The Alviso/Ravenswood is a levee repair and water control structure replacement project in the Don Edwards San Francisco Bay National Wildlife Refuge (NWR) for US Fish and Wildlife (USFWS) Region 1. The project consists of two separate locations with varying scopes of work: Alviso and Ravenswood (an added change order). Levee repair work was deemed necessary by the USFWS at both the Ravenswood and Alviso locations. Alviso will also have an existing water control structure removed and a new structure built. The levee improvements will ensure structural soundness to weather the conditions of the high tide winter storms and the water control structure will monitor water passage between the San Francisco Bay and Pond A9 in the Refuge.
The project began in September 2019 with levee work in Alviso. A total of 6,800 yards of structural fill were placed on the levee and 1,100 linear feet of geotextile fabric and flexamat laid down to prevent exposure of the fill material and maintain the stability of the levee. The protection of endangered species shut the project down until the Fall of 2020, which brought the change order section in Menlo Park called Ravenswood. This Ravenswood change order consisted of roughly 5,000 tons of rip rap that were hauled in to replace the levee structure that had been damaged in winter storms. The crew finished the change order work in a few weeks and mobilized to the Alviso section where 9,000 additional yards of structural fill have been hauled in and placed.
Currently, the crews are working to finish installing the remaining 500 linear feet of geotextile fabric and flexamat on the main levee segment. Structural fill is being hauled out to build up an additional change order segment where fabric and flexamat will be laid down as well. The water control structure has been demolished, excavated and dewatered and the structure is underway to be built over the coming weeks.
Once the structural fill has been hauled to the north segment of the levee, fabric and flexamat will be installed. Topsoil will begin to be placed along the main levee and north additional segment. The water control structure is a small buildout and should be finished soon after Thanksgiving. Once the structure is built, the trash rack, slide gate and handrails will be installed. Fill, fabric and flexamat will go down around the structure and the surface will be hydroseeded with native vegetation to support wildlife growth of the endangered species in the refuge, completing the project Winter of 2020/21.
McMillen Jacobs has worked on several projects at the Don Edwards NWR since 2011. They include A16-A17 Restoration Design-Build project (2011-2015); Water Control Structures AB1 and AB2 and Levee Repairs (2016-2017); Alviso Pond Levee Rehabilitation of Ponds A7, A8, A11, & A14 (2019-2020); and Alviso Pond Levee Rehabilitation Master Plan (2019-2020).