SBCT Final EIS - Govsupport.us

Chapter 3 ⎯ Affected EnvironmentMost military personnel use the training ranges only for brief periods, totaling days or weeks, so thatactual exposures are generally far lower than assumed in the industrial soil PRGs (USAG-HI 2004).Results of the study identified three general classes of compounds: metals, explosives, and semivolatileorganic compounds (SVOCs). Metals occur naturally in Hawaiian soils because of the weatheringof minerals contained in the volcanic rock from which the soils were derived. Training activitiesmay contribute additional metals concentrations to the natural background concentrations present insoils, such as lead that is present in bullets and some explosives. In cases where constituents are detectedat concentrations that significantly differ from the average natural background concentrations,human activities, such as military training activities, may be considered a contributing factor.Explosives. The sampling detected four explosives: 2,4,6-trinitrotoluene (TNT), Octahydro-1357-tetranitro-1357-tetrazocine (HMX), Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and nitroglycerin.Two samples of RDX and one sample of nitroglycerin exceeded their respective industrial PRGs(USAG-HI 2004). Based on these results, it appeared that traces of explosive compounds are presentin areas where high explosives have been used or where munitions demolition occurred including theEngineering Demolition Range, the Mount Assault Course (MAC), and the KR8 Anti-Armor Range.Explosives were not detected in samples collected from the North Firebreak Road Impact Area orfrom the firing point area for 105-mm and 155-mm mortars in the SRAA.Metals. High concentrations of a number of metals, including aluminum, manganese, iron, chromium,and others, occur naturally in Hawaiian soils as major constituents of the minerals in the basalt lavas.Although several concentrations exceeded industrial soil PRGs, they showed near average distribution,with disproportionately few samples containing concentrations significantly lower or higher thanthe average concentration of all of the samples collected (USAG-HI 2004). While arsenic occursnaturally in Hawaiian soils, it is one of several metals known or suspected to cause cancer in humans;therefore, the cancer risk PRG must also be considered. The average arsenic concentration detectedwas well below the non-cancer industrial soil PRG, but exceeded the cancer industrial soil PRG andwas the largest contributor to the total carcinogenic risk among the metals and explosives detected(USAG-HI 2004). Only a few metals (possibly arsenic, lead, cadmium, and vanadium) at sporadicsample locations appeared to be present at concentrations attributable to human activities. With theexception of the discussion of arsenic above, all of the concentrations of these metals detected insamples from the ranges were below industrial soil PRGs. It was unclear whether concentrations ofarsenic could be attributed to natural or human-made sources.Semi-volatile Organic Compounds. SVOCs were detected only in samples collected from the InfantryDemolition Area, none of which contained concentrations above industrial soil PRGs (USAG-HI2004).Depleted Uranium. In August 2005, during the cleanup of unexploded ordnance from a range complexon Schofield Barracks, the Army identified 13 tail assemblies to the M101 spotting round for theDavy Crockett Weapons System. The spotting rounds, which contained DU, were fired for trainingpurposes to determine the proper trajectories for the Davy Crockett warhead. The Army confirmedthese items to have low-level radioactivity.The Davy Crockett Weapons System consisted of a recoilless rifle, a spotting rifle, and a small nuclearwarhead. Recently declassified records indicate the M101 spotter round was used in Hawaiifrom 1961 to 1968. Until the initial discovery of the tail assemblies in 2005, current Army staff wasunaware of the existence of the items in Hawaii. There is no evidence indicating that the warhead wasever fired or stored in Hawaii.February 2008 3–7 2/25th SBCT Final EIS