NC0004979_Traveling Screen Replacement Notification_20191106

November 6, 2019
North Carolina Department of Environmental Quality `
Division of Water Resources
Water Quality Permitting Section NPDES RECEIVED
Attn: Julie Grzyb
1617 Mail Service Center NOV 13 2019
Raleigh NC 27699-1617
GDEA/fWRIPOES
RE: Traveling Screen Replacement Notification
Allen Steam Station, NPDES Permit NC0004979
Dear Ms. Grzyb:
This letter is to provide notification that the Duke Energy Carolinas Allen Steam Station (Allen)
has initiated a project to replace at least four of the existing traveling screens at the cooling water
intake structure. We have determined that it is more cost effective to replace these screens rather
to restore operability than to perform the necessary repairs.
Please note that periodic maintenance is performed for cooling water intake traveling screens as
required to ensure this component functions as designed. This maintenance may include
repairing or replacing various traveling screen components such as baskets, screen mesh, drive
mechanisms, frames, and supporting structures. Maintenance activities can require removal of
the entire traveling screen due to the extent of the work to be performed and/or for accessibility,
including staff safety.
Each of the five Allen generating units utilize two separate cooling water pumps (10 total) and
three separate intake bays (15 total). Each intake bay contains a traveling screen with 3/8" mesh
openings to strain large debris from the source waterbody. The screens are periodically rotated
and debris removed by a screen wash system. The screen wash is discharged approximately 800
feet south of the cooling water intake structure via NPDES Permit NC0004979, Outfall 004.
A project to replace four of the existing traveling screens is scheduled as follows. This schedule
is subject to change due to issues such as but not limited to replacement screen assembly,
transport of replacement screens, installation of replacement screens, and Allen plant operations.
• Screen 1A—November 2019
• Screen 3B —November 2019
• Screen 3C—November 2019
• Screen 5B —December 2019/January 2020
The replacement screens will also have 3/8" mesh openings and, except for Screen 1A, be
equipped with fish protection features such as fish buckets and constructed with more durable
rotating and drive components. Although the replacement screens with fish protection features
will be capable of near continuous rotation as defined by the Clean Water Act 316(b) Rule, these

will be operated only as directed by plant operations or differential pressure in accordance with
current traveling screen operation.
A low pressure screenwash system and fish return trough will not be installed as part of this
project. The design of the selected replacement screens, except Screen 1A, provide protection
for any fish that may be in the fish buckets from high pressure spraywash. Replacement of the
traveling screens will enable Units 4 and 5 to be partially compliant with the 316(b) Rule.
The applicable 316(b) Rule requires submittal of various study reports. As prescribed by
NPDES Permit NC0004979, these reports are required to be submitted no later than January 31,
2022. Three of the Allen units (1, 2, 3) are scheduled to be shutdown by December 31, 2024.
Units 4 and 5 are scheduled to be shutdown by December 31, 2028. Of note, Unit 4 can be
configured to withdraw water from either or both of the Unit 3 and 4 intake bays.
The Allen source waterbody, Lake Wylie, does not have any threatened or endangered species
that would be subject to impingement or entrainment by the cooling water intake structure.
Please contact Robert Wylie (704-382-4669 or [e-mail]) if you have
any questions regarding this notification.
Sincerely,
Terry W. Tuck
General Manger II
Allen Steam Station
Fossil/Hydro Operations—Carolinas Coal Generation