ILLINOIS POLLUTION CONTROL BOARD

September 25,

1986

VILLAGE OF MOUNT MORRIS,

)

Petitioner,

v,

)

PCB 86—155

)

ILLINOIS ENVIRONMENTAL

)

PROTECTION AGENCY,

)

Respondent.

OPINION AND ORDER OF THE BOARD

(by J.D. Dumeile):

This provisional variance request comes before the Board

upon

a September

25, 1986 Recommendation of the Illinois

Environmental Protection Agency (Agency).

The Agency recommends

that a 45—day provisional variance be granted

to the Village of

Mount Morris

(Village)

from 35

Iii.

Adm. Code 302.212 and 35 Iii.

Adm. Code 304.120(c)

as

it pertains to

the biochemical oxygen

demand (BOD), total suspended solids

(TSS)

and ammonia nitrogen

effluent requirements of the Petitioner’s NPDES Permit during the

time period

in which the old rotating biological contactors

(RBC’s)

are

removed from service

for replacement with new, modern

RBC

units.

The Village of Mount Morris owns and operates

a municipal

wastewater treatment facility (WWTP) which has a design average

flow of 0,5 million gallons per

day (MGD)

and consists of an

aerated grit chamber, comininutor, primary clarifier, secondary

claifiers, trickling filter, rotating biological contactors,

aerated chlorine contact tank, gravity sand filters, anaerobic

digesters, aerated excess flow storage lagoon and return of flow

to the treatment process, and land application of sludge.

The

Petitioner’s WWTP, which treats combined domestic

and industrial

flows,

discharges

its effli~ientto an unnamed tributary of Pine

Creek, which discharges

to the Rock River, pursuant to NPDES

Permit #IL0O3003l.

(Rec.

1; Pet. 1).

The Petitioner’s NPDES Permit provides that the Village’s

wastewater treatment facilities must meet monthly average final

effluent limitations of 10 milligrams per liter

(nig/l)

for BOD,

12 mg/i for TSS, and 1/5 mg/l(October)/4.,0 mg/l(Noveinber)

for

ammonia nitrogen.

(Pet.

1).

Additionally, the Village’s NPDES

Permit provides that its WWTP must meet weekly average limits of

20 mg/i for both BOD and TSS.

(Pet,

1).

According

to the Village, one of its rotating biological

contactors is currently rout of service and unrepairable~ and the

72-417

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—2—

other

RBC

unit

is “in very bad condition and may fail at any

time”.

(Pet.

2).

As

a result of the non—repairable structural

failure of these

RBC

units,

the ammonia nitrogen process

efficiency has decreased

to the point of excursions (due to the

loss of one unit)

and the Village believes that,

should

the

second

RBC

unit fail,

the result would be continual excursions

from the applicable ammonia nitrogen effluent limits,(Pet.

2).

The Village has decided that the best solution to avert

the

anticipated environmental problems due

to the structural failure

of its

RBC

units is

to replace both rotating biological

contactors with modern, new

RBC

units.

The Petitioner has

investigated various alternatives

to achieve compliance

and has

ascertained that the planned

installation of the new

RBC

units is

the most desirable solution because the original

RBC

process was

very successful

in providing

compliance

and new,

more efficient

RBC’s will cost less and be faster

to install than any other

alternative equipment.

(Pet.

2;

Rec.

2).

The Agency agrees with

the Village that the proposed installation of new rotating

biological contactor assemblies is the best and most practical

solution.

(Rec.

2).

Earlier

this summer, bids were taken by the Village

to have

equipment suppliers provide two new shaft assemblies

for its

RBC’s.

These

two new shaft assemblies are presently in

fabrication and are scheduled for delivery to the Village

in mid—

October.

The Petitioner

intends

to remove

the old

RBC

shafts

during mid—October,

1986 and

to install the new shafts when the

new shafts

are delivered

(sometime around November

1, 1986).

The

Village estimates that process efficiency will be restored in

approximately three weeks

(i.e.,

sometime around November

24,

1986), providing that the tentative timetable regarding delivery

and installation

is followed and that no unforeseen developments

occur.

(Pet.

2).

During the time period that the rotating biological

contactors

are expected

to be out of service

(i.e.,

from

approximately mid—October, 1986 until November

1,

1986),

the

Village intends

to direct the flow from its secondary claifiers

around

the

RBC

process and directly to the tertiary filters,

while concurrently having

all other treatment processes remain

in

operation.

(Rec.

2).

At the present time, the Petitioner

is in

compliance with all applicable effluent limitations except

for

those pertaining

to ammonia nitrogen concentrations.

The Village

has indicated that “since the second stage of the two—stage

RBC

nitrification went down,

the 1.5 mg/i summer

limit

for ammonia

nitrogen has been exceeded, with typical readings of

2.4

—

2.6

mg/i”.

(Pet.

3).

The Petitioner believes that the environmental

impact of

the

requested provisional variance will be minimal, with a temporary

and

short—term increase

in effluent concentrations for BOD,

TSS

72-418

---

—3—

and ammonia nitrogen.

(Pet.

2).

The Agency has agreed with the

Village’s assessment of the situation and has emphasized that

“the remaining treatment processes will remain

in operation and

provide secondary treatment,

filtration, and disinfection of the

wastewater”.

(Rec.

2).

The Village of Mount Morris contends that denial of its

requested provisional variance would impose an arbitrary or

unreasonable hardship because the present RBC’s are beyond repair

and must be replaced.

Furthermore, the Village indicates that it

has expeditiously taken appropriate

steps

to replace the

RBC’s

and must,

of necessity, wait for the manufacture and delivery of

the new

RBC

shaft assemblies before

it can properly correct the

present situation.

For

the previously mentioned reasons, the Agency agrees with

the Petitioner’s assessment of hardship and has therefore

concluded that immediate compliance on

a short—term basis with

the requisite NPDES Permit standards pertaining

to BOD,

TSS, and

ammonia nitrogen levels would

impose

an arbitrary or unreasonable

hardship upon the Village of Mount Morris.

(Rec.

1;

3).

The

Agency has indicated that there are no federal

regulations which

would preclude the granting of the requested provisional

variance.

(Rec.

3).

Additionally,

there

are no downstream

public water supplies which would be adversely affected by the

grant of the requested

relief.

Accordingly, the Agency has

recommended that the Board grant the Petitioner

a provisional

variance from 35

Ill. Adm. Code 302.212 and 304.120(c)

as

it

pertains

to BOD, TSS and ammonia nitrogen effluent requirements,

subject

to various specified conditions.

Pursuant

to Section

35(b) of the Illinois Environmental

Protection Act,

the Board hereby grantes the provisional variance

as recommended.

This Opinion constitutes the Board’s findings of fact and

conclusions of law in this matter~.

ORDER

The Petitioner,

the Village of Mount Morris,

is hereby

granted

a provisional variance

from 35

Ill. Adm. Code 302.212 and

304.120(c)

as

it pertains

to BOD,

TSS, and ammonia nitrogen

effluent levels

to allow time for the removal from service of its

present rotating biological contactors and the replacement with

new, modern rotating biological coritactors

at

its municipal

wastewater

treatment plant, subject

to the following conditions:

1.

This provisional variance shall commence when the

present rotating biological contactors(RBC’s)

are

removed from service and shall continue

for 45 days

72-419

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thereafter.

2.

During

the term of this provisional variance,

effluent from the Petitioner’s wastewater

treatment

facility shall be limited

to 20 mg/i

for both BOD

and TSS as monthly averages.

3.

The Petitioner

shall collect samples and perform

analysis as set forth in its NPDES Permit

#1L0030031.

Analysis results shall be reported

to

the Agency on its monthly discharge monitoring

reports.

4.

The Petitioner

shall notify Mr. Jack Adam of the

Agency’s Rockford Regional Office via telephone at

815/987—7755 when the present RBC’s are removed from

service; when the new RBC’S are installed and placed

in service,

and when the

RBC

process efficiency is

restored.

Written confirmation of each telephone

notification shall be submitted within

5 days

to the

Agency at the address given below.:

Illinois Environmental Protection Agency

4302 N. Main Street

Rockford, Illinois

61103

Attention:

Mr.

Jack Adam

5.

The Petitioner shall operate and maintain the

remaining treatment

units

so as

to discharge the

best effluent practicable.

6.

Within 10 days of the date of the Board’s Order, the

Petitioner shall execute

a Certificate of Acceptance

and Agreement which

shall be sent to Mr. James Frost

of the Agency at the following address:

Mr. James Frost

Illinois Environmental Protection Agency

Division of Water Pollution Control

Compliance Assurance Section

2200 Churchill Road

Springfield, Illinois

62706

72-420

---

—5—

This certification shall have the following form:

I,

(We)

,

having

read the Order

of

the Illinois Pollution Control Board

in PCB 86—

155 dated September 25, 1986, understand

and accept said Order,

realizing

that such acceptance renders all terms and conditions

thereto binding and enforceable.

Petitioner

By:

Authorized Agent

Title

Date

IT

IS SO ORDERED

I,

Dorothy M. Gunn,

Clerk of the

Illinois Pollution Control

Board, hereby certify that the

ov

Q~inionand Order was

adopted on the

~

day of

~

,

1986 by a vote

of

(o0

.

Pol 1

Control Board