SBCT Final EIS - Govsupport.us

Chapter 5 – Environmental Consequencesterm, local, and less than significant with implementation of standard construction BMPs and the landmanagement practices, previously described, specified in the USAG-HI ITAM annual work plan.Regulatory and Administrative Mitigation 1: The Army continually funds and implements USAG-HIwideland management practices and procedures described in the ITAM annual work plan to reduceerosion and other soil and geologic impacts (USARHAW 2001a and USARHAW 2001b). Currently,these measures include implementing a TRI program, implementing an ITAM program,implementing an SRA program, developing and enforcing range regulations, implementing anErosion and Sediment Control Management Plan, coordinating with other participants in the KoolauMountains Watershed Partnership (KMWP), and continuing to implement land rehabilitation projects,as needed, within the LRAM program. Examples of erosion and sediment control measures identifiedin the ITAM annual work plan include stormwater runoff control structures (silt fences, hay bales,etc.) as part of standard BMPs, which would divert water from the construction sites. Standard rangemaintenance BMPs implemented by USAG-HI include road grading, target repair, and bermrecontouring. Examples of current LRAM activities at USAG-HI include revegetation projectsinvolving site preparation, liming, fertilization, seeding or hydroseeding, tree planting, irrigation, andmulching; combat trail maintenance program (CTP), coordination through the TCCC on roadmaintenance projects; and development mapping and geographic information system (GIS) tools foridentifying and tracking progress of mitigation measures. These land practices and mitigationmeasures would be implemented regardless of permanent stationing of an SBCT under Alternative A.These mitigation measures would reduce soil erosion impacts from construction to less thansignificant.Less Than Significant ImpactsVolcanic and Seismic Hazards. As described previously, portions of the areas that would be impactedunder Alternative A are subject to volcanic eruptions, lava flows, occasional explosive eruptions,volcanic gas venting, and earthquakes. Construction of the BAX ranges and the range maintenancefacility adjacent to PTA are not expected to have any effect on the frequency of volcanic eruptions orearthquakes; therefore, the impact would be the hazards associated with the ranges being constructedin areas in which volcanic and seismic hazards exist.Alternative A may increase the hazard associated with volcanic and seismic hazards relative to NoAction because it would involve construction of temporary and permanent structures on the two newBAX ranges at SBMP and PTA and the new range maintenance facility adjacent to the PTA BAX,which could affect the stability of those structures and increase the potential for constructionpersonnel to be injured by structure features or heavy machinery during damaging events. On Oahu,the expected intensity of ground shaking in a reasonably strong earthquake would be moderate tominor because of its distance from the source of the earthquakes. There is very little risk of renewedvolcanic activity on Oahu, so the impacts on facilities constructed on the ranges at SBMP and KTAare considered less than significant.While the hazard associated with an eruption of lava or volcanic gases is high if directed toward anarea occupied by people or structures during construction, and the probability of a lava flow occurringwithin the PTA during the next 50 to 100 years is moderately high (based on the relatively high riskUSGS Lava Hazard Zone classifications described in Chapter 3 for the majority of PTA), existingwarning systems are expected generally to provide sufficient warning of an eruption such thatpersonnel and equipment would likely have time to evacuate from the path of a lava flow. Thehazards associated with lava flows or earthquakes at PTA, therefore, are considered less thansignificant.February 2008 5-7 2/25th SBCT Final EIS