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. Whi le it is our ultimate goal to recycle plant waters, it is an overstatement to say “the ash po nd 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 w ash waters, bottom ash sluice water, and general plant wash down hoses such as those used in the FGD truck loading area. The waters are co

mingled, 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 w ater 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 Stat ion 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 w astewater.

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