23    TREATMENT OF GROUNDWATER CONTAMINATED WITH
LOW LEVELS OF MILITARY MUNITIONS
R. Mark Bricka, Environmental Engineer
Wayne Sharp, Civil Engineer
USAE Waterways Experiment Station
Vicksburg, Mississippi 39180
INTRODUCTION
Site Description
The site of interest is a military base that was established in the late 1800s. In its early history this
facility was used as a powder depot to fill projectiles with miximite (a propellant). Since World War I,
this facility was used to produce artillery ammunition, bombs, high explosives, pyrotechnics and other
ordinances. Weapons production at this facility has ceased, but as a result of the past activities at this
facility, contaminants are migrating into the groundwater.
One source of drinking water for this installation is a screened well in a stratified-drift aquifer
system at a depth of 75-85 feet below land surface. In the 1980s sampling of this well revealed low
level contamination of trichloroethylene (TCE), RDX and HMX. TCE levels exceeded drinking water
standards and an air stripping column was installed to remove the TCE. RDX and HMX, concentrations were below drinking water standards. Health Advisory (HA) levels for RDX and HMX were
published by the U.S. Environmental Protection Agency (USEPA) in November 1988. The lifetime
HA levels are 2 ppb and 400 ppb for RDX and HMX, respectively (McLellan et al. 1988a, and
McLellan et al. 1988b).1,2 It is expected that continuous withdrawals from this well will increase RDX
and HMX concentrations. In addition, it is believed that future USEPA regulations will adapt the HA
as a drinking water standard. This study was initiated in an effort to have an appropriate cost
effective technology ready to meet any such standard.
RDX and HMX
RDX and HMX are military explosives. RDX (Hexahydro-l,3,5-trinitro-l,3,5-triazine) is a code
name for Research Department Explosive. This explosive is described as a white crystalline solid with
about 1.3 times the explosive power of trinitrotoluene (TNT). RDX is classified as a EPA Group C
compound: Possible Human Carcinogen (McLellan et. al. 1988a).1 HMX (Octahydro-1,3,5,7-
tetranitro-l,3,5,7-tetrazocine) is a code name for High Melting Explosive. This explosive is described
as a colorless crystalline solid with about 1.3 times the explosive power of TNT. HMX is classified as a
EPA Group D compound: Not Classified as to Human Carcinogenicity (McLellan et. al. 1988b).2
Objective of Investigation
The objective of this investigation was to determine the feasibility of using granular activated
carbon (GAC) and UV/Oxidation (UV/OX) to remove low levels of RDX from a drinking water
source. The target treatment level in this investigation was to reduce RDX to less than 1 ppb in the
treated water.
Historical Treatment of HMX and RDX
Until recently, the main concern for the treatment of HMX and RDX was associated with solid
waste or wastewater from processing and manufacturing facilities. GAC is the primary treatment used
for these wastes and has been known to be effective in removing HMX and RDX to limits which
permit discharge. One recently conducted isotherm study by Hinshaw (Hinshaw et. al. 1987),3 investigated the treatment of synthetic and actual "pink water" (wastewater containing explosive) at HMX
and RDX concentration levels around 5 ppm and 20 ppm, respectively. At carbon dosages of around
47th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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