1. Aerial Fire Suppression Activities
Operation of the proposed project could result in several long-term direct adverse impacts to fighting wildland fires aggressively. An important wildland fire suppression tactic is the use of aircraft such as air tankers and helicopters to suppress wildland fires. These aircraft are used for dropping water or other fire suppressants or retardant from the air. As noted in Section C.7.1.2 of the Final EIR/EIS, critical areas to make these drops are on ridge tops and fuel breaks. The proposed project would construct new towers two to three times taller (113-178 feet) than the existing 66-kV towers (60-73 feet). The proposed project route follows the ridge top and Del Sur Ridge fuel break for approximately five miles. The increased height of the towers and conductors would increase the risk of firefighting aircraft or water buckets carried by helicopters colliding with the towers or transmission lines.
Therefore, the proposed transmission line would add complexity to firefighting operations and would require a change of tactics when using the ridge top and fuel break. With these limitations, an incident commander might not be able to fight the fire as aggressively as similar areas where no transmission lines are located. In addition, if aerial drops must occur away from the ridge top and fuel break and into vegetation older than 20 years, it would be difficult to penetrate chaparral older than 20 years and water and retardant drops would be less effective. The outcome could include additional burned acres and suppression costs. This would be considered a significant impact.
Other than a relocation of the towers off the ridgeline, which would occur if Alternative 1, Alternative 2, or Alternative 5 is selected, there is no mitigation measure to decrease or avoid this significant adverse impact (Class I).