ILLINOIS POLLUTION CONTROL BOARD
April 24,
1986
IN THE MATTER OF:
JOINT PETITION OF THE CITY OF
MATTOON AND THE ILLINOIS
)
PCB 85—215
ENVIRONMENTAL PROTECTION AGENCY
)
FOR EXCEPTION TO THE COMBINED
)
SEWER OVERFLOW REGULATIONS
)
MR.
M.
JOHN HEFFNER, JR.,
APPEARED ON BEHALF OF THE CITY OF
MATTOON;
MS. KATHLEEN
C.
BASSI APPEARED ON BEHALF OF THE ILLINOIS
ENVIRONMENTAL PROTECTION AGENCY.
OPINION AND ORDER OF THE BOARD
(by J.
Marlin):
This matter comes before the Board upon the filing on
December
27, 1985 of
a joint petition
for
a combined sewer
overflow
(CSO)
exception from 35
111. Adm.
Code 306.305
(a)
(first flush
of storm flow only)
and
(b)
(additional flows) by
the City
of Mattoon
(City)
and the Illinois Environmental
Protection Agency
(Agency).
A public hearing was held
in
Mattoon,
Illinois
on February 20,
1986.
A few members
of the
public attended but presented no comments.
The City’s March
19,
1986 motion
to supplement
the petition
is granted.
CSO Regulations
The CSO regulations are contained
in 35 Ill. Adm.
Code
306.302
et seq.
They were amended
in R8l—l7,
51 PCB 383, March
24,
1983.
Section 306.305 provides
as
follows:
All
combined
sewer
overflows
and
treatment
plant
bypasses
shall
be
given
sufficient
treatment
to
prevent
pollution,
or
the
violation
of
applicable
water
standards unless
an
exception has been granted
by
the Board pursuant
to Subpart D.
Sufficient treatment shall consist of the following:
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,
as determined by the Agency but not
less
than ten times
to
sic
average dry weather
flow
for
the design year, shall
receive
a minimum of primary
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2
treatment and disinfection with adequate retention time;
and
C)
Flows
in excess
of those described in subsection
(b)
shall
be treated, in whole
or
in part,
to the extent
necessary
to prevent accumulations of
sludge deposits,
floating debris and solids
in accordance with 35 Ill.
Adm.
Code 302.203,
and
to prevent depression of oxygen
levels;
or
d)
Compliance with
a treatment program authorized by the
Board
in an exception granted pursuant
to Subpart D.
Subpart D allows
the discharger
to file
a petition
for an
exception either singly,
or
jointly with the Agency as
the city
has done.
The joint petition seeks
an exception based
on minimal
discharge impact as provided
in Section 306.361(a)
Wastewater System
The city sewage system consists
of 110 miles
of sewers,
including
31 miles of separate sanitary and
79 miles of combined
sewers.
In
the inner
city,
the sewers are combined
and
the area
experiences surface flooding, sewer
surcharging and basement
flooding.
To relieve the flooding,
the City has constructed
at
least
27 overflow diversion structures with 15 direct bypasses to
3 different watersheds.
These
15 CSO outfalls discharge
to
3
different watersheds as follows:
2
to the Little Wabash River,
7
to Kickapoo Creek
and
6
to Riley Creek.
Annual
biochemical
oxygen demand
(BOO)
loadings from the CSO outfalls
to the streams
is as
follows
(Exh.
A, Table
4.4; Exh.
B,
Table 4.9):
Little Wabash:
66,315
lbs.
based
on an average of
21
precipitation events/year
Kickapoo:
207,720
lbs.
based
on an average of 21
precipitation events/year.
Riley:
92,550
lbs.
based on an average of
21
precipitation events/year.
The wastewater system also includes a wastewater treatment
plant
(WWTP).
The existing WWTP consists of
a primary pumping
station with
bar screens,
a grit removal system,
primary
settling, an activated sludge process,
secondary settling,
a
secondary pump station, tertiary filtration,
final chlorination
and effluent discharge to Kickapoo Creek.
Sludge handling facilities consist of two separate
systems:
primary sludge from the primary settling tanks pumped
to the anaerobic digestor and waste activated sludge from the
secondary settling tanks, pumped
to the aerobic digestors.
The
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3
solids from both digestion systems are pumped
to sand drying beds
for drying prior
to final disposal by trucking
to
a landfill.
Sludge collected from two 60 foot and two
40 foot diameter storm
tanks
is pumped either
to the headworks of the grit chamber or
the anaerobic digestor.
Flows
in excess of
12 million gallons per day
(MGD) up to
26.5 MGD are diverted
to the two 60 foot and two
40 foot diameter
storm
tanks where
the excess
flows
are chlorinated and receive
primary sedimentation.
The
60 and 40 foot Storm tanks are
capable
of providing primary treatment for
10 MGD and 4.5 MGD,
respectively, with
a chlorine contact time of forty—five
minutes.
Overflow from the
tanks
is discharged
to Kickapoo
Creek.
City Programs
The City has
a sewer
cleaning program.
Two vacuum—type
catch basin and sewer cleaning trucks are used almost everyday
in
good weather
(R.l9).
Another notable program
is the City’s
street sweeping program.
Two Street sweepers are used five days
a week
(R.
21).
The City contends that this otherwise greatly
reduces the volume
of solids that are deposited in the sewer
system and
that would
be flushed by stormflow into the
receiving
Streams
(R.
19).
The City also forbids by ordinance
the connection of
downspouts
to the City’s sewer
system.
If complaints are
received or violations
are discovered by City crews,
the
violations
are simply noted.
Enforcement
in most areas
is not
carried out because
inflow and infiltration into the sewer system
is minimal
in most subareas
(R. 21—2).
Existing CSO Impact
The City addressed the environmental impact
of the CSO
discharges
on each of the three
receiving streams.
Each
of
the
streams have mainly agricultural land uses adjacent
to them
except
for Kickapoo.
Kickapoo passes
through residential
areas
in the City and through
a golf course.
Outside the City,
the
land uses adjacent
to Kickapoo are mainly agricultural with
limited commercial
development.
An industrial use,
the General
Electric plant, discharges cooling water which comprises
a
large
portion of Kickapoo
flow during dry weather.
Petitioners contend
that for all three streams there are no recreational uses
(R.
8,
14).
The stream biological survey for all
three streams
is found
in Exhibit A, Appendix
1.
The
1982 survey was structured
to
obtain results during dry weather conditions
(August)
and after
a
substantial
rainfall
(October).
Water quality as well as
benthos,
fish and plankton were examined.
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4
In the Little Wabash River, considerable biological
disruption was found.
During dry weather,
organic and fecal
pollution was evident while
it was
less so during wet weather.
Nitrates and dissolved oxygen
(DO) were high during wet
weather.
Tubificid
(sludge) worms dominated at three of the four
sampling
stations
in the Little Wabash.
Benthic populations
indicated disturbed conditions
(Exh.
A at
4 through 54).
A
follow up study
in April
1985
showed the Little Wabash River
was
still disturbed
(R.
40).
In Riley Creek,
the water quality indicated organic
enrichment
other
than human wastes.
Values
for
turbidity,
suspended solids
(SS) and nitrates suggested possible effects
from one or
two nearby landfills.
Downstream of the landfills,
a
small drainage ditch
joins Riley Creek
and
it has flow only when
a CSO occurs
(R.
36).
In the ditch,
the concentrations of DO and
nitrates are low during dry weather while high for BOD,
ammonia
nitrogen,
turbidity,
SS, phosphates
and fecal contamination.
During wet weather
flow,
the water quality
of the ditch
improved
dramatically
(Exh.
A,
App.
1,
pp 25—26,
31—32;
R.
36—37).
Flushing of the streams occurs during wet weather
flow while
stream conditions during dry weather are stagnant,
low flow
conditions.
Different benthic communities
in portions of Riley Creek
indicate water quality differences.
In the upper
reaches of the
creek
study area,
there
are diverse benthic communities,
predominantly chironomids.
After
the juncture of
the ditch and
creek
and the emergence
of several field
tiles,
the water quality
declines.
Oil spills from nearby wells are probably
a
contributing factor
to the poorer water quality.
The area also
shows disturbed benthic communities.
The stream reaches below
the golf course
and the WWTP had organically enriched bottoms
and
some sludge beds were noted 75 meters downstream of the WWTP.
These reaches
improved
in the April
1985 follow up study,
which
was after the 1984 upgrade of
the sand filter.
While the sludge
beds have disappeared,
the benthos was still indicative
of
a
disturbed area
(Exh.
A, App
1 at
6 through
58).
The water quality
in Kickapoo Creek similar
to that
in Riley
Creek,
shows high ammonia nitrate
levels during wet flow,
probably from golf course
runoff.
Turbidity and SS values are
high downstream of the
WWTP.
During low flow,
there
is some
fecal contamination.
The large numbers of
tubificids
and the
presence
of leeches show
a disturbed effect on the stream.
Below
the
WWTP
outfall, however,
the stream quickly recovers.
Kickapoo Creek experienced
a fish kill
in August 1982 during
the survey.
The DO concentration at the
time was 2.4 mg/l.
That
week
there had been fertilizer applied at the golf course with
69-249
5
subsequent watering.
The City’s expert testified that
the
fertilizer runoff could affect
the stream DO
(R.
38,
39,
44—45).
CSO Resolution Plan
The CSO control alter9tives considered by the City are
listed
in Exhibits A and B.
Alternatives
1 through
4 are found
on pages
4—20
through 4—32 of Exhibit A while alternatives
5
through
7
are listed
in Exhibit
B,
pages 4—26 through 4—32.
Exhibit
E
lists the proposed plan,
alternative number
8
(Figures
4,
5;
see
6.2).
Alternative
B will provide transport,
storage
and treatment of first flush flow to
the capacity of the existing
interceptor sewers or
a six month storm, whichever
is smaller,
at
the overflow points
for
the Little Wabash and Kickapoo Drainage
Basins.
It will
and provide flow control, transport and treatment
of
12.5 times
the dry weather
flow at the overflow points
in
Riley Creek Basin
(Exh.
E at
12).
This alternative will
eliminate
all CSO
in the Little Wabash Basin,
protecting water
quality
in Lakes Paradise and Mattoon,
the City’s water
supply
sources.
Alternative
B consists
of the following:
—
Sewer separation in two combined sewer areas
in
the Little
Wabash basin
by constructing about 22,000 lineal feet
of new
sanitary sewer and converting existing combined sewers
to storm
sewers.
Three diversion points will
be eliminated.
—
A new 42—inch
to 84—inch diameter interceptor
of 17,250
lineal
feet will
be constructed
from the southwest corner
of the
City
to the treatment plant.
This will eliminate combined sewer
overflows
in the Little Wabash basin
and reduce
the frequency and
extent
of overflows in the Kickapoo Creek
basin.
—
Two new storm sewers will
be constructed
in the Kickapoo
Creek
basin
to prevent
the surface drainage from a total
of 231
acres from entering the combined sewer
system.
—
Darns
in diversion structures
in the Riley Creek Basin will
be raised
to surcharge the 14 MGD capacity pump station.
This
will
increase the
flow to the
treatment plant from 12.5 to 38.8
times dry weather flow tributary
to the pump station.
—
A 12.5 million gallon basin will
be constructed near
the
sewage treatment plant for storage
of first flush storm flows
from the proposed interceptor
and
for equalization
of wet weather
*Ehibit
B
is
an amendment to Exhibit
A,
the Facilities Plan.
Exhibit B
contains the corrected text of Chapters
1,
6,
7,
8,
9
and 10
of Exhibit A and additions
to Chapters
4 and
5.
69-250
6
flows.
This basin will
be concrete lined
and will include
aeration for mixing and odor control
(Petition at
8,
9,
10).
The Mattoon plant consistently meets
its NPDES permit
limitations
for
10 mg/l BOD and
12 mg/i suspended solids and
needs
no additional facilities
to achieve compliance with the
limitations for treatment of dry weather flows.
Treatment plant
improvements that the City proposes to construct at
its own
expense
to correct operational problems and conserve energy are
described
in Section 6.2
of Exhibit E and include:
—
Replacement of
the existing submerged turbine aerators
with
a fine bubble aeration system for the activated sludge
process;
—
Construction of
a wet weather flow equalization basin
coordinated with
the storage requirements for CSO control;
—
Modifications
to the stormwater pumps and controls;
—
Installation
of baffles and
a positive scum removal system
in the existing secondary clarifiers;
—
Electrical
control modifications
to improve operational
flexibility and
reduce
the frequency of electrical failure due
to
lightning;
and
—
Piping,
valves
and
site improvements related
to the above
(Petition at 8).
The construction cost
for alternative
8
is $7,633,000
with
total CSO project cost being
$9,132,000
(Exh.
E, Table
4;
see
petition at
11).
Annual operating and maintenance
(O&M)
costs
for the CSO alternative will approximate $70,000
(Exh.
D, Table
6.1—8).
The capital costs
for
total compliance alternatives
2
and 3
are $14,500,000
and $24,765,000 respectively (Petition at
7) with capital savings
to the City approximating $5.4 million
and $15.6 million,
respectively.
The City
is hoping
to obtain grant funding for the
Alternative
8 project.
A 50 percent Build Illinois grant for
part
of
the project has been applied for
as well
as
a
55 percent
USEPA grant. The City has grant priority number 1,010
for the
USEPA grant.
Assuming
a
55 percent USEPA grant, the City’s
share
of the capital costs of the proposed plan would approximate $4.5
million
(Exh.
B, Table
8.1
and
at 9—2).
Current sewer charges are $1.43
per 100 cubic
feet.
Assuming
no grants are forthcoming but CSO relief
is granted
by
the Board,
the basic sewer user’s charge would increase
to $2.82
per 100 cubic
feet, which includes debt service
(Exh.
E,
Table
13).
If CSO relief
is granted and a grant
is obtained,
the basic
69.251
7
user charge would
be $2.24 per 100 cubic feet
(Id.,
Table
12
R.
24).
With no CSO exception and no grant,
the estimated charge
would
be $4.15
per
100 cubic
feet
(R.
18).
These charges
do
not
include the usual billing and collection charge
of $0.56 per
bill.
With CSO relief but without grants, annual
sewer
costs
to an
average household would approximate
$200.
If there are no grants
and no CSO relief, the annual figure will approximate
$300 using
the least costly full compliance option
(R.
18,
19, 23,
29).
Conclusion
Having considered
the evidence and the factors enumerated
in
Section 306.361(a),
the Board finds
that, the Mattoon CSO
discharges,
after implementation of alternative
8, will have
minimal
impact.
The project will eliminate all CSO discharges
in
the Little Wabash Basin
and
increase the treatment
of CSO
discharges
in the Riley and Kickapoo Creek Basins.
The plan will
increase
the CSO capture
from 12
times
the ~ry weather flow
to
37
times
the dry weather flow
(R.
7).
Additionally,
58 percent of
the BOD
in Kickapoo Creek will
be eliminated
(R.8).
Plan
implementation will also help alleviate flooding
(R.
77, 78).
The Board will grant
an exception with language similar
to
that recommended by the City and the Agency.
In order
to insure
that this Order
is not construed as authorizing
the City
to
abandon its other
efforts
to reduce
its CSO discharges,
the Board
will add some conditions.
The Board will require
the City
to
certify the acceptance of these added conditions.
One condition
requires separate sanitary and non—sanitary sewer discharge pipes
from new buildings.
This condition will make it easier
to
separate flows
in the future when sewer work occurs.
A condition
to prohibit new connections
of
residential downspouts
to sewers
carrying sanitary wastes
(includes combined sewers)
has been
added
to reduce
the amount
of storm flow into these
sewers.
The
Board notes
that even though water from downspouts often enters
combined sewers,
removing the direct connections delays
the
arrival
of
the flow.
This
in turn allows
a higher percentage of
contaminated water
to be treated.
The City shall continue
its
street and sewer cleaning programs.
The City will
be required
to
separate storm and sanitary sewers
to the extent
feasible when
streets
are reconstructed and when area redevelopment occurs.
The Board recognizes that
in certain situations such separation
may not be feasible from an engineering point
of view.
However,
separation should receive careful consideration when major
redevelopments are planned
in areas with combined sewers.
The Board notes that the relief
is restricted only
to those
substantive
requirements for effluent treatment
of CSO’s,
and not
to relief from water quality standards.
To insure that this
issue
is clear,
the Board will introduce into the Order
language
69-252
8
identifying the scope
of the exception
as granted.
This Opinion constitutes the Board’s findings
of fact and
conclusions
of law in this matter.
ORDER
1.
The City of Mattoon
(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
(b)
for combined sewer overflows,
subject
to the following
conditions:
a)
The City shall modify and upgrade the existing
Wastewater Treatment Plant
(WWTP),
including the
construction of
a wet weather flow/storage basin
as
identified
in Exhibit
E, Municipal Compliance Plan
(October,
1985), pages
10,
11 and
14.
b)
The City shall repair
and maintain the existing
diversion structures tributary
to Riley Creek.
At
such time as storage capacity
is available at the
WWTP,
these diversion structures
shall
be
raised
to
a height adequate
to achieve optimal utilization
of
interceptor sewers prior
to and during any overflow
event.
c)
In conjunction with sewer
separation work as
described
in Exhibit
E,
page
12,
the City shall
construct
interceptor sewers which shall transport
all combined flows tributary
to the Little Wabash
River Basin and
reduce
the frequency and
extent of
overflows
in the Kickapoo Creek Basin,
all
as
described in Exhibit
E, pages 12 and
13.
d)
The City shall have constructed and
in operation
all
of the above conditions and associated
appurtenance work by July 1,
1988.
e)
Within three years of completion of these
improvements,
the City shall perform an evaluation
of their effectiveness,
including chemical and
biological assessment of the affected portions of
Kickapoo Creek,
Riley Creek
and Little Wabash
River.
The results of this evaluation shall
be
reported
to the Agency.
2.
The City of Mattoon shall,
in addition
to the plan
outlined above:
a)
Prohibit new connections
of residential downspouts
to sewers carrying sanitary waste;
69-253
9
b)
Require separate sanitary and non—sanitary sewer
discharge pipes
from new buildings;
c)
Construct separate storm and sanitary sewers to the
extent feasible when streets are reconstructed and
when area redevelopment occurs.
d)
Continue Street and sewer cleaning efforts so as
to
minimize the bypassing of solid materials.
3.
This grant of exception does not preclude the Agency
from exercising
its authority to require as
a permit
condition
a CSO monitoring program sufficient
to assess
compliance with this exception and any other Board
regulations,
including Sec. 306.305(c)
and b)
other
controls
if needed
for compliance,
including compliance
with water quality standards.
4.
This grant
of exception
is
not to
be construed
as
affecting
the enforceability of any provisions of this
exception,
other Board
regulations,
or the Act.
5.
Within forty—five
(45) days
of the date
of this Order,
the City shall execute a Certification of Acceptance and
Agreement
to be bound by all terms and conditions of
the
exception granted.
This Certification shall
be
submitted
to the Agency
at 2200 Churchill
Road,
Springfield, Illinois
62706.
The form of said
Certification shall
be
as follows:
Certification
I,
(We)
,
hereby
accept and agree
to be bound by all terms and conditions of the
Order
of the Pollution Control Board
in PCB 85—215,
dated
Petitioner
Authorized Agent
Title
69-254
10
Date
IT
IS SO ORDERED.
Board Members 3.D. Durnelle,
3.
Anderson and
B.
Forcade
concurred.
I, Dorothy M.
Gunn,
Clerk of the Illinois Pollution Control
Board,
hereby certi~~thatthe above Opi,nion and Order was
adopted
on the
~2~T~(—
day
of
________________,
1986,
by
a vote
of ________________________.
7/
/L-~
p&/~
~.
Dorothy
M.
Guf’in,
Clerk
Illinois Pollution Control Board
.
69-255
