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Vantage to Pomona Heights Chapter 4 230 kV Transmission Line Project FEIS Environmental Consequences PAGE 4-256 widening access roads; preparing and using pulling and tensioning sites, staging areas, and other temporary use areas; geotechnical drilling; and implementing restoration and re-vegetation measures. Ground disturbance could disturb archaeological sites and TCPs. Architectural resources could also be subject to physical disturbance, but no buildings and structures have been identified in areas of potential ground disturbance for the proposed Project. For construction of overhead transmission line route segments, direct visual impacts could result when single-pole and H-frame structures are installed near visually sensitive TCPs and architectural resources that have retained their integrity of setting. New and improved access along proposed Project route segments may lead to increased vandalism at archaeological sites, architectural resources, and TCPs unless access is otherwise restricted, such as at the Joint Base Lewis-McChord Yakima Training Center (JBLM YTC). For construction of underground transmission line route segments, direct physical impacts could result from ground disturbing activities associated with trenching; grading or widening access roads; staging areas and other temporary use areas; geotechnical drilling; and implementing restoration and re- vegetation measures. Ground disturbance could disturb archaeological sites and TCPs. Architectural resources could also be subject to physical disturbance, but no buildings and structures have been identified in areas of potential ground disturbance for the proposed Project. For construction of underground transmission line route segments, direct visual impacts could result in areas that have been cleared of vegetation, changing the setting of visually sensitive cultural resources nearby. For this analysis, it is assumed that cultural resources within 75 feet of the centerline of a route segment would potentially be subject to both physical and visual impacts. It is assumed that cultural resources more than 75 feet from the centerline could potentially be subject to visual impacts and indirect physical impacts (i.e., vandalism), but not direct physical impacts. Overall, the amount of ground disturbance would likely be much greater for an underground transmission line route segment than for an overhead transmission line route segment. However, the likelihood of there being changes in visual setting would be less for an underground transmission line route segment, in which clearance of vegetation would be the most visible evidence, than for an overhead transmission line route segment, in which there would be cleared right-of-way (ROW) corridor, tall structures, and conductors visible from nearby cultural resources. 4.11.2 Impact Levels (High, Moderate, Low, No Identifiable Impact) The impact levels for the cultural resource impact assessment are defined as follows: High - A high level of impact to cultural resources would result if the construction, operation, or maintenance of the proposed Project has the potential to cause a substantial ground disturbance or adverse visual change to known cultural resources that are listed in or eligible for the National Register, to cultural resources that have not been evaluated for National Register eligibility, and on land with a high potential for containing cultural resources that has not been surveyed for cultural resources. Moderate - A moderate impact to cultural resources would result if the construction, operation, or maintenance of the proposed Project would cause ground disturbance or visual changes on land with a moderate potential for containing cultural resources that has not been surveyed for cultural resources.