Document ID: EPA-HQ-OW-2003-0074-1328
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2004-09-02T04:00Z

Metro
Nashville
Airport
Authority
(
Addendum)
NPDES
Permit
No.
TN0064041
Page
No.
A­
1
of
A­
7
ADDENDUM
TO
RATIONALE
Metro
Nashville
Airport
Authority
PERMIT
NO.
TN0064041
September
18,
2003
Addendum
prepared
by:
Mr.
Vojin
Janjic
The
Metropolitan
Nashville
Airport
Authority
(
MNAA)
existing
individual
NPDES
permit
required
MNAA
to
perform
a
Waste
Load
Allocation
(
WLA)
study.
The
purpose
of
the
study
is
to
determine
the
impact
on
water
quality
and
to
set
permit
limits
for
the
discharge
from
the
treatment
facility
which
discharges
to
Sims
Branch
via
Outfall
002.

The
existing
permit
required
that
the
overall
completion
date
of
June
1,
2003
for
the
WLA
study
must
be
met,
regardless
of
what
changes
may
become
necessary
in
the
details
and
interim
reporting
dates.
After
several
revisions
of
the
draft
study
were
made
according
to
division's
recommendations,
the
final
version
was
submitted
in
a
timely
manner,
on
May
30,
2003.
The
significance
to
meet
this
compliance
date
was
to
allow
for
sufficient
time
for
this
permit
to
be
modified
prior
to
the
2003/
2004
deicing
season.
The
purpose
of
this
addendum
to
rationale
is
to
summarize
changes
in
effluent
limitations
and
monitoring
requirements
at
Outfall
002,
based
on
the
findings
of
the
WLA
study.
The
effluent
limitations,
monitoring
requirements
and
other
conditions
for
all
other
outfalls,
as
described
in
the
NPDES
Permit
TN0064041,
will
remain
unchanged.

Several
stream
characterization
samples
were
collected
as
part
of
the
Sims
Branch
WLA.
The
characterization
sampling
was
performed
during
the
different
seasons
of
the
year
to
provide
data
applicable
to
each
season.
Seasonal
sampling
was
a
key
to
this
study
because
of
the
nature
of
discharge
from
MNAA.
Deicing
only
occurs
in
the
colder
months
of
the
year.
For
this
reason,
samples
were
collected
and
analyzed
according
to
the
typical
bounds
of
the
deicing
season.
A
seven
month
period
represents
the
potential
months
when
deicing
may
occur.
This
period,
the
Winter
Period,
includes
October
through
April
of
each
year.
These
months
also
correspond
to
the
wetter
months
of
the
year,
thus
providing
additional
assimilative
capacity
to
deal
with
the
discharged
treated
flow
from
Outfall
002.
The
remaining
period
of
the
year,
the
Summer
Period,
includes
May
through
September.
This
period
does
not
see
any
deicing
activity.
Additionally,
flows
are
lower
in
Sims
Branch,
and
since
temperatures
are
higher,
dissolved
oxygen
(
DO)
is
lower.
Therefore,
this
period
of
the
year
is
considered
separately.
Each
of
these
seasons
is
reflected
in
sampling
schemes,
data
analysis,
and
permit
limits.

The
Winter
Event
was
performed
on
December
28­
29,
2001.
This
was
the
first
of
the
two
extensive
sampling
efforts
performed
as
part
of
the
WLA.
This
twoday
period
is
within
two
weeks
of
the
midpoint
of
the
winter
period.
The
data
obtained
from
the
event
provided
a
good
characterization
of
the
typical
conditions
during
a
Winter
Period
discharge
from
Outfall
002.
2.53
14.03
5.78
8.64
3.72
3.28
4.14
2.69
0
2
4
6
8
10
12
14
16
0
0.5
1
1.5
2
2.5
DISTANCE
FROM
CONFLUENCE
WITH
MILL
CREEK
(
MI)
CBOD
(
mg/
L)
JB2
JB4
JB6
JB14
JB8
JB10
JB11
JB12
TRIB
5
TRIB
6
TRIB
4
STEP
AERATOR
EFF.

Ultimate
CBOD
concentrations
for
the
Winter
Event.
Metro
Nashville
Airport
Authority
(
Addendum)
NPDES
Permit
No.
TN0064041
Page
No.
A­
2
of
A­
7
The
Summer
Event
was
performed
on
July
8­
9,
2002.
This
was
the
second
of
the
two
extensive
sampling
efforts
performed
as
part
of
the
WLA.
This
two­
day
period
is
within
a
few
days
of
the
midpoint
of
the
summer
period.
The
data
from
this
event
characterizes
the
discharge
from
Outfall
002
during
the
warmer
months
of
the
year.

In
addition
to
the
Winter
Event
and
Summer
Event,
environmental
quality
samples
were
also
collected
during
several
one­
day
sampling
events.
The
sampling
was
much
less
extensive
and
did
not
include
ultimate
carbonaceous
biochemical
oxygen
demand
(
CBODu)
sampling
as
was
included
during
the
extensive
Winter
and
Summer
Events.
Also,
additional
time
of
travel
sampling
was
not
performed.
However,
the
data
that
was
obtained
during
these
events
did
provide
sufficient
information
for
a
model
validation
scenario.

Once
the
field
investigations
and
sampling
events
were
complete,
all
relevant
data
available
was
gathered,
and
the
task
of
organization
and
analysis
was
performed.
The
data
was
then
used
to
develop
and
calibrate
a
model
of
Sims
Branch.
The
model
selected
to
perform
the
WLA
study
was
the
Qual2E
model
developed
by
the
U.
S.
EPA.
This
model
requires
many
types
of
data
inputs
to
perform
acceptable
model
runs.
Although
it
is
possible
to
perform
model
runs
using
default
values,
data
developed
through
a
study
such
as
this
one
will
result
in
a
better
and
more
reliable
water
quality
model.
Therefore,
strict
attention
was
given
to
an
accurate
assessment
of
all
available
data
to
improve
the
output
from
the
Qual2E
model
runs.

The
extensive
environmental
data
collected
during
sampling
events
was
analyzed
and
used
to
develop
and
calibrate
the
Qual2E
model.
The
development
and
calibration
of
the
Qual2E
model
was
performed
based
on
the
period
of
the
year
to
be
evaluated.
Each
calibration
was
based
on
the
major
sampling
event
performed
for
each
period
of
the
year.
The
Winter
Event
(
December
28­
29,
2001)
was
used
as
the
base
scenario
for
the
Winter
Period
(
October
 
April).
Likewise,
the
Summer
Event
(
July
8­
9,
2002)
was
used
as
the
base
scenario
for
the
Summer
Period
(
May
 
September).

Several
conservative
measures
have
been
employed
in
the
development
of
this
model.
Some
noteworthy
conservative
aspects
of
the
calibrated
model
for
scenario
assessment
include:
 
A
wide
range
of
headwaters
flow
conditions
is
used
to
perform
the
scenarios;
 
The
75
th
percentile
flow
was
used
for
the
discharge
flow,
even
during
very
low
flow
headwaters
conditions;
 
The
outlying
period
for
the
Winter
Period
was
April
30
(
deicing
activity
typically
is
over
before
April
of
every
year);
and
 
One­
half
the
diurnal
flow
variation
was
used
for
comparison
of
model
results
to
the
water
quality
standard
(
5.5
mg/
L
versus
the
5.0
mg/
L
WQS).
The
conservative
approach
provided
sufficient
safety
factors
toward
developing
appropriate
permit
limits
for
the
Outfall
002
discharge;
however,
some
aspects
of
a
worst
case
scenario
should
still
be
0
2
4
6
8
10
12
14
16
0
0.5
1
1.5
2
2.5
DISTANCE
FRO
CONFLUENCE
WITH
MILL
CREEK
(
MI)
CBOD
(
mg/
L)

model
actual
JB2
JB4
JB6
JB14
JB8
JB10
JB11
JB12
TRIB
5
TRIB
6
TRIB
4
STEP
AERATOR
EFF.

Winter
Event
CBODu
Actual
versus
Model
Metro
Nashville
Airport
Authority
(
Addendum)
NPDES
Permit
No.
TN0064041
Page
No.
A­
3
of
A­
7
evaluated.
This
was
accomplished
by
performing
scenarios
for
the
outlying
limits
of
the
seven
month
and
five
month
periods
to
evaluate
the
potential
impact.

The
ultimate
purpose
of
this
study
is
to
provide
a
basis
for
recommending
appropriate
discharge
limits
for
the
MNAA
Outfall
002.
The
flow
of
Outfall
002
represents
the
treated
stormwater
discharge
from
the
main
terminal
and
ramp
areas
of
the
Nashville
International
Airport
property.
The
stormwater
discharge
includes
flows
from
deicing
activities
during
the
winter
months
of
the
year.

There
is
always
some
element
of
BOD
contained
in
airport
discharge.
However,
levels
remain
very
low
during
the
Summer
Period
of
the
year.
The
major
source
of
BOD
in
airport
runoff
is
deicing
fluid.
Deicing
only
takes
place
during
the
cold
periods
of
the
year;
the
period
is
almost
exclusively
bound
between
the
months
of
October
and
April
of
the
year.
Consequently,
the
limits
recommended
by
this
report
are
relevant
to
this
timeframe.
Limits
are
recommended
for
the
period
between
October
and
April,
and
separate
limits
are
recommended
for
the
period
between
May
and
September.
These
are
the
same
periods
proposed
by
the
division's
personnel
during
the
last
permit
review.

It
is
important
to
note
the
extensive
range
of
variables
that
affect
the
impact
of
any
pollutant
source
on
a
receiving
stream.
The
discharge
from
Outfall
002
is
a
classic
example.
For
any
particular
discharge
flow,
there
is
an
associated
CBOD
concentration.
This
particular
flow
and
concentration
could
have
a
range
of
impacts
on
the
water
quality
of
Sims
Branch.
Factors
that
influence
these
impacts
include:
weather
conditions,
air
temperature,
water
temperatures
(
Sims
Branch
and
effluent),
pre­
existing
dissolved
oxygen
concentrations
(
Sims
Branch
and
effluent),
pre­
existing
CBOD
concentrations
in
Sims
Branch,
and
background
flow
of
Sims
Branch.
It
would
be
preferable
to
develop
a
matrix
or
a
real­
time
model
as
part
of
the
discharge
permit;
however,
this
is
not
currently
practical
for
the
State
of
Tennessee
or
MNAA
because
of
insufficient
staff
and
resources.
Such
a
concept
is
also
limited
because
of
the
required
time
to
evaluate
CBOD
levels
in­
stream
as
well
as
in
the
Outfall
002
discharge.
If
future
advancements
are
made
in
water
quality
sampling
and
analysis
practices
and
the
additional
staff
to
perform
such
an
evaluation
were
available,
such
a
standard
would
provide
a
much
more
real­
time
management
of
the
water
quality
of
Sims
Branch.

The
Winter
Period
recommendations
are
based
on,
a)
model
runs
that
show
no
DO
concentration
that
dips
below
the
water
quality
standard
along
the
entire
length
of
Sims
Branch,
and
b)
the
evaluation
of
the
technological
capability
of
the
treatment
unit.
The
technological
evaluation
demonstrated
that
under
certain
influent
conditions,
even
a
92%
reduction
of
CBOD5
would
yield
concentrations
in
excess
of
250
mg/
L.
However,
these
conditions
typically
occur
when
flows
are
lower
in
Sims
Branch
and
in
the
treatment
unit.
The
critical
period
for
CBOD5
concentrations
is
found
when
a
great
deal
of
deicing
is
required
and
relatively
low
rainfall
or
snow
melt
totals
are
available
to
carry
the
deicing
fluids.
Therefore,
the
major
concern
is
during
cold,
dryer
periods
of
the
winter.
When
these
periods
occur
and
high
influent
concentrations
are
detected,
flow
into
the
treatment
unit
can
be
stopped
and
flows
can
be
retained
until
additional
stormwater
is
available
for
dilution
and
treatment.
This
option
was
exercised
in
December
2002.
If
the
capacities
of
the
treatment
unit
and
retention
ponds
are
exceeded
when
a
high
concentration
is
measured
in
the
influent
of
the
treatment
pond,
flow
can
be
diverted
to
the
Metro
sanitary
sewer
collection
system.
This
addresses
the
critical
time
for
CBOD5
concentrations.

The
limits
for
higher
flow
periods
are
not
problematic
for
the
treatment
unit
because
of
the
available
dilution
from
stormwater.
The
permittee
recommended
the
highest
concentration
allowed
during
the
winter
months
to
be
150
mg/
L
for
a
single
sample
for
any
flow
of
3
cfs
or
greater.
This
recommendation
was
based
on
model
runs
with
the
stream
flow
set
at
3
cfs
with
a
discharge
concentration
of
150
mg/
L.
Although
higher
concentrations
may
be
assimilated
by
Sims
Branch
at
Metro
Nashville
Airport
Authority
(
Addendum)
NPDES
Permit
No.
TN0064041
Page
No.
A­
4
of
A­
7
higher
flows,
concentrations
are
not
critical
at
these
higher
flow
conditions
and
the
recommended
150
mg/
L
concentration
will
further
contribute
to
the
protection
of
the
health
of
Sims
Branch.

The
discharge
permit
limits
recommended
by
the
permittee
for
the
Winter
Period
are
presented
in
Table
A.
One
sample
was
recommended
per
week
during
the
Winter
Period
of
the
year
because
it
is
the
critical
period
of
the
year
for
elevated
CBOD
concentrations
in
the
discharge
from
Outfall
002.

Table
A
Permittee
Recommended
Water­
Quality
Based
Effluent
Limits
for
the
Winter
Period
(
October
 
April)

EFFLUENT
LIMITATIONS
MONTHLY
DAILY
MONITORING
REQUIREMENTS
Receiving
Stream
Flow
>
0
CFS
and
<
0.5
CFS
CBOD5
25
30
1/
Week
Grab
Receiving
Stream
Flow
>
0.5
CFS
and
<
1
CFS
CBOD5
45
50
1/
Week
Grab
Receiving
Stream
Flow
>
1
CFS
and
<
3
CFS
CBOD5
65
75
1/
Week
Grab
Receiving
Stream
Flow
>
3
CFS
CBOD5
135
150
1/
Week
Grab
The
WLA
allocation
study,
as
indicated
above,
showed
that
relatively
high
concentrations
of
CBOD5
can
be
discharged
into
Sims
branch
during
winter
months
without
violating
the
instream
water
quality
criteria.
However,
it
is
division's
position
that
the
entire
assimilative
capacity
of
a
receiving
stream
should
not
be
allocated
to
one
source,
particularly
when
the
receiving
stream
segment
(
Sims
Branch,
ID
TN05130202007_
0150)
is
impaired
for
"
Organic
enrichment/
Low
DO."
Furthermore,
most
surface
water
discharges
must
provide
a
minimum
degree
of
treatment.
For
industries
subject
to
a
federal
Effluent
Limitation
Guideline(
s),
the
guideline
will
provide
the
minimum
degree
of
treatment.
In
the
absence
of
federal
guidelines,
Tennessee
Rule
1200­
4­
5­.
03:
Effluent
Limitations
for
Effluent
Limited
Segments
states,
in
part:

"[ ]
treatment
units
will
be
required
to
achieve
as
a
minimum
the
following
as
maximum
effluent
limitations
when
such
parameters
are
present
as
a
result
of
processes
causing
the
contamination
or
discharges:

(
1)
Municipal
and
domestic
wastewater
treatment
plants
Monthly
Weekly
Daily
Parameter
Avg.
(
mg/
l)
Avg.
(
mg/
1)
Max.
(
mg/
1)

BOD5
30
40
45
TSS
30
40
45
Metro
Nashville
Airport
Authority
(
Addendum)
NPDES
Permit
No.
TN0064041
Page
No.
A­
5
of
A­
7
(
2)
Industrial
wastewater
treatment
plants
Parameter
Daily
Maximum
Concentrations
(
mg/
l)
Oil
and
Grease
(
a)
30
(
b)
No
visible
or
floating
oil
or
grease
pH
(
6.0
to
9.0)
*
Suspended
Solids
40
Settleable
solids
0.5
ml/
l
*
In
the
case
of
biological
treatment
units,
the
daily
maximum
TSS
may
be
120
mg/
l.

The
nature
of
the
MNAA's
treatment
system
and/
or
effluent
can
not
be
classified
in
neither
of
the
two
above
listed
categories.
However,
these
tables
were
included
in
this
addendum
to
rationale
to
illustrate
that
technology­
based
limits,
as
well
as
results
of
treatability
studies,
can
be
used
in
establishing
effluent
limitations
for
point
source
discharges.
During
the
last
two
permit
terms,
the
division
requested
monitoring
of
untreated
and
treated
wastewater
in
order
to
evaluate
efficiency
of
the
wastewater
treatment
system.
A
comprehensive
table
with
efficiency
analysis
is
attached
at
the
end
of
this
addendum
to
rationale.
Outfall
02A
depicts
CBOD5
concentrations
in
untreated,
while
Outfall
002
represents
CBOD5
concentrations
in
treated
wastewater.

In
the
permit
writer's
BPJ,
a
subset
of
this
data
should
be
used
to
better
represent
treatment
efficiency
during
winter,
and
under
CBOD5
loading
originating
from
deicing
activities.
It
was
difficult
to
ascertain
incoming
CBOD5
concentrations
that
positively
correspond
to
application
of
deicing
fluids.
Instead,
measurements
not
likely
to
be
associated
with
deicing
activities
were
excluded
from
the
data
set.

It
should
be
noted
that
exclusion
of
relatively
low
incoming
concentrations
of
CBOD5
(<
100
mg/
L)
did
not
significantly
change
treatment
system
efficiency
from
the
concentration
or
loading
aspect.
However,
the
resulting
average
concentrations
of
treated
wastewater
were
increased.
This,
in
the
permit
writer's
BPJ,
more
accurately
represents
wastewater
treatment
performance
under
full
pollutant
load
in
winter
period.
Table
B
presents
the
recommended
discharge
permit
limits
for
the
92%
83%

Date
02A
Maximum
Concentration
002
Maximum
Concentration
efficiency
efficiency
02A
Maximum
FLOW
02A
Loading
002
Maximum
FLOW
002
Loading
mg/
L
mg/
L
mg/
L
mg/
L
MGD
lb/
day
MGD
lb/
day
09/
30/
1996
524
14
42
86
0.50
2203
0.69
80
02/
28/
1997
190
58
15
31
0.50
799
0.24
114
01/
31/
1998
340
92
28
56
0.62
1755
0.98
749
02/
28/
1998
590
98
48
97
0.47
2308
0.97
789
03/
31/
1998
340
53
28
56
0.47
1330
1.52
672
04/
30/
1998
220
12
18
36
0.47
861
0.72
72
12/
31/
1998
3090
9
251
510
0.01
258
1.10
82
01/
31/
1999
1520
360
123
251
0.49
6212
1.15
3447
02/
28/
1999
133
14
11
22
0.51
561
0.57
66
11/
30/
1999
109
2
9
18
0.49
443
1.30
22
12/
31/
2000
1100
25
89
182
0.59
5413
0.50
104
01/
31/
2001
3110
104
252
513
0.44
11516
0.01
10
02/
28/
2001
488
21
40
81
0.49
2006
0.53
92
12/
04/
2002
1560
18
126
257
0.33
4293
0.04
6
02/
13/
2003
439
55
36
72
0.34
1248
0.34
156
02/
21/
2003
176
42
14
29
0.43
630
0.43
150
02/
28/
2003
318
142
26
52
0.41
1098
0.41
490
03/
07/
2003
528
80
43
87
0.24
1039
0.24
157
03/
14/
2003
249
19
20
41
0.02
31
0.02
2
Average
791
64
64
131
0.41
2316
0.62
382
92%
Efficiency
83%
Load
eff.
Metro
Nashville
Airport
Authority
(
Addendum)
NPDES
Permit
No.
TN0064041
Page
No.
A­
6
of
A­
7
Winter
Period.
The
proposed
daily
maximum
limitations
were
derived
from
monthly
average
limitations,
using
the
ratio
from
Tennessee
Rule
1200­
4­
5­.
03
(
30:
45
mg/
L,
see
table
above),
and
based
on
established
division
practice
applied
to
various
biological
wastewater
treatment
plants
across
the
state.

Table
B
Recommended
Effluent
Limits
for
the
Winter
Period
(
October
 
April)

EFFLUENT
LIMITATIONS
MONTHLY
DAILY
MONITORING
REQUIREMENTS
Receiving
Stream
Flow
>
0
CFS
and
<
0.5
CFS
CBOD5
25
38
1/
Week
Grab
Receiving
Stream
Flow
>
0.5
CFS
and
<
1
CFS
CBOD5
45
68
1/
Week
Grab
Receiving
Stream
Flow
>
1
CFS
and
<
3
CFS
CBOD5
65
98
1/
Week
Grab
Receiving
Stream
Flow
>
3
CFS
CBOD5
65
Report
1/
Week
Grab
Only
one
sample
per
month
is
recommended
during
the
Summer
Period
as
no
deicing
activity
typically
occurs
during
the
Summer
Period.
However,
the
limits
recommended
for
the
Summer
Period
are
much
lower
than
those
for
the
Winter
Period.
This
is
recommended
because
of
the
typically
lower
flows,
higher
air
and
water
temperatures,
and
thus
lower
in­
stream
DO
concentrations
found
during
the
summer
months.
It
is
recommended
that
MNAA
make
every
effort
to
prevent
discharge
when
the
flow
of
Sims
Branch
is
below
0.5
cfs.
However,
permit
limits
are
recommended
to
accommodate
a
situation
requiring
discharge
during
such
a
flow
scenario.

MNAA
does
not
have
any
significant
source
of
BOD
other
than
deicing
activities,
which
only
occur
during
the
colder
months
of
the
year.
Therefore,
it
is
recommended
that
MNAA
only
be
required
to
report
concentrations
when
discharges
occur
when
stream
flows
are
above
1.5
cfs
during
the
Summer
Period.
Table
C
presents
the
recommended
discharge
permit
limits
for
the
Summer
Period.

Table
C:
Recommended
Effluent
Limits
for
the
Summer
Period
(
May
 
October)

EFFLUENT
LIMITATIONS
MONTHLY
DAILY
MONITORING
REQUIREMENTS
Receiving
Stream
Flow
>
0
CFS
and
<
0.5
CFS*
CBOD5
3
4.5
1/
Month
Grab
Receiving
Stream
Flow
>
0.5
CFS
and
<
1
CFS
CBOD5
6
9
1/
Month
Grab
Receiving
Stream
Flow
>
1
CFS
and
<
1.5
CFS
CBOD5
12
18
1/
Month
Grab
Receiving
Stream
Flow
>
1.5
CFS
CBOD5
Report
Report
1/
Month
Grab
*
Note:
Permittee
should
make
every
effort
to
prevent
discharge
when
the
flow
of
Sims
Branch
is
below
0.5
cfs.
However,
if
discharge
is
necessary,
these
limits
apply.

The
WLA
study
has
resulted
in
a
calibrated
model
of
Sims
Branch
capable
of
appropriately
assessing
the
impact
of
the
Outfall
002
discharge
on
the
environment.
The
result
is
proposed
permit
Metro
Nashville
Airport
Authority
(
Addendum)
NPDES
Permit
No.
TN0064041
Page
No.
A­
7
of
A­
7
limits
based
on
real­
world
data
and
the
technological
treatment
capability
of
the
treatment
unit.
The
limits
are
both
reasonable
for
MNAA
as
well
as
protective
of
the
environment.

VMJ
Permit
Addendum
TN0064041.
DOC
Metro
Nashville
Airport
Authority
(
Addendum)
NPDES
Permit
No.
TN0064041
Page
No.
A­
8
of
A­
7
COMPREHENSIVE
TREATMENT
UNIT
EFFICIENCY
ANALYSIS
91%
83%

Date
02A
Maximum
Concentration
002
Maximum
Concentration
efficiency
efficiency
02A
Maximum
FLOW
02A
Loading
002
Maximum
FLOW
002
Loading
mg/
L
mg/
L
mg/
L
mg/
L
MGD
lb/
day
MGD
lb/
day
09/
30/
1996
524
14
48
91
0.50
2203
0.69
80
11/
30/
1996
15
3
1
3
0.50
63
0.48
12
12/
31/
1996
12
10
1
2
0.50
50
0.50
42
02/
28/
1997
190
58
17
33
0.50
799
0.24
114
04/
30/
1997
18
4
2
3
0.32
48
0.33
11
06/
30/
1997
13
6
1
2
0.39
42
0.40
20
07/
31/
1997
28
6
3
5
0.30
70
0.39
19
08/
31/
1997
3
3
0
1
0.37
9
0.26
6
09/
30/
1997
14
5
1
2
0.53
61
0.31
13
10/
31/
1997
33
5
3
6
0.43
118
0.31
13
11/
30/
1997
84
3
8
15
0.28
198
0.39
10
12/
31/
1997
12
11
1
2
0.62
62
0.60
55
01/
31/
1998
340
92
31
59
0.62
1755
0.98
749
02/
28/
1998
590
98
54
103
0.47
2308
0.97
789
03/
31/
1998
340
53
31
59
0.47
1330
1.52
672
04/
30/
1998
220
12
20
38
0.47
861
0.72
72
05/
31/
1998
8
4
1
1
0.47
31
1.84
61
06/
30/
1998
2
2
0
0
0.53
9
2.14
36
10/
31/
1998
3
2
0
1
0.18
5
0.30
5
11/
30/
1998
31
6
3
5
0.03
9
0.36
18
12/
31/
1998
3090
9
280
539
0.01
258
1.10
82
01/
31/
1999
1520
360
138
265
0.49
6212
1.15
3447
02/
28/
1999
133
14
12
23
0.51
561
0.57
66
04/
30/
1999
57
4
5
10
0.40
190
1.16
39
11/
30/
1999
109
2
10
19
0.49
443
1.30
22
12/
31/
1999
17
3
2
3
0.57
81
1.09
27
03/
31/
2000
6
1
1
1
0.38
19
1.19
10
05/
31/
2000
4
4
0
1
0.48
16
0.75
25
11/
30/
2000
8
6
1
1
0.56
37
0.59
30
12/
31/
2000
1100
25
100
192
0.59
5413
0.50
104
01/
31/
2001
3110
104
282
543
0.44
11516
0.01
10
02/
28/
2001
488
21
44
85
0.49
2006
0.53
92
03/
31/
2001
90
10
8
16
0.35
262
0.54
45
04/
30/
2001
41
4
4
7
0.39
134
0.50
17
05/
31/
2001
7
5
1
1
0.48
28
0.64
27
11/
20/
2002
17
5
2
3
0.41
58
0.46
19
11/
27/
2002
2
5
0
0
0.08
1
0.16
7
12/
04/
2002
1560
18
142
272
0.33
4293
0.04
6
12/
28/
2002
35
39
3
6
0.14
41
0.10
33
01/
03/
2003
27
25
2
5
0.32
72
0.33
68
01/
10/
2003
61
20
6
11
0.14
72
0.13
21
01/
15/
2003
61
9
6
11
0.05
23
0.60
45
02/
13/
2003
439
55
40
77
0.34
1248
0.34
156
02/
21/
2003
176
42
16
31
0.43
630
0.43
150
02/
28/
2003
318
142
29
55
0.41
1098
0.41
490
03/
07/
2003
528
80
48
92
0.24
1039
0.24
157
03/
14/
2003
249
19
23
43
0.02
31
0.02
2
Average
335
30
30
58
0.38
975
0.61
170
91%
eff
83%
load
eff.