steam stripping during the exothermic hydration
in the leachable TPH (Table 7), a very significant
of CaO to Ca(OH)2, and in field implementation
reduction was observed in the total volatile hy-
drocarbons, and one to two orders of magnitude
these constituents can be captured using trans-
reductions were observed for the individual
portable treatment units equipped with modular
BTEX constituents.
emissions control systems. Their removal is im-
Both volatilization and Ca(OH)2 encapsulation
portant in that they constitute the more water-
may have played a role in the disappearance of
soluble constituents, which can contribute to
organic constituents. Lower-molecular-weight
leachate or groundwater contamination if not
volatile constituents such as BTEX are no doubt
otherwise controlled.
lost to volatilization; however, intermediate- and
With regard to the pesticides and semivolatile
higher-molecular-weight petroleum hydrocar-
organics in the RMA soils, it should be empha-
bons are probably largely sequestered into the
sized again that the DCR Process is not a destruc-
newly formed Ca(OH)2 matrix.
tive technology. Any liquid (or solubilized) organic
Comparison of TCLP extract organic concen-
wastes treated by the DCR process are homo-
trations to Federal Drinking Water Standards (Ta-
geneously dispersed into very fine (submicron
ble 5) helps place these concentrations in perspec-
sized), hydrophobic particles. Since the pesticides
tive. The benzene concentration from the Fire
present in the RMA soil samples are for the most
part solids under ambient-temperature condi-
Training Pit before DCR treatment (Table 7) was
tions, the ADM soy oils were added in an effort to
the only case where a measured concentration
(110 g L1) exceeded the Federal Drinking Water
partially "solubilize" them and facilitate transfer
Standard (5 g L1); after DCR treatment, ben-
to the CaO before hydration. Therefore, the slight
zene was not detectable. In all other cases, the or-
increase in the gravimetric oil and grease value
(Table 8) for the 64.7% reagent addition is no
ganic concentrations were well below drinking
doubt due to the addition of the ADM soy oil.
water standards and therefore pose minimal pol-
This increase is partially offset by oil sequestra-
lution danger for surface or groundwaters.
tion/adsorption (even against organic solvent
extraction) into the voids, cracks, and fissures of
Rocky Mt. Arsenal study
the newly formed Ca(OH)2 generated during the
Two basic analytical approaches are currently
utilized by the U.S. EPA to evaluate reduction in
DCR Process. More importantly, there is a signifi-
contaminant mobility and total constituent con-
cant decrease in the total resolved pesticides in
centrations. These are Total Waste Analyses
the 64.7% reagent addition as measured by ECD
(organic solvent extraction followed by GC or
GC at SOUND/epic, and this is also reflected in
GC/MS analyses) and leachability usually by the
the individual pesticides reported by the Envi-
TCLP test. The volatile lower molecular weight
ronmental Lab. These reductions in total and
alkylated- and chlorinated-benzenes in the RMA
individual pesticide concentrations are believed
soil sample were essentially eliminated during
to be due primarily to simple dilution from DCR
the DCR Process. This is due to volatilization or
reagent addition. Similar reductions are noted for
Table 8. Summary of selected constituent analyses of RMA Basin F soil sample no.
24216 at different levels of DCR reagent addition with and without compaction.
64.7% DCR
27.4% DCR
27.4% DCR
Raw waste
reagent
reagent
reagent
before
addition
addition
addition
Waste constituent
treatment
(loose)
(loose)
(compacted)
Gravimetric oil & grease1 (mg/kg dry wt)
10,700
12,900
41,800
15,200
Total resolved pesticides1
ECD GC (mg/kg dry wt.)
3,270
2,150
2,110
1,110
Aldrin (ng/g dry wt.)
390,000
270,000
N.A.
350,000
Dieldrin (ng/g dry wt.)
260,000
180,000
N.A.
220,000
Endrin (ng/g dry wt.)
140,000
100,000
N.A.
120,000
1,2,4-Trichlorobenzene (ng/g dry wt.)
210
120
N.A.
< 16
Hexachlorobutadiene (ng/g dry wt.)
6,900
630
N.A.
750
Analyses denoted by superscript one (1) completed by SOUND/epic, all others by U.S. Army Corps of
Engineers Environmental Laboratory, Hubbardston, Massachusetts.
N.A. Not analyzed.
12
Previous Page
