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

This message (including any attachments) is intended only for the use of the individual or entity to which it is addressed and may contain information that is non-public, proprietary, privileged, confidential, and exempt from disclosure under applicable law or may constitute as attorney work product. If you are not the intended recipient, you are hereby notified that any use, dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, notify us immediately by telephone and (i) destroy this message if a facsimile or (ii) delete this message immediately if this is an electronic communication.

Thank you.