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Vantage to Pomona Heights Chapter 4 230 kV Transmission Line Project FEIS Environmental Consequences PAGE 4-190 exist. A total of eight combinations of ROW corridor and structure configurations are possible, including consideration of transition stations for the Underground Design Option. These combinations would result in varying degrees of structure contrast (no existing transmission, distribution underbuild, Project parallels 230 kilovolt (kV) and 115 kV corridor, Project parallels lattice 500 kV corridor, and Project parallels two 230 kV and two 500 kV corridors). For the structure contrast model, only H-frame or single pole structures were assumed along the route segments. Figure 4.8-1 shows the visual characteristics of the structures. Table 4-8.3 - Structure Contrast Matrix shows the various combinations, landscape viewing context, and resulting structure contrast. As the final step in contrast analysis, the overall Project contrast was determined based on the combination of landscape and structure contrast along the route segment centerlines (see Table 4.8-4). Strong structure contrasts but weak landscape contrasts would typically produce strong-moderate Project contrasts. For example, in situations where no new roads are being built and minimal ground cover vegetation is removed (weak landscape contrast), the introduction of a new 90-foot H-frame structure where none currently exists (strong structure contrast) would create strong overall visual contrasts because the transmission line structures are the primary Project elements that affect viewers or landscapes. Table 4.8-4 Project Contrast Matrix LANDSCAPE CONTRAST STRUCTURE CONTRAST Strong Strong-Moderate Moderate Moderate-Weak Weak None Strong S S S/M M M M/W Moderate S S/M M M M/W W Weak S/M M M M/W W W N/A, None M M M/W W W N Key: S=Strong; S/M=Strong/Moderate; M=Moderate; M/W= Moderate/Weak; W=Weak, N=None. 4.8.2.2 Impact Types Direct and indirect visual resource impacts are difficult to distinguish because the effects occur at the same time and place but simultaneously occur at a further removed distance (e.g., impacts as a result of views from sensitive recreation area and scenic quality impacts on vegetation and landform). Impacts may be considered short-term and long-term. The development of the proposed Project has the potential to result in three basic types of impacts to visual resources. Construction impacts would be considered temporary that result from the presence of construction vehicles and equipment that cause ground disturbance, equipment structure contrasts, and air emissions. Operations and maintenance impacts may be short-term or long-term. Maintenance activities would also be considered short-term or periodic if they are also related to the presence of construction vehicles and equipment and associated ground and air disturbances. Operation impacts would be primarily associated with the long-term use and presence of the proposed Project (transmission lines, underground-overhead transition stations, cleared duct bank and access road corridor, structures, substations, overhead transmission line access roads) in the landscape. Visual contrast (see Section 4.8.2.1 above), including the effects of light and glare, would be produced during construction, operations, and maintenance of the proposed Project. The general types of impacts caused by the construction, operations, and maintenance of the proposed Project include: