ILLINOIS POLLUTION CONTROL BOARD
September 20,
1984
MOBIL OIL COMPAt4Y,
Petitioner,
v,
)
PCB 84—37
ILLINOIS ENVIRONMENTAL PROTECTION
AGENCY,
Respondent.
OPINiON AND ORDER OF
THE
BOARD
(by
J. Marlin):
On March 29,
1984 Mobil Oil Company filed a petition for
variance extension from
35
Iii.
Adm. Code 304.122
as
it
relates
to the 3.0 mg/i ammonia nitrogen standard applicable
to its
Joliet Refinery’s discharge into the Des Plaines River.
An
amended petition was filed on May 11, 1984
in response to a
Board more information Order dated April
5,
1984.
On June
18,
1984 the Illinois Environmental Protection Agency (Agency)
~i1ed
a recommendation
that the variance be granted subject to certain
conditions.
On July 31,
1984 Mobil filed a motion to file sup-
plementary information.
On August
2,
1984 the Board denied
the motion but admitted the information as an amended petition.
On September 4,
1984 the Agency filed a first amended recoin—
mendation and motion to supplement the record by incorporating
the
record of
R84--16 into this variance proceeding.
The Board
denied
the motion but held that because Mobil agreed to
the
Agency~smotion that
in effect it was an amended petition.
The
Board
will
vacate the Order of September
6,
1984
in
this matter
and grant the Agency’s motion, thereby incorporating the regulatory
record.
On September
8,
1984 Mobil
filed
a motion for leave
to file instanter a response
to the Agency’s first amended
recomrnendation~.which
is granted,
and
a motion for expedited
consideration,
which is denied as being unnecessary.
The
Board notes that since
this
is a variance petition from an
NPDES permit,
the Board has 120 days to render
a decision.
earing
was waived and none was
held.
Mobil owns and operates a conventional fuels petroleum
refinery with a rated capacity of 180,000 barrels per day 1~—
cated in Will County.
The refinery discharges
2.74 million
gallons
of effluent per day.
Stormwater,
noncontact cooling
water
and process water are discharged from the facility into
the Des Plaines River.
The process water and contaminated sur-
face
runoff
(1600 gpm) are treated in Mobil’s wastewater
treatment plant
(WWTP) which consists of an API separator,
a
dissolved air flotation unit, an equalization basin for primary
treatment and a conventional activated sludge facility for secondary
60-97
2
treatment.
Treated
effluent
from
the final clarifier is routed
tnrough a
4.9 million gallon guard basin where it is retained
for
approximately 51 hours and then aerated in the final aeration
cone prior
to release to the Des Plaines River.
The effluent
meets all
discharge standards other than ammonia nitrogen.
Mobil has been granted four previous variances from the
a:nmonia
nitrogen
standard
of
section
304.122
(old
Rule
406,
Chapter
3):
(PCB
77—22,
PCB
78—97,
PCB
80—54,
and
PCB
82—36).
in
PCD
82—36
(47 PCB 271, June 10,
1982) variance was granted
until July
1,
1984, subject to certain conditions including
ar~
armnonia
nitrogen effluent limitation of
25 mg/i monthly
averaqe
and 40 mg/I daily maximum concentration.
Mobil has substantially complied with all the terms and
conditions
of
the
latest variance.
The only excursions from
the
interim
limitations during the prior variance period
were
in
December,
1982 as shown in Table
3 of the Amended Petition.
The overall average ammonia reduction from influent
levels was
133
in 1983 as compared to 50
in
1982.
During the prior varL—
ance,
Mobil complied with the
3 mg/i standard 64
of the time
in
1983
as compared to 12.7
in 1982 on NPDES monitoring datesJ/
Mobil has expended considerable time and effort in its
attempt
to reach ultimate compliance with the ammonia standards.
The total cost of capital expenditures for the last ten years
is
fri
excess of $2.1 million
(Am. Pet. Table 2).
The average
operating
cost for ammonia reduction projects during
the
last
five
years has been $1,660,000 per year,
including amortization
of capital investments
(Id.).
Equalization system improvements
and
continuous dissolved oxygen monitoring in the aeration
basins
cost
an
additional $52,000 during 1982/1983
(Am.
Pet. at
3).
Projects
have included the purchase and installation of
a
ni~trifi-
cation
pilot
plant,
nitrification
inhibition
studies,
mutant
bacteria
trials,
alkalinity
addition
and
temperature
control
in
the
aeration basins.
Since 1973 these efforts have reduced
~obii’s
discharged ammonia concentration by 95 percent.
However,
Mob.L i
has
been unable to consistently meet the ammonia nitrogen
standard
or
identify
the
technology
needed
to
do
so
(Am.
Pet.
at
13).
The environmental impact of the granting of
variance
is
minimal.
The net increase in river
ammonia
nitrogen
concen-
tration
has
been
calculated
as
0,008
mg/i.
The
minimum
dis-
solved
oxygen
concentration
downstream in the Illinois River
below
Pekin was
5.7
mg/i for the first nine months of 1982 and
5.5 mg/I
in
1981.
Further reduction of Mobil’s ammonia nitrogen
discharge
is not possible given the lack
of
reasonably available
technology.
Mobil will continue efforts to reduce its ammonia
nitrogen
discharge.
1/
NPDES monitoring frequency for ammonia was reduced
from
five
times to twice per week as of February,
1983.
3
Given that technically and economically feasible means
of
meeting the standard have not been
identified
despite
Mobil’s
diligent efforts and the minimal environmental impact of granting
the variance, the Board finds that denial of variance would
impose an arbitrary or unreasonable hardship.
A variance will
be
granted for a period of two years.
Mobil requests that the interim limitations from the prior
variance
for ammonia nitrogen be extended.
The Agency recom-
mends
10
mg/i monthly average and 30 mg/i daily maximum.
Mobiles
own expert
testified in R84—l6 that at the 95th percentile level,
Mobil could
consistently comply
with
ammonia
nitrogen effluent
standards
of
25 mg/i monthly average and 35 mg/i daily maximum
(Pet.
Ex.
2,
53;
Ex.
C,
p.
2 to Mobil 7/31/84 motion) even
though
a few excursions are expected to occur
(R84—l6 at 104,
107).
By introducing process modifications the probability
of
exceeding the
25/35
standards at all would be reduced (R84-16
at 108).
As
for the Agency recommended standards, the same expert
testified that they could not be consistently met (R84-l6 at
105).
The ratio of the ammonia nitrogen concentration peak
value
versus the average influent value
to the pre-stripper
equalization
tank
showed
that
the maximum concentration range
is
approximately 1.9 to 4.7 times above the average value
(R84-16
at
52).
Using a ratio of the peak value versus the average
stripper
effluent value, the ratios become higher
(Id.).
The
higher
ratios indicate that performance variability of the
stripper
during some periods is much greater than that of
the
pre-stripper equalization stage
(Id.).
Thus,
the variability
in the
stripper effluent quality increases the ammonia nitrogen
loading
to the WWTP, and consequently in the final effluent
(R84-16 at 50,
52).
As the nitrogen concentration of the crude
oii
increases,
so does the nitrogen concentration influent
to
the WWTP
and in the final effluent (R84—16 at 122).
Therefore,
the Board
will impose ammonia nitrogen effluent standards
of
25 mg/i
monthly average and
35 mg/i daily maximum as conditions
of this
variance,
The Board notes that Mobil has been operating under
four
variances for more than five years without having presented
a compliance plan.
while the filing for site-specific regula-
tory relief does not obviate the need for a compliance plan
in
a variance proceeding,
the Board realizes that
in some fact
situations the technology does not exist for a petitioner to
reasonably reach compliance.
In that event, the conducting
of research aimed at finding a means of coming into compliance
is sometimes accepted as a compliance plan.
The Board will
order Mobil to continue its research into ways of reducing
its
ammonia nitrogen discharge.
Mobil has filed for site-
specific relief from the ammonia nitrogen standard
(R84-l6).
4
This Opinion constitutes the Board’s findings of fact and
conclusions
of
law
in this matter.
ORDER
Mobil Oil
Corporation is hereby granted a variance from
35
Ill. Adm. Code
304.122 from July 1,
1984 until July 1, 1986
subject to
the
following
conditions:
1.
Mobil’s ammonia nitrogen effluent discharge shall
not
exceed a monthly average concentration of
25
mg/i and a daily maximum concentration of
35 mg/l
during the period of this variance.
2.
Mobil
shall continue its research aimed at com-
plying with the ammonia nitrogen standard and
shall continue to submit bi—monthly reports to
the
Agency outlining its efforts to achieve com-
pliance with 35
Ill. Adm. Code 304.122, including
any studies on nitrificatjon inhibition, alka-
linity addition and any further pilot plant testing.
3.
The Board Order in this proceeding dated September
6, 1984
is vacated and the Agency motion to incor-
porate the record in R84-16
is hereby granted.
4.
Within 45 days of the date of this Order,
Mobil
shall execute and forward to the Illinois Environ-
mental Protection Agency, Compliance Assurance
Unit, Water Pollution Control Division, 2200
Churchill Road,
Springfield, Illinois
62706,
a
Certification of Acceptance and Agreement to he
bound to all terms and conditions set forth in
the
Order.
The 45 day period shall be held in
abeyance during any period in which this matter
is
being appealed.
The form shall be as shown
below:
CERTIFICATION
I,
(We),
________________________,
hereby accept and
agree
to be bo~’EE
bove
terms and conditions of the
Order of
the Pollution Control Board
in PCB 84-37 dated
September 20, 1984.
~tione~
By:
Authorized Agent
4 f~I~
Title
Date
5.
Mobil’s motion for
leave
to
file instanter a
response to the Agency’s first amended recom-
mendation is hereby granted.
6.
Mobil’s motion for expedited decision
is hereby
denied as being unnecessary.
IT IS SO ORDERED.
I,
Dorothy
M.
Gunn,
Clerk
of
the
Illinois Pollution Control
Board,
hereby
certify
tI~t
the above Opinion and Order was adopted
on
the
o?O~
day
of
~
,
1984
by
a
vote
of
___________
Dorothy
M.
Gunn,
Clerk
Illinois Pollution Control Board