ILL1~Ii PC~LLUTi~NCCJN’I±~.3L
&LARD
August 20, 19b7
SCOTT AIR FORCE BASE,
Petitioner,
v.
)
PCB 87—48
ILLINOIS ENVIRONMENTAL
P~OTECTI3N A~EI~C’~.
Respondent.
OPI~1OF~i~i;t.. C~RCR OF TnE BOARE
(by
1~.C. Flemal):
This matter comes before the Board upon the filing by Scott
Air Force Ez~r~(“Scot.: AFb”) on April 17, 1987, of a Petition for
Variance ar~on June 1, 1987. of an Amended Petition for
Varianc~.
~ezi:ioner
re~ouests variance from the five—day
biochemical oxygen de~and (“BC~”)
and total suspended solids
(“TSS’) ii:~.:~n~c~ 3~111. T~on. Coae 3(j4.l2~ij and from th?
NPDES effluent standards of 35 Ill. Adras. Code 304.141(a). These
sections respectively provide in pertinent part that:
No effluent whose dilution ratio is less than five to
one snaIl exceea l~mg/i of
or 12 my/I of
suspended solids.
No person to ~horr.an ~PLLE Permit has been issued may
discharge any contaminant in his effluent in excess of
the standar~s and limitations for that contaminant
which are set forth in his permit.
scott additionally requests that the variance be applicable
only during those times when the hydraulic loadings at the Scott
AlE treatment plant exceed 2.5 million gallons per day (“MGi~”),
and that the term of the variance extend to July 1, 1988.
The Illinois Environmental Protection Agency
(“Agency”)
filed its recommendation (“Rec”) on July 10, 1987. The Agency
recommends that variance be granted, subject to conditions.
Hearing was waived and none was held.
For the reasons discussed below, the requested relief will
be granted.
80- 3 39
Petitionur is a federal agency (Department of Defense) which
operates an air force base in St. Clair County, Illinois. The
base is neaaquar:er~ of the .,,o Air Ease Group.
Scott AFB operates a sewage treatment system which serves an
on—base population of approximately 7,88CJ, with occasional use of
base facilities by an additional approximately 11,422 people.
The sewage treatment system consists of a collection system first
constructed in 1919; a treatment plant consisting of 4 primary
clarifers, 2 trickling tilters (one of which is proposed to be
taken out of service for repairs upon grant of the requested
variance), 3 final clariters, 2 anaerobic digesters, sludge
drying beds and disinfection facilities constructed in 1940; and
final sand filters constructed in 1972 Unoer normal operating
conditions the treatment system accommodates a hydraulic loading
of
i.3 hCL,
with o~:zru~and minimum capacities of 3.6 hGE ano
1.0 MGD, respectively. All effluent standards are met under
normal oper~:ing conditions.
however. Scot: Ako nas experienced difficulties ~ith one ot
the two tricKling filters. As Petitioner notes (Petition at 5):
Cn 23 L~cb~, Ease Civil Engineering ~as forcea
to shut bo~n tric~Iing filter *2. The filter
structure heE spelled and cracked from repeated
freeze—thaw cycles, excessive hydrogen sulfide attack
and extended age. 1~~ostimportantly the media has
crumbled to the point where proper wastewater
treatment is no longer possible. To continue
operation of tne filter would have resulted in a
violation of cur NPLES Permit.
Upon discovery of the deficiencies associated with this
filter, Petitioner consulted with the Agency regarding possible
methods of bringing the deteriorated filter back into full
operation. Several alternatives have been explored, including
partial operation of the filter. None of these alternatives has
proven fully successful. and accordingly Scott AlE has determinec
that it will be necessary to replace the filter.
Construction of the new filter is scheduled to begin prior
to October 1, 1987, and completion is scheduled by June 30,
1986. Curing this period Scott AFB will be operating with only a
single filter. Petitioner asserts that operating with the single
filter will present no difficulties with respect to compliance
80—340
with eriluent stan3ards under normal
nydraulic loading~. but tnat
at high flow conditions the plant will not be able to fully treat
the total plant influent. This condition is expected to occur at
hydraulic loadings exceeding 2.5 MOD, and to present problems
only with respect to
tne
SOC5 and S limitations.
ENViRONMENTAL IMPACT
Scott AlE and the Agency contend that there will be only
minimal environmental impact under the conditions of tne proposed
variance.
Among the reasons cited are: (1) the number of
expected excursions above the 2.5
MOD hydraulic loading level is
limited; (2) flows above 2.5 MOD
will continue to receive partial
treatment;
(3) any inadequately
treated sewage will be discharged
at a time when the receiving stream is also at high flow; and (4)
analysis of ambient water quality in the receiviny stream
indicates no association
between water quality problems and the
Scott
AFS efrl’ucn:.
Scott
~FE
estimates,
based on experience and historical
reccrds of
the
past 10 years, that hydraulic loadings in excess
of
2.5 t•~Go
have occurred wltn a frequency of approximately 37
times per
~ear
(Petition at 1). These excursions coincide with
heavy
re~n±alls (id
at 8). Eorecver, Scott AFE contends that the
estimate of 37
per year may be high
due to the recent cpmpletion
of an inflow and infiltration (“I&I”) reauction project~.
Should the variance be granted, Scott AFB commits to
providing primary treatment and chlorination to all hydraulic
loadings in excess of 2.5 MGD (Id at 10). Scott AlE also agrees
to a cap on both daily maximum and 30—day average concentrations
of BOD~and TSS during the term of the variance, and to conduct
special effluent monitoring during those times when hydraulic
loading exceeds 2.5 MGD (Amended Petition at 4). The caps
requested are specified in the Amended Petition at 3:
~e would like to specify that the BOD—5 load
limit be increased
from 155 lbs/day to
185 lbs/day
(for 30 day average) and from 417 lbs/day to 550
1 Data provided by
the
Agency (Rec. at 10) from Petitioner’s
Discharge Monitoring Reports indicates that Petitioner’s
effluent
has been well within
tti~
current SOD5 and TEE limitations
even
when Petitioner has been operating with
only one effective
trickling
filter.
The Agency cautions, however, that none of
these data were collected under the high flow conditions which
are expected by Petitioner
to cause violations.
2 The Board notes that Scott AFE provides no documentation
that
tne I&I reduction has caused an actual aecrease in wet—weatner
flows to the plant.
80—341
—.~ —
los,iday (icr daily maximum). Likewise, we woulo ask
that the BD—5 concentration limit parameters be
increased from lu my/l to 2u mg/i (for 3u ãay average)
and from 20 m;/l to 30 mg/l (for daily maximum). in
re~arus to the :ss parameter~ we ask that allowable
load limits be increased from 186 lbs/day to 210
lbs/oay (3u day average) and 500 lbs/day to 600
lbs/day (daily maximum). Finally, we request that TSS
concentration limits be raised from 12 mg/l to 20 mg/l
(30 day average) and 24 mg/l to 35 mg/l (daily
maximum),
The Agency agrees with these requested caps, and recommends that
they and the commitment to conduct special monitoring at
hydraulic loadings greater than 2.5 MCD be stipulated within the
conditions of the variance.
Seceuse h~gn influent hydraulic loadings coincide with heavy
rainfalls, there also tends to be a coincidence of high influent
flow with hign discharges in the receiving stream, Silver
Creek. For this reason the Agency concludes (Rec. at 12):
The Agenc~ nes no reason to believe that the
lesser quality effluent Petitioner plans to discharge
will have a significant adverse impact on the
receiving stream because the slight increase in
concentrations will only occur during wet weather and
consequently high stream flows.
Tne Agency further believes that this circumstance will mitigate
any adverse effect on the waters of the State (Rec. at 16).
Both Scott AFH and the Agency have provided analyses of tnc-
ambient water quality in the receiving stream, both upstream and
downstream of the Scott AlE discharge (Amended Petition at 4;
Rec. at 11 and 12). These data indicate generally acceptable
water quality for the parameters identified, and no discernable
affect of the Scott AFE discharge.
HARDSHIP A~D COMPLIANCE PLAi~
As the Agency recognizes~ the hardship upon Petitioner in
the instant matter is not a question of limited resources, but
rather a question of feasibility (kec. at 15). In the absence of
variance, Petitioner can not expect to be in consistent
compliance with the present SOD- and TES limitations, and
therefore, absent variance, wouid be subject to enforcement
action. Petitioner does intend to permanently rectify this
matter by installing a new trickling filter, which it commits to
doing by June 30, 1988 (Petition at 6; Amended Petition at 2;
Rec. at 13). There is no indication in the record that it would
be feasible to install the new filter in a significantly shorter
time, and the Agency contends that approximately one year appears
80—342
—5—
to be a reasonacle pericd in ‘~hichto expect the work to be
completed (Rec. at
13).
CCPCLUSION
Given the entirety of the circumstances in this matter, the
Board finds that Scott AFB would suffer an arbitrary or
unreasonable hardship not justified by the environmental impact
if required to come into immediate compliance. For this reason
the requested variance will be granted, subject to conditions as
presented in the Order below. The conditions are essentially
those recommended by Petitioner and the Agency.
This Opinion constitutes the Board’s findings of fact and
conclusions of iaw in this matter.
ORDER
Scott ~ir Force Base is hereby granted variance from 35 Iii.
Adm. Code 304.120 arid 304.141(a), subject to the following
conQl:ions.
1)
\a~lance ~n~li co~w~.enceon October
ic,
1987, or upon
start of construction of trickling filter *2, and expire
on July 1, l~8E, or upon completion of trickling filter
~2, whichever occurs first.
2) Variance shall be in effect only at such times as when
daily and/or
monthly
plant hydraulic loadings are
greater than 2.5 ~GE..
3) Petitioner shall meet the following effluent limits
during the term of the variance at any time when daily
and/’or monthly average hydraulic loadings are greater
than 2.5 NGD:
a) SOD. concentration 20 mg/i monthly average and 30
mg/i daily maximum;
b) BOL~quantity
=
165 lbs/day monthly average and 550
lbs/day daily maximum;
c) TSS concentration 20 mg/i monthly average and 35
mg/i daily maximum;
d) TEE yuantity
=
210 lbs/day monthly average and 600
lbs/day daily maximum.
4) All flows in excess of 2.5 MGD shall, at the minimum,
receive primary treatment and chlorination.
5) Petitioner snail sample its effluent each day when
hydraulic loadings exceed 2.5 MGD. The effluent samples
80—343
—~ —
shall be analyzed for parameters listed in Petitioner’s
NPDES Permit, Petitioner shall summarize all samples
taken and submit the summaries, along with plant flow
data, with its monthly Discharge Monitoring Report.
6) Petitioner shall report to the Agency’s Collinsville
Regional Office by telephone when repair work is to
begin and wnen it is completed. A written confirmation
of the notification shall be sent to the following
address within five (5) days tnereafter:
Illinois Environmental Protection Agency
Division of ~ater Pollution Control
Compliance Assurance Section
2200 Churchill Road
Post Office Box 19276
Springfield. Illinois 62794—9276
7) Petitioner shall apply for and receive any applicable
permits from the Agency prior to beginning construction.
8) Petitioner shall execute and submit a Certificate of
~cceo:ence to the address in (o) within forty—five (45)
days
of
tnis Order. This forty—five day period shall be
held in abeyance for any period this matter may be
appealed. The form of the Certificate shall be:
Scott ~ir Force Base has received and unãerstands the
Order of the Illinois Pollution Control Board in PCB 87-
46 and hereby accepts said Order and agrees to be bound
by all of the terms and conditions thereof.
By:_____________________________________
P. T. Dixon, Jr., Colonel USAF
Commander
Date
IT IS SO ORDERED.
I, Dorothy N. Gunn. Clerk of the Illinois Pollution Control
Board, hereby certify that the above Opinion and Order was
adopted on tne
~-
day of
4, ~
,
1987, by a vote
of ~
.
Dorothy N. G~n, Clerk
Illinois Pollution Control Board
80—344