Morgan Territory Road Bridges 5.0 & 5.2 Replacement

Morgan Territory Road Bridges 5.0 & 5.2 Replacement

The purpose of the project is to replace two existing bridges on Morgan Territory Road over Marsh Creek located at postmiles 5.0 and 5.2. Prior to demolishing the existing bridges, temporary detour roads and water diversion systems will be constructed at both bridge replacement locations. The detour roads will divert traffic around the closed bridges during construction. Following construction of each bridge, the detour roads and water diversion system will be removed. Both replacement bridges will be clear span, one lane with shoulders supported by reinforced concrete pile abutments and wingwalls; concrete barrier rails and metal guard railings at the bridge approaches will be installed, and adjacent drainage improvements, including new drainage inlets, cross culverts, and grading to reestablish roadside drainage ditches. Construction depth will vary among project elements; the maximum depth will be approximately 25 feet for installation of the abutment piles. The profile grade of the roadway and bridges will be raised, and the lengths of both bridges will increase to meet hydraulic requirements for the 100-year storm event and restore the natural width of the channel under the bridges; riprap will be placed in the creek at both bridge locations and at four (4) outfall locations within the project area to prevent future scour and continued degradation of the creek. Utility relocations are anticipated at both bridge locations. Staging will occur on previously disturbed areas near the project. Vegetation trimming and removal, including removal of approximately six (6) trees (California sycamore, California bay, coast live oak), and work within the driplines of approximately twenty-two (22) trees (California sycamore, California bay, coast live oak, valley oak, big leaf maple) located outside of County right-of-way, some of which will need to be trimmed, are necessary to accommodate construction activities. Temporarily impacted areas will be restored by hydroseeding with native plants. The project is a covered activity under the East Contra Costa County Habitat Conservation Plan/Natural Community Conservation Plan and therefore will comply with applicable requirements to minimize impacts to covered species and their habitats, such as preconstruction nesting bird surveys. Other applicable regulatory permits for impacts to the creek will be obtained before construction. Real property transactions, including right-of-way acquisitions and temporary construction easements, will be necessary in support of the project. Work will take place during the dry season and is anticipated to be completed in approximately 120 working days, which may take up to two years to complete. Emergency vehicles will have access at all times.

Clayton, unincorporated County

Contra Costa

Unincorporated

Contra Costa