological treatment system consists of the following equipment and took around 18

months to construct: (includes the leachate surge pond discussed above)

o First stage feed tank (with sulfuric acid (93%) addition)

 pH monitored

o First stage reactors (with molasses-based nutrient addition; includes 6 reactors)

 ORP and pH monitored at each reactor cell

 The first stage removed the nitrate-nitrite and a portion of the selenium.

o Second stage feed tank

 pH monitored

o Second stage reactors (with molasses-based nutrient addition; includes 6 reactors)

 ORP and pH monitored at each reactor cell

 Use of the second stage achieves another order of magnitude reduction of

selenium, which is sufficient to achieve compliance with the proposed ELG 

limits.

o Effluent tank

 During the ABMet biological treatment system start-up period, Bill Kennedy of Duke Energy

worked on-site to help with getting the biological treatment system up and running. AEP stated

that there were large swings in the ORP during this period. AEP also noted that the start-up

period lasted a few months.

 AEP noted that the FGD treatment system takes a lot of manpower. AEP estimated that, on

average, the physical/chemical system requires one full-time operator and the CP plus

biological treatment system requires two full-time operators.

 The molasses-based nutrient contains trace metals (including selenium and aluminum) so that if

the unit to which it is being added is offline, the microbes will stay alive. In addition, there is a

filter for the nutrient feed system to prevent clogging of the feed system. The rate that the

nutrient is fed into the system is based off of the ORP measured in the reactor cells.
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 The biological system is automatically degassed when trapped nitrogen and some hydrogen

sulfide gases build-up within the system from microbial metabolism. If the system is degassed

twice in one day the system is flushed and the flush water is sent back to the beginning of the

physical / chemical system.

 AEP indicated that temperature is often an issue with the biological treatment system and needs to 

be monitored daily to make sure that the temperature does not exceed 105°F or dip below 50°F.

While AEP indicated that the treatment system sometimes reaches temperatures around/above

105°F (maximum observed was 106°F before comingling with leachate), the temperature

after commingling with the leachate remains below 105°F. A low treatment system temperature is 

of particular concern during the winter months when the water being pumped from the leachate

surge pond is significantly below 50°F.

 AEP noted that the total arsenic spike attributed to start-up conditions (1,000 ppb) in the WWT

plant influent increased the average in the bar graph of all five plants (average arsenic in the

influent is 199 ppb).

 The selenium limits for AEP’s current NPDES permit are 83 ppb daily and 33 ppb monthly

average at the final outfall.