Document ID: EPA-HQ-OW-2002-0033-0334
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2003-04-14T04:00Z

Randomly
Assigning
Facilities
to
POTWs
In
order
to
represent
all
facilities
in
Ohio
discharging
to
POTWs,
the
screener
facilities
must
be
assigned
to
random
POTWs
based
on
the
sample
weight
of
the
facility.
That
is,
the
facility
itself
is
matched
to
the
nearest
POTW
for
use
in
the
analysis.
The
weight
of
the
sample
facility
minus
one
(
to
account
for
the
facility
itself)
represents
the
other
facilities
which
must
be
matched
to
random
POTWs.
This
is
done
for
all
indirect
dischargers
with
a
sample
weight
greater
than
1.
A
sample
weight
of
1
signifies
a
large
discharger.

Sheet
Facilities
Contains
information
on
the
sample
facilities
including
weight
and
discharge
type.
The
weights
are
rounded
up
to
the
neaerst
integer
in
order
to
determine
the
number
of
random
assigns.

Sheet
POTWs
Contains
the
NPDES
number
of
all
the
POTWs
in
Ohio.
These
are
randomly
chosen
for
a
given
facility/
weight
and
referenced
by
their
row
number.

Sheet
Randomly
Assigned
This
sheet
performs
the
actual
matching
and
contains
the
facilities
matched
to
their
POTWs.
The
subroutine
is
in
VB.
An
adjusted
SITEID
is
generated
based
on
the
facility
SITEID
and
the
number
of
the
representative
facility
based
on
the
sample
weight.
For
example,
SITEID
70009
has
a
weight
of
11,
so
there
must
be
10
random
assigns
(
the
weight
of
11
minus
1
for
the
actual
facility.)
Each
of
these
will
have
an
adjusted
SITEID
of
70009.01
thru
70009.10
to
represent
it.