Manufactured Gas Plants
Former St. Helena Manufactured Gas Plant
PG&E is working to address environmental impacts at the site of a former manufactured gas plant (MGP) located at 1301 Mitchell Drive in St. Helena, California. The MGP operated from 1883 to 1930. PG&E acquired the property in 1930 and used it as an electrical substation until 1989. All work is being conducted voluntarily by PG&E and is being overseen by the California Department of Toxic Substances Control (DTSC).
PG&E completed investigation work at the site and continues to clean up soil and groundwater. In 2007, PG&E completed Phase One of a large-scale soil excavation and installed a treatment system to remove MGP residues from soil and groundwater at the site. PG&E expanded the system in January 2011 to remediate another portion of the site.
PG&E will begin Phase Two of the cleanup in May 2014 and expects to complete site remediation by fall 2014. During this work, PG&E will excavate impacted soil and backfill these areas with clean, imported fill. Area residents and businesses may experience some short-term noise and vibrations typical of heavy construction work as well as a small increase in area truck traffic. Activities will be coordinated with nearby businesses and the City of St. Helena to limit community impacts to the greatest extent possible.
Under an agreement with PG&E, the City of St. Helena used a portion of the remediated property as a free, all day parking lot through April 15, 2014.PG&E and the City of St. Helena will be discussing possible post-remediation site uses.
PG&E will continue to keep the community informed about this project through fact sheets, work notices and other outreach, as appropriate.
- DTSC Work Notice – April 2014 (PDF, 1.3 MB)
- PG&E Fact Sheet – April 2014 (PDF, 218 KB)
- City of St. Helena E-newsletter Article – Public Works Featured Project: PG&E Parking Lot - July 2013
- St. Helena: PG&E Shares Parking Lot During Busy Tourist Season – June 2013
- City of St. Helena E-newsletter Article – Downtown Parking Comes to PG&E Lot on Mitchell Drive - June 2013
- City of St. Helena E-newsletter Article – Downtown Parking Ribbon Cutting Event - June 2013
- Soil Sampling Work Notice - April 2013 (PDF, 196 KB)
- Work Notice – December 2010 (PDF, 100 KB)
- DTSC Resources & Contact Information
Site-related documents can also be found at:
St. Helena Public Library – Reference Desk, 1492 Library Lane, St. Helena (707) 963-5244