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Vantage to Pomona Heights Chapter 4 230 kV Transmission Line Project FEIS Environmental Consequences PAGE 4-187 4.8 VISUAL RESOURCES Visual resource impacts would be created as result of the construction, operation, and maintenance of the proposed Project and would be caused by proposed Project components (e.g., structures, lines, roads, equipment) being seen from sensitive viewpoints; the effects of proposed Project components on the inherent aesthetic values of the landscape or compatibility developed landscape; and from the effects on the Visual Resource Management (VRM) Classes as identified by the U.S. Bureau of Land Management (BLM). The effects on VRM Classes is determined by an assessment of whether or not the proposed Project is in compliance with the stated objectives as defined in the BLM Manual 8400 series and current policy. Compliance with other state, regional, or local applicable policies, goals, and objectives as identified in the land management documents (e.g., county general plans) was also considered as part of the compliance analysis. 4.8.1 Methods and Impact Types 4.8.1.1 Analysis Methods The impact assessment closely follows the procedures identified in the BLM’s VRM system as detailed in the Contrast Rating Manual 8431-1, with modifications appropriate to the proposed Project and lands not under the jurisdiction of the BLM. The modified process considered the Project’s visual compatibility with the developed landscape as well as the VRM components of scenic quality, viewer sensitivity, distance zones, and contrast. A contrast analysis was conducted along all Action Alternative route segment centerlines using Form 8400-4 and geographic information system (GIS) modeling that utilized the access road disturbance model (see Section 2.4.3.2), vegetation and slope data, and existing transmission line configuration data. The effects analysis utilized a combination of GIS modeling, primary observation, and visual simulation development to evaluate the effects of the proposed Project on visual resources. Viewshed modeling in combination with contrast analysis was used to assess viewer impacts, an assessment from identified Key Observation Points (KOPs) was conducted, mitigation measures were developed for agency consideration and residual impacts were determined. Simulations were produced to assist in the assessment and were used to illustrate the major visual impacts from KOPs (see Appendix C-4). Visibility from sensitive viewpoints was generated by GIS using digital terrain data from the U.S. Geological Survey and the sensitive viewpoints mapped. Because the proposed Project structures have not been sited and engineered for each Action Alternative, landscape visibility was mapped using a 90-foot uniform structure height for the centerline of each route segment and for the overhead-underground transition stations. The 90-foot height is representative of the height expected for the majority of structures. Typical H-frame structure height is expected to be approximately 65 to 90 feet; however, a single pole structure may be up to 110 feet tall. Visibility of the Underground Design Option considered visibility of the ground plane from sensitive viewpoints. Digital imaging, GIS, computer aided design, and global positioning system (GPS) software assisted in the development of the photo-simulations. The software used in photo-simulation includes: • Adobe Photoshop CS5 – Used for photo manipulation and merging. • Bentley MicroStation v8i – Used for modeling transmission line structures photo matching, lighting, materials, and rendering simulations. • Bentley Inroads v8.5 – Used for Digital Terrain Mapping and modeling. • ArcView – Used for geographic information proposed Project data mapping.