ILLINOIS POLLUTION CONTROL BOARD
May 11,
1978
COMMONWEALTH EDISON COMPANY,
)
Petitioner,
v.
)
PCB 77—309
ENVIRONMENTAL PROTECTION
)
AGENCY,
Respondent.
OPINION
AND
ORDER OF THE BOARD
(by Mr. Goodman):
This matter comes before the Board on a November 28, 1977
petition for hearing filed by Commonwealth Edison Company pur-
suantto
Rule 203(i) (5)
of Chapter
3:
Water Pollution Regula-
tions.
The rule requires the Petitioner to demonstrate that
its thermal discharge has not caused and cannot be reasonably
expected to cause significant ecological damage to the receiving
waters,
A hearing was held in Chicago on February
3,
1978.
Petitioner owns and operates Kincaid generating station
in
Christian County,
a mine—mouth facility consisting of two gene-
rating units of 616 MW each.
The 1975 plant capacity factor was
43.
Cooling water is drawn from Lake Sangàhris,
an impoundment
created between 1964 and 1966 for this purpose by damming three
branches of Clear Creek, an intermittent stream tributary to the
Sangamon River.
The lake surface is approximately 2700 acres with
a maximum depth of 40 feet and an average depth of
15
feet.
Water is drawn from the west
(intake)
arm of the lake by four
pumps,
each with a 160,000 gpm capacity.
Normally,
only three of
the four pumps are in operation,
due to maintenance difficulties
attributable
to pump design.
At full load,
the combined heat
rejection from the two generating units
to the cooling water
is
5,44 x 1O~Btu/hr.
The heated water is discharged to a 3320 foot
canal that empties into the middle
(discharge)
arm.
Because of
the lake’s configuration,
the cooling water system operates as a
10.7 mile loop with temperatures decreasing continually along
the
pond and a cycle time of 11 days.
Water from the third
(control)
30~185
—2—
arm of the lake does not circulate
in the cooling cycle and has
served as
a control area
in the studies prepared for Petitioner.
Water
is discharged to Clear Creek over a dam at the confluence
of the arms of the lake; however,
usually no discharge occurs
during the period from June to mid-October,
the time of greatest
lake temperature.
Lake Sangchris is used extensively
for
recreational fishing~
and some boating,
generally related to fishing,
is allowed.
The
lake and surrounding area also serve as
a hunting ground.
Swim-
ming is not allowed because of possible hazards due to prolonged
exposure to water heated
in excess of 104°Fand because of possi-
ble liability for accidents.
Lake Sangchris has been the subject
of
extensive studies
in
conjunction with cases previously before
the
Board.
This facility
has been considered in PCB 73—245,
-248
(consolidated),
R75-2,
and
R76—ll.
The extensive records of these cases were incorporated
into the present proceeding.
It was anticipated in R76—ll that
the record already generated would suffice for purposes of a 203(i)
(5)
hearing, and the Board concludes that it does.
Only a brief
review of that information is necessary to determine that the
operation of the Kincaid station has not caused nor can reasonably
be expected to cause significant environmental harm.
Thermal
studies generated as part of R76—ll show that with an assumed
average load of 844 MW
(68.5
capacity factor),
the temperature of
the lake would be consistently higher than 90°?in July and August,
and occasionally higher in June and September.
Between December
and March,
the average lake temperature would be 60°F,exceeded
occasionally in March.
The thermal discharge standard adopted in
R76-11, 99°Fwith an allowable excursion to 111°Fduring no more
than
7
of the hours
in any one year period,
reflects historical
operation.
The 99°Fstandard is summer temperature; the generating
facility lacks the capacity to raise the water temperature that
high on a year-round basis.
The period of July
1
to August 31,
1975 appears to form the basis for the regulation.
The maximum
discharqe
temperature
recorded
in
that
period
was 110.5°Fwhen
the
p1an~
was
qeneratinq
910
MW
with
three
pumps
in
operation.
The
highest
discharge
temperatures
during
the
1968-1975
period
studied
as
part
of
R76—ll
occurred
during
the
summer
of
1969.
The
hourly discharge temperature during that period exceeded 107°F
43
of the time, with a maximum discharge of 112.1°F.
It was
determined that meteorological conditions were not atypical as no
low lake levels were present and near or slightly less than average
air temperatures and precipitation were experienced.
The high dis-
charge temperatures are attributed to the high capacity factor
experienced during that period;
the maximum ever recorded at the
30—186
—3—
station,
74.9,
occurred
during this time.
Although excursions
over the 99°Fstandard occurred during only 5.2
of the annual
period, the 99°Fstandard was exceeded during 17
of the summer
hours.
Rather than establish a higher standard or require the
installation of costly cooling devices,
it has been determined
that
in situations where excursions above the Board standards
would be likely the load at Kincaid will be reduced so that dis-
charge temperatures remain within the permitted range.
Such a
procedure will not result in any loss of service to Petitioner’s
customers.
Extensive studies of the impact of
the thermal
discharge on
the ecology of Lake Sangchris have been done.
Three years of study
by the Illinois Natural History Survey were reported in R76-ll and
these studies were to have continued through June,
1978.
Although
admitted in R76-ll that it would probably be beneficial not to have
temperatures over 99°Fin the lake,
the studies have shown little
adverse impact.
The present fishery in Lake Sangchris
is the result of Depart-
ment of Conservation stocking.
Fourteen species are reported; none
have been eliminated due to thermal stress~ Studies of particular
species show that the largemouth bass remove themselves from stress—
causing temperatures.
This movement within temperature gradients
has been shown to increase the reproductive area of the lake.
The
warm temperatures also accelerate plankton growth to provide a
greater food supply.
Studies of bluegill show some stunting but
this is attributable to overpopulation rather than thermal effects.
Similarly, carp reproductive problems have been observed.
The higher water temperatures produce a direct benefit by
providing a winter habitat for fish that would not be otherwise
present in central Illinois lakes.
It has been determined that
the fish population in Lake Sangchris is so good that it is atypi-
cal.
The lake is at an age where fish populations generally
decline, but that effect has not been observed during the period
studied for R76-i1 or
from
that proceeding through the present
one.
The only adverse effect attributable to thermal discharges
is
the loss of Asiatic clams.
During 1975,
a kill was observed in the
canal area when temperatures reached high levels.
This loss does
not appear significant because the Asiatic clams repopulate during
cool weather.
Additionally, they are not a beneficial use since
the species tends to clog the intake structure and also competes
with more desirable food sources.
30~87
—4—
The Board is aware that the cooling lakes present special
considerations.
The effects of their operation, particularly
that of Lake Sangchris,
have been sufficiently studied.
The
standard set
in R76—ll
is reasonable and possible adverse effects
are controllable.
In addition,
the possibility of environmental
harm during summer operation must be weighed against the definite
environmental benefit presented during winter operation.
In
examining the record before us, we determined that no significant
adverse environmental impacts have been experienced or are likely
to occur.
This Opinion constitutes the findings of fact and conclusions
of law in the matter before the Board.
ORDER
It is the Order of the Pollution Control Board that:
1.
The Petitioner has satisfied the requirements
of Rule 203(i) (5)
of Chapter
3:
Water Pollu-
tion Regulations.
2.
The thermal discharge from Petitioner’s Kincaid
generating station has not caused nor can reason-
ably be expected to cause significant damage to
Lake Sangchris.
I,
Christan
L.
Moffett, Clerk of the Illinois Pollution
Control Board,
hereby certify the above Opinion and Order
were adopted on theJ~~day of~,
1978 by a vote
Q~stanL.Mofett~
Illinois Pollution C
rol Board
30-188