SBCT Final EIS - Govsupport.us

Chapter 5 – Environmental Consequencesdeposition is a naturally occurring phenomenon in any landscape, adverse impacts may occur whenerosion rates are accelerated by human or natural disturbances.Activities that disturb or remove vegetative cover are presently occurring or would occur in thereasonably foreseeable future, which would continue to result in greater soil erosion and loss thanwithout these activities. Areas with well-developed (deep) soils have the potential to be revegetatedand stabilized; however, areas with newly formed soils or shallow soil profiles may not be able torecover from soil erosion or soil loss impacts. In areas of the PTA where soils can be thin and fragile,the effects of soil loss may be irreversible. Maintaining a persistent vegetative cover in areas ofintensive use or development would not be possible because of the nature of the proposed use.In light of past, ongoing, and reasonably foreseeable future actions, the cumulative soil erosionimpacts associated with the Alternative A could be locally significant. Combined with regional-levelsoil loss, project-related impacts are expected to be cumulatively significant. The implementation ofBMPs, as required by federal and state regulations, will reduce the cumulative impact, but not to aless than significant level.Seismic or volcanic eruption hazards could result in cumulative effects if, for example, evacuation ofpersonnel or treatment of casualties were to overwhelm the capacity of the available infrastructure.The most likely site for severe seismic or volcanic impacts to occur is at PTA, where the seismic andvolcanic hazards are greatest. However, the Army is expected to have internal capacity to evacuate itspersonnel and to support civilian emergency response efforts in a seismic or volcanic emergency.No other cumulative geologic impacts are expected from Alternative A.5.6.1.2 Water ResourcesFor Alternative A, cumulative impacts to water resources could occur where Alternative A would beimplemented, within the watershed downstream of the installation boundaries (for surface waterimpacts), or the aquifer(s) downgradient of the installation boundaries (for groundwater impacts).Nonpoint source pollution is recognized as one of the principal causes of degradation of surface waterquality. Enforcing stormwater management regulations would help reduce pollutant loading tosurface waters by requiring industrial facilities, municipalities, and military and other facilities toimplement stormwater management practices to reduce their individual nonpoint source contributionsof pollutants. Any contribution to pollutant loading from a source in the watershed of an impairedwater body, if it is greater than natural background levels, can be regarded as substantive. However,with the implementation of required Regulatory and Administrative mitigation measures the Armyconcludes that the impacts on surface water quality from nonpoint source pollutants would besignificant but mitigable to less than significant level.There would potentially be less than significant to significant but mitigable long-term cumulativeimpacts on surface water quality from suspended sediment resulting from training activities. Tracelevels of explosives residues could be transported by runoff from training ranges to streams.However, the trace concentrations that have been found to be present in soils and that may betransported by runoff into stream waters are not expected to be much greater relative to backgroundconcentrations of natural organic compounds. Also, with the implementation of required BMPs forAlternative A under the Clean Water Act, and the other potentially cumulative actions, the Armyconcludes that the cumulative impacts on surface water quality from contaminated sedimentsuspension would be significant but mitigable to less than significant.February 2008 5-250 2/25th SBCT Final EIS