ILLINOIS POLLUTION CONTROL BOARD
May
9,
1986
IN THE MATTER OF:
)
)
THE JOINT PETITION OF THE CITY
)
OF ROCK ISLAND AND THE ILLINOIS
)
PCB 85-214
ENVIRONMENTAL PROTECTION AGENCY
)
FOR EXCEPTION TO THE COMBINED
)
SEWER OVERFLOW REGULATIONS
)
MR. ROY HARSCH APPEARED ON BEHALF OF THE CITY OF ROCK ISLAND
MR. THOMAS DAVIS APPEARED ON BEHALF OF THE ENVIRONMENTAL
PROTECTION AGENCY
OPINION AND ORDER OF THE BOARD (by R.
C. Flemal):
This matter comes before the Board upon a joint petition for
a combined sewer overflow
(CSO)
exception filed pursuant to 35
Ill.
Adm.
Code,
Subtitle
C,
Chapter
I,
Part 306,
Subpart
D, by
the City of Rock Island (“Rock Island”) and the Illinois
Environmental Protection Agency (“Agency”).
Petitioners
specifically request exception from 35
Ill. Adm.
Code 306.305(a)
and 306.305(b).
The Board conducted
a public hearing
in Rock Island on March
3,
1986.
In addition to testimony presented by the Joint
Petitioners,
testimony
in support of the requested relief was
presented by Ms. Emily
Smith, chairperson of the Rock Island
Facilities Study Jury of Experts.
The Jury of Experts consists
of thirteen citizens, representing
a cross-section of community
interests,
who have followed the progress of all phases of the
CSO program for several years.
CSO
•REGULATI~NS
The CSO regulations are contained
in
35
Ill. Adm.
Code,
Subtitle
C, Chapter
I,
Part 306.
They were amended in R81-17,
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.
69-425
-2-
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 average dry weather flow
for the design year, shall receive
a minimum of
primary 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 Rock
Island has done.
A joint petition may seek an exception based on
minimal discharge impact
as prov~idedin Section 306.361(a):
An exception justification based upon minimal discharge
impact shall include,
as
a minimum, an evaluation of
receiving stream ratios,
known stream uses,
accessibility to stream and side land use activities
(residential, commercial,
agricultural, industrial,
recreational),
frequency and extent of overflow events,
inspections of unnatural bottom deposits, odors,
unnatural floating material or color,
stream morphology
and results of limited stream chemical analyses.
Rock Island and the Agency believe they have made the “minimal
impact” showing pursuant to Section 3O6.361(a).
SUPPORT DOCUMENTS
Rock Island has undertaken several studies of its CSO
situation,
the reports of which have been submitted as exhibits
in support of the petition.
The principal among these is the
R~ckI~sl~and.,
i1I.inois
Combined
Sew-er-
Overflo-w
.St-udy,
prepared
by
Missman,
Stanley
& Associates, dated May,
1982,
and
submitted
as
Exhibit
2 (referenced
as Exhibit
B in Joint
Petition).
This
document
is augmented by two other
Missrnan,
Stanley
& Associates
studies,
a response supplement
to the IEPA review letter dated
August,
1983 (Ex.
1; referenced
as Exhibit
A in Joint Petition),
69-426
—3—
and Propos-ed•Pla-n-for-POTW-a-ndTra-nsport-Iii~prove~ent-s•-for-•3oin-t
CSO -Exception dated
September, 1984
(Ex.
5;
referenced as Exhibit
E in Joint
Petition).
These studies consider, among other
matters, description of the Rock
Island sewage transport and
treatment system, characterization of alternate control
mechanisms,
determination of the quantity and quality of CSOs,and
assessment
of the impact of the overflows on the Mississippi
River.
A fourth major document submitted as Exhibit
3
(referenced
as
Exhibit
C
in Joint Petition)
was prepared by James
E.
Huff,
P.E., and deals with CSO effects on stream bottom sediments.
The
record before the Board also contains several exhibits submitted
in support of particular aspects of the testimony presented at
hearing.
BACKGROUND
The City of Rock Island, which has
a population of 46,862
(1980 census),
is located in northwestern Illinois on the
Mississippi and Rock Rivers.
Rock Island owns and operates its
own system of sewers
and waste treatment plants.
The system
includes approximately 170 miles of sewers.
It also includes
two-
treatment plants,
the Main Plain and the Southwest Plant.
Only
the Main Plant and its tributary sewer system are the subject of
the joint petition.
The Main Plant
is
served by two major
interceptor
sewers,
the North Slope Interceptor and the South
Slope Interceptor.
As with many older cities
in the Midwest, Rock Island
originally constructed combined sewers to convey both municipal
sewage and stormwater.
Between 1970 and 1979 Rock Island
undertook
a $6.9 million program to separate combined sewers
serving about 2,830 acres of the 5,600 acres
tributary to the
Main Plant
(R.
at
10).
At present approximately 17
of the area
tributary to the Main Plant
(970 of 5,600 acres)
remains
combined.
The combined areas are located
in the north-central
section of the city
(Ex.
10),
and correspond with the principal
commercial areas of the community (Ex,
2, Table
1)
where
separation would be most difficult and expensive
(R. at 11).
The requested exception concerns six outfall structures:
outfall OO1A is
a bypass located at the Main Treatment Plant;
outfalls 002-006 are overflows
from the North
Slope
Interceptor.
Outfall OO1A discharges directly to the Mississippi
River.
Outfalls 002-006 discharge in the lower reaches of Sylvan
Slough,
a high-velocity side channel of the Mississippi River
which has been developed as
a race-way for
a hydroelectric plant
located upstream from the CSO discharges
(R.
at
59).
69-427
—4—
The Main Treatment Plant consists of two parallel grit
removal chambers, eight primary settling tanks,
the complete mix
activated sludge process, two secondary clarifiers,
and
chlorination facilities.
The plant has an
8 million gallons per
day
(“mgd”) design average flow capacity and a
16
rngd maximum
flow capacity.
The North Slope
Interceptor is
a ninety-six
inch
sewer with
a full pipe capacity of 204 mgd.
As conditions associated with granting of the requested
exception, Rock Island agrees to undertake certain modifications
to its system.
These involve the construction of head works
improvements to allow operation of the treatment plant at the
design maximum level of 16 uigd and improvements to the North
Slope Interceptor to assure that maximum available transport
capacity will be utilized prior to overflow events.
The
modifications consist of
(1) improvements to the screening system
at an estimated installation cost of $75,000,
(2) interceptor
chamber modifications at an estimated cost of
$23,000,
and
(3)
increase in elevations of diversion weirs
at an estimated cost of
$3,000,
The agreed to improvements thus aggregate to
a total
estimated cost of $101,000.
The improvements are further
detailed
in Exhibit
5.
DOCUMENT-ATION- OF MINIMAL -IMPACT
The Mississippi River in the reach of the CSO and the bypass
outfalls has recreational use for boating and fishing (R. at 22);
small boating use
is characterized as
“heavy”
(R.
at 28).
Some
water skiing does occur, but the amount of swimming which occurs
is not addressed
in the record
(R.
at 29).
The river, but not
Sylvan
Slough,
is also used for commercial barge traffic.
The
nearest downstream known withdrawal of water for public water
supply is at Muscatine,
Iowa,
approximately 25 miles downstream.
Access
to the river in the vicinity of the CSOs and bypass
is limited.
Through most of the reach
in question the community
is separated from the river by a levee which does not have any
point of public access
(R.
at
21).
Land between the levee and
the river
is variously barren sand flats, rock flats, and/or
woods which range
in width up to 150 yards, depending in part on
river stage
(R.
at 21-8).
Additionally, much of the landward
side of the levee
is occupied by industrial land of limited
access.
From March to August of 1980, an overflow monitoring and
sampling program was conducted to collect basic data on the
quantity and quality of the CSO overflows.
This program
consisted of measuring flow at the six discharge points with
continuous flow meters, monitoring of the length of time the Main
Plant pumps directed discharge to outfall OO1A,
sampling of water
quality,
and physical inspection of the five CSO discharge
points.
69-428
—5-
Data from the 1980 monitoring and sampling program was
utilized, along with historical rainfall data,
to estimate the
number and volumes of overflow events that could be expected
in
an average year;
the estimation was done utilizing the computer
program,
Simplified
Storm Water Management Model (SSWMM).
This
analysis indicates the following number and volumes of events
from each discharge point per year
(Ex.
11):
NUMBER
VOLUME
OUTFALL
OF- -EVENTS
~-mg/y-ea-r•)
OO1A
103
697.2
002
16
12.5
003
24
7.6
004
50
10.3
005
40
79.3
006
50
9.6
These data indicate that bypass OO1A can be expected to discharge
approximately 700 million gallons from 103 events during the
average year.
Similarly,
the five other
CSOs can be expected to
discharge approximately 120 million gallons during approximately
50 events per year
(R.
at 36-7).
The
120 million gallon figure
would be reduced by 20
and the number of events decreased to 40
per year
if the improvements as agreed to by Petitioners are
implemented
(R. at 43).
Not all of the 700 million gallons discharged at OO1A is
derived from the combined sewer system.
Due to the particular
configuration of the Main Plant
(Ex.
19),
some separated storm
sewer discharges are directed through outfall OO1A (Ex.
19).
It
is estimated that about 1/3 of the 700 million gallons derives
from separated storm
sewers
(R.
at
73).
Similarly,
some of the 103 annual events estimated for
outfall OO1A are apparently triggered by infiltration into the
separated storm sewer system rather than by storm surcharging of
the combined sewer system
(R. at
55,
61-71).
The pumps at OO1A
are afixed to wet wells which receive flow from both the storm
and sanitary sewer system
(Ex.
19).
The filling of these wet
wells causes the pumps
to activate and drain the wells via the
outfall.
The record
is unclear as to what percentage of the 103
events are related to simple emptying of the wet wells.
At one
point
it
is
surmised
that
infiltration
is responsible for causing
the wells
to fill and discharge approximately
20 to 30 times per
year
(R.
at 49-50).
Later in the record
it
is indicated that
these could constitute
“the majority” of the pumping events at
OO1A
(R.
at
61), and that they constitute approximately half of
the 103 events
(R.
at
76).
Petitioners have presented testimony
that during 1985 there were only seven occurrences of bypasses at
OO1A which were occasioned by flow to the Main Plant exceeding
the plant’s
16 mgd design maximum flow
(R. at 105).
69-429
—6—
In comparing the volumes of the
CSOs to the flow
in the
receiving stream, Petitioners note that the mean daily discharge
of the Mississippi River at Rock Island
is 31,085 mgd, and that
the ten-year seven-day low flow is 8,900 mgd
(Petition,
par.
12).
In contrast, an overflow event of
a one-year frequency
would discharge about 52.7 million gallons
(Petition, par. 12).
Thus, if the one-year recurrence interval discharge were to occur
at the time of average flow in the Mississippi,
it would be
subject
to
a receiving ratio
of 590:1; if it occurred
at the time
of the ten-year seven-day low flow it would be subject to a
mixing ratio of 169:1.
Chemical analyses of the CSO discharges
as conducted- in
1980
included the following parameters: biochemical oxygen demand
(BUD),
chemical oxygen demand
(COD),
total suspended solids
(TSS), total dissolved solids
(TDS), ammonia nitrogen,
phosphorous, and lead.
Volume analysis indicated that the six
CSOs in combination make an average annual contribution of 0.6
million pounds
of BOD and 4.5 million pounds of TSS to the
Mississippi River.
Over 80
of these contributions are
discharged from at the Main Plant via OO1A due to the larger
volume, number of events,
and pollutant loadings
at that point
(R.
at
37).
Given the high flows of the Mississippi River,
Petitioners conclude that
“the Rock Island CSOs by themselves
have
a negligible effect on the Mississippi River water quality”
(Petition,
par.
12; Ex.
2,
p.
176).
In
a more recent study (Huff Study,
Ex.
3), assessment was
made of the impact of Main Plant outfall OO1A*
on bottom
sediments.
The assessment was undertaken through independent
sampling of the bottom sediments and by analysis of previous
sampling data collected by the Agency in July 1984,
and by
Missman, Stanley & Associates
in May,
1985.
All samples were
subjected to chemical analysis as well as physically inspected.
Samples were analyzed for lead,
zinc,
oil and grease, volatile
solids, and total solids.
In addition, the samples were ranked
blind
by
three
individuals
for
odor
intensity.
The
Huff
Study
found
that
discharges
from
the
bypass
CSO
has
resulted
in a limited area along the near shore of the river with
elevated pollutant levels.
This area
is approximately five
hundred feet in length by fifty
feet in width.
To provide
perspective to the levels of pollutants
as found,
Huff compared
the observed levels to those recorded in
a general Agency study
of bottom sediments collected from sites downstream of sewage
treatment plants
(Ex.
16).
In the case of CSO OO1A all mean
values of observed constitutents are below the mean values found
‘There
is no sedimentation below the five North Slope Interceptor
CSOs, where the river bottom consists of solid rock.
69-430
—7—
by the Agency
in the general survey of sediment collected within
one mile of wastewater treatment plant outfalls.
On this basis,
Huff concludes that the “impact from the existing Rock Island
combined sewer overflows on the Mississippi River
is not
discernible based upon these sediment results
in the zone of
impact”
(R.
at
84).
To further assure that the CSOs have minimal environmental
impact,
Rock Island has agreed,
as
a condition to granting of the
exception,
to implement
a one-year shoreline inspection
program.
This program
is intended to quantify and document
the
amount of debris attributable to the CSOs
(R.
at.
16).
ECONOMIC -HARDSHIP
Rock Island has determined preliminary cost estimates for
full compliance with
Section 306.305(a) and 306.305(b).
Under
these rules Rock Island would be required to provide complete
treatment for the first flush of storm flows.
An additional ten
times the average design dry weather flow would require primary
sedimentation and disinfection.
The Petitioners believe that
these requirements would necessitate,
as the least expensive
option,
the provision of below ground,
covered, off-line storage
-
facilities to capture and reduce the occurrence of overflows or
plant bypasses.
These storage facilities would operate
in
integration with the main treatment plant, and would allow for
total capture and subsequent secondary treatment of the first
flush.
Additionally, full compliance would require upgrading the
Main Plant to allow attainment of current design standards for
treatment plant components and hydraulic capacity (Petition,
par.
4).
In aggregate the full compliance alternative was estimated
in 1982 to cost $25.2 million, and the annual operation and
maintenance costs were estimated
to be $3.7 million (Ex.
2,
p.
181).
Later figures,
as set forth in Exhibits
1 and
12, raise
these figures
to a total of $54.9 million in capital costs and
$6.9 million in operating costs under the assumption that total
suspended solids control would also be required.
The latter
amounts would be
“slightly lower
if treatment based upon
biological
(sic) oxygen demand
(BUD)
was required”
(Petition,
par. 4).
At hearing Mr. Robert
T. Hawes,
City Engineer of Rock
Island,
further testified that the cost of full compliance is
estimated to be $54,330,000, and if these costs were spread over
a
20 year period at
an interest rate of 8,
the average
residential sewer use charge would increase from $3 charge would
increase from S37.21 to $103.90 per quarter.
69-431
—8-
DISCUSSION -OF- ORDER
The
Board
determines that Petitioners
have
shown
pursuant
to
35
Ill.
Adm.
Code
3O6,361(a)
that exception to
35
Ill.
Adm.
Code
306.305(a),
as
it relates to first
flush of storm flows, and to
35 Ill.
Adrn.
Code
306.305(b)
would
produce
minimal
impact
on
the
receiving stream.
Accordingly, the Board will grant the
exception.
The Board further will accept the conditions
as
agreed to by Petitioners.
The Board notes that the Agency has emphasized that its
support of this petition is predicated on the assumption that the
relief is restricted only to those substantive requirements for
effluent treatment of CSOs, and not to relief from water quality
standards
(R.
at 94).
Rock Island appears to have been aware of
this condition, and has not objected
to it.
The Board itself
notes that up to the present time, the United States
Environmental Protection Agency has indicated that only variance
(i.e. non-permanent) relief from water quality
standards can be
granted consistent with the Clean Water Act (see document
entitled “Status Report on Discussions with USEPA”,
dated October
4,
1985;
this document
is part of the record of, and is cited in,
Bor-den--Chemic•al-Gompa-ny--v-~-Illinois--Env-ir-onment-al -Protect-ion
~enc•y, PCB 82-82,
PCB
,
December
5,
1985).
To assure
that this issue is clear,
the Board will introduce into the
Order,
as proposed by Petitioners, language identifying the scope
of the exception
as granted.
ORDER
1.
The City of Rock Island is hereby granted an exception
from the treatment requirements of
35
Ill.
Adm.
Code 306.305(a),
as such provision relates to first flush of storm flows, and from
35 Iii. Adm.
Code 306.305(b),
subject to the following
conditions:
a.
Such
exception
shall
be
limited
to
combined
sewer
outfalls 002, 003,
004,
005,
and
006
and to bypass
OO1A,
as
identified in this proceeding.
b.
The City of Rock Island shall implement all
modifications to its sewer system as identified
in
paragraphs 14,
15, and
16 of the petition in this
proceeding.
c.
The City of Rock Island shall implement the
shoreline inspection program described
in paragrpah
15 of the petition in this proceeding.
2.
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
69-432
-9—
this exception and any other
Board regulations, including Section
306.305(c); and b) other controls
if needed for compliance,
including compliance with water quality standards.
3.
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.
4.
Within forty-five days of the date of this Order, the
City shall execute
a Certification of Acceptance and Agreement to
be bound
to all terms and conditions of the exception granted.
The Certification shall be submitted to the Agency at 2200
Churchill Road, Springfield,
Illinois,
62706.
The forty-five day
period shall
be held
in abeyance during any period that this
matter is being appealed.
The form of said Certification shall
be as follows:
CERTIFICATION
I,
(We),
___________________________,
having read the
Order of the Illinois Pollution Control Board,
in PCB 85-214,
dated May
9, 1986, 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.
Board Members Joan Anderson and Jacob
D. Dumelle concurred.
I, Dorothy
M. Gunn,
Clerk of the Illinois Pollution Control
Board, hereby certify that the above Opinion and Order was
adopted on the
_______
-~7-cZ.
day
of
-)7a~-~
,
1986,
by
a vote of
-
-
-~‘7--.~
~Z-fl-~
Dorothy
M. G~znn, Clerk
Illinois
Pollution Control Board
69-433
