Hewlett-Packard operated an optical electronics manufacturing facility at 620-640 Page Mill Road in Palo Alto, California, from 1962 to 1986. A leaking underground storage tank released volatile organic compounds (VOCs) into soil and groundwater, leading to the site's listing on the EPA's National Priorities List (NPL) in February 1990. The site covers 10 acres in Santa Clara County and is currently occupied by commercial businesses employing over 1,100 people.
EPA identified 33 contaminants of concern at the site. The main group is VOCs, including trichloroethene (TCE), tetrachloroethene, 1,1,1-trichloroethane, 1,2-dichloroethane, benzene, toluene, xylene, acetone, and dichloromethane. Arsenic has also been found in soil. Most contaminants appear in both soil and groundwater across the site.
A Record of Decision issued in March 1995 set the cleanup goals: return groundwater to drinking water standards, control VOC movement in groundwater, and remove soil contamination sources. Cleanup methods include soil excavation, soil vapor extraction, and groundwater extraction and treatment using carbon adsorption and air stripping. An in-place bioremediation program uses microbes to break down VOCs at source areas. One sub-grade electrical utility area tested positive for unhealthy TCE vapor levels and received a ventilation system. Vapor intrusion testing found no unhealthy levels in homes or regularly occupied workspaces. Groundwater in the Palo Alto area is not used for drinking water, as the municipal supply comes from the Hetch Hetchy reservoir, but cleanup standards protective of drinking water are in place for the future.
EPA performance measures show human exposure is currently under control and construction cleanup is complete. The site is considered ready for its anticipated use. Groundwater migration has insufficient data to confirm whether contamination spread is fully stabilized, so monitoring continues. The most recent five-year review, completed in September 2025, found the remedial action is short-term protective. A feasibility study under state oversight, started in July 2021, is addressing the overall site area. Institutional controls prohibit residential use and groundwater use without further cleanup, and any new construction must include vapor intrusion prevention measures.
Community members with questions can contact EPA's Community Involvement Coordinator, David Yogi, or Remedial Project Manager Max Williams. The U.S. Geological Survey Library in Menlo Park, California, at 345 Middlefield Road, Building 3, serves as the public information repository for site documents and EPA administrative records.
