Document Type

Book

Publication Date

2-2006

Abstract

This environmental assessment I assessment of effect examines in detail two alternatives: no action and the National Park Service preferred alternative. The preferred alternative considers rehabilitation of the roadway and associated structures on either side of Route 10 (Zion-Mt. Carmel Highway) tunnel. The road work would primarily occur on the east side of the tunnel in a 0.25-mile segment beginning at the east tunnel entrance. Modifications on the east side of the tunnel would include slurry sealing the road surface and scaling rock slopes on both sides of the road; re-configuring two parking areas; creating a painted center median with rumble strips; relocating the crosswalk from parking area 1 to the Canyon Overlook Trail; constructing a sidewalk from parking area 2 to the Canyon Overlook Trail; eliminating three informal pullouts, one of which would be reconfigured as a slow vehicle passing lane; establish erosion-control measures for the Pine Creek slot canyon access; and replacing and relocating the ranger kiosk. The area outside the west tunnel entrance would be modified by adding rumble strips to the existing painted center median, replacing the ranger kiosk.

The proposed project would provide a safer traffic control situation for park rangers and visitors; provide visitors with safer access to the Canyon Overlook Trail; reduce the potential for rockfalls onto waiting vehicles and traffic control rangers on the east side of the tunnel; create better defined parking areas, and better defined areas within which park rangers can direct traffic; eliminate informal parking and the problems associated with traffic control for these areas; provide a slow vehicle passing lane; and minimize erosion on the Pine Creek slot canyon access.

This action is needed because the east side of the tunnel is congested and traffic controls are difficult to maintain for vehicle, pedestrian, and ranger safety; informal parking areas allow vehicles to leave the road in areas not specifically designated for parking and create a safety risk; and rock slopes overhang portions of the road on the east side creating a potential for rockfalls and preventing the roadway from being widened to accommodate safety features such as a center median and a defined pedestrian sidewalk. The west side of the tunnel has a poorly defined median creating a safety risk and the potential for injury to rangers who stand in the middle of the road to direct traffic, and erosion occurring on the Pine Creek slot canyon access is creating an unstable hiking surface that allows sediment to enter into the creek below.

The preferred alternative would have no or negligible impacts on air quality, water quality, floodplains, wetlands, wildlife, threatened and endangered plant species and plant species of special concern, archaeological resources, ethnographic resources, museum collections, Indian trust resources, prime and unique farmlands, ecologically critical areas, wild and scenic rivers, other unique natural areas, environmental justice, lightscapes, visual resources, transportation, and socioeconomics. The preferred alternative would have short-term, negligible, adverse impacts to vegetation, cultural landscapes, and park operations; short-term, negligible to minor, adverse impacts to health and safety; short-term, minor, adverse impacts to soils and historic structures; short-term, minor to moderate, adverse impacts to soundscapes; and short-term, moderate, adverse impacts to visitor experience. Long-term impacts would be minor and adverse for soundscapes, historic structures, and cultural landscapes. Beneficial impacts would occur to soils, vegetation, park operations, visitor experience, and health and safety. Anticipated impacts to the Mexican spotted owl would be short term, negligible, and adverse. There would be no long-term impacts to the Mexican spotted owl. There would be no short- or long-term impacts to the California condor.

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