A.41 McCormick & Baxter Creosoting Co., Stockton, CA

A.41.1 Contacts:

Patricia Bowlin

USEPA Site Manager

Mail Code SFD74
75 Hawthorne Street
San Francisco
CA 94105


[email protected]


State Contact: Sam V. Martinez, Jr. (DTSC) 916-255-6583

A.41.2 Summary





Contaminants of Concern:

Mainly PAHs and dioxin in sediments

Source Control Achieved Prior to Remedy Selection?

Yes. 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 yd3 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 capA covering over material (contaminated sediment) used to isolate the contaminants from the surrounding environment. was installed in the central site to prevent infiltration and to control dust migration.

Final Remedy:

Bank stabilization, cappingTechnology which covers contaminated sediment with material to isolate the contaminants from the surrounding environment., installation of permanent log boom for protection, relocation of occupants

MNR viewed as a success?

Yes. The installation of the stormwater collection ponds and perimeter dike, site security improvements, chemical and sludge disposal, demolition and disposal of processing equipment and site structures, construction of a sheet piling wall along Old Mormon Slough, excavation and backfilling at the oily waste pond area, installation of a cap over the most heavily contaminated central portion of the site, and installation of a sand cap in Old Mormon Slough have reduced threats to public health and the environment from these areas of the site.

A.41.3 Site Description

The McCormick & Baxter Creosoting Co. site (USEPA CAD009106527) is a 29-acre former wood-preserving facility located in an industrial area near the Port of Stockton. The site is located at 1214 West Washington Street in Stockton, CA and on the north, borders the Old Mormon Slough, which is connected to the Stockton Deepwater Channel. 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 ft 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. No drinking water supplies, however, are currently threatened by site-related contamination. Drinking water is a concern because approximately 105,000 people live and work within four 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.

A.41.4 Remedial Objectives and Approach

USEPA made changes to the sediment cleanup plan for the McCormick & Baxter Superfund Site in Stockton, California. The changes are detailed in the Explanation of Significant Differences (ESD). The ESD, signed in September 2005, describes the following changes to the original sediment remedy that was selected in the 1999 ROD.

The California Department of Toxic Substances Control (DTSC), the state support agency for the site, reviewed the ESD and concurred. USEPA and DTSC believe that the modified remedy remains protective of human health and the environment, complies with federal and state requirements that are applicable or relevant and appropriate to this remedial action, and is cost-effective.

The sediment cleanup plan selected in the ROD was the placement of a two-foot thick cap of clean sand in Old Mormon Slough, which is part of the site. The cap will isolate the contaminated sediment in the slough and eliminate the threats it poses to human health and the environment. The cap will cover about three-quarters of the slough and, after it is finished, a log boom will be installed at the outer end of the slough to prevent boat traffic from entering and damaging the cap.

Inspections conducted during the design of the cap showed that the banks along Old Mormon Slough were eroding. Tests showed that the northern shoreline was not contaminated but the southern shoreline (along the McCormick & Baxter property) was. It was necessary to reinforce the southern bank before the cap was installed. Without this reinforcement, contaminated soil could fall into the slough and recontaminate the clean sand. USEPA added bank stabilization to the remedy and divided the work into two separate phases: bank stabilization (Phase I) and construction of the cap (Phase II).

Phase I was completed in 2002, and Phase II was scheduled to begin in July 2003. However, the capping had to be delayed due to the presence of several vessels in the slough, including a large wooden barge that was being used as a residence. The vessels could not be temporarily moved out and then returned to the slough after construction, as moving them back in would damage the cap.

Because neither the owner nor USEPA could find an alternate location for the barge where it could continue to be used as a live-aboard, it became necessary to relocate the owner. People displaced from their residences by federal projects, such as the cleanup of Superfund sites, may be eligible for relocation benefits under a federal law called the Uniform Relocation Assistance and Real Property Acquisition Policies Act (URA). In this case, USEPA felt it was appropriate to assist the owner in moving to a new location.

A.41.5 Completion of Cap Construction and Monitoring

In October 2006, USEPA completed construction of a cap of clean sand over the contaminated sediment in the slough. To protect the cap, a permanent log boom was placed across the slough to prevent boat and barge traffic from damaging the cap. USEPA is currently conducting tests to determine whether the cap is intact and performing as intended. Long-term maintenance of the cap will be turned over to DTSC. USEPA and DTSC will periodically evaluate the cap to determine whether it continues to cover the contaminated sediments and meet performance standards.

A.41.6 Reference

USEPA Pacific Southwest Region 9: Superfund Website McCormick & Baxter Creosoting Co. Last updated March 2009.

Publication Date: August 2014

Permission is granted to refer to or quote from this publication with the customary acknowledgment of the source (see suggested citation and disclaimer).


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