Durphy Creek Fish Passage and Design Project

Durphy Creek Fish Passage and Design Project

The project proposes to replace two (2) undersized culvert crossings with two (2) bridges to restore natural channel processes along Durphy Creek within Richardson Grove State Park to reconnect over 1.8 miles of high-value spawning and cold-water rearing habitat for Coho and Chinook salmon. The project will also benefit Northern California Steelhead and Pacific Lamprey as well as multiple species of terrestrial wildlife and native vegetation. Work for the two (2) replacements will include the following: Capture and relocate aquatic species from the project areas prior to dewatering and in-stream work; Dewater and/or divert the stream along a portion of the channel to facilitate construction and to exclude and protect aquatic species during construction; Temporarily remove of any existing fencing, signage and/or guardrails and store for reuse; Remove and salvage existing native vegetation for replanting during site restoration and install protective tree fencing where necessary; Remove existing asphalt and concrete pavement, the corrugated metal culverts and haul off-site and dispose of at appropriate facility; Excavate and stage streambed materials for potential reuse; Construct temporary access routes to support construction activities and channel grading; Replace existing culverts with prefabricated steel girder bridges, approximately 45 feet long by 30 feet wide, supported by soldier pile wall abutments; Backfill bridge abutments and construct roadway approaches using engineered fill to raise the approaches to approximately 3 feet above existing grade; Construct wingwalls to retain fills near sensitive creek areas and reduce scour potential at the bridge sites; Install cast-in-place, asphalt-surfaced, concrete approach slabs at both ends of the bridge, as well as approx. 4-foot-wide by 9-foot-long concrete pedestrian sidewalks along the roadway approaches; Install, reconnect, and tie in any utilities disconnected for the project and remove any temporary utility bypass systems installed outside the direct work area to maintain service during construction; Use stockpiled native materials to grade the channel beds and banks within each bridge footprint and project area to reestablish continuous, natural channel profiles and restore sediment and streamflow continuity where suitable; and Use native seed, salvaged on-site plants, and as needed, container plants or cuttings to revegetate disturbed areas at project’s end.

unincorporated area; Richardson Grove State Park

Humboldt

Northern California