NC0004979_Authorization to Operate_20080522

t WAT�c Michael F. Easley, Governor
State of North Carolina
O; PG
� William G. Ross, Jr., Secretary
co Department of Environment and Natural Resources
Coleen H. Sullins, Director
Division of Water Quality
May 22, 2008
Ronald E. Lewis
Duke Energy Company
Water Management.
EC13K P.O..Box 1006
Charlotte, North Carolina 28201-1006
Subject: Authorization to Operate
Temporary Cooling Water Intake Structure
NPDES Permit NC0004979
Duke Power/ Allen Steam Station
Gaston County
Dear Mr. Lewis:
This letter authorizes the operation of a temporary supplemental cooling water pumping system at the existing
Allen Steam Station electric plant. The system will consist of nine floating intake pipes with screened openings
(3/8 inch square mesh) and pumps designed to withdraw at a through screen velocity at or below 0.5 feet per
second (fps). The intake pipes will pump water from the Catawba River to the station's condenser cooling water
(CCW) discharge canal, which flows to the South Fork Catawba River. The temporary supplemental cooling
water pumping system will initially pump at the rate of 60, 000 gallons per minute (gpm) and will be an 11%
increase of the current pumping capacity. . (This temporary intake system will be replaced by a permanent
pumping system of submerged wedge wire screened piping and pumps designed to withdraw a total of 240,000
gpm into four manifolds and four pipes that will discharge into the CCW canal in July 2009.)
This temporary pumping plan has been proposed to ensure uninterrupted power production at this base load
facility, while mitigating effects on the aquatic community and downstream users. The current proposal has been
reviewed by staff of the NC Division of Water Quality (DWQ).
The temporary pumping plan is authorized to be implemented with the following operational and design measures
to minimize water quality and biological impacts:
➢ The .temporary supplemental cooling water pumping system will operate continuously from July 2008
through. September 2008 in conjunction with the operation of the Allen Steam Station's electrical
generating units.
➢ The Catawba River intake pumps willbe positioned above the river bottom and have an approach
velocity less than or equal to 0.5 feet per second across screening with 3/8 inch mesh openings to
minimize fish entrainment and impingement.
➢ . The temporary supplemental cooling water pumping system will initially pump at the rate of 60, 000
gallons per minute (gpm) and will be an 11%u increase ofthe current pumping capacity.
• The withdrawal location will be downstream of the existing intake structure and pump the water from the
Catawba River to the condenser cooling water discharge canal, which flows to the South Fork Catawba
River.
➢ The facility will perform routine monthly lake monitoring during the period of pumping to assess
limnological conditions in the Catawba River. During July, August and September, thermal and DO
profiles will be. taken in the vertical water column at designated downstream sampling locations.
1617 MAIL SERVICE CENTER, RALEIGH, NORTH CAROLINA 27699-1617 - TELEPHONE [phone]/FAX [phone]
VISIT us ON THE WEB AT http://h2o.enr.state.ne.us/NPDES

.� � �r 'P
a

' NC00049.79
Page 2 of 2
May 22, 2008
Please note that this authorization does not affect the legal requirements to obtain other permits which may be .
required by the Division of Water Quality, the Division of Land Resources, the Coastal Area Management Act, or
any other federal or local governmental permits.
If you have any questions or need additional information, please do not hesitate to contact Jacquelyn M. Nowell of
my staff at [phone], extension 512.
Sincerely,
Susan A. Wilson
Supervisor, Western NPDES Program
cc: Central -Files.
NPDES File/NC0004979
Mooresville Regional -Office -Surface Water Protection
Bryn Tracy/Environmental Sciences Section

� � 17

Div of water Qua I'i til Fax: [phone]
T r a n s m i -t Conf_ Relao r -t
P.1 May 29 2008 10:26
FaxlPhone Number
Mode
Start
Time
Paye
Result
Note
917043820249
NORMAL
29,10:26
0'29"
3
# 0 K
Michael F. Easley, Governor
• William G. Ross fr., Secretary
NC Deportment of Environment and Natural ,Resources
Coleen H. Sullins. Director
Division of Wafer Qvaliry,
To: Ronald Lewis -puke Energy Fax: [phone]
From:
Jackie Nowell-NCDENR DWQ ESE
Date.
May 29, 2008
Re:
Permit# NC0004979
Pages:
—L (including cover page)
CC:
❑ Urgent ❑ For Review ❑ Plmse Comment ❑ Plea Repiv ❑ Please Recvcle

RE: Status of Allen Steam Station supplemental CCW pumping project...
Subject: RE: Status of Allen Steam Station supplemental CCW pumping project request
- From: "Lewis, Ronald E" <[e-mail]>
Date: Thu, 29 May 2008 07:41:55 -0400
To: "Jackie Nowell" <[e-mail]>
Jackie,
If the authorization letter has been signed, could you please fax a copy
to the following Phone number (704)-382-0249 or send me a scanned copy
via email?
Thanks,
Ron
Duke Energy
Mail Code: EC13K
526 S. Church Street
Charlotte, NC 28202
Office 980-373-5710
Mobile [phone]
-----Original Message -----
From: Jackie Nowell [mailto:[e-mail]]
Sent: Thursday, May 22, 2008 1:51 PM
To: Lewis, Ronald E
Subject: Re: Status of Allen Steam Station supplemental CCW pumping
project request
Ron,
The authorization: letter went up for review by senior staff today. If
there are no concerns or questions, the letter should be forwarded to
you next week. Reminder that we are out of the office on Monday.
Jackie
Lewis, Ronald E wrote:
Jackie,
Hope you had a great weekend. When you have a moment, please give me
an
Iupdate
Thanks,
Ron
on the status of the Allen request.
Duke Energy
Mail Code: EC13K
526 S. Church Street
Charlotte, NC 28202
Office 980-373-5710
Mobile [phone]
-----Original Message -----
From: Jackie Nowell[mailto:[e-mail]]
Sent: Wednesday, April 23, 2008 12:30 PM
To: Lewis, Ronald E
Subject: Re: Status of Allen Steam Station supplemental CCW pumping
project request
Hello Ron, this has not been finalized yet. Both Susan and I were out
of the office last week and this week for a couple of days. Hope to
have send it for review by the first of next week.
Jackie Nowell
Lewis, Ronald E wrote:
1 of 2 5/29/2008 9:57 AM

RE: Status of AIlen Steam Station supplemental CCW pumping project...
Jackie,
Hope all is well with you. When we spoke last week, I think you were
forwarding to Susan Wilson for final approval of the request. Has
this been completed?
Duke Energy
Mail Code: EC13K
526 S. Church Street
Charlotte, NC 28202
Office 980-373-5710
Mobile [phone]
2 of 2 5/29/2008 9:57 AN

NC0004979 jmn
Duke Energy- Allen Steam Station
Gaston County 030834
Rec. Streams : Catawba River (Outfalls 002,002A, 0025, and 004)
and South Fork Catawba River (Outfalls 001 and 003)
As a potential drought mitigation option, Duke Energy wants to install a temporary
supplemental cooling water pumping system at Allen Steam Station. The system would
withdraw water just downstream of the existing intake structure and pump the water from
the Catawba River to the station's condenser cooling water discharge canal, which flows
to the South Fork Catawba River. There would be nine floating intake pipes with
screened openings and pumps and would withdraw at a velocity of 0.5 fps. A modified
CE -QUAL -W2 model using low flow conditions experienced in the summers of 2002
and 2007 has shown that water quality impacts from the operation of the supplemental
cooling water system would be negligible,
The first phase would operate continuously from July through September 2008 and
would be a temporary supplemental cooling system of 60,000 gpm. The next phase
would be a 240,000 gpm permanent supplemental cooling system with planned operation
in 2009. The first. phase represents an 11% increase in the supplemented cooling water
flow and the following phase would be a 441/o increase in the summer of 2009.
60,000 gpm = 86.4 MGD =133.68 cfs.
240,000 gpm = 345.6 MGD = 534.72 cfs
A similar temporary cooling system was submitted and approved by DWQ for the
Belews steam station plant in early 2008.
From the narrative of the erosion and sedimentation plan The lake water is at least
twenty degrees cooler than the station's condenser cooling water discharge. Mixing the
two streams lowers the temp of the cooling water discharged from the plant property.
Telephone conversation with Ron Lewis --the temporary cooling system will help in
the drought situation.' • During low lake levels, had a question as to how to keep the .
station operating without a water loss. The water will just be moving around the lake,
from the Catawba River to the South Fork Catawba. They need the approval of the
temporary 60000 gpm structure. Duke will register the additional water use. They are
still developing the intake structure. With Lake Wylie, the lake level just sits there. They
will turn the pumps on in July, run it continuously from July through September and then
turn them off. They want to be able to run the station during a drought situation. If they
can run July, August, September its an additional water source and it knocks down; the
spike in temperature. With additional load during peak generating hours it will knock
down the temperature. It will cool the discharge temperature faster.

Monthly sampling is proposed and if anything different in data appears, they will increase
the frequency.
The withdrawal velocity is 0.5 fps- will not run during the spawning season.
DWQ/NPDES comments — per Sergei Chernikov
Duke and DWQ (Chuck, Sergei, and Bryn Tracy) met in Jan. 2008 and discussed the
temporary cooling water system, it was decided that the system would not cause any
problem since the water was being moved from one side of the lake to the other (from the
Catawba River side to the South Fork Catawba River side). The withdrawn water would
come back into the Catawba River from the South Fork Catawba River.
Model Results
From the Environmental Assessment submitted
Model shows that: 1) lake effects will be generally limited to changes in the temperature
in the South Fork Catawba River. 2) Minimal temp and DO changes in the main arm of
Lake Wylie, including Catawba Nuclear Station intake and the Wylie hydro fore bay.
Worst case scenarios — 24 hr full generation capacity and current thermal discharge
limits, The model predicted modest thermal increases, Worst case temp increases were
1-2 F in the South Fork Catawba River downstream of Allen, Also had same temp
increase on the area of the Allen condenser cooling water intake. Further downstream at
other sites, no thermal effects were seen. DO vertical profiles were practically the same,
when the low flow summers were modeled, w/ and w/o the supplemental pumping
system.
In order to evaluate the first summers of bypass operation, a supplemental monitoring
program for Lake Wylie is proposed. During July, August and September, thermal and
DO profiles will be taken in the vertical water column at several stations. This profile
data will be compared to the predicted model results.
Fisheries impacts
There is a diverse fish community present in portions of Lake Wylie around the Allen
Plant. the supplemental cooling water" system. will avoid the fish spawning
period of March through June and minimize spikes of the discharge water temp during
peak electrical generation demand. The current monitoring program is adequate to
document any changes in the fish population.
Operation and site plan
An erosion and sedimentation control plan has been submitted.