20060638 Ver 5_Email from Duke to Tom Reeder_20150501

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Mr. Tom Reeder
Assistant Secretary of the Environment
N.C. Department of Environment and Natural Resources
1601 Mail Service Center
Raleigh, NC 27699-1601
Subject: HF Lee, Riverbend, Asheville
Dear Mr. Reeder:
James Wells
Vice President
Environmental, Health & Safety-
Coat Combustion Products
526 S. Church Street
Wit Code: EC 12H
Chariotte, NC 28202
[phone]
As a follow-up to our previous discussion, this serves to provide your office with courtesy
notification that Duke Energy is proceeding with a plan to capture and return specifically-
identified seepage flows at three facility sites in North Carolina — HF Lee, Riverbend, and
Asheville.
H Lee
Several previously identified seeps may contribute water to an existing drainage swale
located immediately east of the Active Ash Pond. The drainage swale also receives storm
water runoff from the adjacent watershed and flows toward the Neuse River, located
immediately south of the Ash Pond, Based on preliminary calculations by our consultant, the
adjacent watershed is approximately 200 acres in size and contributes a large quantity of
runoff to the drainage swale during storm events. The specifically-identified "seeps" using
supplied GPS coordinates plots out at Duke Energy's previously-identified location S-9,
which is a sampling point of the drainage swale before it connects to the Neuse River. This is
not an actual seep itself.
The design will utilize one pump with plastic discharge png laid upon the ground to convey
the captured flow into the ash basin. A back-up pump will be available in case of a failure.
The box and pump will be sized to manage normally expected flows, estimated to be up to
150 gpm. Normal operation would maintain a certain level within the $wale as opposed to
pumping dry, but would serve to manage the flow. Float controls would cycle the pump as
needed to maintain the level. In the event of storm inflows or river flooding, the excess flow
contribution into the drainage swale would overtop the boxisandbag blockage and continue
toward the river. Additionally, throttle controls for the pump would prevent excessive water
input into the ash basin during such events. The vault pump will be electric but use of

May 1, 2015
Mr. Tom Reeder
Page 2
gasoline or diesel-driven generators may be utilized for an initial period as an extern
electrical supply must be developed, I
It y.
The schedule to have the system functional is May 13, 2015
Asheville
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western abutment of the 1964 Ash Pond Dam. This seep collects into a rip rap lined surface
water d itch wh ich passes uncle r the abutment access road. The seep f lows throug h an 18-
inch corrugated HDPE p1pe just to the west of the access road into a grassy area. Duke
Energy will collect this seep flow and convey it to the toe drain outlet at the base of the 1964
Ash Pond Dam foir collection.

May ":ed
M r. . > R
Page 3 1
for
the, coping system, This system will manage the toe drain discharges, including the flow
from seep 64EO-3- The weir feature would enable collection /nom / j f lows but would allow
excess water from storm events to spill over and continue downstreaiii.
1,111UMPIA, R brag RIO
The schedule to have the system functional is May 13, 2015,
83 ii qne re I
r
Jam�e Wells
Vice resident, EHS-CCP