Canyon Tunnel Project

Canyon Tunnel Project

The work would include temporary construction access, laydown, and staging areas; permanent downstream tunnel portal and tie-in to the existing canal; approximately 12,000 lineal feet of new tunnel; permanent upstream tunnel portal and tie-in to either the existing Goodwin Reservoir; and permanent access improvements leading to the existing Goodwin Dam right abutment: The Project specifically includes the following components: • Construction of approximately 12,000 feet tunnel; approximately 16-feet-wide by 13.8-feet-high; • Use of existing roads paved and dirt roads to be rehabilitated where necessary; • Rehabilitation of an existing barge landing and new barge platform: o Sectional barge would consist of eight pre-cast concrete segments (each 10 feet by 15 feet) with a combined 30-foot by 40-foot area, measuring 7 feet in depth, which is required for 65,000 pound of live load weight during construction; o Rehabilitation of the existing landing would be constructed at the same location and same footprint at the south shore of Goodwin Dam Reservoir at the current parking lot location; o Protective cofferdam would be used to dewater around the existing barge landing; o Tensioned guide cable would be secured for barge movement alignment: •South end would be attached below the reconstructed concrete landing with rock bolts; •North end would be attached to the existing concrete trash rack wall; and •Electric winches would be used to move the barge platform back and forth. • Improve and re-align existing livestock fences including barbed wire fencing and panel gates; • Tunnel inlet would start on the north side of the reservoir, upstream of the dam, above the existing diversion canal and on the dry side of the forebay and trash rack; • Installation of new control gates at the tunnel inlet; o The tunnel size would be approximately 16 feet in diameter • Temporary installation of stop logs at the existing trash rack for forebay dewatering; • Installation of a concrete cover cap over the existing forebay to provide rockfall protection; • Existing ram pump to be abandoned; • Proposed vertical conduit to be drilled vertically to tunnel for upland property owner (well with steel casing, removable screen and sump at tunnel sidewall, submersible solar power pump); • Existing canal gates at dam to remain for side-spill • Existing canal inlet gates to be abandoned • Tunnel Outlet would be located at the south end of the Project area at the downstream portal. • The proposed Canyon Tunnel would bypass the existing canal for approximately 12,000 feet and tie back into the existing canal through a downstream tunnel portal. Construction Phases are as follows and are referenced throughout the document: 1. Excavate Portal Work Area 2. Shotcrete Portal Face 3. Excavate First 916 LF D + S 4. Tunnel Excavation, Stage 1 Shotcrete 5. Stage 2 Shotcrete 6. Place Concrete Slab D+S and Invert Concrete 7. Tunnel Cleanup

Calaveras, Stanislaus, Tuolumne

Northern California

Calaveras, Stanislaus, Tuolumne