ILLINOIS POLLUTION CONTROL BOARD
June 5, 1986
IN THE MATTER OF
JOINT PETITION OF THE CITY OF
)
PCB 85—139
METROPOLIS AND THE ILLINOIS
)
ENVIRONMENTAL PROTECTION AGENCY
)
FOR EXCEPTION TO THE COMBINED
)
SEWER OVERFLOW REGULATIONS
)
MR. PAUL HENRY APPEARED ON BEHALF OF THE CITY OF METROPOLIS.
MR. THOMAS DAVIS APPEARED ON BEHALF OF THE ILLINOIS ENVIRONMENTAL
PROTECTION AGENCY.
OPINION AND ORDER OF THE BOARD (by 3. Theodore Meyer):
This matter comes before the Board upon a September 12, 1985
joint petition filed on behalf of the City of Metropolis (City)
and the Illinois Environmental Protection Agency (Agency) for an
exception to 35 Ill. Adm. Code 306.305(a) and (b) of the Boardts
combined sewer overflow (CSO) regulations. An amendment to the
joint petition was filed by the parties on November 5, 1985 which
indicated that the City had complied with the notification dates
of Section 306.351. Hearing was held on December 17, 1985 at
which testimony and exhibits were presented by the parties.
There was no disagreement as to the facts. No members of the
public were present.
Sections 306.305(a) and (b) provide as follows:
a) All dry weather flows, and the first
flush of storm flows as determined by
the Agency, shall meet the applicable
effluent standards; and
b) Additional flows i.e. not dry weather
flows or first flush storm flows
,
as
determined by the Agency but not less
than ten times the average dry weather
flow for the design year, shall receive
a minimum of primary treatment and
disinfection with adequate retention
time.
The City contends that the existing overflows from its combined
storm and sanitary sewer system have minimal impact on the water
quality of the Ohio River (the receiving water) and do not
restrict stream use, and that construction of CSO treatment
70-93
—2—
facilities at an estimated cost of $2.5 million (1980 dollars)
would produce little benefit.
The City is located at the southern tip of Illinois in
Massac County on U.S. Route 45 about 3 miles west of Interstate
24 on the northern bank of the Ohio River. The existing sewage
treatment plant (STP) consists of a 1.5 million gallons per day
(MGD) design flow primary treatment plant with peak flow of 2.0
MGD. Major units of the STP include bypass screens, primary
clarifiers and a vacuum filter. A barminutor and grit chamber
are presently out of service. The City asserts that, based on
the Agency’s monthly grab sample results, the present discharge
of the City’s STP exceeds the effluent limitations in its NPDES
permit albeit no data is given on which to support this
assertion.
The City is served by 13 miles of combined storm and
sanitary sewers and 39 miles of separate sanitary sewers
collecting wastes from approximately 7,200 people. The combined
sewer collection system drains through a single 50 inch
interceptor which has an estimated capacity of 50.7 MGD.
Overflows from the 50 inch interceptor drain into the Ohio
River. The only other overflow which exists in the system is an
emergency STP bypass which is reserved for use when the STP is
inoperable. The joint petitioners assert that no major local
industries are connected to the City’s sewer system. (Joint Pet.
pp. 1—2). The Agency alleges that the City will receive Build
Illinois Grant funds for design of the facilities recommended in
the City’s proposed STP upgrade. With the grant, the City’s
share will be about $1.5 million.
Pursuant to an Administrative Order issued by the United
States Environmental Protection Agency, the City submitted a
Municipal Compliance Plan to USEPA which outlines the City’s
efforts to assure full compliance with the Clean Water Act by
July 1, 1988 which includes upgrading the present STP to a 2.0
MGD secondary treatment facility with a peak capacity of 4.25
MGD, rehabilitation of the wastewater collection system to remove
an average of 0.7 MGD of infiltration and inflow and fixing a
broken valve and constructing a sluice gate at the combined sewer
outfall to eliminate flooding of the system during high river
levels. The estimated cost of this upgrading is approximately
$3.5 million. (Joint Exh. no. 5 pp. 5—7). The Agency, in
support of this joint petition, has also required that the City
screen overflows prior to discharge and provide for pumping wet
weather flows during high river stages when gravity bypassing is
not possible and protect manhole 707 from river intrusion.
(Joint Pet. p. 3).
At the CSO discharge point, the Ohio River is generally used
as a barge mooring area. The joint petitioners assert that a
visual inspection of the slough leading to the Ohio River and the
70-94
—3—
river bank in the area surrounding the discharge point indicated
that there was no effect of the CSO discharge on the river or the
river bank. (Joint Exh. no. 3 and 4). The impact of the
existing method of operation on the Ohio River was examined in
the CSO Impact Evaluation Phase I, October 1983 which stated:
“The 7 day 10 year low flow of the Ohio River in
the vicinity of Metropolis is 44,820 CFS, or
28,966 MGD. Assuming all of the sewage from the
combined system were dumped into the river, which
it is not, the total discharge into the river
would only be 0.22 MGD. This provides a dilution
ratio of 130,000 to 1 at low flow. At average
flow rates, the dilution ratio would be
considerably higher, making the impact of the
discharge on the Ohio River insignificant.”
The CSO Phase II Report stated further that the expenditure of
$2.5 million is not justified to cope with the City’s CSO problem
since it contributes such a minor flow to the Ohio River and the
biochemical oxygen demand (BOD) and suspended solids (SS)
concentrations in the receiving water would not be appreciably
altered by the City’s storm flow discharge. (Joint Pet. p. 3).
A Combined Sewer Overflow Study was conducted by Clark,
Dietz Engineers in October 1980 (1980 CSO study) which addressed
the quality and quantity of the City’s CSO discharge during two
storms in September and October of 1979 and provided several
alternatives to solve the City’s CSO problem. Based on the data
received from the two storms, the climatological background and
visual observation, the report concluded that the overflow has a
considerable impact on the area surrounding the overflow and the
river itself. Presently, water ponds immediately below the CSO
outfall and when temperatures are high and conditions are dry,
the odors from this pool are strong. Also, floating paper and
rags have accumulated on limbs of trees that have been pushed
into the slough creating a nuisance. (Joint Exh. no. 1, p. 27).
The 1980 CSO study also determined that the first flush
volume for the design storm (1 year
—
1 hour) would be 400,000
gallons. By relating the amount of rainfall, including the BOD
load, of the September and October 1979 storms to that of the
design storm, the study concluded that the design storm would
generate 325 lbs. of BOD which converts to a concentration of
approximately 98 mg/i. No data was presented on the SS
concentration of the first flush of the design storm. (Joint
Exh. no. I p. 36).
Four alternatives were examined to handle the City’s CSO
problem. Alternative no. 1 would provide treatment of all dry
weather flows and first flush flows at an estimated cost of $2.5
million (1980). Alternative no. 2 is the same as alternative no.
70-95
—4—
1 except that, after the first flush basin is filled, the excess
flow will be directed to a 5.0 MGD primary treatment and
disinfection system, then discharged to the Ohio River. The
estimated cost of this alternative is $3.15 million (1980).
Alternative no. 3 is the same as Alternative no. 1 except that,
after the first flush basin is filled, excess flow will be
directed to a 10.0 MGD primary treatment and disinfection system,
then discharged to the Ohio River. The estimated cost of this
alternative is $3.3 million (1980). Lastly, Alternative no. 4 is
the same as Alternative no. 1 except that, after the first flush
basin is filled, the excess flow will be directed to a 20.0 MGD
primary treatment and disinfection system, then discharged to the
Ohio River. The estimated cost of this Alternative is $4.2
million (1980). All of these alternatives are predicated on the
present STP being upgraded in accordance with the Municipal
Compliance Plan referred to above. In accordance with the
Municipal Compliance Plan, the City purposes to modify the
combined sewer overflow structure for $200,000. These
improvements will include screening of overflows, protecting
against backup under flood conditions, pumping of wet weather
flows during high river stages as needed to prevent river
intrusion and providing treatment to plant capacity prior to
allowing overflows.
Another study was conducted by Cepheus Industries, Inc. in
September 1984. (1984 Cepheus study). This study sampled the
soils both upstream and downstream as well as the soils in the
slough which leads from the CSO discharge to the Ohio River for
copper, lead and zinc. The study concluded that in all cases
there is an increase in metal concentrations in the downstream
samples as compared to the upstream samples with the percent
variation ranging from an increase of 16 for zinc to a 592
increase for lead. The study went on to state that considering
the small number of samples and the high readings from the
“uncontaminated” upstream sample, the significance of these data
is difficult to determine (Joint Exh. no. 4).
At the outset, the Board notes that the City’s CSO
discharges to a slough which floods at least one or more times
every year. (R. 11). The 1980 CSO study examined the slough and
the surrounding area and concluded that the City’s CSO has a
considerable impact on the area surrounding the overflow and the
river itself with strong odors present when temperatures are high
and conditions are dry as well as floating paper and rags. In
contrast, the .1984 Cepheus study examined the slough and
concluded that there was little indication that the slough was
utilized for sewage overflows. The study also examined the pool
under the CSO outfall and concluded that small pockets of gray
material on the pool bottom felt and smelled like sludge but the
bottom was comprised mostly of red—brown clay, sticks and leaves
with very little sludge present. In attempting to reconcile
these two studies, the Board concludes that the impacts observed
70-96
—5—
during the 1980 CSO study were either no longer present or
present in small amounts during the 1984 study. The Board notes
that sludge was observed in the pool at the base of the CSO
outfall but concludes that the environmental impact of these
amounts are minimal.
An analysis of the sediments in the area surrounding the
overflow and in the river itself were also examined by the 1980
CSO study and the 1984 Cepheus study though the sediments were
examined for different constituents. The 1980 CSO study
concluded that “very few of the overflow plume area samples
contain definite sludge or organic deposits. Apparently the
dilute overflow after first flush and the volume of flow in the
river tend to carry and disperse the settleable solids further
downstream.” (Joint Exh. 1, p. 28). The 1984 Cepheus study
which obtained samples from the same area concluded that there
was an increase in some metal concentrations in the downstream
sediment samples as compared to the upstream sediment samples.
However, the study concluded that because of the small sample
size and the contaminated upstream samples, the significance of
the samples was difficult to determine.
Based on the 1980 CSO study, the Board concludes that the
impact from the City’s CSO is minimal. While this study observed
the presence of sludge, these amounts were insignificant. The
Board reaches a similar conclusion based on the 1984 Cepheus
study. Though this study revealed increased metal concentrations
in the sediments surrounding the CSO outfall area, this study was
inconclusive. Since the area surrounding the CSO outfall
regularly floods, it is difficult to determine the origin of
these metals. Nothing in the record suggests that the increased
metal concentrations are being produced by the City’s CSO and
may, in fact, be produced upstream of the CSO outfall. Moreover,
no conclusions can be drawn on the impact of the City’s CSO based
on this study because of the small sample size and the
contaminated upstream samples. The Agency testified that its
inspections convinced them “that there are no problems and no
aesthetic problems or evidence of pollution in the receiving
stream.” (R. p. 17). Therefore, on balance, the Board concludes
that the adverse environmental impacts, if this exception is
granted, are minimal.
In examining the alternatives, the Board concludes that
Alternative nos. 2—4 are not justified environmentally or
economically. These alternatives are designed to capture
increasing amounts of excess flows and transport them to a
primary treatment and disinfection system. These excess flows
are those past first flush and consequently have lower
concentrations of pollutants and will have a minimal impact on
the slough and the Ohio River. In light of these facts, the
construction of additional CSO facilities is not economically
justified. The City asserts that in lieu of Alternative no. 1,
70.97
—6—
it believes that the upgrading of the present STP including the
conditions required by the Agency will solve the City’s CSO
problems at a savings of approximately $2.0 million. The Board
agrees. The pollutant load of the first flush will not have a
significant impact on the receiving water. This conclusion is
supported by the CSO Phrase II report which determined that the
BOD and SS concentrations in the receiving water would not be
appreciably altered by the City’s CSO discharge. Also, upgrading
the present STP will enable the City to capture and treat greater
amounts of flows, thereby decreasing the occurrence of overflow
events.
In conclusion, the Board finds that the evidence in the
record supports granting the City an exception to 35 Ill. Adm.
Code 306.305(a) and (b), subject to conditions. The Board notes
that the impact of the City’s CSO discharge on the water quality
of the Ohio River.will be minimal. In addition, the Board notes
that alternative controls as well as the cost of complete control
are high. The Board will require that the City implement its
Municipal Compliance Plan along with the requirements suggested
by the Agency and maintain its sewer system in optimal operating
condition prior to and during any overflow event.
ORDER
The City of Metropolis (City) is hereby granted an exception
from 35 Ill. Adm. Code 306.305(a) as such provision relates to
first flush of storm flows and 306.305(b) for its combined sewer
overflows into the Ohio River at River Mile 944.1, subject to the
following conditions:
1. The City shall construct the necessary improvements to
its sewage treatment plant pursuant to the timetable in
its Municipal Compliance Plan which is hereby
incorporated by reference.
2. The City shall provide for screening of overflows prior
to discharge and protect the overflow structure against
river water backing into the sewer during high river
stages.
3. The City shall provide for pumping overflows during
high river stages when gravity bypassing is not
possible.
4. Overflows shall occur only while the treatment plant is
receiving and treating its design maximum flow.
5. The City shall maintain its Municipal Sewer System in
optimal operating condition prior to and during any
overflow event.
70-98
—7—
6. This grant of exception does not preclude the Agency
from exercising its authority to require as a permit
condition:
a. A CSO monitoring program sufficient to assess
compliance with this exception and any other Board
regulations, including Section 306.305(c); and
b. Other controls if needed for compliance.
7. This grant of exception is not to be construed as
affecting the enforceability of any provisions of this
exception, other Board regulations, or the
Environmental Protection Act.
IT IS SO ORDERED.
Board Member B. Forcade dissented.
I, Dorothy M. Gunn, Clerk of the Illinois Pollution Control
Board, hereby certify that the above Opinion and Order was
adopted on the ~iZ
day of
Q~~c
,
1986 by a vote
of
__________.
Dorothy M. G nn, Clerk
Illinois Pollution Control Board
70-99