The Beneficial Reuse of Excavated Material in Tidal Marsh Restoration Project will place excavated or other “fill” 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. The Project will include the transport and placement of 3.7 million cubic yards of excavated material from VTA’s BART Silicon Valley-Phase II Extension Project for the purpose of raising the deeply subsided pond bottoms at Ponds A4, A8/A8S, and A12/A13. 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.
Sediment material is normally moved and delivered by the ocean through tidal action, which is the natural rise and fall of the sea, bays, and estuaries . 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 could take nearly 40 years to raise the salt ponds to a level that allows tidal marsh to develop. Projected 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 Alviso Pond A8 (left) and Pod A12 (right)
VTA’s BART Silicon Valley-Phase II Extension 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, portals). This process will remove a large amount of material that must be continually hauled offsite to keep pace with construction and limited storage space.
The Beneficial Reuse Project takes the challenge of managing the excavated material and turns it into an opportunity to 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.
Work Completed to Date
VTA is the lead agency under the California Environmental Quality Act (CEQA), and U.S. Fish and Wildlife Service is the lead agency under the National Environmental Policy Act (NEPA). VTA and U.S. Fish and Wildlife Service are currently conducting the Project's environmental review in compliance with CEQA and NEPA, respectively. The work completed to date includes:
- VTA filed a Notice of Preparation on January 19, 2024, and accepted scoping comments through February 19, 2024
- VTA held scoping meetings on February 6, 2024 (virtual), and February 7, 2024 (in-person)
- U.S. Fish and Wildlife Service filed a Notice of Intent in the Federal Register on April 1, 2024, and accepted comments through May 16, 2024
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 rising 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 VTA’s BART Silicon Valley-Phase II Extension 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 farther from VTA’s BART Silicon Valley-Phase II Extension Project. 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 Coastal Conservancy’s 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 excavated or other “fill” 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. The Project will include the transport and placement of 3.7 million cubic yards of excavated material from VTA’s BART Silicon Valley-Phase II Extension Project for the purpose of raising the deeply subsided pond bottoms at Ponds A4, A8/A8S, and A12/A13. 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.
Sediment material is normally moved and delivered by the ocean through tidal action, which is the natural rise and fall of the sea, bays, and estuaries . 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 could take nearly 40 years to raise the salt ponds to a level that allows tidal marsh to develop. Projected 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 Alviso Pond A8 (left) and Pod A12 (right)
VTA’s BART Silicon Valley-Phase II Extension 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, portals). This process will remove a large amount of material that must be continually hauled offsite to keep pace with construction and limited storage space.
The Beneficial Reuse Project takes the challenge of managing the excavated material and turns it into an opportunity to 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.
Work Completed to Date
VTA is the lead agency under the California Environmental Quality Act (CEQA), and U.S. Fish and Wildlife Service is the lead agency under the National Environmental Policy Act (NEPA). VTA and U.S. Fish and Wildlife Service are currently conducting the Project's environmental review in compliance with CEQA and NEPA, respectively. The work completed to date includes:
- VTA filed a Notice of Preparation on January 19, 2024, and accepted scoping comments through February 19, 2024
- VTA held scoping meetings on February 6, 2024 (virtual), and February 7, 2024 (in-person)
- U.S. Fish and Wildlife Service filed a Notice of Intent in the Federal Register on April 1, 2024, and accepted comments through May 16, 2024
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 rising 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 VTA’s BART Silicon Valley-Phase II Extension 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 farther from VTA’s BART Silicon Valley-Phase II Extension Project. 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 Coastal Conservancy’s 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.