Construct Rock Buttress for Slope Failure Repair along Tompkins Hill Road
Construct Rock Buttress for Slope Failure Repair along Tompkins Hill Road
Summary
SCH Number
2010128059
Lead Agency
Regional Water Quality Control Board, Region 1 (North Coast), Santa Rosa
Document Title
Construct Rock Buttress for Slope Failure Repair along Tompkins Hill Road
Document Type
NOE - Notice of Exemption
Received
Document Description
Winter storms of 2005-2006 caused a slide above Tompkins Hill Road at Post Mile 0.33. The slide pushed dirt, trees and debris onto the road. Emergency repair work consisted of cutting downed trees and clearing debris from the roadway. The project involves excavation of the slide area to accommodate installation of a rock slope buttress will be approximately 15 feet tall and extend approximately 100 feet along the roadway. Excavated material will be stockpiled in the roadway. Some of the excavated material will be used as structural backfill and any excess material will be hauled offsite to an appropriate upland disposal site.
A roadside drainage channel along the east side of the road collects storm water runoff and seepage from the adjacent hillside. The drainage channel contains seasonal wetlands that will be temporarily impacted during the proposed project. The drainage channel has been disturbed repeatedly since the 2005-2006 storm events due to the frequent maintenance that has been conducted to remove slide material that sloughs off the hillside and blocks the drainage channel and northbound lane of the roadway. The drainage channel will be restored to its existing form following construction of the rock buttress and the channel will experience less frequent disturbance after the hillside is stabilized.
