Table 6. Total extractable concentrations of TPH and BTEX constituents in organic-
contaminated soils.
Oil/water sep. pond
Cell 21 oiled peat
Fire training pit
Compound
Units
Untreated
Treated
Untreated
Treated
Untreated
Treated
g kg1
Benzene
n.d.(20)*
n.d.(20)
7030
n.d.(54)
621
n.d.(25)
g kg1
43
115
121,000
713
8040
25
Toluene
g kg1
Ethylbenzene
39
27
138,000
2,290
7010
n.d.(25)
g kg1
Total xylenes
185
360
584,000
11,500
29,500
62
Total volatile
mg kg1
hydrocarbons
8.25
6.66
10,600
164
518
2.8
mg kg1
TPH
39,600
4,870
111,000
39,000
35,500
38,700
* n.d. = not detected at the stated minimum laboratory reported level in parentheses.
Table 7. Total extractable concentrations of TPH and BTEX constituents in TCLP
extracts of organic-contaminated soils.
Oil/water sep. pond
Cell 21 oiled peat
Fire training pit
Compound
Units
Untreated
Treated
Untreated
Treated
Untreated
Treated
g L1
n.d.(1) †
n.d.(1)
n.d.(1)
n.d.(1)
110
n.d.(1)
Benzene
g L1
Toluene
3.6
4.9
5.6
11
97
6.2
g L1
Ethylbenzene
n.d.(1)
n.d.(1)
64
8.3
33
n.d.(1)
g L1
Total xylenes
n.d.(1)
n.d.(1)
308
54
183
1.7
Total volatile
mg L1
hydrocarbons
0.183
0.026
1.93
0.446
1.00
0.169
mg L1
TPH
2.93
1.06
0.718
2.72
1.92
1.93
* n.d. = not detected at the stated minimum laboratory reported level in parentheses.
line and diesel range) volatile hydrocarbons in
is presumably due to the increased surface area of
these samples were not present at very high con-
the dry, finely dispersed product compared to the
centrations to begin with (those constituents
wet peat sample, which would be more difficult
would have long since been lost from the soil/
to leach. The leachable total volatile hydrocar-
water separator pond), and as such, there was not
bons were reduced as were ethylbenzene and
a large reduction in the total volatiles for these
total xylenes (Table 7).
samples. As shown by the BTEX values, there is
For the Fire Training Pit samples, the majority
no benzene either before or after DCR treatment,
(>98 %) of the hydrocarbon contamination would
and it appears that the toluene and total xylenes
come from higher-molecular-weight diesel resid-
may have been slightly liberated by the increased
uals which had not been volatilized or burned off
surface area of the dry, finely dispersed product
during fire training exercises. Therefore, the total
compared to the wet pond sludge that originally
extractable TPH constituents remaining in the
made up the sample. TPH in TCLP extracts was
soil/tar would not be expected to be altered sig-
reduced by a factor of three, and total volatile
nificantly by the DCR process (Table 6). The DCR
hydrocarbons were reduced by a factor of six
process is designed to convert liquid (mobile)
(Table 7). The individual BTEX constituents were
hydrocarbons into a solid nonmobile phase,
either not detected or just at the limit of detection,
which will resist all natural forms of migration
both before and after DCR treatment.
(i.e., surface runoff and groundwater), but not
The Cell 21 oiled peat was heavily contamin-
necessarily extraction by organic solvents such as
ated with JP4 and other volatile fuels. There was
methylene chloride. Therefore, it is not surprising
a dramatic reduction in both the extractable TPH
to see the high extractable TPH values both be-
and total volatile hydrocarbons after DCR treat-
fore and after treatment in this instance. Those
ment (Table 6). Benzene and toluene were re-
volatiles that were still present in the sample at
duced by over two orders of magnitude, and the
518 ppm were reduced to less than 3 ppm during
other volatile constituents were reduced by a fac-
the exothermic reaction; this was also reflected in
tor of 50 to 60. The TCLP data for these samples
the significant reductions of BTEX constituents to
were somewhat more variable (Table 7). TPH in
nearly nondetectable levels. For these Fire Train-
TCLP extracts appeared to increase slightly; this
ing Pit samples, there was essentially no change
11
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