Historical firing records
Firing records for the six most heavily used rounds indicated that the
105-mm artillery round was the item most heavily fired, followed by the 81-mm
mortar and the 155-mm artillery round (Table 11). Range loading of explosives
residues from each type of round can be estimated by making several assump-
tions and using known low-order detonation rates (Table 12). For example, in the
year 2000 firing records indicate that 7,458 rounds were fired into the Fort Lewis
impact area by 105-mm howitzers (Table 11). On average, about 0.07 percent of
those fired undergo a low-order detonation (Table 12). Thus, five of the 105-mm
rounds can be estimated to have undergone a low-order detonation. If all of these
contained Composition B as the main charge, then each round would contain
about 1,252 g of RDX (Table 13). If half of the main charge remained undeto-
nated for each low-order detonation, then 626 g of RDX would be deposited on
the Fort Lewis range from low-order detonations of 105-mm rounds in 2000.
Table 11
Firing Record of the Most Commonly Fired Munitions for 1997- 2000
at Fort Lewis1
2
3
Round
DODIC
1997
1998
1999
2000
Total
81-mm
C256
1,997
2,112
2,789
2,075
8,973
105-mm
C445
10,585
3,166
9,505
7,458
30,714
4
120-mm
C623
474
-
-
359
833
120-mm
C788
-
75
288
-
363
107-mm
C697
219
128
262
216
825
155-mm
D544
207
7,564
261
841
8,873
1
Records encompass the available electronic database from January 1997 through July 2000 and
include the most commonly fired items as indicated by Mr. Del Larson, Range Operations Officer.
2
Department of Defense Identification Code.
3
Data through July 2000 only.
4
No record of firing for this item in this year.
Table 12
Mean Dud and Low-order Detonation Rates for Munitions Items Commonly Used at Fort
Lewis1
2
Round
DODIC
Items Tested
Duds, %
Low Orders, %
81-mm
C256
9,122
2.16
0.22
105-mm
C445
10,003
4.39
0.07
2
120-mm
C623, C788
-
-
-
3
107-mm (4.2-inch)
C697
1,518
2.24
0.02
155-mm
D544
6,216
2.75
0.02
1
Rates based on test data acquired by U.S. Army Defense Ammunition Center, McAlester, OK (Dauphin and Doyle 2000).
2
No data.
3
Department of Defense Identification Code.
46
Chapter 2 Characterization of Explosives Contamination at Military Firing Ranges
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