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Pacific Southwest, Region 9: Superfund

Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations

McCormick & Baxter Creosoting Co.

EPA #: CAD009106527

State: California(CA)

County: San Joaquin

City: Stockton

Congressional District: 11

Other Names:

Bulletin Board


Description and History

NPL Listing History

NPL Status: Final

Proposed Date: 02/07/92

Final Date: 10/14/92

Deleted Date:

The McCormick & Baxter Creosoting Co. site is a 29-acre former wood-preserving facility located in an industrial area near the Port of Stockton. Old Mormon Slough, which is connected to the Stockton Deepwater Channel, borders the site on the north. Except for an 8-acre portion of the site owned by Southern Pacific Railroad Company, McCormick & Baxter owns the entire property. From 1942 to 1990, McCormick & Baxter treated utility poles and railroad ties with creosote, pentachlorophenol (PCP), and compounds of arsenic, chromium and copper. Wood treating chemicals were stored in tanks, and oily waste generated by the wood-treatment processes was stored in unlined ponds and concrete tanks on the site. The site came to the attention of state agencies in 1977 when a fish kill in New Mormon Slough and the Stockton Deepwater Channel was attributed to a release of pentachlorophenol (PCP)-contaminated stormwater runoff from the McCormick & Baxter facility. In 1978, McCormick & Baxter constructed a perimeter dike to prevent stormwater runoff from the site and installed two stormwater collection ponds. The unlined oily waste ponds were closed in 1981. Sampling has shown that soils throughout the site and groundwater in the shallow aquifer beneath the site are contaminated with PCP, various constituents of creosote, dioxin (a contaminant in industrial-grade PCP) and metals. Soil contamination extends to greater than 40 feet below ground surface (bgs) in the central processing area of the site. Site investigations indicate that the shallow aquifer (0 - 200 ft bgs) is connected with the deeper aquifer, which is a drinking water source. However, no drinking water supplies are currently threatened by site-related contamination. Approximately 105,000 people live and work within 4 miles of the site. Sediment in Old Mormon Slough adjacent to the site is also contaminated, primarily with PAHs and dioxin. Site-related contaminants have been detected in fish caught in the vicinity of the site. People fish in the Stockton Channel and in Old Mormon Slough, although the McCormick & Baxter site is fenced and posted with warning signs.

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Contaminants and Risks

Contaminated Media
  • Groundwater
  • Surface Water
  • Soil and Sludges
  • Environmentally Sensitive Area

Soils and groundwater are contaminated with PCP, dioxin, polycyclic aromatic hydrocarbons (PAHs), which are constituents of creosote, arsenic, chromium, and copper. In addition, non-aqueous phase liquids (NAPLs) are widespread beneath the site. Sediment in Old Mormon Slough adjacent to the site is also contaminated, primarily with PAHs and dioxin. Individuals who accidentally ingest or come in direct contact with contaminated soil, sediment or groundwater could be at risk. Drinking water from the deep aquifer has not been affected by any contaminants from the McCormick & Baxter site. Oily seeps from the former oily waste ponds into Old Mormon Slough occurred in the past, although the seeps are now controlled. Site-related contaminants have been found in locally-caught fish, which may be consumed by nearby fishermen and their families. Sediment contamination also poses an environmental threat to aquatic organisms in the vicinity of the site.

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Who is Involved

This site is being addressed through Federal and potentially responsible parties' actions.

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Investigation and Cleanup Activities

The site has been divided into three operable units (OUs) based on media. The site is being addressed in four stages: immediate actions and three long-term remedial phases focusing on cleanup of the groundwater (OU 1), soils (OU 2), and sediment (OU 3).

Initial Actions

EPA improved site security and disposed of chemicals and sludges remaining at the site. EPA completed demolition of all site treatment vessels, structures and above-ground tanks and piping in 1994. In 1996-1997, EPA installed a 437-foot sheet piling wall along the shoreline of Old Mormon Slough to control seepages from the former oily waste ponds, excavated approximately 12,000 cubic yards of oily waste and backfilled the area with clean fill. The excavated material is contained on-site in a lined repository in the central portion of the site. A cap was installed in the central site to prevent infiltration and to control dust migration.

Site Studies

Groundwater (OU 1): In mid-1992, the EPA began a multi-phase investigation into the nature and extent of groundwater contamination at the site. These studies have included sampling to define the extent of non-aqueous phase liquids (NAPLs) beneath the site. EPA selected an interim groundwater remedy (pumping and treatment) in March 1999. However, the remedy was not implemented because the groundwater plume is moving very slowly. In addition, there is evidence that some of the contaminants may be naturally breaking down at the plume's edges. EPA is conducting groundwater investigations and monitoring as part of a focused feasibility study (FFS) to support the selection of a revised groundwater remedy for the Site. EPA plans to propose a revised groundwater cleanup plan in 2016. EPA will continue to monitor the groundwater plume until a groundwater remedy is implemented.

Remedy Design

Soils (OU 2): In early 1993, the EPA began a two-phase study of the nature and extent of soil contamination at the site. EPA selected a final cleanup remedy for soils (on-site consolidation and capping) in March 1999. EPA and Union Pacific Rail Road (UPRR) signed a consent decree in 2006 for UPRR to conduct the remedial design/remedial action for the soil remedy. The soil remedy design was completed in 2008, and construction of the soil remedy was completed in 2011.

Cleanup Ongoing

Sediment (OU 3): EPA began a two-phase study of sediment in Old Mormon Slough, New Mormon Slough and the Stockton Deepwater Channel in 1993. EPA selected a final cleanup remedy for sediment (in-place capping) in March 1999. EPA completed Phase I of the sediment remedy (bank stabilization) in 2003 and completed Phase II (placement of a sand cap over the contaminated sediment) in 2006. Periodic monitoring will evaluate the effectiveness of the sediment cap.

Site Studies

Ecological Risk Assessment: EPA conducted a study of fish and benthic organisms to determine ecological impacts related to the McCormick & Baxter site. This investigation has provided information used in selecting a final remedy for sediment cleanup.

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Cleanup Results to Date

The Second Five-year Review Report, completed in September 26, 2013, concluded that -

  • The interim groundwater remedy has not been implemented to date and will not be addressed in detail in this FYR. EPA is currently conducting semiannual groundwater monitoring as part of the focused feasibility study (FFS) to support the selection of the final groundwater remedy for the Site.
  • The remedy for the surface water-sediment OU is protective of human health and the environment. All exposure pathways have been eliminated or controlled through the installation of the sediment cap and implementation of institutional controls.
  • The remedy for the soils OU is protective of human health and the environment. All exposure pathways have been eliminated or controlled through the excavation of contaminated soils, installation of the asphalt cap, and partial implementation of institutional controls. To be protective in the long term, all land use restrictions need to be implemented.
  • The implemented remedies for the McCormick and Baxter Superfund Site are protective of human health and the environment because all exposure pathways have been eliminated or controlled.

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Potentially Responsible Parties

Potentially responsible parties (PRPs) refers to companies that are potentially responsible for generating, transporting, or disposing of the hazardous waste found at the site.

Online information about the PRPs for the site is not yet available.

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Documents and Reports

Show details for Administrative RecordsAdministrative Records
Show details for Fact SheetsFact Sheets
Show details for Records of DecisionRecords of Decision
Show details for Technical DocumentsTechnical Documents

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Community Involvement

Public Meetings:
1) March 1994 - Public Meeting
2) June 1995 - Visitor's Day
3) September 1998 - Proposed Plan Public Meeting & Comment Period
4) August 2006 - Open House for Sediment Capping Work

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Public Information Repositories

The public information repositories for the site are at the following locations:

Cesar Chavez Central Library
605 N. El Dorado Street
Stockton, CA 95202-1907

The most complete collection of documents is the official EPA site file, maintained at the following location:

Superfund Records Center

Mail Stop SFD-7C

95 Hawthorne Street, Room 403

San Francisco, CA 94105

(415) 820-4700

Enter main lobby of 75 Hawthorne street, go to 4th floor of South Wing Annex.

Additional Links

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EPA Site Manager
Patricia Bowlin
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
David Yogi
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
State Contact
Christine Parent
California Department of Toxic Substances Control
8800 Cal Center Drive
Sacramento, CA 95826-3200
PRP Contact
Community Contact
Other Contacts
After Hours (Emergency Response)
(800) 424-8802

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