Southern California Edison Co. (Visalia Poleyard)

Overview

The Southern California Edison Visalia Poleyard is a former utility pole treatment facility that operated in Visalia, California from the 1920s until 1980. It was added to the EPA's National Priorities List (NPL), the federal roster of the most serious contaminated sites, in 1989. The site has since completed cleanup and was deleted from the NPL in 2009.

The site contaminated both soil and groundwater with chemicals used in wood treatment. EPA identified 13 contaminants of concern, including polycyclic aromatic hydrocarbons (PAHs) such as naphthalene, benzo[a]pyrene, chrysene, and phenanthrene. Pentachlorophenol, dioxins, and dibenzofurans were also found. Most contaminants appeared in both soil and groundwater, though pentachlorophenol was detected only in soil.

Cleanup used several methods over many years. Extraction wells started pulling contaminated groundwater in 1975, and a slurry wall built in 1977 slowed contaminant spread. An on-site water treatment plant ran from 1985 to 2004. Between 1997 and 2000, an innovative steam injection and vapor extraction system removed and destroyed over 150,000 gallons of contaminants from soil and groundwater. After that, a biological degradation system using bioventing and biosparging ran from 2000 to 2004 to break down remaining contamination naturally. Contaminated surface soil was excavated and confirmed clean in 2006. Groundwater monitoring from 1985 to 2007 confirmed all cleanup standards were met by June 2004. Access and deed restrictions remain in place at the site.

Human exposure is currently under control, with no unacceptable exposure pathways identified. Groundwater migration is stabilized with no unacceptable discharge to surface water, though monitoring continues to confirm contamination stays in its original area. EPA five-year reviews in 2010, 2015, 2020, and 2025 all concluded the cleanup remains protective of human health and the environment. As of December 2024, one business was operating on the site.

Community members who want to learn more or access site records can contact the EPA Community Involvement Coordinator. Physical records are available at the EPA Regional Records Center at 75 Hawthorne Street, Room 3110, San Francisco, California 94105, reachable at (415) 947-8717.