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MEMORANDUM
TO:
304(
m)
Record
(
EPA
Docket
Number
OW­
2003­
0074)

FROM:
Betsy
Bicknell
DATE:
December
5,
2003
SUBJECT:
Toxic
Weighting
Factor
for
Petroleum
Bulk
Storage
Terminal
PACs
Polycyclic
Aromatic
Compounds
(
PACs),
sometimes
known
as
Polycyclic
Aromatic
Hydrocarbons,
are
a
class
of
organic
compounds
consisting
of
two
or
more
fused
aromatic
rings.

EPA's
TRI
program
has
identifies
21
chemicals
that
are
included
in
the
PAC
category.
Facilities
with
10
or
more
employees
in
specified
SIC
codes
that
manufacture,
process
or
use
more
than
100
pounds
of
PACs
must
report
the
releases
of
these
compounds
to
EPA.
Facilities
report
combined
mass
of
PACs
released
to
TRI
and
do
not
report
releases
of
individual
compounds.

EAD
uses
Toxic
Weighting
Factors
(
TWFs)
for
various
chemicals
to
prioritize
industrial
discharge
categories.
TWFs
are
available
for
8
of
the
21
individual
compounds
included
in
this
chemical
group.
Because
facilities
report
combined
mass
of
PACs
and
EAD
has
TWFs
for
individual
compounds,
ERG
had
to
make
an
assumption
about
which
PAC
comprised
the
reported
PACs.
Discharge
loads
for
individual
PACs
discharged
by
Petroleum
Bulk
Storage
Terminals
were
reported
in
PCS
2000.
EPA
calculated
a
weighted
TWF
for
PACs
released
by
Petroleum
Bulk
Storage
Terminals
from
discharge
data
available
from
PCS.
This
value,

219.3411,
was
applied
to
the
pounds
of
PACs
releases
reported
in
TRI,
to
calculate
TWPE.

This
calculation
is
developed
in
the
MS
Excel
 
spreadsheet
found
in
the
file
PBST
PAC
TWF.
xls.
