Threemile Slough Pipeline Crossings Remediation and Decommissioning Project

The Threemile Slough Pipeline Crossings Remediation and Decommissioning Project, led by the California State Lands Commission for Pacific Gas and Electric Company, involves the remediation of active natural gas pipelines L-131Y and L-131Z to address shallow burial depths and the decommissioning and removal of two previously abandoned pipelines. Located in Rio Vista, Sacramento County, the project scope encompasses area preparation, pipeline remediation and removal, and post-construction restoration. Work is scheduled for a three-month window from August 1 through October 31, 2026, to protect special-status fish species, with a possible extension to November 30 upon authorization from the National Marine Fisheries Service. The project is subject to extensive environmental and regulatory oversight, including the California Environmental Quality Act, the Clean Water Act, and the Rivers and Harbors Act. Key compliance requirements include the identification of 3.51 acres of federal jurisdictional waters, the management of asbestos-containing materials through certified testing and approved disposal, and the implementation of a Mitigation Monitoring Program to address impacts on air quality, biological resources, and cultural sites. Safety and operational standards mandate adherence to Cal/OSHA regulations, the Lempert-Keene-Seastrand Oil Spill Prevention and Response Act, and technical standards from ASME, NACE, and ANSI. Hazardous materials must be stored in dedicated staging areas with secondary containment capable of holding 110 percent of the largest container's volume.