May
12,
2003
To:
Alan
Rubin,
PhD.,
U.
S.
EPA,
Office
of
Water
From:
Dana
Greenwood,
RTI
Work
Assignment
Leader
Subject:
Maximum
Soil
Concentrations
if
All
Application
are
Maximum
Rate
and
Duration
The
soil
concentrations
calculated
in
the
analysis
to
determine
maximum
soil
concentration
assumes
that
sewage
sludge
is
applied
biennially
for
40
years
at
a
rate
of
10
metric
tons
per
hectare
(
dry
weight).
A
full
distribution
of
sample
concentrations
is
used
but
the
application
rate
and
frequency
are
assumed
to
be
maximum
values
in
all
cases.
In
addition
the
reported
concentration
are
the
maximum
annual
concentration
(
the
last
year
of
sludge
addition)..
In
addition,
I
have
included
for
comparison
the
table
of
TCDD­
TEQ
concentrations
in
the
crop
soil
using
the
distribution
of
application
rates
and
durations.

TCDD­
TEQ
Concentration
for
Soil
in
Crop
Land
and
Biosolids
Distribution
of
Maximum
Annual
Soil
Concentrations
Percentile
Maximum
Annual
TCDDTEQ
in
Soil
(
ppt)
50th
1.7
75th
2.4
90th
4.0
95th
5.2
99th
35.0
TCDD­
TEQ
Concentration
for
Soil
in
Crop
Land
and
Biosolids
Variable
Application
Rate
and
Duration
Percentile
Cropland
Applied
Biosolids
50th
0.4
24
75th
0.7
35
90th
1.3
55
95th
1.8
74
99th
4.2
453
