Table 2. Physical characteristics of Fort Lewis soils

Table 1. High-explosive load carried by munitions items commonly fired at Fort Lewis.1

Main

Pellet

Main

charge

Supplemental

Pellet

auxiliary

charge

(g)

charge

booster

total

DODIC2

HE3 Wt (g)

Round

RDX

TNT

HE

Wt (g)

HE

Wt (g)

(g)

Source of data is the Munitions Items Disposition Action System (MIDAS) and personal communica-

tion, Mark Serben, Office of the Product Manager for Mortar Systems, TACOM, Picatinny Arsenal,

New Jersey, 19 March 2000.

2

Department of Defense Identification Code.

3

High explosive.

4

Main charge is Composition B, which is typically composed of 60 percent RDX and 39 percent TNT.

5

Not present.

in each, have been used to a similar extent. We chose

nade contains about 100 g of RDX, 11 g of HMX, and

Range 3 for extensive soil sampling. Range 3 is approx-

72 g of TNT in the main charge. The detonator in the

imately 11 m wide at the launch end (Fig. 1). The side-

M67 also contains 1.3 g of RDX and thus each grenade

walls that enclose the impact area widen to approxi-

contains a total of about 101 g of RDX, 11 g of HMX,

mately 25 m where they ended some 25 m from the

72 g of 2,4,6-TNT, with less than a gram of 2,4-DNT,

launch bunker. The presence of a number of craters indi-

TNB, and other impurities. The mass of the various

cated that grenades had landed well beyond this 25-m

high-explosive chemicals present in the M67 grenade

distance. The range was heavily cratered indicating

and other ordnance commonly fired at Fort Lewis is

extensive use. Over the last four years EOD cleanup

provided in Table 1. The M26 grenade contains about

practices (detonation of duds and low-order detonations)

84 g of RDX, 9 g of HMX, 60 g of TNT, and 0.6 g of

involved the use of C-4 explosive (RDX). In years prior

2,4-DNT and other impurities.

The soil in the grenade impact area is a coarse grav-

to the use of C-4, TNT was used for this activity.

elly sand with stones as large as 15 cm (Table 2). Grasses

Within Range 3, three lanes perpendicular to the

sparsely cover areas not recently affected by range use.

launching bunker were laid out for soil sampling. These

The four impact areas within the grenade range are con-

lanes were located at 15, 20, and 25 m from the launch-

secutively numbered, and from the numbers of craters

ing area (Fig. 2). At a distance of 15 m from the launch

Table 2. Physical characteristics of Fort Lewis soils.1

Total

Particle size

TOC2

CEC3

Total Fe4

inorganic N5

distribution (%)

(meq 100 g1)

(mg kg1)

Sample location

(%)

pH

Sand Silt

Clay

Artillery range

Firing point

11.3

47.4

1,530

5.6

63.2

17.5

19.3

Impact area

7.38

38.0

1,960

3,484

5.7

64.7

19.2

16.1

Hand grenade range

Surface

0.26

6.8

3,030

175

6.8

82.3

7.8

9.9

Subsurface

0.12

6.8

2,010

151

7.0

84.6

4.5

10.9

1

Values represent a single composite of samples from each location.

2

Total organic carbon.

3

Cation exchange capacity.

4

Total iron.

5

Total inorganic nitrogen.

3

To contents