NC0004979_Temporary Construction Dewatering_20171212

(> DUKE
ENERGY
December 12, 2017
RECEBVE®!®ENRIOWR
Mr. Jeff Poupart, Section Chief � �
NC DWR Permitting Section DEC 20 20V
1617 Mail Service Center
Raleigh, NC 27699-1617 Water Resources
Permitting Section
Subject: Temporary Construction Dewatering
Marshall Steam Station
NC0004979
Catawba County
Dear Mr. Poupart:
This letter is intended to follow up on correspondence sent to your office on November 13, 2017 regarding
construction activities at the subject facility. In accordance with requirements found in North Carolina's Coal
Ash Management Act, Duke Energy is required to re-route certain wastewaters from ash basins. To continue
to treat these wastewaters, new lined wastewater treatment basins will be constructed. For the lined wastewater
treatment basins to be constructed, groundwater dewatering activities will be necessary so that construction
activities can occur "in the dry."
Duke Energy is currently extracting groundwater in West Coal Basin well area referenced in the November 13,
2017 letter. After evaluating preliminary sample results of water to be extracted for construction of the East Coal
Basin well, Duke Energy has made the decision to add OrganoSulfide to the extracted groundwater to enhance
the precipitation of mercury in the ash basin. Duke Energy will also be conducting benchtop testing and
implementing a sampling regiment to validate the treatment during extraction.
In conclusion, this activity will not significantly change the characteristics of the ash basin discharge.
The temporary construction dewatering will not cause the flow volumes to exceed previous flow volumes
used for determining permit limits. This dewatering project will not result in the contravention of any
water quality standards. The groundwater extraction is likely to occur for approximately 6 months. It is
our understanding that DEQ concurs that this operation is deemed permitted and can begin.
If there are any questions about this matter, please contact me at [phone] or Brad Loveland at (704)
609-5637.
Sincerely,
E Shannon Langley
Lead Environmental Specialist
cc: Richard Baker via email
Brad Loveland /Filenet via email
Jackson Rollins — via email
Scott Kalau — via email
Julie Grzyb — NC DWR 1617 Mail Service Center Raleigh, NC 27699-1617
Andrew Pitner — Mooresville Region -610 East Center Avenue, Suite 301, Mooresville, NC 28115