SBCT Final EIS - Govsupport.us

Chapter 5 – Environmental Consequenceswould involve increasing personnel and SBCT equipment in the maneuver training areas, whichcould increase the risk of injury caused by earthquakes or volcanic eruptions. On Oahu, the expectedintensity of ground shaking in a reasonably probable earthquake would be moderate to minor becauseof its distance from the source of the earthquakes. There is very little risk of renewed volcanic activityon Oahu, so the impacts on SBMR, DMR, and KTA are considered less than significant.Liquefaction potential at DMR has not been characterized, and the potential for injury or propertyloss in the event that liquefaction occurs is probably less than significant, because of the low potentialfor significant ground shaking. Despite the lack of information on liquefaction potential in a strongearthquake, DMR may be impacted by liquefaction because of the high water table and sandysediments underlying the facility. Liquefaction could cause damage to the Dillingham Trail, whichcould impact the ability to use it during SBCT maneuver training and could present a safety risk tothe personnel in the SBCT vehicles. Alternative A is not expected to result in any significant newhazards associated with earthquakes or liquefaction relative to existing conditions, and no newstructures would be constructed at DMR under Alternative A. Therefore, the impact is considered lessthan significant.The discussion of impacts related to volcanic and seismic hazards can be divided into two broad typesof impacts: those that may be caused by the Alternative A and those that are the result of the projectbeing constructed in an area in which hazards exist. The impacts summarized below are mainly of thelatter type, as the use of explosives at PTA is not expected to have any effect on the frequency ofvolcanic eruptions or earthquakes.While the hazard associated with an eruption of lava or volcanic gases is high if directed toward anarea occupied by people or structures, and the probability of a lava flow occurring within the PTAduring the next 50 to 100 years is moderately high (based on the relatively high risk USGS LavaHazard Zone classifications described in Chapter 3 for the majority of PTA), existing warningsystems are expected to provide generally sufficient warning of an eruption such that personnel andequipment would likely have time to evacuate from the path of a lava flow. The hazards associatedwith future earthquakes at PTA are considered less than significant because new BAX rangestructures would be designed to withstand the expected range of seismic shaking and because the areais underlain by thin soils and hard rock, which, unlike thick alluvial deposits, transmits rather thanamplifies seismic wave energy.5.2.3 Water ResourcesRange construction at SBMR could result in impacts to surface water quality from nonpoint sourcecontamination of surface water. These impacts would be significant but mitigable to less thansignificant. Continually funded mitigation measures would minimize these affects to less thansignificant levels. Impacts to water quality from nonpoint source contamination at PTA would be lessthan significant. Other less than significant impacts include impacts to water quality from dust controland potential spills.Live fire training could result in impacts to surface water quality from introduction of munitionschemical residues present in soils from training activities at SBMR and KTA, and impacts fromwildland fires. These impacts would be significant but mitigable to less than significant. Continuallyfunded mitigation measures would minimize these affects to less than significant levels. Impacts onsurface water and groundwater quality from live fire training at PTA would be less than significant.Maneuver training could result in impacts to surface water quality from nonpoint source sedimentloading at SBMR and KTA. Impacts to surface and groundwater quality could result fromFebruary 2008 5-16 2/25th SBCT Final EIS