29    ENVIRONMENTAL ASSESSMENT OF LEAD
CONTAMINATION IN ARID SOIL DUE TO THE
DETONATION OF A CONVENTIONAL EXPLOSIVE
DEVICE
Peter Worland, Research Assistant
Fernando Cadena, Professor
Department of Civil Engineering
New Mexico State University
Las Cruces, New Mexico 88003
INTRODUCTION
Conventional explosive devices containing lead, used in modern warfare, can upon detonation melt
and even vaporize some of the lead. The shock wave from the explosion then distributes the lead in
solid, liquid and gaseous states onto the surrounding soil. This study examined the environmental
impact of the 1984 detonation of a lead backed conventional explosive device. The lead contaminated
soil is a potential source of air pollution by the suspension of fine grained particulates and also a
possible source of water pollution by the dissolution and mobilization of lead into the groundwater.
The findings have application to the environmental quality of arid regions with calcareous soils of
elevated pH that have experienced conventional, modern warfare.
SITE DESCRIPTION
The study area is located on alluvial material derived from the mountains which lie to the east of the
test site. The land slopes to the west with a gradient of about 25 meters per kilometer. The site of the
detonation is enclosed by a four-foot high barbed wire fence which forms a 77 meter by 62 meter
rectangle around the site.
Excavated trenches parallel the north-south and east-west axes of symmetry of the fenced rectangular area. The trenches are approximately 3 meters deep at the center of the rectangular area and slope
upward to surface elevation just a few meters before reaching the fenced perimeters. Figure 1 shows a
map view of the study area.
The surface soil is a silty sand. The vegetation is dominated by annual weedy species such as
tumbleweed and summer cypress. There are no perennial grasses anywhere within the test site. The
nearest established perennial grasses and shrubs are over 50 meters from the fence line boundary.
Metal shrapnel is abundant within the fenced area. The area lying to the north of the fenced area is
littered with scraps of plywood, pieces of pipe and metal shrapnel. To the west, south and east of the
site there is occasional metal shrapnel and other debris.
SAMPLING PROCEDURE
Lead contamination of the surface soil at the study area was suspected as a result of several soil
analyses. A more extensive soil sampling program was planned to determine the areal extent and the
level of lead contamination at the site. This sampling program is defined as Phase I and was accomplished on July 21 and 22, 1992. Figure 1 shows the detonation site with the locations of the sampling
points for the Phase I investigation. Eight sampling transects were performed. Each transect originated at the center of the fenced-in rectangular area. Surface soil samples were collected at 5 meter
intervals. A duplicate sample was also taken at the first, eighth, 15th, 22nd, 29th and 36th sampling
location on each transect. Fifteen percent of the samples were duplicated. Table I summarizes the
sampling transects for Phase I.
At each sampling location, samples were collected from within a 10-foot square quadrant. Within
each quadrant, three randomly selected 6-inch square samples of the top 2 inches of soil were collected
48th Purdue Industrial Waste Conference Proceedings, 1993 Lewis Publishers, Chelsea, Michigan 48118. Printed in
U.S.A.
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