SBCT Final EIS - Govsupport.us

Chapter 5 – Environmental Consequencessurface to avoid slope failure, properly sizing drainage systems, designing storm drainage outfalls forefficient performance, and properly monitoring and maintaining the road.The Army continually funds and implements USAG-HI-wide land management practices andprocedures described in the ITAM annual work plan to reduce erosion and other soil and geologicimpacts (USARHAW 2001a and USARHAW 2001b). Currently, these measures includeimplementing a TRI program, implementing an ITAM program, implementing an SRA program,developing and enforcing range regulations, implementing an Erosion and Sediment ControlManagement Plan, coordinating with other participants in the Koolau Mountains WatershedPartnership (KMWP), and continuing to implement land rehabilitation projects, as needed, within theLRAM program. Examples of erosion and sediment control measures identified in the ITAM annualwork plan include stormwater runoff control structures (silt fences, hay bales, etc.) as part of standardBMPs, which would divert water from the construction sites. Standard range maintenance BMPsimplemented by USAG-HI include road grading, target repair, and berm recontouring. Examples ofcurrent LRAM activities at USAG-HI include revegetation projects involving site preparation,liming, fertilization, seeding or hydroseeding, tree planting, irrigation, and mulching; combat trailmaintenance program (CTP), coordination through the TCCC on road maintenance projects; anddevelopment mapping and geographic information system (GIS) tools for identifying and trackingprogress of mitigation measures. These land practices and mitigation measures would be implementedregardless of permanent stationing of the SBCT.Volcanic and Seismic Hazards. The potential for strong ground motion or volcanic eruptions thatcould present a hazard to people or property would be the same as that described for the AlternativeA. The impacts would be greatest at PTA, but they are not expected to be significant, because existingwarning systems would provide sufficient warning of an eruption such that personnel and equipmentwould likely have time to evacuate from the path of a lava flow. The hazards associated with futureearthquakes at PTA are considered less than significant because the area is underlain by thin soils andhard rock, which, unlike thick alluvial deposits, transmits rather than amplifies seismic wave energy.5.5.2.1.3 Impacts from Live-Fire TrainingSignificant Impacts Mitigable To Less Than SignificantImpact 1: Soil Erosion and Compaction. Live-fire training would continue on existing ranges.Compaction in the craters caused by larger ordnance explosions can alter the permeability and waterholdingcapacity of the soils and harden silty clays affecting the ability of vegetation to recover inthose areas. Surface disturbance caused by munitions impact would result in larger areas of bareground than observed under current conditions. Munitions impact can directly create craters andremove patches of vegetation, which normally protects soil from erosion by slowing runoff, interceptsraindrops before they reach the soil surface, and anchors the soil. Compaction in the craters caused bylarger ordnance explosions can alter the permeability and water-holding capacity of the soils andharden silty clays affecting the ability of vegetation to recover in those areas. These direct impactsindirectly create large areas of bare ground and exposed soils that are susceptible to wind and watererosion, which can indirectly cause large-scale removal and redeposition of soils, gullying, orunstable slopes in areas of steep slopes and rapid runoff. Although weapons training events would beperiodic, long-term impacts are expected because soil disturbance typically requires time and effort toamend.Regulatory Administrative Mitigation 1: Implementation of standard BMPs, as well as revegetationand other land restoration projects implemented by the LCTR, LRAM, and TRI programs of theINRMP and ITAM annual work plan would reduce these impacts to less than significant.February 2008 5-195 2/25th SBCT Final EIS