ILLINOIS POLLUTION CONTROL BOARD

June

10,

1982

MOBIL OIL COMPANY,

)

Petitioner,

)

PCB 82—36

ILLINOIS ENVIRONMENTAL PROTECTION

AGENCY,

)

Respondent.

OPINION AND

ORDER OF

THE BOARD

(by

J.D. Dumelle):

On March 31, 1982 Mobil Oil Company filed a petition for

variance for a period of two years from Rule 406 of Chapter 3:

Water Pollution,

as

it

relates to

the

3.0

mg/I

ammonia nitrogen

standard applicable

to its Joliet Refinery~s

discharge into the

Des Plaines River.

On

May 26, 1982 the

Illinois Environmental

Protection Agency

(Agency)

filed

a recommendation that the variance

be granted subject

to

certain

conditions.

Hearing was waived and

none was held.

Mobil owns and

operates a

conventional fuels petroleum

refinery with a rated capacity of 180,000 barrels per day

located in Will County.

Stormwater,

noncontact cooling water

and process water are discharged

from

the facility into the

Des Plaines River.

The process water and contaminated

surface

runoff

(2.74 MGD) are treated in Mobiles wastewater treatment

plant

(WWTP) which consists of an API separator, a dissolved

air

flotation unit, an equalization basin for primary treatment and

a conventional activated sludge facility for secondary treatment.

Treated effluent from the final clarifier is routed through a

4.9

million gallon guard basin

where it is

retained an average of

45

hours and then aerctted in the final aeration cone prior to release

to the Des Plaines River,

The

effluent meets all discharge standards

other than ammonia nitrogen.

Mobil has been granted three previous variances

from the

ammonia nitrogen standard of Rule 406

(PCB 77-22, PCB 78-97,

and

PCB

80—54).

In PCB 80—54

(39

PCB

50,

July

10,

1980)

variance was

granted until July

1,

1982,

subject to certain conditions including

an ammonia nitrogen effluent limitation of

25

mg/l as

a monthly

average and

40

mg/l daily maximum concentration.

47~271

---

During the period of ~:re~i~es

variance

Mobil

has

substan-

tially

complied

~iib all

ths ben~and conditions of

variance.

Ammonia

nitrogen

effluent

daLa

submiLted

:Ln

response

to

thaL

order

shows

an

overall

range

of

~

mg/i,

an

average

monthly

range

of

6—28

mg/l,

and

an

overall

aver~~eof

15

mg/i.

The

overall

average

ammonia

reduction from

:Lnf:lueet

levels was 35

as compared to

20

for

the previous variance period~ However, the effluent levels

have

actually

increased

an

overall

average

of

3 mg/i.

This has

apparently resulted

frcrna

higher influent

concentration

due to

deterioration

of

the

qua3Jtv

of

c’~udeoil used.

Only

during

two

months

of

the

labest variance period

(January

and

February,

1982) were the interim standards

exceeded,

and

those

excursions

resulted

from

difficulties

caused

by

the

extremely

cold

weather

of January

9 and 10,

1982,

wnich caused

malfunctions

and

freeze—ups in the refinery process units and sour water

system,

resulting in

the

discharge

of

1~l?Lconcentrations

of

ammonia

to

the

7.9 millio;~

ga

Ion

equal

:L2~a

i~e

tank,

These

discharges

were

slowly

drained to

the

~WTP until

continuing

cold

weather

necessi-

tated

normal

equalization

service

for

the

tank

beginning

January

23

to

protect

ths

NWTP

from

shac~

loading of

ammonia

and other contarni—

nants.

Thereafter,

excursions

a :!ourred

from

January

25

through

February

9,

1982.

Mobil

has

expended

conoiderabie

time

and

effort

in

a

good

faith

attempt

to

reach

ultimate

compliance

with

the

ammonia

standards.

Capiba~ ouLlays

during

the

period

of

1979

through

1981

for

ammonia

source

contrc:.

and

pilot

plant

research

totalled

$300,000.

Operating

costs

for

au

ammonia

reduction

projects

totalled

in

excess

of

$2.5

miUion

in 1981.

Projects

have

included

the

purchase

and

installation

of

a

nitrification

pilot

plant,

nitrification

inhibition studies,

mutant bacteria trials

and

temperature

control

in

the

aeration

basins.

The

environmental impact

of

the

granting

of

variance

is

not

clear.

Dissolved

oxygen

:Ieveis

in

the

Illinois

River for 1981

were not

presented.

Although no analysis of

ammonia nitrogen

levels at

the edge of the mixing zone

is

presented,

the net

increase in

river ammonia nItrogen

concentration

has

been calcu-

lated as

0.005 mg/

The environmental

impact

is

thus

not

fully

known

but

is

probably

outweighed by the

economic

hardship

upon

Mobil

should

the

variance

be

denied,

Further,

granting

of

variance

would

allow

continued

research

and

experimentation

leading

toward

eventual

compliance.

The

Board,

therefore,

finds that denial

of variance

would

impose

an

arbitrary

or

unreasonable

hardship.

Variance

will

be

granted

for

a

period

of

two years.

Mobil

requests

that

interim

limitations

for

ammonia

nitrogen

be

set

at

44

mg/i

as a monthly average and 65

mg/i

as

a

daily

maximum,

which represents Best Available Technology

standards.

47~272

---

—3—

However, given the overall

compliance

during the last variance

period and the unusual

circumstances

leading to the excursions,

the Board

finds that the interim limitations set during the last

variance period remain reasonable and that unforeseeable excursions

should be addressed when and if they occur.

The Board notes that Mobil will have been operating under

four variances for more than five years by the end of this variance

period without having presented a compliance plan.

The reason

for that is apparently that the technology does not presently exist

to reasonably reach compliance.

However, variances are not

intended to act as seriatim simplified site—specific regulations.

The Board will, therefore,

require that a compliance plan be

submitted by May 1,

1984.

If no such plan

is feasible by then,

Mobil should consider submitting

a proposal for a site—specific

regulatory change.

This Opinion constitutes the Board’s findings of

fact and

conclusions of law in this

matter.

ORDER

Mobil Oil Corporation

is hereby

granted a variance from Rule

406 of Chapter

3

until July 1,

conditions:

1.

Mobil’s ammonia nitrogen effluent discharge shall

not exceed

a monthly average concentration of 25

mg/i and a daily maximum concentration of 40 mg/i

during the period of this variance.

2.

Mobil

shall continue efforts to develop a program

which will result

in

Chapter 3.~

3.

Mobil shall continue to submit bi—monthly reports

compliance with Rule 406 of Chapter

3.

4.

Mobil shall, by May

1,

1984, provide the Agency

schedule for compliance with Rule 406 of Chapter

3.

5.

Within

45

days of the date of this Order,

Mobil shall execute and forward to the Board

and to the Illinois Environmental Protection

Agency,

Compliance Assurance Unit, Water

Pollution Control Division,

2200 Churchill Road,

Springfield,

Illinois 62706,

a Certification of

Acceptance and Agreement

to

47-273

---

—4—

and

conditions set forth in the

Order.

The 45

day period

shall be held in

abeyance during any

period in

which

this matter

is

being appealed.

CERTIFICATION

I

(We),

,

the Pollution Control Board in PCB 82—36, dated June 10,

By:

Title

Date

IT

IS

SO

ORDERED.

I,

Christan

L.

Moffett,

Clerk

of

the

Illinois

Pollution

Control Board, hereby ~ertify that the above Opinion and Order

were adopted olLthe

)cS’~—

day of_~

,

by a vote of

Illinois Pollution1-~’ntrolBoard

47-274