Porapak RDX cartridge (Waters), and the retained analytes were eluted using
5.0 mL of acetonitrile. The extracts were analyzed by GC-ECD as described in
the section "Soil sampling and analysis." At EL the water samples were extracted
using solid-phase extraction as described previously. Analyses were conducted
by RP-HLPC with a UV detector according to SW-846 Method 8330 (USEPA
1994) on a Waters system composed of a 610 Fluid Unit pump, a 717 plus auto
sampler with a 200-:l loop injector, a 486 tunable UV absorbance detector moni-
tored at 245 nm, and Millennium 2.1 chromatography software (Waters). Separa-
tions were obtained on a Supelco LC-18 RP-HPLC column 25 cm by 4.6 mm
(5 :m) with second column confirmation on a Supelco LC-CN reverse phase
column (25 cm by 4.6 mm, 5 :m). At the contract laboratory, the samples were
also analyzed by RP-HPLC according to SW-846 Method 8330 (USEPA 1994).
Laboratory analyses included the following, which are target analytes for Method
8330: HMX, RDX, TNB, 1,3-dinitrobenzene (DNB), tetryl, TNT, nitrobenzene
(NB), 4ADNT, 2ADNT, 2,4DNT, 2,6DNT, o-nitrotoluene (2NT), m-nitrotoluene
(3NT), and p-nitrotoluene (4NT). Additional transformation products of TNT
and TNB assayed by the EL laboratory included DNA, 2,4-diamino-6-
nitrotoluene (2,4DANT), 2,6-diamino-4-nitrotoluene (2,6DANT) and 2,2,6,6-
tetranitro-4,4-azoxytoluene (44AZOXY). Additional transformation products of
RDX assayed by the EL laboratory included 1,3,5-hexahydro-1-nitroso, 3,5-
dinitrotriazine (MNX), 1,3,5-hexahydro, 1,3,5-trinitrosotriazine (TNX), and
1,3,5-hexahydo-1,3-dinitroso-5-nitrotriazine (DNX).
Laboratory analyses for geochemical parameters included total iron, calcium,
magnesium, and manganese (Method 6010, USEPA 1988a), total organic carbon
(Method 505C, American Public Health Association 1985), nitrate-nitrite
nitrogen (Method 353.2, USEPA 1982), sulfate (Method 375.2, USEPA 1982),
and chloride (Method 325.2, USEPA 1979). Samples for total iron, calcium,
preserved with 0.4 g NaHSO4 to 250 mL of water. Samples for sulfate and
chloride were not preserved. Iron speciation was achieved by ion
chromatographic separation (Dionex Corporation, Sunnyvale, CA) of samples
preserved with 1 percent HCl followed by analysis according to Method 6020
(USEPA 1988a) on a Perkin Elmer (Norwalk, CT) inductively coupled plasma
mass spectrometer.
Historical firing records
Historical firing records contained in an electronic database at Fort Lewis
were reviewed to understand the major components potentially contributing to an
explosives contamination source term on the heavy artillery impact range. These
records were available from 1997 through the time of sampling, July 2000. Only
munitions items identified by the Fort Lewis Range Operations Office as high
use were included. These were 81-, 120-, and 107-mm mortars and 105- and
155-mm howitzers. The database provided the number of rounds by Department
of Defense Identification Code (DODIC) number and date when and location
where firing was scheduled to occur. Composition of these rounds was deter-
mined by consulting the Munitions Items Disposition Action System (MIDAS)
20
Chapter 2 Characterization of Explosives Contamination at Military Firing Ranges
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