ILLINOIS POLLUTION CONTROL BOARD
May
26,
1977
PEOPLE OF THE STATE OF ILLINOIS,
Complainant,
v.
)
PCB 76—181
DECATUR SANITARY DISTRICT,
)
Respondent.
OPINION AND ORDER OF THE BOARD
(by Mr.
Goodman):
On October 12, 1976,
the People of the State of Illinois
(People)
by the Illinois Attorney General filed
a Complaint against the
Decatur Sanitary District
(District).
The Complaint alleged that,
since February
1,
1976 and on specific dates thereafter,
the District
had emitted odors from its sewage treatment plant so
as
to cause air
pollution as defined by Section
3(b)
of the Environmental Protection
Act
(Act),
in violation of Section
9(a)
of the Act.
Hearings were
held in this matter on November
8 and
9,
1976,
and April
11,
1977,
in Decatur,
Illinois.
Several citizen witnesses testified at the
hearing.
At the April
11 hearing the parties submitted
a Stipulated
Statement of Facts and Proposed Settlement
(Stipulation)
.
The final
Stipulation was submitted to the Board on April
20,
1977.
The Decatur Sanitary District serves a population of approxi-
mately 110,000.
The District’s sewage treatment plant has been opera-
tional since
1923.
The area east and northeast of the plant
is
predominantly residential,
consisting of homes built generally
in
the 1950’s throuqh
1970’s.
The nearest residences are approximately
1/4 mile
from
thu
p1 ~inL.
In
February,
1972,
the District began renovation and expansion
of its facilities.
Prior to renovation,
the plant’s
sewage treatment
system consisted of a primary system comprised of Imhoff tanks and
separate sedimentation tanks followed by trickling filters
as well
as
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a parallel activated sludge process with a capacity of
18 million
gallons of sewage per day
(MGD).
Renovation included the following
changes
in the plant and its operation:
abandonment of existing grit
removal facilities and construction of new grit handling facilities;
expansion of the separate primary sedimentation system;
installation
of a Unox pure oxygen activated sludge system; renovation of the
conventional activated sludge system;
abandonment of the trickling
filter process; construction of an aerated tertiary polishing lagoon;
expansion and renovation of anaerobic digestion facilities; abandon-
ment of
5 Imhoff tanks and reconstruction thereof into secondary
stage digesters; conversion of another Imhoff tank to an aerated waste
activated sludge tank addition; and addition of complete chlorination
facilities.
Although ~rior
to 1976 the persons residing near the plant had
experienced intermittent odors from the plant, the odors increased
in duration commencing
in January of 1976 and reached a peak during
the period of April through July,
1976.
Numerous witnesses testified
during the hearings that the odor during that period was extremely
offensive,
causing them to curtail outdoor activities, refrain from
inviting guests to their homes,
and excessively use their air condi-
tioners and aerosol sprays
to lessen the strength of the odor indoors.
Several witnesses also testified that the odor caused them physical
discomfort,
such as headaches and nausea.
The parties
stipulate that the major cause of the increased odors
from the plant was odors from two sludge lagoons.
These lagoons en-
compass approximately
25 acres
in area and have an average depth of
ten feet.
Because the plant’s Imhoff tanks and digesters were inopera-
tive due to reconstruction and renovation, the District, commencing
in
September,
1975, placed approximately 90,361,000 gallons of raw and
partially digested sludge into the lagoons.
During September
-
November,
1975,
the Imhoff tanks were sequentially taken out of service
for conversion to secondary digesters.
The converted tanks were placed
in partial operation in March,
1977,
and were to be fully operational
by April
30,
1977.
Primary digesters
1,
2 and
3 were taken out of
service on June 28, July
13 and August
2,
1976,
respectively, and were
placed back
in operation on July
13 and December
2,
1976,
and January
12,
1977,
respect;ivelv.
However, on January
29,
1977, digester
#2 was
taken out of service due to freeze damage.
It was to be placed back
in service on April
11,
1977.
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564
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In
June,
1976,
the
District
stopped
pumping
sludge
to
the
east
lagoon
and
thereafter
pumped all
unstabilized
sludge
to
the
west
lagoon.
The
parties
stipulate
that
in
aoproximately
six
weeks
the
odors from the east lagoon
stopped.
On
July
29,
1976,
the
District
began chlorination of the west lagoon.
Several citizens testified
that
subsequent
to
that
date
the
odor
problem
eased.
The
parties
stipulate
that. from
March,
1976,
to January,
1977,
the District spent $61,481.53 to control odors
at
the
plants.
In
December,
1976,
the attorney General’s office retained an expert to
identify
the
cause
of
odors
emanating
from
the
plant
and
to
evaluate
various solutions
to the
odor
problem.
on
March
10,
1977,
the
expert,
Dr.
Sernmens,
took six samples from each lagoon.
In summary, the
results of the ~laboratory analysis
of these samples indicate that the
east lagoon, which had not received any sludge for approximately ten
months, was quite stable.
The pH values,
the percentage of volatile
solids
in the bottom sludge and the volatile acid content of the sludge
samples were characteristic of
a well-digested sludge.
The parties
indicate that the east lagoon
should,.
therefore, not present any od9r
problem this summer beyond what. is normal for this type of lagoon.
The
results
for the west lagoon indicate the sludge had not yet stabilized.
The sludge in the west; lagoon would still support biological activity
and cause offensive odors.
The parties agree that,
if the sludge
discharge were redirected
to the east lagoon and the west lagoon was
chlorinated for odor control, the west
lagoon will eventually stabi-
lize.
In the Proposal for Settlement,
the District agrees to continue
chlorination
in the west lagoon until
the
sludge
in
the
lagoon
has
stabilized to 25 to
35
volatile solids and volatile acids
less than
400 mg/l.
Until
that time the District agrees to chlorinate
in quan-
tities sufficient to minimize odors
to the greatest degree possible.
The
District
also
indicates
that
the
west
lagoon
will
receive
all
sludge
until
the
digesters
are
functioning
satisfactorily
and
pro-
ducing a well--digested sludge at which time the District will stop
pumping
to
the
wn~-;L
1 aijoon and pump ~-;o1e~
y
to the
vast;
lagoon.
The
District also aqrues
to place the secondary
digust ers on line and
cease
venting
gases
from
the
diqesters
by
April
30,
1977.
In
addition,
the
District
agrees
to
carry
out
several
other
actions
in
an
attempt
to
reduce
the
odor
emissions
from
its
plant.
The
parties
agree
that the
District
has
made
a good faith effort
to
control
the
odor problem.
They furthermore
recommend
that
no
penalty he assessed against the District.
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565
—4—
The Board finds that the District has violated Section 9(a)
of
the
Act
in
its
emission
of odors from its sewage treatment plant.
The
Board
furthermore
finds
that
the
Stipulation
and
Proposed
Settlement
submitted by
the
parties
is
an
acceptable
solution
to
the
serious
odor problem presented herein.
However,
the Board finds that a penalty
in this case would not aid
in enforcement of the Act and will, there-
fore,
assess no penalty.
This Opinion constitutes the findings of fact and conclusions
of law of the Board in this matter.
ORDER
It is the Order of the Pollution Control Board that:
1.
The
Decatur
Sanitary
District
is found to have emitted
odors of such quantity,
characteristics and duration as to
have caused air pollution in Illinois,
in violation of
Section
9(a)
of
the
Act.
2.
The
District
shall
comply
with
all
the
terms
of
the
Proposal
for
Settlement
submitted
by
the
parties
on
April
20,
1977,
which
is incorporated by reference
as if fully
set forth herein.
Mr. Dumelle concurs.
I,
Christan L.
Moffett, Clerk of the Illinois Pollution Control
Board,
hç~rebycertify the above Opinion and Order were ad9pted on
the
~(~‘
day
of
,
1977 by a vote of
~‘-
0
QA~~
~
Christan L.~Moff
~
Clerk
Illinois Pollutio~’Contro1Board
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566