Beneficial Reuse of Excavated Material in Tidal Marsh Restoration Project

The Beneficial Reuse of Excavated Material in Tidal Marsh Restoration Project will place up to roughly 3.5 million cubic yards of sediment material into several former salt production ponds around South San Francisco Bay to raise the pond bottoms for the purpose of accelerating the timeline for tidal marsh habitat restoration. Placing excavated material into the pond bottoms would accelerate the timeline for eventual tidal marsh restoration relative to sedimentation from natural processes (i.e., tidal action) alone. This is especially important in the face of sea-level rise and the sediment deficit in San Francisco Bay. 

Watch the video of the February 2024 Public Meeting to learn more about the Beneficial Reuse Project.

Scoping Period 
The CEQA public scoping period for the joint EIS/EIR was held from January 19 to February 20, 2024. During this period, the public was encouraged to provide input on the scope of the Project by attending either the in-person or virtual meeting, emailing and mailing comments, or using the online comment form. 

beneficial reuse locations of excavated material from the BSVII Project


Sediment material is normally moved and delivered by the ocean through tidal action, which is the natural rise and fall of the sea current. When this project returns tidal action to the ponds, the natural movement of the ocean will deliver sediment to the ponds over time. However, experts estimate that relying on this natural process alone would take nearly 40 years to raise the salt ponds to a level that allows tidal marsh to develop. Current sea level rise, increased by climate change, makes the natural process an unrealistic option. There is an urgent need to find ways to bring large volumes of sediment material from other sources to help raise the pond bottoms. The Beneficial Reuse Project presents an opportunity to provide a large volume of sediment material to help offset the natural shortage.

San Francisco Bay Area salt ponds

San Francisco Bay Area Alviso Salt Pond A8

VTA’s BART Silicon Valley Phase II (BSVII) Project will use a tunnel boring machine to excavate soil during the construction of the project’s five-mile-long subway tunnel. Surface excavation will also be required for other sites (e.g., underground stations). This process will remove a large amount of material that must be continually hauled offsite to keep pace with construction and limited project storage space. 

The Beneficial Reuse Project takes the challenge of managing the excavated material and turns it into an opportunity speed up tidal marsh habitat restoration in the South San Francisco Bay. The Project will use the excavated material to raise the sunken, former salt production pond bottoms. Raising the pond bottoms and restoring tidal action to the ponds will enable tidal marsh habitat to develop for the benefit of many plant and animal species. 

Project Benefits

Habitat Restoration

The San Francisco Bay is an important habitat that supports over a million migratory birds each year. By sustaining hundreds of species of plants and wildlife, the San Francisco Bay and its shoreline are some of the United States’ most important habitats.  

The industrial salt production process that took place over the last century and a half caused a decline in native species populations by removing the tidal marsh habitat they call home. The Beneficial Reuse Project will help restore the tidal marsh by using clean excavated material to raise pond bottoms that have been sunken during the era of salt production. Adding material to the ponds from the BSVII Project and other projects will help raise the pond bottoms to a height where tidal marsh can grow. Tidal marsh habitat restoration is essential to support the protection and recovery of the Bay’s diversity of plants, fish, and wildlife, including several endangered and threatened species in the South Bay, like the salt marsh harvest mouse. 

Sea Level Rise

Tidal action naturally brings sediment into the salt ponds over time. However, with climate change and sea level rise, this natural process is unable to bring in this material to fill in the sunken salt ponds fast enough to keep up with increasing sea levels. Tidal marshes function as natural sponges absorbing flood waters and reducing wave energy during storm events. Restoring the salt ponds to tidal marsh habitat will help protect against sea level rise – a benefit that would be uncertain without the large amount of excavated material available from the BSVII Project.

Greenhouse Gas Reduction

The Beneficial Reuse Project takes clean excavated material that would typically be hauled to a landfill or quarry and repurposes it to help raise the pond bottoms in South San Francisco Bay. The Beneficial Reuse Project’s short-term greenhouse gas reduction benefit comes from the removal of thousands of miles worth of truck trips that would have been required to take the material to landfills and quarries far away from the BSVII Project site. Using the excavated material at the salt ponds is a much shorter and more beneficial trip. The more long-term benefit will be in the reduction of greenhouse gases that will be minimized from the Beneficial Reuse Project’s contribution to re-developing future tidal marsh. This is due to tidal marshes’ natural ability to not only remove large amounts of carbon dioxide (a greenhouse gas) from the atmosphere but also store it, which decreases the magnitude of global warming. 
 

Acknowledgements

The Coastal Conservancy is a California state agency, established in 1976, to protect and improve natural lands and waterways, to help people get to and enjoy the outdoors, and to sustain local economies along California’s coast. It acts with others to protect and restore, and increase public access to, California’s coast, ocean, coastal watersheds, and the San Francisco Bay Area.
 
The California Wildlife Conservation Board protects, restores, and enhances California’s spectacular natural resources for wildlife and for the public’s use and enjoyment in partnership with conservation groups, government agencies, and the people of California.
 
The shared vision of the Coastal Conservancy and the Wildlife Conservation board is of a future in which California’s wildlife, biodiversity, and wild places are effectively restored, conserved, and accessible for current and future generations. With the Conservatories’ contribution of $1.5 million and the Wildlife Conservation Board’s Contribution of $2.98 million to this project, VTA can aid in achieving this shared vision.

The Beneficial Reuse of Excavated Material in Tidal Marsh Restoration Project will place up to roughly 3.5 million cubic yards of sediment material into several former salt production ponds around South San Francisco Bay to raise the pond bottoms for the purpose of accelerating the timeline for tidal marsh habitat restoration. Placing excavated material into the pond bottoms would accelerate the timeline for eventual tidal marsh restoration relative to sedimentation from natural processes (i.e., tidal action) alone. This is especially important in the face of sea-level rise and the sediment deficit in San Francisco Bay. 

Watch the video of the February 2024 Public Meeting to learn more about the Beneficial Reuse Project.

Scoping Period 
The CEQA public scoping period for the joint EIS/EIR was held from January 19 to February 20, 2024. During this period, the public was encouraged to provide input on the scope of the Project by attending either the in-person or virtual meeting, emailing and mailing comments, or using the online comment form. 

beneficial reuse locations of excavated material from the BSVII Project


Sediment material is normally moved and delivered by the ocean through tidal action, which is the natural rise and fall of the sea current. When this project returns tidal action to the ponds, the natural movement of the ocean will deliver sediment to the ponds over time. However, experts estimate that relying on this natural process alone would take nearly 40 years to raise the salt ponds to a level that allows tidal marsh to develop. Current sea level rise, increased by climate change, makes the natural process an unrealistic option. There is an urgent need to find ways to bring large volumes of sediment material from other sources to help raise the pond bottoms. The Beneficial Reuse Project presents an opportunity to provide a large volume of sediment material to help offset the natural shortage.

San Francisco Bay Area salt ponds

San Francisco Bay Area Alviso Salt Pond A8

VTA’s BART Silicon Valley Phase II (BSVII) Project will use a tunnel boring machine to excavate soil during the construction of the project’s five-mile-long subway tunnel. Surface excavation will also be required for other sites (e.g., underground stations). This process will remove a large amount of material that must be continually hauled offsite to keep pace with construction and limited project storage space. 

The Beneficial Reuse Project takes the challenge of managing the excavated material and turns it into an opportunity speed up tidal marsh habitat restoration in the South San Francisco Bay. The Project will use the excavated material to raise the sunken, former salt production pond bottoms. Raising the pond bottoms and restoring tidal action to the ponds will enable tidal marsh habitat to develop for the benefit of many plant and animal species. 

Project Benefits

Habitat Restoration

The San Francisco Bay is an important habitat that supports over a million migratory birds each year. By sustaining hundreds of species of plants and wildlife, the San Francisco Bay and its shoreline are some of the United States’ most important habitats.  

The industrial salt production process that took place over the last century and a half caused a decline in native species populations by removing the tidal marsh habitat they call home. The Beneficial Reuse Project will help restore the tidal marsh by using clean excavated material to raise pond bottoms that have been sunken during the era of salt production. Adding material to the ponds from the BSVII Project and other projects will help raise the pond bottoms to a height where tidal marsh can grow. Tidal marsh habitat restoration is essential to support the protection and recovery of the Bay’s diversity of plants, fish, and wildlife, including several endangered and threatened species in the South Bay, like the salt marsh harvest mouse. 

Sea Level Rise

Tidal action naturally brings sediment into the salt ponds over time. However, with climate change and sea level rise, this natural process is unable to bring in this material to fill in the sunken salt ponds fast enough to keep up with increasing sea levels. Tidal marshes function as natural sponges absorbing flood waters and reducing wave energy during storm events. Restoring the salt ponds to tidal marsh habitat will help protect against sea level rise – a benefit that would be uncertain without the large amount of excavated material available from the BSVII Project.

Greenhouse Gas Reduction

The Beneficial Reuse Project takes clean excavated material that would typically be hauled to a landfill or quarry and repurposes it to help raise the pond bottoms in South San Francisco Bay. The Beneficial Reuse Project’s short-term greenhouse gas reduction benefit comes from the removal of thousands of miles worth of truck trips that would have been required to take the material to landfills and quarries far away from the BSVII Project site. Using the excavated material at the salt ponds is a much shorter and more beneficial trip. The more long-term benefit will be in the reduction of greenhouse gases that will be minimized from the Beneficial Reuse Project’s contribution to re-developing future tidal marsh. This is due to tidal marshes’ natural ability to not only remove large amounts of carbon dioxide (a greenhouse gas) from the atmosphere but also store it, which decreases the magnitude of global warming. 
 

Acknowledgements

The Coastal Conservancy is a California state agency, established in 1976, to protect and improve natural lands and waterways, to help people get to and enjoy the outdoors, and to sustain local economies along California’s coast. It acts with others to protect and restore, and increase public access to, California’s coast, ocean, coastal watersheds, and the San Francisco Bay Area.
 
The California Wildlife Conservation Board protects, restores, and enhances California’s spectacular natural resources for wildlife and for the public’s use and enjoyment in partnership with conservation groups, government agencies, and the people of California.
 
The shared vision of the Coastal Conservancy and the Wildlife Conservation board is of a future in which California’s wildlife, biodiversity, and wild places are effectively restored, conserved, and accessible for current and future generations. With the Conservatories’ contribution of $1.5 million and the Wildlife Conservation Board’s Contribution of $2.98 million to this project, VTA can aid in achieving this shared vision.