Table 3. Estimates for total residues deposited from detonations
of 81-mm rounds with C4 at Camp Ethan Allen, Vermont.
Detonation
1
2
3
RDX
(g/m2)
4.9
1540
22.5
Ave. surface conc.
Total contaminated surface area (m2)
158
81.3
74.2
Total mass deposited (g)
1.25 105
774
1670
Mass of RDX in 81-mm plus C4 (g)
1.1 109 1.1 109
1.1 109
Total RDX recovered (%)
0.00007
0.011
0.00015
Estimate of mean soil conc. (g/kg)
0.58
181
2.6
resulting from detonation*
TNT
Ave. surface conc. (g/m2)
0.035
10.7
0.19
2)
Total contaminated surface area (m
158
81.3
74.2
Total mass deposited (g)
5.53
870
14.1
3.8 108
3.8 108
Mass of TNT in 81-mm (g)
3.8 108
Total TNT recovered (%)
0.000001
0.00023
0.000004
Estimate of mean soil conc. (g/kg)
0.004
1.3
0.022
resulting from detonation*
* A soil density of 1.7 g/cm3 and a soil depth of 0.5 cm were used to compute
the estimate.
for RDX, below detection to 0.86 g/m2 for HMX, and
observed, the total mass of residues deposited in each
below detection to 0.01 g/m2 for NG. No TNT was
case can be estimated (Table 3). Using this assump-
tion, estimates of the mass of RDX deposited range from
detected above background. Concentrations for the sec-
774 to 1.25 105 g (125 mg). Likewise, for TNT,
ond mortar round were two to four times higher than
estimates range from 5.5 to 870 g. In terms of the
for the first. The highest concentrations were located
percentage of initial explosive that was deposited as
approximately 9 m from the point of detonation.
residues, the estimates range from 0.0007 to 0.011%
The fired-in 60-mm mortars produced less residue
for RDX, and from 0.000001 to 0.00023% for TNT. If
overall and no high concentrations, unlike those from
these residues were homogeneously distributed over the
the 81-mm mortars detonated by C4, and NG was not
surface area where deposition was observed, and con-
found at high concentrations. For the fired rounds, the
taminated the top 0.5 cm of soil, we estimate resulting
ignition cartridge would have detonated, but the fins of
soil concentrations of RDX ranging from 0.58 to 181
the rounds remained intact and were deposited near the
g/kg and of TNT ranging from 0.004 to 1.3 g/kg.
detonation craters. When one of the mortar fins was
rinsed with acetone and the acetone analyzed by GC-
We must acknowledge the uncertainty in the esti-
ECD, approximately 2 mg of NG was found in the
mates discussed above that stem from our assumption
that the mean concentration that we obtained was repre-
rinsate. The significance of NG residues on training
sentative of the total area affected by the blast. For exam-
ranges will require further investigation. A review of
ple, we made no attempt to measure the concentration
the gas chromatograms for soil samples that we col-
gradient that might result perpendicular to the center
lected at an antitank firing range at Canadian Force Base
line of the deposition, nor did we make sufficient meas-
Valcartier revealed the presence of NG in these sam-
urements to get an overall analytical uncertainty. This
ples as well.
study was preliminary in nature, the emphasis being on
Similar to the 81-mm mortar detonations, TNT con-
demonstrating the technique. Thus, the estimates pro-
centration estimates at Fort Drum (Table 5) were much
lower than RDX, even though the filler was Composi-
vided should be considered preliminary, but in the
tion B (59.5:39.5 RDX:TNT). Thus, TNT appears to
absence of better estimates, they can serve as ballpark
estimates until better data are available. We anticipate
be more completely consumed during detonations than
making improved measurements in future studies.
RDX.
Analysis of the snow sample collected in front of
Analytical results from Fort Drum experiment--
the mortar tubes at Fort Drum revealed the presence of
60-mm mortar rounds fired
RDX, NG, and TNT. The presence of NG was expected,
RDX, HMX, and NG were detected in the snow
since it is a common component of propellants, but the
samples from the mortar detonations at Fort Drum
presence of TNT and RDX was unexpected. Only one
(Table 4). Surface concentrations of these compounds for
sample was collected. Thus, this result should be viewed
the first mortar round ranged from 0.32 to 6.13 g/m2
as preliminary at this time.
10
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