From: Messinger, Lisa C.

To: Thomas Finseth

Subject: A. B Brown (Vectren) Scrubber Diagram

Date: Wednesday, January 29, 2014 6:18:00 PM

Attachments: Scrubber diagram_EPA2014.BMP

 TJ - When we spoke on the phone last week, you had a question about what appeared to be

conflicting information between my ICR submittal and ELG comments concerning the volume of water

from our FGD system at our A. B. Brown plant. Our water balance in the ICR showed 1.2 MGD, but my

ELG comments indicated the source was the wash down of truck bays and belt filters. You also asked

for clarification of what was involved in the belt filter wash. After discussing with my scrubber engineer,

I called back to state the wash water was from continuous run hoses that use recirculated ash pond

water and the belt filter wash is from the underside of the belt, after the solids have been removed so

there was minimal additional solids. I also explained that our dual alkali scrubbers are unique in design

(there are no others still operating in the US power industry) so our FGD waste water is not equivalent

to an FGD purge from a limestone based / gypsum scrubber. We agreed that 1.2 MGD seemed high,

but that was the most current water balance I had available.

After we spoke, I asked a project engineer to provide a simplified drawing of our scrubbing system that

I could send to you for further explanation of how and why our scrubbers are different. I also asked

that on the diagram, he include arrows to better show flow through the system since much of the water

is recycled back into the scrubbing system and to fine tune the water volumes. Our water balance

noted that evaporation losses were not accounted for on the drawings. This volume can be significant

which likely attributed to the higher than typical water volumes in some areas. For us, lack of precision

was of little consequence since most waters recirculate through our pond or scrubber. However, when

trying to extrapolate pollutant loadings, it could be detrimental.

As part of a new water treatment system and upgraded electronic control system, we have added flow

meters and cycle counts that allow us to more accurately calculate the water volumes in many areas of

our plant. This has all been done within the last couple years, after the submittal of the ICR. Attached

is a detailed drawing of the scrubbing system which shows the calculated FGD wastewater sump volume

is 0.772 MGD. The diagram attempts to further explain where and what volume of fresh water and

"reuse" (recirculated water) is used in the system. We have not yet updated the full plant water

balance as we are in the middle of construction of a new water treatment system that will go into

service in early fall 2014. We intend to update our WB at that time, unless you feel we need to provide

EPA an updated drawing sooner.

Hopefully this helps in your assessment. Feel free to call or e-mail with any additional questions.

Lisa C. Messinger

Manager, Utility Environmental Compliance

Vectren Corporation

812-491-4666

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