ILLINOIS POLLUTION CONTROL BOARD

April

13, 1978

ILLINOIS POWER COMPANY

(Wood River Station)

Petitioner,

)

PCB 77-321

v.

ENVIRONMENTAL PROTECTION

AGENCY,

Respondent.

OPINION AND ORDER OF THE BOARD

(by Mr. Dumelle):

This matter comes before the Board on a petition for

hearing pursuant to Rule 203(i) (5)

in Chapter

3:

Water

Pollution Regulations.

A hearing was held in Chicago on

February

10,

1978.

The Wood River generating

station

is located on the

Mississippi River at mile

197, downstream of Lock and Dam 26

at Alton and upstream of the confluence of the Mississippi

and Missouri Rivers.

The station has five units and a total

generating capacity of 696 MW gross.

Units

1,

2,

and 3

(51

MW each)

burn oil, while Units

4 and

5

(104 and 405 MW) burn

coal.

The overall plant capacity factors during the last five

years are:

1972—53.0;

1973—44.4;

1974—40.7;

1975—45.3;

and 1975-41.2.

The projected 1977—81 plant

capacity

factors

are between 40 and

50 percent.

No retirement date has been

established for any unit and no expansion has been planned

during the last five years.

Complete plant shutdowns

were reported in 1973

(543 hours total)

and 1974

(78 hours).

Petitioner submitted a timetable for boiler and turbine over-

hauls

throuqh

1987

(Petitioners Exhibit

#1,af-

1—4).

Mississippi River water

is used for once through con-

denser cooling at the Wood River station.

Water is withdrawn

from the river and pumped through a one—pass condenser for

Units

1,

2, and

3, and through a two-pass condenser for units

4 and

5.

Typical usage

is 773 cfs; maximum capacity is 954.7 cfs.

The amount of heat rejected

in the cooling water discharge

is directly proportional to electric generation. At maximum

capacity

(696 MW)

and maximum cooling water flow conditions

(954.7 cfs), heat rejected from the steam condenser to the

cooling water at a rate of 3388 million

Btu/hr~ could increase

the cooling water temperature by 15.8°F in spring, fall and summer.

Data prepared by Petitioner Exhibit

#1, at 2-1)

shows actually

observed monthly mean cooling water discharge substantially

30—23

---

—2—

below maximum capacity (range from

384

to

914

cfs)

and

induced temperature rise across the condenser in the range

of 15 to 20°F.

Recirculation of

warm water to the intake

structure for ice melt during winter operation explains the

occurrence of observed effluent temperature rises

in excess of

those predicted at maximum generating capacity.

Actual field measurements were made on

34 occasions

from June 1973 through October,

1975.

The percentage of

river flow used for cooling ranged from 0.11 to 1.58.

The

highest daily maximum discharge temperaturc

at the river

was 96.8°F;the lowest daily maximum discharge was 47.8°F.

Four of the

34 temperature reports included calculation of the

area of the thermal plume 5°Fabove ambient river temperature.

These surface areas ranged from 0.27 to 0.63 acres

(Exhibit

#1, Table

3—1).

Theoretical studies were performed for a shoreline—

attached plume such as exists at the Wood River station.

The overall appearance of this kind of plume

is an elongated

shape which follows the shoreline and gradually spreads

across the river.

Conditions were modeled for all seasons

under typical and worst case conditions.

An unobserved

worst case condition was calculated for a combination of

7 day,

10-year low flow and maximum temperature of record.

Typical

and worst case conditions for operation were modeled on

maximum generating capacity although that capacity may be

approached at only brief

intervals during the year.

Under typical conditions for all seasons the surface

area of the thermal plume which is 5°For more above ambient

river, temperature

is less than one

(1)

acre.

The area of the

5°Fisotherm at its maximum point occupies less than

1

of the total cross—sectional area of the river.

Under worst

case seasonal conditions the surface area of the thermal plume

which is 5°For more above ambient river temperature

is less

than

one acre

in

all

cases.

During

winter,

summer,

and spring

worst

(

-a

(~ot1(1

I

I

i ole;

,

tie

a rea~

()

I

I

h’

r1

sot he rm

at

the

I

IIkIX

IlliUfli

OCUUI)Y

~Ius~

Lhan

t~ol

the

Iota

I

eios:;—seet.

iuLIt.Li

area of the river.

During fall,

the season of lowest river

flows,

the cross—sectional area

is

3

of the total river area.

Under unobserved worst case conditions,

the surface area

was less than one acre and the cross—sectional area was 3.

The size of this mixing zone is well within

the

standards

set forth

in Rule 201

in Chapter

3 of

26 acres maximum

surface area and 25

maximum of the cross—sectional area for

the 5°Fisotherm.

30—24.

---

—3—

Petitioner

has

provided

data

showinq

1°F

isotherms

for all conditions modeled

(Exhibit

1,

Figures 3—10 through

3—18)

.

At no time

is the maximum temperature for main

river locations in violation of the Board standards.

Studies of the aquatic ecology of the Mississippi River

were conducted by Petitioner during the period 1973-75.

The parameters and components of the study were temperature,

dissolved oxygen, phytoplankton,

zooplankton,

benthos,

and fish.

The study showed that none

of the biota wer

excluded downstream from the site as a result of the

thermal

plume.

Fish did tend to avoid the discharge plume when

water exceeded 88° F during typical summer conditions; however,

this

is a highly localized area of less than one acre.

Possible adverse effects on the aquatic community due to

temperature changes under worst case seasonal conditions

are mitigated by other factors such as river flow and the

small area of the thermal plume.

Some acclimation could

result

in localized areas;

however,

in no case is a lethal

temperature approached.

Small shifts in community structure

will

shift

back

to

typical

community

as

the

river

returns

to ambient conditions.

Permanent ecosystem damage due

to temperature rise

is unlikely even under worst case conditions.

No changes

to the riparian habitat were foreseen as

a result of the thermal plume.

The area surrounding the

Wood River Station is not conducive to amphibians, water-

fowl, and mammals that are often found at the water—land

interface.

Additionally, changes would

be more likely

attributable

to changes in river stage and substrate than to

the Petitioner’s thermal discharge.

Adverse effects from

the thermal discharge are also unlikely

in

regard to human

activities such as recreation and commercial fishing on

the Mississippi River.

Because

t-hc’

ef

feel-

of the

thermal

di seharjo

is hi’;hly

I oca I

I zed ~nd we

I

I

Wi.

Lii

I u

LIie

sLaiidards

ot

(‘hapLer

3,

the

Board concludes

Lhat: there

has

been

no significant ecological

damage

to

the

ecosystem

and

that

there

is

no

reasonable

expectation that such damage woulc occur even under worst

case conditions.

Because there are no significant adverse

effects,

corrective

measures

and

management

practices

need

not be addressed.

This

constitutes

the

findings

of fact and conclusions

of

law

of

the

Board

in

this

matter.

30—25

---

—4—

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 Pollution

Regulations and Part VI of the Board’s Procedural

Rules

.

2.

The

thermal

discharge

from

Petitioner’s

Wood

River

generating

station

has

not

caused

nor

can

reasonably

be

expected

to

cause

significant

ecological

damage

to

the

Mississippi

River.

I, Christan

L. Moffett,

Clerk of the Illinois

Pollution Control Board,

hereby certify the above Opinion

and Order were adopted on the

/3~’

day of

___________

1978 by

a vote of

Ao

.

Christan L.~1off,~~,Clerk

Illinois PcIl~Uon

ontrol Board