Vectren A. B. Brown

9/8/15

Response to EPA Email dated 9/2/15 RE. Call Notes for Review

The FGD wastewater generated from the truck bay wash area and the belt filter wash area are 

transferred to the ash pond and the ash pond does not discharge to surface water. All the ash 

pond water is reused at the plant; therefore, there is no discharge of FGD wastewater from the 

plant. In terms of the large flow rate for the belt filter wash water, the plant continually washes 

the underside of the belt filter with fire hoses using ash pond water as the source of the wash 

water. This operation results in a large volume of water that is transferred to the ash pond but is 

ultimately returned to the FGD system for use as belt filter wash water.

The above summary is not an accurate description of the January 2014 conversation or 

our actual operations. While it is our ultimate goal to recycle plant waters, it is an 

overstatement to say “the ash pond does not discharge to surface water.” The plant 

recirculates ash pond water for use in various plant processes, including the FGD 

thickener tank, belt filter wash waters, bottom ash sluice water, and general plant wash 

down hoses such as those used in the FGD truck loading area. The waters are comingled, used, and recirculated in a variety of plant processes, then pumped to the ash 

pond via ash transport water, process and storm water drains, or the waste water 

treatment system (The WWT system uses the ash pond for settling. It was installed in 

fall of 2014 and therefore not referenced in our phone call). In normal operations we

reuse and recirculate as much water as possible, however, following or in preparation 

for heavy or prolonged precipitation events, it is necessary to discharge from the ash 

pond. Because ash pond water is used in a variety of processes, the water that is 

discharged could include, or have been in contact with, bottom ash transport water, 

FGD wash waters, plant process waters, or fly ash transport water (if the dry fly ash

barge loading facility is unavailable).

In the questionnaire responses, the company noted that the A.B. Brown Station had a flue gas 

desulfurization (FGD) wastewater flow rate of 1.242 MGD coming from the truck bay wash and 

the belt filter wash area. However, in the company’s comments on the proposed ELGs, the 

company stated that the plant did not discharge any FGD wastewater.

It was stressed in our ELG comments that the scrubbers at the facility are of unique 

design and therefore do not have the typical FGD slurry blowdown found in a limestone 

based scrubber. As shown in the Scrubber Process Flow diagram which was submitted 

with an email dated 01/29/14, water is recycled back into the thickener tank where the 

unused chemical is recovered and reused in the scrubbing process. While there is no 

direct discharge of waste water from the FGD system, we do discharge water that 

comes into contact with FGD material. This water is from washing the underside of the 

belt filter and from the floor hoses and drains in the truck loading area. Our Information 

Collection Request Section B comments (p. B-31) specified that the listed waste water 

was not FGD absorber purge water, but vacuum filter (belt) wash water.