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VA Wetland Construction Contract Awarded

Article updated 4:30 p.m. March 24 to remove unverified information and include further quotes from USACE spokesperson Jeremy Croft.

On March 2, Dixon Marine Services was awarded $3.6 million to expand the existing wetland on land owned by U.S. Department of Veterans Affairs (VA). The firm was hired by the U.S. Army Corps of Engineers Sacramento District, which is managing the entire VA project at Alameda Point.

Alameda Post - VA wetland construction area
View of VA wetland area with future city De-Pave Park tidal wetland area in the background on the western side of the Seaplane Lagoon. Strips of white matting in the center were placed there after stripping non-native vegetation and to prevent regrowth. Eventually it will be planted with native vegetation. Photo Richard Bangert.

Due to the impacts that the VA’s columbarium cemetery will have on existing wetlands, the VA is offsetting those impacts at a wetland located on the south side of Alameda Point adjacent to the channel used by ferries. The 80-acre veterans cemetery will be constructed in phases over the next century, with the first phase being 20 acres.

“Features of the project include the creation of a new intertidal marsh connected to the bay along with the enhancement of an existing adjacent wetland complex,” states the Army Corps news release. “A breach in the existing seawall will allow for a connection to the bay and intertidal influence to the new wetland.”

Alameda Post - VA tidal marsh creation area
View of the area on VA property that will be converted to a tidal marsh next to the existing wetland. Looking north, with hangars on Monarch Street visible on the right and Port of Oakland in the background. The wooden pier bottom right was built with lights to orient Navy pilots at night. It now serves as a bird roosting site and occasional nesting site for gulls. Photo Richard Bangert.

The new tidal salt marsh will be 7.3 acres and features a meandering network of channels that will allow for water to flow to all parts of the marsh. The network will consist of a main channel that feeds smaller secondary channels, which in turn feed even smaller channels. “The pilot channel system is designed to emulate the structure and function of a well-developed slough channel system in a natural, mature tidal salt marsh of similar size,” states the work plan drafted by HDR Engineering and H.T. Harvey and Associates in 2018.

Alameda Post - Wetland construction and mitigation overview
Wetland mitigation overview showing the new tidal marsh with its channel system in purple and the portion of the existing wetland to be enhanced in green. Diagram courtesy H.T. Harvey and Associates Ecological Consultants.

The channel system has been designed such that at high tide, the channels will be completely filled, and by low tide, they will completely drain.

“Once the soil is excavated, we will test it for contaminants and invasive species,” said Jeremy Croft, spokesperson for the Corps of Engineers. “Our decision of whether to re-use this soil onsite will depend on the results of these tests.”

The breach in the seawall for the tidal channel will be next to the wooden landing light pier that juts out into the channel.

In addition to the 7.3 acres of new wetland, an adjacent 3.3 acres of uplands and tarmac will be excavated to create and re-vegetate a transition zone to provide the created marsh with resilience to sea level rise, according to the work plan.

Croft said he anticipates Dixon Marine commencing work this summer. Once Dixon Marine is finished with their part of the project, another contractor, Adanta, will remove non-native vegetation on 14.8 acres of existing wetland and plant new native vegetation.

“That contract was awarded in August 2020, and the contractor collected seeds of various native wetlands vegetations and have grown these seeds at the nursery to be ready when the construction contractor completes grading and channel work,” said Croft. “Invasive species removal or control has been ongoing over the last year by application of herbicide, solarization and mechanical removal.”

The existing wetland abuts city property at the site where De-Pave Park is planned on the west side of the Seaplane Lagoon.

In total, there will be 25.4 acres of new and enhanced wetland habitat when the project is completed in late 2023.

Contributing writer Richard Bangert posts stories and photos about environmental issues on his blog Alameda Point Environmental Reporthttps://alamedapointenviro.com/.

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