Regional Water Quality Control Board, Region 1 (North Coast), Santa Rosa
State Route 299 Storm Damage Project
NOE - Notice of Exemption
At PM 26.0, a slip-out is present below the roadway adjacent to the eastbound lane. Project activities at this location would involve: Removal of approx. 6,200 cubic yards of slide debris on the downhill slope; Construction of a 230-foot long, 1-ton rock buttress on the downhill slope, extending between 20 and 50 feet down the slope; Replacement of a drainage structure consisting of a 65.4 foot by 18 inch cross culvert beneath the roadway and a 14.7 foot by 24-inch downdrain that transitions into an approx. 70 foot long flume. The new structure would be placed at a slightly shallower angle and consist of a 61.9 foot by 24-inch cross culvert, a 68.6 by 24 inch downdrain, and a 26-foot by 13-foot rock channel. The last two feet of the downdrain would be incorporated into the rock channel which would outlet at the toe of the slope. An existing rock energy dissipater at the toe of the slope would remain in place.