NC0004961_Temporary Construction SW Handling_20180817

EHS CCP Environmental Programs
elifDUKE Duke Energy
1®C 526 South Church Street
ENERGY® Charlotte,NC 28202
Mailing Address.
Aug. 17, 2018 EC13K/P O.Box 1006
Charlotte,NC 28201-1006
V Mr.Jeff Poupart, Section Chief
NC DWR Permitting Section
1617 Mail Service Center
Raleigh,NC 27699-1617
Ms.Annette Lucas RECEIVED/DENR/DWR
Division of Water Resources
1617 Mail Service Center
Raleigh,NC 27699-1617 AUG 2018
Subject: Temporary Construction Stormwater Handling Water Resources
Permitting Section
Riverbend Station
Permit#: NC0004961
Gaston County
Dear Mr.Poupart and Ms.Lucas:
In accordance with requirements in North Carolina's Coal Ash Management Act, Duke Energy is required to close
the ash basin at the subject facility by removal of all coal combustion residuals by August 1, 2019. Significant
progress has been made towards this requirement and guidance on handling non-contact stormwater in excavated
areas of the basin is requested.
Duke Energy will complete excavation of the ash basin and document this activity is complete in accordance with
previously provided DEQ guidelines. Once ash has been completely excavated from low areas of the ash basin,
non-contact stormwater will collect in these areas. Duke Energy is seeking concurrence on the handling of this non-
contact construction stormwater in an effort to ensure the statutory dates for closure are met.
Erosion control permit (GASTO-2019-001), was approved and received on August 9, 2018 for finished grading of
the Riverbend Ash Basin. In this plan, under the project description it states "The starting point for this project is at
the completion of verification of coal combustion residual removal". Construction stormwater from clean closed
areas of the basin will be collected via diversion ditches into sumps and then pumped to multiple silt bags which will
act as a filter and a velocity dissipater. This water will be allowed to discharge into existing vegetation and
Mountain Island Lake outside the footprint of the ash basin in accordance with the approved erosion control permit
since it is classified as construction stormwater. This activity is planned to commence in the beginning of
September 2018. Duke Energy is submitting this letter to make you aware of this forthcoming change to handling
stormwater from within the footprint of the basin and requests your acknowledgement and understanding of this
handling of water within the basin footprint as we move forward with this transition phase of the closure activities.
If there are any questions about this matter,please contact Brad Loveland(704)609-5637.
Sincerely,
Richard E.Baker,Jr.,P.E.,PMP
Director,EHS CCP Environmental Programs
Duke Energy
cc Brad Loveland/Filenet
Shannon Langley
Corey Basinger—NCDEQ
Annette Lucas-NCDEQ