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ILLINOIS ENVIRONMENTAL PROTECTION AGENCY
Exelon Generation Company, LLC
Dresden Nuclear Generation Station
Petitioner,
V .
ILLINOIS ENVIRONMENTAL
PROTECTION AGENCY,
Respondent.
October 23, 2006
OCT 2 6 2006
IEPA
-
07-08 PollutionSTATE
(Provisional Variance-Water)
OControl
ILLINOISBoard
Re:
Provisional Variance From Special Conditions 4A, 4D, and 4G
of NPDES Permit IL0002224 1
Dear Mr.Wozniak :
The Illinois Environmental Protection Agency (Agency) has completed its technical
review of the attached provisional variance request (Attachment A) submitted by Dresden
Nuclear Generation Station (Dresden Station) on October 10, 2006
. Dresden Station is
requesting a provisional variance for a six-day period, beginning November 7, 2006,
through November 12, 2006, in order to repair a Lift Station Automatic Bus Transfer
(ABT) switch
. This switch was damaged by a lighting strike on July 27, 2006 . Based on
its review, the Agency GRANTS a provisional variance subject to the specific conditions
set forth below .
Background
Dresden Station is a nuclear-fueled steam electric generating facility located at the
confluence of the Des Plaines and Kankakee Rivers near Morris, Illinois, at River Mile
272.3 . The two boiling reactors have a maximum generating capacity of 1824 megawatts
electric . Circulating water used to cool and condense the steam from the generating
process is discharged to a 1275 acre cooling pond .
RECEIVED
CLERK'S OFFICE
' NPDES Permit No . IL0002224 expired on October 31, 2005 . Because the permittee timely filed for
renewal, however, the permit continues in full force and effect .

 
Dresden Station normally operates in a closed cycle mode from October I through June
14 (about 8 V2 months)
. In the closed cycle mode, approximately 1,000,000 gallons per
minute (gpm) of cooling water is drawn into the station's cribhouse intake structure,
passes through the station's heat exchangers, and discharges to a hot canal that routes the
water approximately two miles to the lift station
. The lift station lifts the 1,000,000 gpm
of the cooling water approximately 20 feet from the hot canal to the aboveground cooling
pond. The cooling water routes around the cooling pond and spills over a spillway into
the cold canal, which routes the cooling water approximately two miles back to the
station
. The flow regulating gates direct the majority of the cooling water back to the
cribhouse intake structure through a return canal
. These gates divert approximately 5
percent or 50,000 gpm of the cooling water flow (limited to 72 million gallons per day
(MGD)) to the Illinois River via Outfall 002
. The Kankakee River provides makeup flow
through a %4-mile intake canal
. The volume of makeup flow is equal to the blowdown
flow and water lost to evaporation
.
From June 15 to September 30 of each year (about 3 V2 months), Dresden is allowed to
operate in an indirect open cycle mode
. In this mode, approximately 1,000,000 gpm of
cooling water is drawn into the station's cribhouse intake structure from the Kankakee
River via the intake canal . This cooling water passes through Dresden's heat exchangers
and discharges to the hot canal that routes the water approximately two miles to the lift
station. The lift station lifts the cooling water approximately 20 feet from the hot canal to
the above ground cooling pond . The cooling water routes around the cooling pond and
spills over the spillway into the cold canal, which routes the cooling water approximately
two miles back to the station
. The flow regulating gates divert all the cooling water flow
(approximately 1,000,000 gpm) to the Illinois River via Outfall 002
. The Illinois
Pollution Control Board approved this operational scheme and the related alternate
thermal standards on July 9, 1981 .
The lift station is equipped with six lift pumps, each with a 167,000-gpm capacity
. The
pumps provide motive force that allows the cooling water to flow around the cooling
pond, over the spillway, through the cold canal to the flow regulating gates .
Relief Requested
Dresden Station seeks a variance from Special Conditions 4A, 4D,and 4G of NPDES
Permit IL0002224 (Attachment B) . Special Condition 4A requires that the maximum
temperature rise above natural temperature must not exceed 5° F at the edge of the
mixing zone, in accordance with Section 302 .211(d) of Subtitle C (35 Ill . Adm
. Code
Sec. 302
.211(d)) when operating in closed cycle mode . Special Condition 4D requires
that Dresden operate in the closed cycle mode during the period October 1 to June 14 .
Special Condition 4G allows Dresden to bypass the cooling pond only when both
generating units are out of service
. A variance from these conditions will allow Dresden
Station to operate in open cycle mode (i .e ., bypass the cooling pond)
.
Dresden Station requests that the provisional variance begin on Tuesday, November 7,
2006, and continue through Sunday November 12, 2006, during which time Dresden

 
Station can operate in open cycle mode for 144 hours . During this period, Dresden will
repair the existing Lift Station ABT switch and make other related electrical repairs . This
activity will restore the Lift Station electrical equipment redundancy and reliability .
To minimize the thermal discharge from the plant, the provisional variance period
coincides with a scheduled refueling outage of one of the facilities two units .
Agency Determinations
The Agency has reviewed the requested provisional variance and has concluded the
following :
No significant environmental impact will occur as a result of this
provisional variance .
Dresden Station will closely monitor the
environmental impact from the requested relief and will immediately
notify the Agency of any significant impact along with actions taken to
remedy the problem ;
2 .
No reasonable alternatives appear available
;
3.
No public water supplies will be affected ;
4 .
No federal regulations will preclude the granting of this request ; and
5.
Dresden Station will face an arbitrary and unreasonable hardship if the
request is not granted
.
Conditions
The Agency hereby GRANTS the Dresden Station a provisional variance from Special
Conditions 4A, 4D, and 4G of NPDES Permit 1L0002224, subject to the following
conditions :
A.
The provisional variance shall begin on Tuesday, November 7, 2006, and
continue through November 12, 2006, during which time Dresden Station
can operate in open cycle mode for 144 hours ;
B.
Dresden Station shall comply with the General Use thermal discharge
standards outlined in its NPDES permit's Special Condition 4B during
the variance period ;
C .
Dresden Station shall continuously monitor intake, discharge and Dresden
Lock and Dam temperatures so it can document
environmental
conditions during the variance period . Dresden Station shall also
conduct visual inspections on a daily basis in the vicinity of the intake
and the discharge, so it can document the effects of any increased

 
thermal output to the river . Dresden Station shall notify the Agency if
it identifies any unusual or unexpected environmental impact ;
D .
Dresden Station shall conduct additional biological monitoring of the
resident fish community, which shall consist of fish sampling during and
after the variance period
. Dresden Station shall conduct two surveys at
eight locations using electrofishing, and two surveys at seven locations
using seining
. Dresden Station shall also monitor the physical conditions
by compiling temperature and oxygen profiles in all appropriate survey
locations;
E .
Dresden Station shall conduct additional biological monitoring of the
benthos community, which shall consist of macro invertebrate sampling
just prior to and just after the variance period
. These two surveys shall be
performed at six locations using a Ponar grab sampler ;
F .
Dresden Station shall notify Roger Callaway of the Agency by telephone
at 217/782-9720 when the need to operate in direct open mode begins, and
again when the 144 hours are utilized
. Written confirmation of each
notice shall be sent within five days to the following address
:
Illinois Environmental Protection Agency
Bureau of Water - Water Pollution Control
Attention : Roger Callaway
1021 North Grand Avenue East, MC #19
Springfield, Illinois
62794-9276
G.
Dresden Station shall sign a certificate of acceptance of this provisional
variance and forward that certificate to Roger Callaway at the address
indicated above within one day of the date of this order
. The certification
should take the following form:
I (We)
,
hereby accept and agree to be bound by all terms
and conditions of the provisional variance granted by the Agency in
dated
Petitioner
Authorized Agent
Title

 
Date
Dresden Station shall continue to monitor and maintain compliance with all other
parameters and conditions specified in its NPDES Permit No
. IL0002224 .
Conclusion
The Agency grants this provisional variance in accordance with its authority contained in
Sections 35(b), 36 (c), and 37(b) of
the Illinois Environmental Protection Act (415 ILCS
5/35(b), 36(c), and 37(b) (2004)
. The decision to grant this provisional variance is not
intended to address compliance with any other applicable laws or regulations
.
Robtrt A
. Messina
Chief Legal Counsel
c:
Marcia Willhite
Roger Callaway
Vera Herst

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