Manufactured gas plants

Project overview: PG&E is voluntarily cleaning up the site of a former manufactured gas plant (MGP) that operated near Riverside Drive and Elm Street in Napa (site). This work is conducted with the approval and oversight of the California Department of Toxic Substances Control (DTSC) and the City of Napa.

The DTSC-approved cleanup plan addresses both soil and groundwater at the site and the adjacent property, the Elm Street Townhomes. The cleanup plan includes excavation of soil that was impacted by historic gas-making activities and off-site disposal, with replacement of excavated soil with clean fill. In addition, on-site deeper impacted soil will be treated in place by mixing soils with a stabilizing agent to protect groundwater. Groundwater will continue to be monitored for a minimum of five years after the cleanup.

Current conditions do not present a health risk to current site users. The cleanup will protect long-term public health and the environment while minimizing impacts to the local community and supporting future site redevelopment.

PG&E is completing the design and engineering, and obtaining permits for the cleanup work. Fieldwork this summer and fall includes collecting additional soil samples to help design the cleanup and removing groundwater monitoring wells and soil gas probes in on- and off-site locations that are no longer needed. Cleanup work is expected to begin in late 2023 or early 2024 and last approximately one year.

Public Safety and Outreach: Safety is of the utmost importance to PG&E. Work is conducted in accordance with a DTSC-approved, site-specific health and safety plan that includes proven best practices for air and vibration monitoring, dust management, and truck traffic control. Cleanup work in the most impacted areas on-site will be performed under a tent with negative air pressure to control dust and odors. PG&E will inform the community about the project through weekly updates, work notices prior to the start of each cleanup phase, and additional project updates, as needed. PG&E is committed to keeping interested parties informed of this work and staying involved with the community on a local level. This includes coordination of work with the City of Napa, surrounding neighborhood, local schools and social organizations.

Site history: The former Napa MGP operated from 1889 to 1924 at Riverside Drive and Elm Street. The plant provided a constant source of energy for cooking, lighting, heating, and hot water and greatly modernized the community. The Napa MGP shut down when natural gas became available and some waste was left buried on site, which was a common practice before environmental laws were created. The property was redeveloped, and later PG&E purchased the site to facilitate investigation and cleanup work.