ILLINOIS POLLUTION CONTROL BOARD

June

23,

1994

IN

THE

MATTER

OF:

PETITION OF RHONE-POULENC BASIC

CHEMICALS

COMPANY

and

THORN

CREEK

)

AS 94-7

BASIN

SANITARY

DISTRICT FOR AN

)

(Adjusted Standard)

ADJUSTED

STANDARD

FROM

35

ILL.

ADM.

CODE 302.208

and

304.105

OPINION AND ORDER OF THE BOARD

(by R.C. Flemal):

This matter comes before the Board upon a petition for

adjusted standard filed by Rhône-Poulenc Basic Chemicals Company

(Rhône-Poulenc)

and the Thorn Creek Basin Sanitary District

(TCBSD)

(collectively as petitioners).

Petitioners request an

adjusted standard from

35

Ill.

Adm.

Code

302.208

and 304.105,

as

those sections apply to the discharge of total dissolved solids

(TDS)

and sulfate from TCBSD’s treatment plant to Thorn Creek and

the Little Calumet River.

Rhône—Poulenc desires to construct a new silica production

plant.

This plant would produce a wastewater with high sodium

sulfate content (and hence also high TDS).

Petitioners intend to

treat this wastewater at TCBSD’s wastewater treatment plant

(WWTP).

Although TCBSD has the capability of treating the

projected Rhône-Poulenc discharges to a high degree, petitioners

nevertheless believe that the new loadings to the

WWTP

would

contribute to excursions from the water quality standards for TDS

and sulfate in Thorn Creek and the Little Calumet River.

On this

basis, Rhône—Poulenc and TCBSD contend that an adjusted standard

from Section 304.105 and Section 302.208

is necessary for TCBSD

to be able to accept Rhône—Poulenc projected new discharges.

The Board’s responsibility in this matter arises from the

Environmental Protection Act

(Act)

(415 ILCS 5/1 et seq.)

The

Board is charged therein to “determine,

define and implement the

environmental control standards applicable in the State of

Illinois”

(415 ILCS 5/5(b)) and to “grant

***

an adjusted

standard for persons who can justify such an adjustment”

(415

ILCS 5/28/1(a)).

More generally,

the Board’s responsibility in

this matter is based on the system of checks and balances

integral to Illinois environmental governance:

the Board is

charged with the rulemaking and principal adjudicatory functions,

and the Agency is responsible for carrying out the principal

administrative duties.

Based upon the record before it and upon review of the

factors involved in the consideration of adjusted standards, the

Board finds that petitioners have demonstrated that grant of an

adjusted standard in the instant matter is warranted.

The

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—2—

adjusted standard accordingly will be granted, with conditions

consistent with this opinion.

PROCEDURAL HISTORY

The petition in this matter was filed on February 18,

1994.

The Illinois Environmental Protection Agency

(Agency) filed

its statutory response to the adjusted standard petition on March

22,

1994.

The Agency recommended that the adjusted standard be

granted with conditions.

On April 11,

1994 petitioners filed a response to the

Agency’s recommended conditions.

On May 3,

1994 the Agency filed

an amended response to the original adjusted standard petition.

The Agency therein continued to recommend that the petition be

granted with conditions.

On May

5,

1994 petitioners filed a motion for decision.

The

Board today grants that motion and issues its decision on the

petition.

Petitioners waived hearing; no other person requested a

hearing, and the Board did not require a hearing.

Consequently

no hearing has been held.

ADJUSTED STANDARD PROCEDURE

The Act provides that a petitioner may request, and the

Board may impose, an environmental standard that is different

from the standard that would otherwise apply to the petitioner as

the consequence of the operation of a rule of general

applicability.

Such a standard is called an adjusted standard.

The general procedures that govern an adjusted standard

proceeding are found at Section 28.1 of the Act and within the

Board’s procedural rules at 35

Iii.

Adiu. Code Part 106.

Where, as here,

the regulation of general applicability does

not specify a level of justification required for a petitioner to

qualify for an adjusted standard, the Act at Section 28.1(c)

specifies four demonstrations that must be made by a successful

petitioner:

1)

Factors relating to that petitioner are substantially

and significantly different from the factors relied

upon by the Board in adopting the general regulation

applicable to that petitioner;

2)

The existence of those factors justifies an adjusted

standard;

---

—3—

3)

The requested standard will not result in environmental

or health effects substantially or significantly more

adverse than the effects considered by the Board in

adopting the rule of general applicability; and

4)

The adjusted standard is consistent with any applicable

federal law.

FACILITY DESCRIPTIONS1

Rhône-Poulenc Facility

Rhône—Poulenc owns and operates a plant at 1101 Arnold

Street, Chicago Heights, Cook County,

Illinois.

The facility has

been in operation since 1902 when it was Victor Chemical Works.

Stauffer Chemical Company bought Victor Chemical in 1959.

Rhóne-

Poulenc purchased the Basic Chemicals Division of Stauffer

Chemical Company in December 1987.

The name was officially

changed to Rhóne-Poulenc Basic Chemicals Co.

in September 1989.

The facility currently employs 328 people and manufactures

inorganic phosphate chemicals and sodium bicarbonate, primarily

for food use.

Most of the manufacturing processes involve the

chemical reaction of phosphoric acid with either soda ash or

slaked lime.

All process wastewaters are discharged to TCBSD.

(Pet.

at 2,

4.)

Rhône—Poulenc proposes to add a new silica plant,

at which

it intends to manufacture silica through the reaction of liquid

sodium silicate and sulfuric acid.

The new facility will produce

fused silica,

a powder to be used primarily in the production of

tires, with a secondary use as toothpaste additive.

Rhóne—

Poulenc has proposed this addition at its Chicago Heights plant

because the site is ideally located relative to both the raw

materials necessary for the silica process and the receiving

market.

The silica plant will provide an additional 25

employees, not including construction contractors.

The intent is

to manufacture 20,000 metric tons of silica per year.

(Pet. at

4.)

A process flow diagram for the proposed production of silica

is set forth at Figure 2-4 of Attachment A to the petition.

A byproduct of the proposed silica production process

is

sodium sulfate in aqueous solution.

Part of the sodium sulfate

is recovered,

by there remains a residual which constitutes the

wastestream at issue here.

Four general grades of silica will be produced (termed Z—

160, T-73,

GT, and Z-45).

Z-160

is proposed to be produced 77

1

All information on the facilities

is extracted from the

petition at pp.

1-4.

---

—4—

of the time, T-73 12

of the time, GT 10

of the time,

and Z-45

1

of the time.

The process begins by reacting sodium silicate

in two 14,700 gallon reactors.

Once the reaction is complete,

the silica

is removed from the solution via filtration.

Filtrate

from the production of Z-160 or Z-45 is filtered on one of three

filter presses operated on a batch basis.

For Z-160 and Z-45,

the filtration cycle lasts four minutes, and the filtrate will

typically contain 4.10

TDS

(as sodium sulfate)

in 2,700 gallons

per batch for Z-l60, and 4.75

TDS in 1,600 gallons per batch for

the Z-45.

The filtrate produced during the filtration cycle is

diverted to the mother liquor tank.

The filter cake is then

washed with water and squeezed to remove residual sodium sulfate,

and the filtrate is directed to a 20,000 gallon equalization

tank.

The wash cycle typically lasts 35 minutes and uses 7,900

gallons of water for Z-160, and lasts 60 minutes and uses 13,000

gallons of water for Z-45.

The TDS concentration of these

streams declines toward 0 percent sodium sulfate by the end of

each cycle.

(Pet.

at 4—6.)

Two

rotary vacuum filters are used to remove the silica from

solution for the production of the T-73,

GT, and some of the Z-45

grade silica production.

The rotary filters operate on a

continuous basis during the production of these silica products,

and thereby equalize the resulting filtrate stream from these

filters.

During the production of the T-73, the rotary filter

will produce

a stream of 256 gallons per minute with a projected

TDS concentration of 2.64.

The ST grade silica will produce a

stream of 287 gallons per minute with a projected TDS

concentration of 2.63

while the Z-45 grade silica, when filtered

on the rotary vacuum filters, will produce a stream of 198

gallons per minute with a projected TDS concentration of 1.72.

All streams from the rotary vacuum filters are diverted to the

same 20,000 gallon equalization tank as the filter press wash and

squeeze streams.

The mother liquor tank and equalization tank

flows are combined prior to discharge.

The net result is a

continuous discharge to the sanitary sewer which is relatively

consistent with respect to both sodium sulfate concentration and

flow rate.

(u.)

Although state-of-the art process controls are part of the

proposed facility design, the silica reaction may occur under

less than optimal operating conditions from time to time (e.g.,

fluctuations in pH).

Based upon operating experience at Rhóne—

Poulenc’s silica plant in Collonges,

France, such occurrences are

expected to be infrequent.

Silica precipitated under varying

process conditions has a different crystalline structure, and

therefore different performance characteristics,

than that

required for the intended product.

It is therefore necessary to

divert low-grade silica from the process.

(u.)

Low-grade silica batches leaving the reactor will be

diverted to a 20,000 gallon process drainage tank.

Like normal

---

—5—

batches leaving the reactors (prior to filtration and washing),

these batches will typically contain 4.10 to 4.75

TDS, depending

on the silica being produced.

Because these batches must be

diverted prior to filtration, they will also contain precipitated

silica

(suspended solids).

The stream from the process drainage

tank would be metered into the combined mother liquor

tank/equalization tank flow to maintain a continuous discharge

with respect to sodium sulfate, suspended solids and flow rate to

the sanitary sewer.

(u.)

TCBSD Facility

Wastewaters from the new silica plant are proposed to be

discharged to TCBSD’s WWTP.

The

WWTP

is located in Chicago

Heights, Illinois, and provides wastewater treatment for the

communities of Chicago Heights, Park Forest, Homewood,

South

Chicago Heights,

Steger, and Crete.

The treatment plant was

originally constructed in 1933 and has undergone a number of

construction projects including an expansion to accept flows from

the Homewood Regional Plant.

(Pet. at 7.)

In addition to a population of over 100,000, the TCBSD

WWTP

serves 350 industrial and commercial users.

This industrial and

commercial sector accounts for one percent of the users and 15

percent of the influent flowrate based upon February 1993 values.

The major industrial users are manufacturing facilities,

including steel manufacturing and stamping facilities.

Included

in the industrial users besides Rhóne-Poulenc are Ford Motor

Company, Calumet Industries, Chicago Heights Steel, Rohm

& Hass,

and AL Laboratories.

The TCBSD

WWTP

has been cited as an exemplary treatment

plant, based on its overall efficiency and environmental control,

by both an independent engineering team of the Agency and the

Central States Water Pollution Control Association.

The

WWTP

represents a $40 million investment, including an on—site

laboratory and computer monitoring and control.

A schematic of

the

WWTP

is presented in Figure 2-3 of Attachment A to the

petition.

TCBSD’s

WWTP

has a design average flow of 15.9 mgd and

design maximum flow of 40.25 mgd.

Current dry—weather average

flow is 12.5 mgd, based upon the average of the lowest three

months in 1992.

This is 3.4 mgd below the design average flow of

15.9 mgd.

Thus, the TCBSD contends that the

WWTP

has available

capacity for future growth, including the proposed Rhóne-Poulenc

discharges.

TCBSD is also capable of treating Rhône-Poulenc’s

wastes to the degree necessary to achieve the adjusted standard.

Table 2-3 of Attachment A to the petition, repeated below,

sets forth the projected quality and quantities of the proposed

discharges from Rhône-Poulenc to TCBSD.

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—6—

TABLE

2-3

PROJECTED LOADING FROM PROPOSED

RHONE-POULENC SILICA PROJECT

Annual

Daily

Parameter

Averaae

Maximum

Flow,

gpd

536,000

743,000

TDS, mg/L

18,600

26,500

Sulfate, mg/L

12,500

17,900

TDS,

lbs/day

83,100

91,800

Sulfate,

lbs/day 56,100

62,100

The peak daily discharge of TDS, 26,500 mg/L, takes into account

the wastewater added to the effluent from the process drainage

tank after low—grade silica batches are generated2.

RULES OF

GENERAL

APPLICABILITY

The Board’s general effluent regulations do not include

specific limitations for either TDS3 or sulfate.

However, they

2

The feasibility of other options for the handling of low-

grade silica batches was investigated by Rhóne-Poulenc, including

the feasibility of processing (filtering and drying) the batches

between product line “campaigns”.

Marketing personnel indicated

that there were no known markets for such a product.

Engineering

personnel familiar with the Collonges silica plant have indicated

that reuse of low-grade silica batches

(either processed or

unprocessed)

in the production of the liquid sodium silicate raw

material is not feasible due to its crystalline structure.

Absent an identified market for use/reuse, processed low—grade

silica would require disposal in an off—site landfill.

TCBSD is

capable of accepting an unprocessed,

low—grade silica batch as an

occasional component of the silica plant’s effluent.

Since TCBSD

is capable of removing suspended solids from the silica plant

effluent, and since there is no net increase in TDS discharged to

Thorn Creek, the high opportunity cost of an additional

processing step is not justified.

In addition, TCBSD’s sludge is

used for beneficial land application and does not require

disposal in a landfill.

Finally, TCBSD has determined that the

addition of the proposed silica plant effluent will have no

negative impact on the 1beneficial land application of its sludge.

~

The Board at one time adopted an effluent standard of

3,500 mg/I for TDS

(R70—18,

3 PCB 419, January 7,

1972), but

later repealed it after recognition that the treatment processes

for TDS are expensive,

consume large amounts of energy, and

produce dry solids or brines, that themselves require disposal.

(see Board’s opinion in R76—21,

43 PCB 367, September 24,

1981),

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—7—

do prohibit any discharge that would cause or contribute to a

violation of a water quality standard

(35 Ill.

Adin. Code

304.105);

there are water quality standards for both TDS and

sulfate.

In the instant case, the pertinent water quality standards

are the Board’s General Use Water Quality Standards found at 35

Ill. Adm. Code 302.208.

The General Use Water Quality Standard

for TDS is 1000 mg/L and the General Use Water Quality Standard

for sulfate is 500 mg/L.

The intent of these standards is to

protect aquatic life and to safeguard the quality of waters of

the state for consumptive uses,

including public water supply.

They apply in most of Thorn Creek and the portion of the Little

Calumet River to which Thorn Creek is tributary.

The Board notes that the applicable water quality standard

for TDS in a portion of Thorn Creek already departs from the

1,000 mg/L General Use Standard due to an adjusted standard

granted by this Board in 1991 in Docket AS 89-3k.

The TDS

standard established in AS 89-3

is 2,100 mg/L.

It is applicable

on the reach of Thorn Creek between the mouth of Deer Creek at

mile 8.1 on Thorn Creek River and the U.S. Geological Survey

(USGS)

gaging station at mile 4.2 of Thorn Creek.

The TCBSD

outfall is located upstream of this reach at approximately mile

10.1 of Thorn Creek.

RELIEF REQUESTED

Petitioners request adjusted water quality standards for TDS

and sulfate.

The values that are requested decrease downstream,

as follows:

1.

2,100 mg/L for TDS and 1,000 mg/L for sulfate on

Thorn Creek from the TCBSD outfall (approximately

mile 10.0 on Thorn Creek)

to the USGS Gaging

Station 05536275 in Thornton

(mile 4.2 on Thorn

Creek).

2.

1,900 mg/L for TDS and 850 mg/L for sulfate on

Thorn Creek from the USGS Gaging Station 05536275

to Thorn Creek’s confluence with the Little

Calumet River (mile 0.0 on Thorn Creek)

with final action at 44 PCB 203, December 3,

1981.)

‘~

In the matter of: Petition of the Nutrasweet Com~anvand

Consumers Illinois Water Com~anvfor an Adiusted Standard from 35

Ill.

Adin.

Code 304.105 and 302.208. AS 89—3,

119 PCB 105,

February 28,

1991.

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—8—

3.

1,700 mg/L for TDS and 750 mg/L for sulfate on the

Little Calumet River from Thorn Creek

(mile 25.0

on the Little Calumet River) to the Cal-Sag

Channel

(mile 16.2 on the Little Calumet River).

The existing provision against causing or contributing to

violation of any water quality standard at 35 Ill.

Adm.

Code

304.105 would remain in effect for petitioners.

It the only the

value of the water quality standards for TDS and sulfate that are

at issue hare.

COMPLIANCE ALTERNATIVES

ADplicable Technologies

It is uncontested that order for Rhóne-Poulenc and TCBSD to

consistently comply with the instrealu water quality standards

absent the adjusted standard,

it would be necessary for Rhóne-

Poulenc to pretreat its proposed discharge.

Rhóne—Poulenc

accordingly has analyzed various pretreatment processes and

assessed their viability.

The proposed silica plant wastewater design characteristics

suggest several TDS/sodium sulfate pretreatment removal and

disposal technologies.

Taking into consideration the flow and

variability of the wastewater stream, Rhóne—Poulenc considered

the following options:

1)

Electrodialysis;

2)

Evaporation;

3)

Evaporation with Mechanical Vapor Recompression

(MVR);

4)

Ion Exchange

5)

Nanofiltration with Evaporation with MVR; and

6)

Reverse Osmosis.

(Pet.

at 8.)

Rhóne—Poulenc states that it was informed by vendors that

electrodialysis, ion exchange, and reverse osmosis were not

suitable for its wastestream due to the high sodium sulfate

concentration, and that evaporation schemes would require

multiple effects

(or evaporators).

Rhóne—Poulenc also learned

that electrodialysis has not yet been adequately developed for

this type of industrial use.

(Pet. at 8.)

Rhóne—Poulenc

therefore evaluated the remaining technologies:

1)

Quadruple-Effect Evaporation;

2)

Double-Effect Evaporation with MVR; and

3)

Nanofiltration with Double—Effect Evaporation

with NVR.

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—9—

Quadruple-Effect Evaporation (Alternative 1):

This

technology produces dry sodium sulfate from a dilute aqueous

solution.

This result is achieved by concentrating and

subsequently crystallizing the sodium sulfate out of the process

liquor.

Four evaporators (effects) are required, and the feed

must be pumped through them in series.

The aqueous feed stream

is preheated prior to its introduction into the evaporators.

Backward feed is employed (dilute liquor enters the last and

coldest effect, and leaves concentrated in the first effect,

which is at the highest temperature).

The feed stream is

concentrated in the evaporators.

Crystallization occurs in the

first effect,

where the feed undergoes further concentration.

Centrifugation and drying steps follow evaporation and

crystallization in the evaporators.

(Pet. at 9; Attachment B.)

Double-Effect Evaporation with MVR (Alternative 2):

This

technology also produces dry sodium sulfate from a dilute aqueous

solution by concentrating and subsequently crystallizing the

sodium sulfate out of the process liquor.

However,

for energy

conservation reasons, both evaporator and crystallizer vessels

are used,

as well as a centrifugal compressor.

The compressor

compresses the vapors generated in the evaporator and

crystallizer vessels to a higher pressure, and these vapors are

then used as the heating steam in the evaporator and crystallizer

heating elements.

Two evaporators are required.

The aqueous

feed stream is preheated prior to its introduction into the

evaporators where it is concentrated.

The concentrated feed

stream is then pumped to a crystallizer, where the feed undergoes

further concentration.

Evaporation of water after concentration

in the crystallizer results in sodium sulfate solids

precipitation.

This is achieved by heating the slurry in the

crystallizer (with steam supplied by the compressor).

Centrifugation and drying steps follow evaporEtion and

crystallization.

(Pet at 9; Attachment C.)

Nanofiltration with Double-Effect Evaporation with MVR

(Alternative 3):

This technology is a membrane process which

lies between ultrafiltration

(UF) and reverse osmosis

(RO)

in

terms of salt rejections.

As applied to Rhóne—Poulenc’s process,

this technology yields a four-fold concentration of the sodium

sulfate with approximately a two percent leakage of the permeate

stream.

Thus,

75 percent of the feed water volume would be

“sodium sulfate free,” and 25 percent of the feed water would be

enriched in sodium sulfate and, therefore,

suitable for

evaporation

(to dry and concentrate the sodium sulfate).

The

feed water must be free of any suspended solids and silica must

be below 25 ppm in the feed water to prevent precipitation.

Therefore, pretreatment via clarification followed by multimedia

filtration (and possibly carbon filters)

is also required.

(Pet.

at 10; Attachment D.)

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—10—

Comparative Costs

A summary comparison of the demonstrated sodium sulfate

removal systems discussed above is presented by petitioners as

Attachment E to the petition.

Attachment E also contains a

summary including estimated capital and annualized capital and

operating costs for the three alternatives studied5.

These

capital and total annualized costs are as follows:

Capital Cost

Annual Cost

Compliance Alternative

(in millions)

(in millions)

Quadruple-Effect

$

9.8

$3.3

Evaporation

Double-Effect Evaporation

$10.8

$3.5

with MVR

Nanofiltration with Double-

Effect Evaporation

& MVR

$

8.2

$1.3

The benchmark against which petitioners compare these costs

is the cost of sending the Rhóne-Poulenc wastewaters to TCBSD

without additional pretreatment.

Since TCBSD has adequate

capacity to handle Rhóne—Poulenc’s wastewaters, the no-

pretreatment strategy has no significant capital cost; only

annual operating costs are significant.

TCBSD charges $0.80/bOO

gallons of wastewater treated.

Since Rhône—Poulenc’s annual

average discharge is projected to be 195,534,720 gallons, the

operating costs

(and annual costs)

would be approximately

$156,428 per year.

(See Attachment E).

Rhóne-Poulenc observes that the first two pretreatment

strategies

(see table above)

would be more than 21 and 15 times,

respectively, the cost of simply discharging to the WWTP; these

strategies,

it is contended, would accordingly add 14 percent and

10 percent, respectively, to the cost of the product silica.

Alternative

3

(Nanofiltration with Double-Effect Evaporation with

MVR), although it is the most economical pretreatment system,

is

nevertheless more than

8 times more costly than simple

WWTP

treatment and would add approximately 5 percent to the cost of

the product silica.

(Pet.

at 11.)

~ All of the pretreatment alternatives produce dry sodium

sulfate, which requires ultimate disposition, including possible

disposal.

However, disposal costs are not included in the

summary figures since sodium sulfate is a commodity chemical with

some resale value

(i.e., the possibility exists that a beneficial

use might be identified which would eliminate the need for

disposal).

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—11—

On this basis, Rhóne-Poulenc contends that, although

technically feasible, even the most economical solution for

pretreatment sodium sulfate removal would result in considerably

higher costs to Rhóne—Poulenc.

Rhóne—Poulenc contends that such

cost increases would result in a non—competitive price for its

silica and would force it to utilize an alternative location for

this plant.

(Pet. at 11.)

HEALTH

AND

ENVIRONMENTAL EFFECTS

Much of the analysis of health and environmental effects

present in the instant record is provided in a study prepared for

Rhóne-Poulenc and TCBSD by Huff

& Huff,

Inc.

The Huff

& Huff

study is presented in a report entitled “Environmental Assessment

for the Proposed Total Dissolved Solids Discharge from the Thorn

Creek Basin Sanitary District”, which is Attachment A to the

petition.

Huff

& Huff’s assessment includes a review of Rhóne—

Poulenc’s proposed silica production processes,

as well as the

existing treatment processes and influent and effluent flows at

TCBSD’s WWTP.

Based upon that review Huff

& Huff was able to

project the maximum and average TDS and sulfate concentrations

and loadings which would be discharged by TCBSD upon completion

of Rhóne-Poulenc’s proposed facility.

Huff & Huff also reviewed the flows and water quality of

Thorn Creek from Thorn Creek’s headwaters at Monee to its

confluence with the Little Calumet River, and the flows and water

quality of the Little Calumet River between Thorn Creek and the

Calumet-Sag Channel.

With these data, Huff

& Huff was able to

model the projected water quality for TDS and sulfate in various

reaches of Thorn Creek and the Little Calumet River.

Huff

& Huff reviewed available acute toxicity data to

determine whether the projected water quality would be

anticipated to result in any acute toxicity, and it retained Ips,

Inc., to perform chronic toxicity testing using Thorn Creek water

with various levels of TDS and sulfate added to determine whether

any chronic toxicity would be anticipated.

(Pet. at 13—14.)

Lastly, Huff

& Huff performed a biological assessment of

Thorn Creek.

This included the sampling of macroinvertebrates

and fish in Thorn Creek both upstream and downstream of the TCBSD

outfall.

Using these data along with other existing data on the

stream quality, Huff

& Huff determined the stream’s

---

—12—

Macroinvertebrate Biotic Index

(MBI)

and its Index of Biotic

Integrity (IBI)6.

Based on these studies, Huff

& Huff conclude that Thorn

Creek in the vicinity of the TCBSD outfall,

including both

upstream and downstream from the outfall, classifies as a

“Limited Aquatic Resource” stream.

(Attachment A at 80.)

This

is a classification common to urban streams.

In detail, there is suggestion,

based on slightly lower

MBI

values, of better water quality below the TCBSD outfall than

above

(8.3 to 7.3).

However, the IBI values of two sampling

stations above the outfall and two below the outfall were found

to be identical at 28.

(Attachment A at 78-80.)

Huff

& Huff also concluded that,

in light of the urbanized

nature of Thorn Creek’s basin, there is limited potential for

future improvements in the aquatic community of Thorn Creek.

Similar conclusions were drawn by Michael Ander of Dames

& Moore

(1990)

during an environmental impact study of Deer Creek.

(Attachment A at 104).

Deer Creek,

a tributary of Thorn Creek,

was stated as having limited potential uses due to the limited

amount of water and habitat available.

The Agency noted a

similar water quality classification in its annual water quality

report

(IEPA 1992).

(~~)

The quality of the Little Calumet

River was classified in that report as a nonsupport waterway, a

lower quality than in Thorn Creek.

(Pet.

at 14-15.)

The Agency disagrees with Huff and Huff’s conclusion that

Thorn Creek has limited potential for improvement.

The Agency

believes that Thorn Creek has the habitat potential to be

classified as a “Highly Valued Aquatic Resource”,

even though it

may not be so classified at present; this is two classification

steps higher than the classification claimed by petitioners.

The

Agency is concerned that allowing TDS that are too high may cause

additional stress on the aquatic biota and accordingly delay

achievement of the higher status.

(Am. Rec.)

Under median flow conditions in Thorn Creek and the Little

Calumet River, and average Rhóne—Poulenc loadings, petitioners

predict that the 500 mg/L sulfate standard would not be exceeded

~ MBI values are used by the Illinois Environmental

Protection Agency to assess stream water quality.

These values

range from 1 to 11, with

1 representing the best water quality

and 11 the worst.

(Attachment A at 63).

IBI values are also

used by the Illinois Environmental Protection Agency to assess

stream quality and are based upon the fish assemblage at a given

site.

Values of this index range from 12 to 60, with 60

representing the best stream quality and 12 the worst.

(Attachment A at 64).

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—13—

in any reach,

and that the existing TDS water quality standard

would be exceeded only in the first few miles below the TCBSD

outfall.

(Pet.

at 15.)

However, under worst—case conditions, Huff

& Huff’s modeling

studies indicate that both TDS and sulfate concentrations would

exceed the 1,000 and 500 mg/L water quality standards for a

distance well downstream of TCBSD outfall.

Worst—case would

occur under the conditions of low stream flow and peak loadings

from Rhône—Poulenc.

The modeled worst—case concentrations are as

follows, with concentrations in mg/L:

Parameter

Reach #1

Reach #2

Reach #3

Reach #4

TDS

2,120

2,120

1,920

1,680

Sulfate

980

970

850

760

Reach #1

=

Thorn Creek mile 10.1 to 8.1

(TCBSD

outfall to Deer Creek); Reach #2

=

Thorn Creek

mile 8.2 to 4.2 (Deer Creek to USGS Thornton

Gauge); Reach #3

=

Thorn Creek mile 4.2 to 0.0

(USGS gauge to mouth of Thorn Creek); Reach #4

=

Little Calumet River mile 25.0 to 16.2

(Thorn

Creek to Cal-Sag Channel)

(Table 7-3 of Attachment A at 102).

Petitioner’s contend that, whether one looks at either the

median or worst—case conditions,

the projected increases in TDS

and sulfate are not likely to have any adverse environmental

impact.

(Petition at 15.)

In reaching this conclusion,

petitioners direct attention to the “uses” that underlie the

General Use Standards, and how studies done on the Thorn Creek

area and aquatic toxicity support the conclusion of no adverse

environmental impact.

Petitioners observe that the General Use Water Quality

standards for TDS and sulfate were intended to preserve three

specific “uses”: aquatic life,

crop irrigation,

and public water

supplies.

As regards aquatic life,

petitioners observe that Huff and

Huff’s review of available acute and chronic toxicity data

indicates that no adverse impact on aquatic life is to be

expected at concentrations of TDS and sulfate projected for the

worse—case scenario (i.e.,

2,120 and 980 mg/L,

respectively)

(Chapter

5 of Attachment A).

However, due specifically to the

lack of literature regarding chronic toxicity levels for sodium

sulfate, Huff and Huff also performed original chronic toxicity

bioassays.

These used Thorn Creek water, collected downstream of

the

WWTP

discharge, to evaluate the effects of increasing levels

---

—14—

of sodium sulfate on the water flea (Ceriodaphnia dubia)

and the

fathead minnow

(Pimephales promelas).

The Thorn Creek water was

initially analyzed for sulfate and then spiked with sodium

sulfate to obtain seven targeted levels of sulfate.

The targeted

levels are percentages of the projected peak effluent sulfate

concentration of 980 mg/L.

The sulfate levels examined are as

follows

(Pet.

at 17; Attachment A at 56):

Measured

of Projected

Measured

Sulfate

Peak Effluent

TDS

Level.

ncl/L

Sulfate

Level. m~/L

1,300

133

2,500

1,270

130

1,010

103

873

89

852

87

1,940

710

72

595

61

At none of the test levels was chronic toxicity observed in

either the waterflea or fathead minnow.

Petitioners next observe that a TDS water quality limit of

2,100 mg/L was supported for Thorn Creek below the TCBSD outfall

in the AS 89-3 proceeding (see preceding text and footnote)

in

part because of the Limited Aquatic Resource Classification of

Thorn Creek, and in consideration of the low level of toxicity of

TDS.

A biological assessment performed in support of the AS 89-3

petition concluded that a TDS water quality level of 3,000 mg/L

would not cause any undue stress to the aquatic life

(Dames &

Moore,

1981).

(Attachment A at 104).

Petitioners state that

this opinion was supported by the Agency (Studer,

1990).

(a.)

A toxicity investigation by Reed and Evans

(1981)

also concluded

that water quality sulfate levels of 1,000 mg/L would not be

harmful to the aquatic biota.

(Id.)

Based upon these results, along with the literature

regarding acute toxicity, petitioners conclude that there should

be no acute or chronic toxicity impact upon aquatic life in Thorn

Creek or the Little Calumet River from the proposed Rhóne-Poulenc

project.

Moreover, historical TDS concentrations are within the range

here being considered as worst—case.

(Attachment A at 22).

In

the early 1980’s, TDS concentrations in Thorn Creek averaged

1,559

ing/L.

(u.)

In recent years TDS levels have decreased,

---

—15—

apparently as a consequence of communities shifting from well-

water to Lake Michigan water7.

As regards cropping activity, petitioners observe that the

areas surrounding Thorn Creek from TCBSD’s outfall to the merger

with the Little Calumet River are limited to forest preserves and

developed areas.

Only two owners/operators grow crops

in the

Deer Creek Basin.

Neither of these owners/operators conduct crop

irrigation.

No commercial crops are grown,

and no evidence of

water withdrawal from Thorn Creek for irrigation of crops was

observed during the stream study performed by Huff

& Huff.

(Attachment A at 98).

As regards public water supply use, Huff

& Huff concludes

that there would be no adverse impact upon public water supplies.

Communities along Thorn Creek downstream of TCBSD’s outfall all

derive their water supply from Lake Michigan.

Communities

including Chicago Heights, Flossmoor, Harvey, Glenwood, Homewood,

South Holland, Thornton,

Caluinet City, Dolton, and Lansing were

all contacted and confirmed that each municipal water supply

system currently uses Lake Michigan water.

Most water supply

wells have been capped and taken out of service in these

communities.

Based upon this investigation, petitioners conclude

that Rhóne-Poulenc’s proposed project will not increase TDS or

sulfate in any public water supply.

(Attachment A at 98).

As a final facet of their position on health and

environmental impact, petitioners assert that adverse cross—media

impacts would result in the absence of Rhône—Poulenc’s ability to

discharge to TCBSD.

For example, pretreatment of TDS would

produce dry sodium sulfate that would have to be disposed on land

if it could not be sold,

creating the potential for land

pollution and for water pollution should

it leach from a landfill

to groundwater.

Also,

pretreatment would necessitate increased

energy consumption, which not only would deplete energy

resources,

but also potentially would result in air pollution

from the generation of the necessary energy.

Thus, while TDS and

sulfate levels in Thorn Creek and the Little Calumet River would

increase under the proposed adjusted standard, no adverse

environmental impact would result.

Conversely,

if compliance

with the generally applicable standards were to be required,

there might be some adverse cross-media impacts.

(Pet.

at 18—

19.)

~ Lake Michigan has a lower TDS concentration than most

groundwaters.

Lake Michigan water is also soft water, and many

persons have ceased using water softeners as Lake Michigan water

becomes available.

This decreases TDS discharges to Thorn Creek.

---

—16—

CONSISTENCY WITH

FEDERAL LAW

Both the Agency and petitioners agree that the Board’s water

quality standards have been approved by U.S. EPA and are

consistent with the requirements of the Clean Water Act.

Thus,

in a sense,

these standards exist pursuant to Section 303(a) of

the Clean Water Act.

(Am.Rec. at 2; Pet. at 3.)

Rhóne-Poulenc and TCBSD do not believe that the granting of

the requested adjusted standard would be violative of any

provisions of the Clean Water Act.

The requested relief is

predicated solely upon potential violations of the TDS water

quality standard and the standard for sulfate.

There are no

applicable federal or state TDS or sulfate effluent standards.

The adjusted standard is also consistent with federal law in

that under 40 C.F.R. 131.4,

“states are responsible for

reviewing,

establishing and revising water quality standards”.

These standards are to be protective of the designated uses.

40

C.F.R.

131.5(b).

Under 40 C.F.R.

131.4 “states are responsible for reviewing,

establishing and revising water quality standards.”

In turn,

pursuant to 40 C.F.R.13l.5, “EPA is to review and to approve and

disapprove the State-adopted water quality standards.”

These

standards are to be protective of the designated uses

(S131..5(b))

and, where those uses are not protected, this must be supported

by “appropriate technical and scientific data and analyses.”

(Sl31.5(d)).

A state is allowed to remove a designated use,

which is not an existing use,

if

it “can demonstrate that

attaining the designated use is not feasible” because of several

enumerated causes.

(S131.10(g)).

Petitioners believe that the granting of this adjusted

standard will not impair any beneficial use of the receiving

stream.

This, they believe, has been established by the Huff &

Huff study discussed above.

Federal Procedural Reauirements

The Board’s grant of the adjusted standard requested herein

arguably requires some mechanism for public participation

pursuant to 40 C.F.R.

§131.20(b).

However, Rhóne-Poulenc and

TCBSD do not believe that a hearing is necessary and agree with

the U.S.

EPA’s current position that if authorized states follow

approved state procedures, those procedures are federally

acceptable.

Under federal law, public participation includes a public

hearing for the purpose of reviewing the proposed standard in

accordance with the provisions of state

law, the U.S. EPA’s water

quality management regulation

(40 C.F.R.

130.6(b)) and the U.S.

---

—17—

EPA’S public participation regulation

(40 C.F.R. Part 25).

Notice of such hearing must be well-publicized and must be given

at least forty-five

(45) days prior to the date of the hearing.

The notice must identify the matters to be discussed and should

include a discussion of the Board’s tentative determination on

major issues

(if any) and procedures for obtaining further

information.

Reports, documents and data relevant to the

discussion at the public hearing must be available to the public

at least thirty

(30) days before the hearing.

40 C.F.R.

S25.5(b).

At the hearing, the Board must inform the audience of

the issues involved, considerations the Board will take into

account, and information which is particularly solicited from the

public.

40 C.F.R. §25.5(e).

Rhóne-Poulenc and TCBSD understand that the U.S. EPA has

recently changed its position regarding the federal requirement

for a hearing in state proceedings involving the potential

amendment of water quality standards.

The U.S. EPA formerly took

the position that hearings were required in all such proceedings.

Rhône-Poulenc and TCBSD understand, however, that U.S.

EPA’s

present position is that the fulfillment of the state

requirements for notice and hearing is all that is required and

that if the state allows for waiver of the hearing requirement,

hearing can be waived without conflict with federal laws.

35

Ill.

Adm. Code 106.705(j)

allows for waiver of hearing.

The Agency agrees that the requested relief is consistent

with federal law.

(Ain.Rec. at 14.)

ADJUSTMENT OF WATER QUALITY STANDARDS

The request placed before the Board in this matter involves

an alteration of the instream General Use Water Quality

Standards.

If granted, the request would raise the water quality

standards for TDS and sulfate over a 18.9—mile length of waterway

that drains a basin of 291 square miles8.

Most of the basin is

urbanized, and industrial development is significant.

The basin

is mostly within Cook County, but also includes parts of Will

County,

Illinois, and Lake County,

Indiana.

The justification is based on the particular needs and

economics faced by Rhóne-Poulenc and TCBSD, and upon the limited

negative health and environmental effects of the particular

quality and quantity of the discharges anticipated as a

consequence of Rhóne—Poulenc’s discharge.

8

The drainage area of the Little Calumet River above the

Calumet-Sag Channel is 291 square miles.

The drainage area of

Thorn Creek alone is 107 square miles.

---

—18—

At the onset, the Board observes that it believes that

Rhóne-Poulenc and TCBSD have adequately justified relief based

upon their particular circumstances.

The Board further notes,

however, that the relief that is being asked of the Board could

have the effect of giving other dischargers located on these

streams essentially the same relief given to Rhóne-Poulenc and

TCBSD, even though other dischargers have not made (and may well

not be able to make)

the same demonstrations.

To understand this circumstance, it is necessary to

recognize first that for water at concentration X, any additional

amount of water at concentration X may be added, and the

resultant concentration will remain at

X.

Thus, for example

under the relief requested,

if TCBSD were discharging such as to

cause Thorn Creek to have a 2,100 mg/L TDS concentration at the

WWTP

outfall, all other sources of discharge between the TCBSD

outfall and the USGS gauge at Thornton could have a TDS

concentration of 2,100 mg/L and the resultant mixed concentration

through the whole reach would remain 2,100 mg/L.

Moreover,

it is within the mathematics of the situation

that,

if TCBSD were to discharge so as to cause Thorn Creek to

have a TDS concentration below 2,100 mg/L

(as the Agency would

have TCBSD strive for), all of the other sources of discharge

between the outfall and the USGS gauge could have a TDS

concentration above 2,100 mg~Lwithout causing violation of a

2,100 mg/L instream standard

Based on these considerations, the Board finds that the

potential license that would result from altering the water

quality standards as Rhóne-Poulenc and TCBSD plead is beyond the

justification that has been presented to the Board.

In a regular

rulemaking, either general or site—specific, the Board would not

likely amend a water quality standard for so large an active

stream segment without knowing more about other dischargers and

sources of flow.

Here we don’t know how many or what kind of

dischargers there are now, or are likely to be in the future;

neither do we know the nature of the TDS that might be

contributed by them or the impact their loadings might have.

The Board believes that the resolution of this matter is to

let the water quality standards of 35 Ill.

Adin.

Code 302.208

remain unaltered,

and to grant the adjusted standard solely to

the “cause or contribute to a water quality violation” provision

of 35 111.

Adju. Code 304.105 u~to the concentration limits

~ro~osed by petitioners.

We intend that this stratagem present

no practical consequences for Rhâne—Poulenc and TCBSD different

~ The Board notes that it is here not making judgement on

whether potential other discharger’s permits would or should

allow for such discharge.

---

—19—

from those which would flow from modification of the water

quality standards: TCBSD would have an exception to causing or

contributing to water quality violations up to the concentration

limits proposed,

Conversely, we explicitly intend that this stratagem have a

different effect than that which would follow from modification

of the water quality standards as regards other existing or

potential dischargers: these dischargers would have no increased

license or potential for discharge based on the case made by

Rhône-Poulenc and TCBSD.

The Board is aware that in the short history of adjusted

standards relating to discharges to water,

it has been the

practice, unlike what we do here, to modify the water quality

standards.

The Board does not here reconsider the merits of

these other decisions.

We do believe that the instant matter is

distinguishable on the basis of the nature of the drainage basin

and dischargers to it, and on the particular character of the

contaminants at issue.

On this basis, we conclude that today’s

course of action is correct as regards Thorn Creek and the Little

Calumet River.

The Board is also aware that water quality standards have a

two-fold purpose.

They stand as the limiting measure of quality

that is expected of a waterbody.

They also serve, however,

through the NPDES permitting process, as the basis of

determination of effluent limits.

Since we here do not change

the water quality standards, we are interested that TCBSD not

encounter NPDES difficulties that would deny the relief they have

justified.

We desire that the additional conditions to the grant

of adjusted standard, as we next discuss, will form the basis for

granting TCBSD’s NPDES permit consistent with the relief granted

in this adjusted standard.

ADDITIONAL CONDITIONS

It is agreed by both petitioners and the Agency that grant

of adjusted standard be conditioned upon two general

considerations:

(1) that the adjusted standard terminate if the

justification for it terminates, and

(2) that operations at TCBSD

and Rhóne-Poulenc be such as to minimize the TDS and sulfate

loadings, and hence their impact on the receiving waterway.

The Board accepts that conditions effectuating these ends

are necessary.

The Board accordingly will add them as conditions

of grant of the adjusted standard.

In general, the Board has

attempted to preserve the actual language recommended to it by

petitioners and the Agency, modifying only to accommodate the

issue of the water quality standards discussed above, and a few

grammatical matters.

---

—20—

There are two matters regarding the conditions that warrant

observation.

The first is that the Agency proposes, and the

petitioners accept, that the adjusted standard be effective only

if Rhóne—Poulenc actually constructs and operates the planned

facility, and that the adjusted standard terminate if Rhóne-

Poulenc ceases to operate the facility or other certain process

changes occur such that the relief is no longer needed.

(Am.

Rec. at 15.)

In the proposed language directed to this

condition,

the parties recommended that the Board be served with

periodic status reports assessing RhOne—Poulenc’s progress, as

well as monitoring reports.

The Board has deleted these service

provisions as unnecessary.

It is sufficient that the Agency,

as

the administrative agency, be served, and the Board be re—entered

in the process only when its adjudicative or rulemaking

authorities are required.

The second matter is related to calculation of load limits.

The Agency believes, and petitioners accept, that the adjusted

standard should be granted only with conditions intended to

maintain the TDS and sulfate concentrations at the lowest values

consistent with allowing Rhóne—Poulenc to construct and operate

its proposed silica facility.

(Am. Rec.

at 5.)

This would occur

by the imposition of load limits, as based on petitioners

Attachment

5.

The Agency believes that absent actual discharge

data,

it is appropriate to use these projected loadings as

monthly averages.

(~.

at 6.)

The Agency further recommends that monitoring be done to

establish limits based on actual operating data, utilizing a

procedure also used by petitioner’s consultant and included in

Attachment 5.

(Am. Rec. at 7.)

Petitioners agree to the load limit provisions recommended

by the Agency with the exception of “the development and

potential appeal of daily maximum and revised monthly average

load limits as set forth

in requested tc)ondition #6 and as

discussed at pages

10 and 11 of the Agency’s

amended

response”.

(Motion for Decision at 1.)

In their reply to the Agency’s response, petitioners state

that there should be some mechanism for petitioners to appeal the

load limits determined by the Agency from the monitoring data.

While the proposed procedure for determination of such limits is

acceptable to petitioners, petitioners are concerned about

possible disagreement in the future.

Petitioners recommend that

the Board include language concerning the right to appeal in the

order or opinion in this matter, or alternatively, that the Board

retain jurisdiction and provide for disputes over the propriety

of the limits to be brought before the Board by motion.

Petitioner’s point to Section 5(d)

of the Act as authority for

---

—21—

bringing an appeal of the Agency’s determination of limits10.

(Pet. Reply at 3.)

The Agency does not believe including language concerning

the right to appeal is necessary or desirable.

The Agency

believes that including such language would set a precedent for

subsequent adjusted standards and could result in more conflict

over acceptable language, and may result in language conferring

“rights”

that

do not exist pursuant to the Act.

(Am. Rec.

at 10-

11.)

The Board believes that is unadvisable for it to retain

jurisdiction and consequently leave this docket open for years to

come simply on the prospect that petitioners may bring a motion

challenging the limits determined by the Agency.

The Board

further concludes that whether or not appeal rights language is

included in the order or opinion in this matter, jurisdictional

issues concerning subsequent appeals would be determined at the

time of the filing of any future appeal based on the information

in that future petition and the language of the Act at the time

of the filing of that petition.

The Board also notes that

condition #6 has a provision that requires the Agency to revise

TCBSD’s NPDES permit consistent with this adjusted standard,

“including such load limits and monitoring requirements as are

required by this adjusted standard”.

Denial of NPDES permits or

a grant of permit with conditions are currently appealable to the

Board under Section 40 of the Act.

CONCLUSION

The Board finds that petitioners,

in cooperation with the

Agency, have demonstrated that grant of adjusted standard is

warranted.

The Board accordingly will grant the adjusted

standard consistent with this opinion.

The Board additionally observes that in this instant action

we attempt to find resolution between granting the relief that

Rhône-Poulenc and TCBSD have justified and the larger effects

that would seem to be consequent to a modification of the water

quality standards.

If our resolution should prove to be

10

Section 5(d)

of the Act states “(t)he Board shall have

authority to conduct hearings upon complaints charging violations

of this Act or of regulations thereunder,

upon petitions for

variances; upon petitions for review of the Agency’s denial of a

permit in accordance with Title X of this Act; upon other

petitions for review of final determinations which are made

pursuant to the Act or Board rule and which involve a subject

which the Board is authorized to regulate; and such other

hearings as may be provided by rule”.

---

—22—

unworkable,

or should there be an alternative more commendatory

than that which we here provide, the Board as always stands

willing to give reconsideration.

This opinion constitutes the Board findings of fact and

conclusions of law in this matter.

ORDER

The Thorn Creek Basin Sanitary District (TCBSD) and Rhóne-

Poulenc Basic Chemicals Company

(Rhône—Poulenc)

are hereby

granted a partial adjusted standard from 35 Ill. Adm. Code

304.105.

Pursuant to this grant,

35 Ill. Adm. Code 304.105 does

not apply to discharges from TCBSD’s wastewater treatment plant

located at mile 10.1 of Thorn Creek as regards total dissolved

solids

(TDS)

or sulfate for TDS or sulfate instreain

concentrations that are less than or equal to:

2,100 mg/L for TDS and 1,000 mg/L for sulfate in Thorn

Creek from the TCBSD wastewater treatment plant

discharge to the U.S. Geological

(USGS) Survey Gaging

Station 05536275.

1,900 mg/L for TDS and 850 mg/L for sulfate in Thorn

Creek from the USGS Gauging Station 05536275 to Thorn

Creek’s confluence with the Little Calumet River.

1,700 mg/L for TDS and 750 mg/L for sulfate in the

Little Calumet River from Thorn Creek to the Cal-Sag

Channel.

This grant of adjusted standard is contingent upon each of the

following conditions being met:

1.

The adjusted standard is effective upon the

commencement of operation of the silica production

facility proposed by Rhóne-Poulenc.

Rhóne-Poulenc

shall provide the Agency notice of its decision to

construct the silica production facility, and shall

provide an expected timetable for completing

construction of the silica facility to the Agency, as

soon as this information is available to Rhóne—Poulenc.

Further, Rhône-Poulenc shall provide the Agency with

notice of any production process changes or similar

changes that eliminate the need for continued relief as

soon as this information is available to Rhóne—Poulenc.

2.

The adjusted standard terminates in the event that

production process changes or other similar changes

occur that eliminate the need for continued adjusted

---

—23—

standard relief.

Relief will terminate upon filing of

any such notice with the Board.

3.

Until the monthly load limits described in condition 4,

below, become effective, TDS discharges and sulfate

discharges from Rhône-Poulenc’s production facility may

not exceed, on

a monthly average basis,

91,800 pounds

per day

(lbs/day) and 62,100 lbs/day, respectively.

4.

PJiône-Poulenc shall monitor its TDS and sulfate

discharges to TCBSD seven days a week the first three

years of operation of its silica production facility,

and shall submit this information to the Agency at the

end of the first three years of discharge from its

silica production facility.

At the discretion of the

Agency, the recording of conductivity may satisfy this

requirement two

(2) days per week,

if Rhóne—Poulenc can

document the relationship between TDS and conductivity

and sulfate and conductivity.

The Agency shall

determine daily maximum load limits and adjust monthly

average load limits for TDS and sulfate using the

method described in the Agency’s response to the

adjusted standard petition of Rhóne-Poulenc and TCBSD

filed in AS 94-7.

The Agency shall notify Rhóne-

Poulenc and TCBSD of these limits in writing.

In

addition to the load limits described in paragraph

3 of

this adjusted standard, Rhône—Poulenc shall not exceed

these daily maximum and monthly average load limits for

TDS and sulfate once determined by the Agency.

5.

Rhóne-Poulenc and TCBSD shall perform a

Macroinvertebrate Biotic Index

(MBI)

survey of Thorn

Creek prior to Rhóne-Poulenc discharging from its

silica production facility to TCBSD.

A second MBI

survey shall be conducted twelve to twenty-four months

after Rhóne—Poulenc begins to discharge from its

expanded facility.

The second survey shall be

performed during the same month of the year as the

first survey and use the same sampling locations as in

the first survey so that a before—discharge and after—

discharge comparison can be made of Thorn Creek.

The

results of these surveys must be submitted to the

Agency within sixty

(60) days of their completion.

6.

Rhóne-Poulenc shall obtain all required permits from

the Agency prior to the start of operation of its

silica production facility, including an Agency permit

for the sewer connection of the silica production

facility to TCBSD.

The Agency shall revise TCBSD’s

National Pollutant Discharge Elimination System (NPDES)

permit consistent with this adjusted standard,

including such load limits and monitoring requirements

---

—24-

as are required by this adjusted standard.

Rhóne-

Poulenc and TCBSD shall perform all monitoring

requirements for the discharge of TDS and sulfate, and

monitoring

of the water quality in Thorn Creek and the

Little Calumet River,

as may be required pursuant to

TCBSD’s NPDES permit.

IT IS SO ORDERED.

Section 41 of the Environmental Protection Act (415 ILCS

5/41

(1992) provides for the appeal of final Board orders within

35 days of the date of service of this order.

The Rules of the

Supreme Court of Illinois establish filing requirements.

(See

also 35 Ill. Adm. Code 101.246, Motions for Reconsideration)

I, Dorothy M.

Gunn,

Clerk of the Illinois Pollution Control

Board, hereby certify that the above

inion and order was

adopted on the

~~~‘~-day of

____________________,

1994, by

avoteof

_____________.

_~*_~z_1

~t,

~I

Dorothy M.

~nn,

Clerk

Illinois Pql~tutionControl Board