SBCT Final EIS - Govsupport.us

Chapter 5 – Environmental ConsequencesAlthough a relatively small number of samples were collected to represent SBMR, the samples werecollected specifically from locations that were considered highly probable to represent the mostcontaminated sites. The sample results, therefore, represented above average concentrations onSBMR overall. RDX was detected in the highest relative concentrations among the chemicalsdetected, exceeding the PRG in two of 39 composite samples taken, which represented the highestconcentrations on the range. The actual exposures would be lower than assumed in the analysis.Arsenic was detected at levels slightly above the cancer industrial PRG, although the levels were wellbelow the non-cancer industrial PRG. Alternative A on SBMR is not expected to result in increasedexposure to these chemicals, because military personnel would not experience contact withcontaminated soils that is additional to existing contact levels or for durations (25 years) that triggerrisk under industrial soil PRGs. Moving SBCT maneuver training to SRAA would actually reducesome of the potential for exposure because it does not contain any of the most contaminated sites.With regard to pesticide use within the SRAA, USEPA did not find concentrations of farm chemicalsthat would raise concern for human exposure.The area of the proposed PTA BAX presents a potential opportunity for contact with contaminatedsoils. The construction of the BAX would require the conversion of a portion of Training Area 12 to atraining area where Soldiers could be exposed to the soils. Their exposure would be limited totraining for a period of days or weeks. The level of chemical compounds present at Range 12 are allbelow their respective PRGs. Considered together, the potential duration of exposure to the chemicalconcentrations on the training ranges at PTA, including Range 12, represent a low risk to personnelwho use them.Composite soil sampling at selected ranges within PTA revealed the presence of metals, explosives,and semi-volatile organic compounds. The observed concentrations were generally lower thanindustrial PRGs. One explosive compound, RDX, was detected in samples from Ranges 5 and 9 atconcentrations above the industrial PRG, while Training Area 12 was below that. The risks frommultiple chemical exposures are additive, and similar calculations can be done for each of thecontaminants to which people may be exposed at PTA. The risks from HMX, nitroglycerin, and TNTare very small compared to the risk from RDX, and the sum of their risks is lower than 0.74 x 10-6.The risks associated with each of the metals can be calculated similarly, and the results would besimilar. The highest risks are associated with the iron and aluminum in the soil, both of which occurnaturally at high concentrations.Overall, the sum of the carcinogenic and non-carcinogenic risks, based on the available soil samplingdata and using the PRGs to estimate risk, is lower than the USEPA threshold for worker exposure. Itis unlikely that troop exposures to RDX or other chemicals on the ranges would be similar to workerexposures in an industrial setting. For example, workers are assumed to ingest 100 mg of soil per day,250 days per year, for 25 years. This assumption over-estimates troop exposures because troops arelikely to be exposed only temporarily, and only for short durations. Minimal public contact with thesesoils would occur. It is based on the assumption that the highest concentration of windblown dustwould be close to the source (i.e., the maneuver areas) that are off-limits to the general public. Thefarther away from the source, the more dilution occurs. The Army is also implementing a Dust andSoils Mitigation Monitoring Plan (DuSMMoP) for inhalable PM 10 emissions (see section 5.2.11 AirQuality) and will also implement fugitive dust control through engineering oroperational/administrative controls. Based on the conservative analysis described above, thisrepresents a less than significant impact.Volcanic and Seismic Hazards. Portions of the areas that would be impacted by maneuver training aresubject to volcanic eruptions, lava flows, occasional explosive eruptions, volcanic gas venting, andearthquakes. Alternative A would increase the hazard associated with these conditions because itFebruary 2008 5-15 2/25th SBCT Final EIS