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Shell Pond Cleanup and Wetland Restoration

Cleanup and Restoration

Cleanup and Restoration: PG&E’s cleanup plan (called a Corrective Measures Plan and Design) for the Shell Pond property was approved by the Department of Toxic Substances Control (DTSC) in June 2011. In January 2012, unanticipated off-site odors occurred as a result of this work. PG&E has since suspended cleanup until we can implement a new engineering design to more effectively manage the odors. PG&E will clean up the former wastewater pond in order to return the site to natural wetlands. Following is an overview of the cleanup plan:

Phase 1 – Construction of Access Road: September - October 2011

Field crews constructed a temporary access road to the PG&E property from McAvoy Harbor to the south end of Shell Pond. This will allow project traffic to enter and exit the Shell Pond property from McAvoy Road.

Phase 2 – Dredging and Excavation: Date to be determined

Field crews will remove approximately 240,000 cubic yard of impacted material from the bottom of Shell Pond using backhoes, excavators, barges, and work boats. Covered trucks will transport impacted material for disposal at an approved off-site location.

Phase 3 – Wetland Restoration: Date to be determined

The levee surrounding Shell Pond will be breeched to allow water exchange between the pond and the adjacent Bay slough. The bottom of the pond will be graded to help support different types of wetland habitats and areas for plants and animals to live.

Impacted Material on-site: The material in Shell Pond is not classified as hazardous waste. This means it is not flammable, corrosive, reactive or highly toxic. The material is mostly carbon mixed in with peat. It has a petroleum-like smell and looks and feels like wet, ground up charcoal.

Addressing impacted material at the site will involve the removal of approximately 240,000 cubic yards of the material from the pond through hydraulic and mechanical excavation using water and land based equipment.

Adjacent to the Pond is an area of material known as the Carbon Black Area (CBA). The CBA will be enhanced as part of the project. Areas of CBA that have no plants currently growing will be covered with up to one foot of clean soil and native plants and grasses will be planted. All waste material removed from the site will be transported to and disposed of at an approved off-site location.

Water on-site: The water in Shell Pond is brackish and previous tests have shown it is not hazardous. During cleanup activities, the water will be reused on-site to aide in cleanup operations and, once the sediment removal is finished, will be tested to ensure it is clean enough to discharge into the bay. Breeching the pond levee will allow a water exchange between the Shell Pond and surrounding delta.

Benefits of a wetland: A wetland is an open space that provides a transition between water and land. Wetlands are also referred to as marshes or swamps. The restoration of this wetland offers many benefits to the Bay Point Community including:

  • Filters and cleans water runoff from the surrounding area;
  • Absorbs water and limits flooding of nearby areas;
  • Improves air quality in the community;
  • It is a home to animals, plants, and fish; and
  • Provides an opportunity for recreation and education – the access road built as part of the project is proposed to become the first section of the Great California Delta Trail, operated by the East Bay Regional Park District.

Additional Resources: