Sears Point Wetlands Restoration

The Sears Point Wetland Restoration project in Sonoma County, California, presented multifaceted challenges across its phases.
 
Phase 1 involved excavating two basins and swales to restore wetlands, using the excavated material as fill for constructing access roads. We faced the task of establishing infrastructure for site drainage, groundwater control, and equipment access amid soft Bay Mud soil conditions. Environmental considerations, including endangered species habitats, required careful planning and execution to ensure compliance and minimize ecological impact.
 
Phase 2 presented challenges in the environmental remediation of contaminated areas. Working with qualified subcontractors, we employed precise GPS-guided excavation to remove and safely dispose of contaminated materials. We implemented rigorous environmental controls, including continuous water monitoring and air quality management, to protect workers and the sensitive ecosystem. Additionally, constructing a new setback levee required meticulous soil conditioning and compaction techniques to meet engineering specifications and environmental standards.
 
Phase 3 focused on the extensive restoration of tidal wetlands and lowering existing levees to enhance habitat diversity. Collaborating with environmental agencies like the California Department of Fish and Game (CDFG) and the U.S. Fish and Wildlife Service (USFWS), we aimed to complete the final restoration of 955 acres of tidal wetlands. This phase aimed to create an inlet channel and multiple breaches along the outboard levee to improve hydrologic connections and provide sanctuary for endangered species like the salt marsh harvest mouse and California clapper rail.

To address Phase 1 challenges, we deployed specialized earthwork equipment suited for soft soil conditions, a crucial aspect of heavy civil construction. Over-excavation and subgrade conditioning ensured stable foundations for infrastructure. Advanced GPS technology enabled precise grading and alignment, essential for maintaining project timelines and adhering to environmental specifications. We strategically installed drainage and electrical systems to manage water flow and support future phases of the restoration.

In Phase 2, we focused on meticulous planning and execution of remediation activities. We carefully excavated, tested, and wrapped contaminated material in geotextile fabric for safe disposal. Continuous environmental monitoring ensured compliance with cleanup criteria and regulatory standards. We constructed the new setback levee, consisting of over one million cubic yards of soil excavated from onsite, creating a system of channels and islands for wildlife habitats, using systematic soil conditioning and compaction techniques to achieve optimal stability and environmental resilience, supporting long-term restoration goals.

Phase 3 marked a collaborative effort between us, the client, and environmental agencies to restore tidal wetlands and enhance ecological resilience. The project involved careful removal of existing vegetation and protection of the engendered salt marsh harvest mouse, dredging an inlet channel between the bay and existing outboard levee while ultimately breaching and lowering multiple segments of the levee to facilitate natural tidal flows, benefiting native vegetation and wildlife habitats. Innovative techniques, such as hydraulic dredging for channel excavation and habitat diversification by planting native species in upland areas, promoted biodiversity and supported the recovery of endangered species within the San Francisco Bay estuary system.

We completed Phase 1 on time, under budget, and within environmental constraints critical for protecting endangered species habitats.

In Phase 2, we successfully remediated contaminated areas, meeting stringent cleanup criteria while ensuring worker safety and environmental compliance and constructed major components of the wetland habitat including the new setback levee, channels and islands. Our adherence to advanced environmental controls and mitigation measures minimized ecological disturbance and facilitated the restoration of disturbed habitats.

Phase 3’s comprehensive restoration efforts culminated in the main levee breach event which resulted in the return of 955 acres of tidal wetlands and the establishment of vital hydrologic connections in San Pablo Bay. Lowering existing levees and creating breaches enhanced habitat diversity and resilience to climate change impacts. The project not only provided recreational opportunities and public access but also contributed significantly to the recovery of numerous species protected under federal and state conservation laws.