Honeydew Bridge Replacement

prospective

The County proposes to replace the bridge with the objective of providing a bridge that meets modern highway standards and can serve the local and regional transportation needs. The proposed project will replace the existing single-lane steel truss bridge with a new two-lane bridge. In addition, the roadway approaches on both ends of the new bridge will be widened to accommodate two 12-foot wide lanes, 4-foot wide shoulders and 3-foot wide unpaved shoulders. Humboldt County Public Works retained Morrison Structures, Inc. to prepare a Bridge Type Selection Study (January 2013) to assist in the County’s selection of bridge type for a replacement bridge. Morrison Structures developed the type selection study based on using the existing alignment and providing a clear roadway width of 26 feet (two 12-foot travel lanes with two two-foot shoulders). The County has not made a determination on the design type for the new bridge. This decision will be made during the preparation of the Environmental Impact Report for compliance with the California Environmental Quality Act. Construction is expected to require two seasons due to the amount of work to be performed and the limited allowable work period. Foundations and support walls for a new pier (or piers) and the south abutment would be constructed in the first season. This will require water diversion and excavation of channel sediment. A detour would not be required during the first season. Detour construction, dismantling and removal of the existing bridge, and construction of new piers, abutments, superstructure, and approaches would be performed during the second season. Work during the second season will require erection of falsework and temporary support bents. The detour road will be built over a low water crossing on the Mattole River, approximately ½-mile downstream from the bridge. The existing bridge will be dismantled using a crane to remove the steel truss sections and excavators with demolition tips to break apart the piers and abutments. The existing bridge pier in the river channel and both abutments will be completely removed and pile supports will be excavated and cut off at a minimum of 5-feet below the surface. All bridge, abutment, and pier debris will be removed from the streambed using heavy equipment.

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