cide concentrations are believed to be due pri-
volatiles will no longer be a contributing factor in
marily to simple dilution from DCR reagent addi-
leachate or potential groundwater contamination.
tion. Similar reductions are noted for most of the
In this low-reagent case (Table 5), the gravimetric
semivolatile constituents, with an order of mag-
oil and grease concentration increased more than
nitude decrease in hexachlorobutadiene (presum-
was the case for the high-reagent addition (Table
ably from volatilization).
3). This is particularly true with the loose 27.4%
product before compaction and reflects the fact
Leachability
that less CaO was added, so there would be less
The TCLP test is carried out using an acidic
sequestering of the soy oil against organic solvent
leaching solution to mimic an acidic landfill envi-
extraction. With subsequent compaction, however,
ronment. Table 3 presents the results obtained on
it is more difficult to extract the oil and grease
the RMA 24216 soil sample before and after DCR
with organic solvents, and a concomitant decrease
treatment. These are worst-case data, in that all
in gravimetric oil and grease content is observed.
TCLP testing on treated waste material was per-
As noted with the higher DCR reagent additions,
formed on the powdered DCR product in a
significant reductions in total resolved pesticides
noncompacted state. Leachable constituent analy-
by ECD GC are observed, and this reduction is
ses completed in Europe using the standard DEV
further improved with compaction. No individual
S4 method demonstrated that compaction of the
pesticide data are available for the loose 27.4%
DCR-treated material reduces the leachable or-
DCR-treated product, but with the compacted
ganic constituents by yet another order of magni-
product, individual constituent concentrations are
tude compared with the highly dispersed, pow-
reduced, as expected, to an intermediate value
dered DCR product (Gerschler 1984).
between those observed in the raw soil and the
The only volatile constituent detected in the
64.7% DCR-treated material. The reductions of
TCLP leachate of the raw soil was the aromatic
aldrin, dieldrin, and endrin can be accounted for
1,4-dichlorobenzene at 0.47 ppb. There was also a
by a simple dilution with reagent CaO. The re-
trace of the semivolatile hexachlorobutadiene at
duction of total resolved pesticides in the com-
3.4 ppb. Both of these constituents were below
pacted sample, however, cannot be due entirely to
the reported detection limits in the DCR-treated
dilution and implies some sequestration against sol-
product. There was a 4043% reduction in leach-
vent extraction due to either microencapsulation or
able aldrin, dieldrin, and endrin (Table 3), which
macroencapsulation.
was probably due largely to dilution by the 64.7%
The effects of sample compaction are also re-
CaO addition. While these decreases are signifi-
flected by decreases in the complexity of the ECD
cant, the reduction for endrin to 44 ppb did not
gas chromatograms obtained on the raw, DCR-
satisfy the RCRA limit of 20 ppb, so additional
treated loose, and DCR-treated compacted
testing was undertaken with the
compacted 27.4% DCR-treated prod-
uct (see below). There are no re-
Table 4. TCLP metals analyses of RMA Basin F soil sample no.
ported limits for aldrin and dieldrin.
24216 before and after DCR treatment with 64.7% CaO.
For TCLP-extractable metals,
TCLP concentrations
TCLP concentrations
there were significant reductions in
from raw waste
from
RCRA
leachability for several metals (most
Waste
before treatment
DCR-treated product
limits
notably As, Cd, Cu, and Hg) (Table
(g/mL)
(g/mL)
(g/mL)
constituent
4). In all cases, however, metals
Silver (Ag)
< 0.0089
< 0.0089
5.0
passed RCRA limits before treat-
Arsenic (As)
0.13 J
< 0.075
5.0
ment.
Barium (Ba)
0.11
0.11
100.0
Cadmium (Cd)
0.017
< 0.0021
1.0
Chromium (Cr)
0.022
0.053
5.0
27.4% DCR-treated product
Copper (Cu)
36.0
1.6
n.a.
Mercury (Hg)
0.0009
0.0003
0.2
Total waste analyses
Lead (Pb)
< 0.84
< 0.84
5.0
As was the case with the higher
Selenium (Se)
< 0.26
< 0.26
1.0
reagent addition, all of the volatile
Analyses completed by U.S. Army Corps of Engineers Environmental Labora-
constituents present in the raw un-
tory, Hubbardston, Massachusetts.
treated soil were removed by the
J = Estimated value; less than the practical quantitation limit.
DCR process (Table 5). As a result,
n.a. = Not applicable
10
Previous Page
