ILLINOIS POLLUTION CONTROL BOARD
November 21, 1985
GREATER PEORiA SANiTARY DISTRICT,
)
)
Petitioner,
)
)
V.
)
PCB 85—193
)
)
ILLINOIS ENVIRONMENTAL
)
PROTECTION AGENCY,
)
)
Respondent.
)
OPINION AND ORDER OF THE BOARD (by W. 3. Nega):
This provisional variance request comes before the Board
upon a November 21, 1985 Recommendation of the Illinois
Environmental Protection Agency (Agency). The Agency recommends
that a 45—day provisional variance be granted to the Greater
Peoria Sanitary District (GPSD) from 35 Ill. Mm. Code 304.120
(deoxygenating wastes), 35 Ill. Mm. Code 304.121 (bacteria), and
35 Ill. Mm. Code 304.122 (nitrogen) while portions of GPSD’s
secondary treatment facilities are temporarily out of service
during the time period that necessary repairs are being made.
The Greater Peoria Sanitary District owns and operates
wastewater treatment facilities serving the City of Peoria, some
outlying communities, and several industries. The Petitioner’s
facilities include screening, grit removal, primary and secondary
clarification, activated sludge, nitrification utilizing rotating
biological contactors (RBC’s), tertiary ponds, and chlorination
equipment. Prior to its disposal, sludge is first thickened,
treated anaerobically, and then dried. The Petitioner’s
treatment plant has a design average flow of 37 million gallons
per day (MGD) and discharges directly into the Illinois River
pursuant to the appropriate NPDES Permit authorization. (Rec.
1).
During Mid—October of 1985, the Petitioner discovered that,
due to groundwater related erosion problems, portions of its
secondary treatment system’s aeration tanks, aeration gallery,
and secondary clarifiers had become seriously undermined.
Bottoms of several aeration tanks, a part of the aeration gallery
floor, and at least one corner of the bottom of one secondary
clarifier had dropped up to two inches into the voids below. As
a result of the leaks that had started developing in the walls
and floors of its activated sludge tanks, mixed liquor was
flowing in a stream up to 4 inches deep into the aeration
gallery. The aeration gallery, which houses equipment for the
Ca
Ito
aeration tanks, is a tunneI~1ike structure which is below grade
and next to the aeration tanks~
To stop these leaks and to provide access for investigatory
work and repairs as well as to minimize additional undermining at
the tanks, the Petitioner removed nine of its twelve aeration
tanks and three of its five secondary clarifiers from service in
mid~-October. Of the remaining three aeration tanks, two are
being utilized as contact tanks and the third is being utilized
as a reaeration tank. The Petitioner~semployees have begun to
dewater various aeration tanks in order to find the leaks, The
apparent cause of the leaks is the development of “voids” (i.e.,
areas of water and/or mud) beneath aeration tanks. (Rec, 1).
The Petitioner is currently required by its NPDES Permit
#1L0021288 to meet effluent limitations of 20 mg/I of biochemical
oxygen demand (BOD) on a 30 day average with a 40 mg/l BOD limit
as a weekly average, and to meet effluent limitations of 25 mg/i
of total suspended solids (TSS) on a 30 day average with a 45
mg/i TSS limit as a weekly average. This NPDES Permit also
delineates a 2.5 mg/l effluent standard for ammonia nitrogen as N
during the months of April through October, and a 4.0 mg/i
effluent standard for ammonia nitrogen as N during the months of
November through March. (Rec, 2).
According to discharge monitoring reports submitted to the
Agency by the Petitioner, the following results were indicated:
Monthly Average NH3~N
BOD
TSS
Month
Flow
(MGD)
(mg/I)
9/85
22.29
4
4
1.9
8/85
22.65
4
4
1.9
7/85
22.31
5
7
1.2
6/85
23.24
7
11
2.5
5/85
23.21
7
10
3.1
4/85
29.06
5
10
2.5
3/85
34,39
7
20
1.8
2/85
29.12
5
8
2.6
1/85
25.57
7
8
2.1
12/84
28.18
4
7
1.4
11/84
26.14
7
7
3.0
10/84
22.99
12
7
3.8
Average
25.76
6.2
8.7
2.3
(Rec, 2),
However, due to the groundwater~re1ated erosion problems and
the tank leaks, the Petitioner has indicated to the Agency that
its effluent quality has already significantly deteriorated. Fo~
example, the average BOD for all of October 1985 was 15 mg/i,
while the average BOD for the last half of October, 1985, when
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flows had begun to be diverted, was 22 mg/i. (Rec. 2). The
petitioner has reported that TSS levels have experienced similar
deterioration due to the problems at the facility. Moreover, it
is possible that fecal coliform levels might rise due to
increased chlorine
diiäd and
GPSD anticipates that the effluent
quality will deteriorate even further in the near future. (Rec.
2).
Since GPSD’s rotating biological contactor nitrification
system is currently receiving much of the plant’s primary
effluent, a very real risk of overloading the
REC
shafts
exists. The Petitioner is now providing effluent treatment by
use of its three in—service aeration tanks and by diverting flows
to the Mc’s, and then to the polishing pond and chlorination.
In reference of this diversion of flows to the RBC’s, the Agency
has stated that:
“...
the RBC’s were not designed to treat the
strength of wastes
that are now being applied to
them. Based upon the Agency’s past experlience with
RBC’s, structural failure of the RBC’s could result
due to the increased biomass growth on the units
thus causing the shafts to break due to the extra
weight of the biomass. Petitioner’s personnel are
routinely monitoring the performance of the RBC’s
and will be able to provide minimum treatment
consisting of primary clarification, tertiary
clarification, the polishing lagoon, and
chlorination.’ (Mc. 2).
The Agency has noted that GPSD has already begun corrective
action in that core drillings which are about two inches in
diameter have been completed which led to the determination that
some of the voids beneath the aeration gallery floor are as deep
as 89 inches. The Petitioner’s core drillings were taken about
every five to ten feet through the aeration gallery floor and
core samples which are about five inches in diameter are
presently being analyzed. The Petitioner is currently awaiting
the results of the core sample tests before ascertaining the best
plan of corrective action and before commencing the requisite
repair and maintenance work. (Rec. 2).
The Agency expects that there will be little adverse
environmental impact upon the Illinois River from GPSD’s
presently degraded discharge, because the Illinois River at
Petitioner’s discharge point provides a dilution ratio of about
74 to 1 using the Illinois River’s 7 day, 10 year low flow and
GPSD’s average flow over the past year (Mc. 2—3). The Agency
also emphasizes that the Illinois River is presently at flood
stage because of recent heavy rains and is expected to remain
high for
some
time to come, thereby providing an even greater
dilution ratio than 74 to 1. Moreover, the Petitioner will also
be providing as much treatment as possible which will serve to
reduce the environmental impact further over the discharging of
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raw sewage. (Rec. 3). The Petitioner’s discharge in
approximately 168 miles upstream from the nearest public water
supply intake which is the City of Alton’s intake on the
Mississippi River. (Rec. 3).
Based on the inability of the Petitioner to provide full
treatment when units had to be taken out of service to retain
what was left of their structural integrity, the Agency has
stated that the ‘Petitioner’s hardship in this case is readily
apparent.’ (Rec. 2). The Agency has also indicated that there
are no federal regulations that would preclude the granting of
the provisional variance.
The Agency has therefore concluded that compliance with
applicable standards would impose an arbitrary or unreasonable
hardship upon the Greater Peoria Sanitary District. (Rec. 2).
Accordingly, the Agency has recommended that the Board grant
Petitioner a provisional variance from 35 Ill. Adm. Code 304.120,
304.121, and 304.122, subject to certain conditions.
Pursuant to Section 35(b) of the Illinois Environmental
Protection Act, the Board will grant the provisional variance as
recommended.
This Opinion constitutes the Board’s findings of fact and
conclusions of law in this matter.
ORDER
The Greater Peoria Sanitary District is hereby granted a
provisional variance from 35 Ill. Mm. Code 304.120, 304.121, and
304.122, subject to the following conditions:
1. The provisional variance shall commence on November 21,
1985 and shall terminate 45 days thereafter.
2. During the term of this provisional variance, the
Petitioner’s effluent shall be limited as follows:
Parameter
Monthly Average
BOD
50 mg/l
TSS
50 mg/l
Ammonia nitrogen discharges shall not cause a violation of
water quality standards.
3. Chlorination shall be provided for all flows discharged
through Outfall OOla and the Petitioner shall make every effort
to comply with the 400/100 ml fecal coliform standard.
4. The Petitioner shall provide the maximum degree of
treatment possible by using all treatment units possible.
86.452
5,
r~
Petitioner shall immediately notify the Agency~s
Peoria Regional Office by telephone if more units are removed
from service and when the aeration units are returned to
service. This notification shall be supplemented by a written
notice within 5 days submitted to:
Illinois Environmental Protection Agency
Division of Water Pollution Control
Compliance Assurance Section
2200 Churchill Road
Springfield, Illinois 62706
Attention: Mr. Roger Cruse
6. Within 10 days of the date of the Board~sOrder, the
Petitioner shall execute a Certification 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
2200 Churchill Road
Springfield, Illinois 62706
Attention: Mr. Roger Cruse
This certification shall have the following form:
I, (We),
_____
____
,
having read
the Order of the Illinois Pollution Control Board in PCB 85—193,
dated November 21, 1985, understand and accept the 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 certif that the above Opinion and Order was
adoLted on the
day of
1985 by a vote
Dorothy N. nn, Clerk
Illinois Pollution Control Board
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