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Notes from Site Visit at Northern Indiana Public Service Company’s 

Bailly Generating Station on April 19, 2007 

EPA conducted a site visit at Northern Indiana Public Service Company’s (NIPSCO’s) Bailly 

Generating Station on Thursday, April 19, 2007 to learn about the operations at the plant and 

determine where and how samples would be collected if the plant was selected for sampling. 

Table 1, at the end of this memorandum, identifies the site visit participants. 

This memorandum summarizes the information collected during the site visit and the pre-site 

visit phone call, which was held on April 16, 2007. 

Ownership/Operation 

• NIPSCO is a subsidiary of NiSource, Inc. 

• Pure Air owns and operates the FGD system and the FGD wastewater treatment 

(WWT) system used at the Bailly plant. NIPSCO and Pure Air entered into a 20-year 

contract agreement when the FGD system was brought on line in 1992. Under this 

contract, NIPSCO transfers flue gas to Pure Air’s FGD system and Pure Air transfers 

treated wastewater from the FGD WWT system to NIPSCO’s outfall. 

Introduction of Plant 

 

• The plant operates two coal-fired steam electric units, Units 7 and 8. 

• The plant operates one gas turbine, Unit 10. 

• Units 7 and 8 have cyclone boilers, and have capacities of 160 and 320 MW, 

respectively. Unit 7’s boiler includes four cyclones and Unit 8’s boiler includes eight 

cyclones. Both units were brought on line in the 1960s: Unit 7 in 1962 and Unit 8 in 

1968. 

• The plant burns approximately 35,000 lbs per hour of coal in each of the 12 cyclones. 

The plant burns approximately 5,000 tons of coal per day in total. 

• 75% of coal burned in Units 7 and 8 is Illinois Basin (Bituminous); 25% is Northern 

Appalachian (Eastern Bituminous). 

• The coal used at the plant is pulverized prior to use in the cyclone boilers, but it is not 

pulverized as finely as coal burned in other types of boilers. 

• 20 – 30% of ash produced in the cyclone boilers is fly ash. The rest is bottom ash. 

Donna Hill mentioned that more common boiler types produce the opposite ratio of 

fly/bottom ash. 

• Fly ash from Units 7 and 8 is handled in a pneumatic dry system. The plant sells 

most of the fly ash produced. 

• Bottom ash from Units 7 and 8 is handled in a wet system. 

• Units 7 and 8 each have an ESP. 

• Unit 8 has an SCR and the plant is currently constructing an SCR for Unit 7. 

• The plant will be in an outage from October through November 2007 for construction 

of the Unit 7 SCR. The Unit 7 SCR will be in service in 2008. 

• The plant currently operates the Unit 8 SCR during “ozone season” (May through 

September). 
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FGD System 

• Units 7 and 8 exhaust to one FGD scrubber, which came on line in 1992. 

• The FGD scrubber is a spray tower, in which limestone is used as the sorbent. 

• A Pure Air representative stated that the plant uses approximately 400 tons of 

limestone per day. 

• The plant injects dry limestone into the FGD absorber, in which the dry limestone is 

slurried with water. 

• The plant stores hydrated lime in a silo for use in upset/emergency situations. 

• In the FGD absorber, which holds approximately one million gallons of slurry, forced 

oxidation is used to convert calcium sulfite to calcium sulfate (gypsum). 

• The pH in the FGD absorber is typically maintained between 5.8 and 6.2. The 

maximum allowable chlorides concentration in the absorber is 20,000 ppm, but the 

plant typically maintains the chlorides concentration between 10,000 and 15,000 

ppm. 

• There is a continuous bleed from the absorber to maintain 20-22 wt% gypsum in the 

FGD absorber. The bleed stream is transferred to the Centrifuge Feed Tank. 

• The Centrifuge Feed Tank, which is used as a surge tank, is about 25,000 to 35,000 

gallons. A plant representative stated that the wastewater residence time is relatively 

short in the Centrifuge Feed Tank. 

• Wastewater from the Centrifuge Feed Tank is transferred to nine centrifuges, 

operated in parallel, in which gypsum is separated from the filtrate. 

• Gypsum separation occurs in the centrifuges in the following batch process: 

- Wastewater is transferred to the centrifuges; 

- Spin cycle; 

- Wash water (filtered intake water) is added to remove chlorides; 

- Spin cycle; 

- The separated gypsum solids are transferred to a storage building and sold 

for wall board manufacturing; 

- Remaining gypsum cake is scraped out of centrifuges; and 

- Centrifuges are washed out. 

• All wastewater from the centrifuges is transferred to the Filtrate Sump. 

• From the Filtrate Sump, wastewater is transferred to the Filtrate Thickener tank. The 

main purpose of the Filtrate Thickener is to remove fly ash from the wastewater (fly 

ash is not removed very well in the centrifuges). Underflow from the Filtrate 

Thickener is recycled to the Centrifuge Feed Tank, mainly to cause the fly ash to be 

removed from the system as part of the gypsum. Rarely, under upset/emergency 

conditions, the underflow may be transferred to the FGD WWT system. 

• Note that the plant no longer adds hydrated lime to the Filtrate Sump or the 

Centrifuge Feed Tank, as is shown on the plant’s FGD system flow diagram. 

• The overflow from the Filtrate Thickener is transferred to the Thickener Overflow 

Tank. A portion of the thickener overflow is recycled back to the scrubber, a portion 

is recycled back to the Filtrate Sump for level control, and a portion is transferred to 

the FGD WWT system (as a continuous stream at a flow rate of approximately 200 to 

250 gpm) to maintain an acceptable chlorides concentration in the scrubber. 
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• The Pure Air representatives stated that the pH and chlorides concentration of the 

wastewater stream to the FGD WWT system is typically higher than that in the 

absorber, but they did not know the pH/concentration. 

• Note that the plant’s FGD system diagram shows a wastewater stream from the 

Thickener Overflow Tank to the Unit 8 flue gas stream, between the air preheater and 

the ESP. This transfer line no longer exists and is an artifact of a DOE pilot study in 

which the plant was involved during startup of the FGD system. During this pilot 

study, the plant tested an evaporation FGD WWT system. The plant injected the 

FGD wastewater into the Unit 8 flue gas ductwork, the wastewater was flashed to 

steam, and the solids were removed in the precipitator. The plant ceased operation of 

this evaporation WWT system because the system did not have enough capacity and 

it had operational issues. The flue gas ductwork system was not hot enough and fly 

ash collected inside of the ducts. 

FGD WWT 

• The FGD WWT system is a segregated WWT system for FGD wastewaters. 

• The first tank in the FGD WWT system is the Equalization Tank, which receives 

overflow from the Thickener Overflow Tank, as well as water that drains from the 

gypsum storage building (almost entirely gypsum truck tire wash water). 

• Wastewater is transferred from the Equalization Tank to the Neutralization Tank. 

Note that the plant does not add sodium hydroxide to the Neutralization Tank, as is 

shown in the plant’s FGD WWT system flow diagram. 

• Wastewater from the Neutralization Tank is transferred to the Coagulation Tank, in 

which polymer is added (using a dosing pump) based on wastewater flow rate. Pure 

Air representatives stated that the plant used to add ferric chloride to the Coagulation 

Tank, but switched to a polymer addition, which is less hazardous. The plant did not 

notice any negative effects on internal monitoring (turbidity) with polymer use and 

thus, has continued to use the polymer in place of ferric chloride. 

• Wastewater from the Coagulation Tank is transferred to the Reactor Tank, in which a 

flocculent polymer is added. 

• Wastewater from the Reactor Tank is transferred to the “Densadeg” tank, which is an 

upflow, plate-settling clarifier/thickener, designed by Infilco Degremont. The 

overflow from the Densadeg tank is transferred to the Clear Well. Note that the plant 

does not add sulfuric acid to the Clear Well, as is shown in the plant’s FGD WWT 

system flow diagram. 

• From the Clear Well, wastewater is discharged through NIPSCO internal outfall 

401A. This is the mechanism for the plant to remove chlorides from the FGD system. 

Internal outfall 401A, which is exclusively FGD waste, has a typical flow rate of 

approximately 200 gpm. 

• The wastewater from the Clear Well is measured for turbidity. 

• The wastewater from the Clear Well may be recycled back to the Equalization Tank 

under upset/emergency conditions. 

• The majority of the underflow from the Densadeg tank is transferred to the Sludge 

Tank. A portion of the underflow is recycled back to the Neutralization Tank to 

provide additional surface area for solids removal. 
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• The sludge from the Sludge Tank is dewatered in the Filter Press and landfilled. The 

filtrate from the Filter Press is recycled to the Equalization Tank. 

• No pH adjustment occurs anywhere in the FGD WWT system. 

• Pure Air does not know the residence time of wastewater in the FGD WWT system. 

• The FGD WWT system was designed to remove ash buildup and chlorides. 

• The plant has not conducted any treatability studies for investigation of the pollutant 

removal performance of the FGD WWT system. 

• Pure Air representatives stated that the plant does not sample at any point in the FGD 

WWT system for metals concentration. The only metals sampling occurred during 

DOE’s test program when the FGD system came on line. 

• The entire FGD system was partially funded by DOE as a “Clean Coal” pilot program 

in 1992. 

Plant Outfalls 

• The plant has the following internal outfalls: 

- 100: Bypass from Misc. Drains Collection to 001 (around ash pond). 

- 101: Discharge from ash ponds. 

- 111: Air heater wash water. To segregated pond and then ash ponds. 

- 201: Sanitary water. Feeds into ash ponds. 

- 301: Unit 7 boiler blowdown. 

- 401A: FGD wastewater. 

• Internal outfalls 101, 301, 401A, once-through condenser cooling water commingle 

into final outfall 001. 

• Final outfall 001’s typical flow rate is approximately 300 MGD (note that the NDPES 

water balance diagram provided by NIPSCO presents maximum design flows), the 

majority of which is once-through condenser cooling water. 

Plant Monitoring 

• The plant’s NPDES permit is currently “in flux” while the limits for outfall 401A are 

decided upon. Specifically, there is an issue regarding a limit for low-level mercury. 

• Currently the plant is monitoring at internal outfall 401A for TSS, oil and grease, pH, 

and mercury (total recoverable and low-level mercury). The plant monitors twice 

weekly. 

• The plant’s NPDES permit requires “interim” limits at outfall 001 for copper and 

mercury. 

• The plant has experienced some issues related to mercury sampling and analysis at 

internal outfall 401A. The lab has encountered interference with the field/trip blanks 

because the detection limit is so low. The contamination is in the parts per trillion 

range. Additionally, the lab has measured varying concentrations in duplicate 

samples (e.g., one sample is measured as non-detect for mercury, while a significant 

detectable concentration is measured in the duplicate sample). 

• NIPSCO and UWAG agreed that chlorides and sulfates contained in FGD wastewater 

can interfere with low-level metals analysis. 

• NIPSCO has encountered similar issues (as with FGD wastewater) with mercury 

sampling and analysis for outfall 001. 
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• Donna Hill suggested that NIPSCO should find out whether their lab is diluting the 

samples properly for low-level metals analysis. 

Sampling Information 

• EPA/ERG evaluated the following potential sampling points: 

- To Equalization Tank: A pipe is lifted to access the wastewater flow. 

- To Neutralization Tank: This point is where the wastewater flow from the 

Equalization Tank enters the top of the Neutralization Tank, just prior to 

the recycle addition from the Densadeg tank. The sample well looks as if 

it has not been used in a long time and contains a significant layer of 

solids that could potentially contaminate a sample. Figure 1 presents a 

photo of this potential sampling point. 

- Effluent from Clear Well (just prior to outfall 401A): The sample well at 

this point is completely filled with water. EPA/ERG/UWAG discussed 

the possibility of submerging a sample bottle or pumping out of the 

sample well, but determined that the solids in the well could potentially 

contaminate a sample. Figure 2 presents a photo of the sample well. A 

better option appears to be an unused port that could be flushed for several 

minutes prior to sample taking. Figure 3 presents a photo of the potential 

sample port. 

- Intake Water: A sample could be taken in the pumphouse on the 

lakeshore. The pumphouse contains uncovered pools of intake water (on 

left) and plant effluent water (on right). 

• In general, clean hands/dirty hands procedures would be difficult at the plant because 

of dusty conditions. 

• There are flow meters for all sample points. 

• The plant representatives cautioned EPA, in case Bailly is chosen as a sampling site, 

that the plant power production fluctuates. In particular, the plant sometimes reduces 

Unit 7 (the smaller of the two units) to half load. 

• Samplers would need to go through a 30 minute contractor orientation, including 

safety video, and obtain a safety work permit. 

• There should be space at the production service center for a staging area. 

• A plant representative thought that EPA/ERG would be able to use a small area of 

counter in the laboratory, but would need to check with his manager. 

• The nearest hospital is the Porter Memorial Hospital. 

• For an on-site emergency, dial 311 and plant personnel will call emergency 

responders. 

• The plant suggested shipping sampling materials from the nearest FedEx location. 

Coal Pile Runoff 

• The majority of runoff from the coal pile is absorbed in the ground under the coal 

pile. The remaining coal pile runoff is transferred to an “absorption field”. 

• There is no discharge of coal pile runoff from the plant. 
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Bottom Ash Handling 

• Bottom ash is sluiced to a pond system. 

• The ash pond receives the following streams: 

- Bottom ash sluice; 

- Sanitary water; 

- Water from the air heater wash water pond; and 

- Water from miscellaneous drains, which includes water from intake water 

filters and demineralizer wastes. 

• The majority of water from the ash pond system is recycled as bottom ash sluice. 

• A bleed stream from the ash pond system (internal outfall 101) is used to control the 

level in the ash pond system. 

Other Plant Water 

• Intake water from Lake Michigan is filtered to remove relatively large solids from the 

water. This filtered intake water is used in the FGD system. 

• Cooling water is a once-through system. No biofouling is required for this cooling 

water. 

Other Notes 

• NIPSCO has provided EPA with the plant’s NPDES permit and Form 2C. 

• NIPSCO representatives mentioned that the RM Schahfer plant, also operated by 

NIPSCO, does not operate an FGD WWT system. 
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Figure 1. Sampling Location for Influent to Neutralization Tank 

(from Equalization Tank in FGD WWT System) 

Figure 2. Sample Well at Effluent from Clear Well (just prior to Outfall 401A)
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Figure 3. Sample Port for Effluent from Clear Well 
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Table 1. Site Visit Attendees 

Name Organization (Representing) Telephone E-maDean McDevitt NiSource, Inc. (219) 647-5268 damcdevitt@nJeff Neumeier NiSource, Inc. (219) 787-7298 jneumeier@niGreg Costakis NiSource, Inc. (219) 956-5125 gcostakis@nisJim Snoeyink NIPSCO (219) 787-7310 jssnoeyink@nLarry Dora NIPSCO (219) 787-7304 lldora@nisourBert Valenkamph NIPSCO (219) 477-6265 bcvalenkamphTim Wright NIPSCO (219) 787-7379 tewright@nisoEd Gastenveld Pure Air (219)787-9551 gastenet@apcGeorge Nyers Pure Air (219)787-9551 nyersgs@apciDonna Hill Southern Company (205) 257-5234 dbhill@southeLindy Johnson Tennessee Valley Authority (423) 751-3361 lpjohnson@tvJosh Hall EPA/Office of Water (202) 566-1002 hall.josh@epaRon Jordan EPA/Office of Water (202) 566-1003 jordan.ronald@T.J. Finseth ERG (Contractor to EPA) (703) 633-1698 thomas.finsethSarah Holman ERG (Contractor to EPA) (703) 633-1661 sarah.holman@