Pacific Southwest, Region 9: Superfund
Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations
Southern California Edison Co. (Visalia Poleyard)
EPA #: CAD980816466
Congressional District: 20
Other Names: SCE/ VPY
This site was deleted from the NPL on August 27, 2009.
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Description and History
NPL Listing History
NPL Status: Final
Proposed Date: 01/22/87
Final Date: 03/31/89
Deleted Date: 08/27/09
The 20-acre Southern California Edison Co., Visalia Pole yard (VPY) site was operated as a utility pole treatment yard from the 1920s until 1980, and approximately 275,000 poles were treated at the site. Wood preservatives, including 2,500,000 gallons of creosote and 900,000 gallons of pentachlorophenol (PCP), were used and stored on site during site operations. Leaking tanks and stored treated poles have contaminated groundwater and soil. The VPY Superfund site is located at 432 North Ben Maddox Way in northeastern Visalia, Tulare County, California. Visalia is approximately midway between Fresno and Bakersfield in the Central Valley of California and is a growing metropolitan area with a population of approximately 124,000. Agriculture is the dominant industry in the region and walnuts, olives, and citrus are the primary crops.
Contaminants and Risks
- Soil and Sludges
Groundwater and soil are contaminated with wood-treatment chemicals including creosote and PCP. Potential health threats include accidental ingestion of or direct contact with contaminated soils or groundwater.
Who is Involved
This site was addressed through Federal, State, and potentially responsible parties' actions.
Investigation and Cleanup Activities
This site was addressed in two stages: immediate actions and a long-term remedial phase focusing on cleanup of the entire site.
Immediate Actions: In 1977, a slurry wall was built to slow contaminant migration in the shallow aquifer. Southern California Edison (SCE), the potentially responsible party, removed all facilities and in 1981, 2,300 cubic yards of contaminated soil and disposed of it off-site at an approved disposal facility. The facility has installed a subsurface barrier wall and a groundwater extraction and on-site treatment system. The potentially responsible party now discharges the treated groundwater to the City of Visalia Water Treatment Plant. This discharge is licensed by the State.
Entire Site: Southern California Edison (SCE) and the State, Department of Toxic Substances Control (DTSC), under EPA supervision, conducted an investigation into the nature and extent of the contamination at the site. In 1976, the State issued a Cleanup and Abatement Order, requiring Southern California Edison to abate discharge of treatment fluids into the soil, to contain contaminated soil and water on the property, to pump shallow groundwater under the site before and during construction of an underground slurry wall around the site, to pump and lower the confined aquifer to remove contamination, and to clean up contaminated shallow groundwater off site. In 1987, Southern California Edison and the State signed an agreement requiring the utility to perform a study to determine the nature and extent of site contamination and to recommend alternatives for final cleanup action. In 1994, the State approved a Remedial Action Plan, and a Record of Decision was signed on June 10, 1994. The major components of the selected remedy include: in-situ bioremediation, property access restrictions and deed restrictions. A Preliminary Close-out Report (PCOR), dated September 25, 2001, documents that the EPA completed construction activities for the Southern California Edison (SCE), Visalia Pole Yard (VPY) in accordance with Close Out Procedures for National Priorities List Sites (OSWER Directive 9320.2-09A-P).
In mid-1994, the State selected a final cleanup remedy for the site and the EPA concurred. Since the immediate actions at the site addressed the principal threats, the final remedy includes bioremediation of the remaining contaminated soil, establishing access and deed restrictions, and capping the soil, if necessary. An innovative pilot-scale steam injection/vapor extraction system designed by Lawrence Livermore Laboratories and the University of California at Berkeley to enhance the bioremediation process and remove the pole-treating chemical mass was installed in 1997. This pilot system, Dynamic Underground Stripping (DUS), was used over a 30 month period and removed and destroyed over 150,000 gallons of contaminants from the site. It consisted of 14 steam injection wells surrounding a plume of soil and groundwater contaminants. Steam was injected into the ground at a depth of 80-100 feet, forcing groundwater, creosote, an emulsion of diesel oil and water, and hydrocarbon vapors towards central extraction wells which were used to recover the contaminants. In addition to contaminants being recovered, some contaminants were also broken down below the ground into carbon dioxide and water, a process called in situ hydrous pyrolysis/oxidation (HPO). HPO takes advantage of the elevated subsurface temperatures to oxidize the residual pole-treating chemicals (PTCs) that were not removed or destroyed by the DUS process. In addition, air is injected into saturated aquifers to enhance dissolved oxygen in the groundwater. Following the completion of the DUS process, some of the injection wells were converted to air spargers as part of the bioremediation remedy. The bioventing system was designed to inject low volumes of air into unsaturated soil zones to enhance biodegradation by native hydrocarbon-utilizing bacteria. (This process requires temperatures below 70oC for the native soil microbes/bacteria to become active). All equipment needed to implement this bioventing system has been constructed. The project steam injection activities were initiated during May 1997 and concluded in June 2000.
Initially, daily contaminant mass recovery rates were approximately 13,000 pounds of contaminants. By June 2000, the recovery rate dropped from about 160 pounds per day to about 4 pounds per day. The diminishing recovery rate (<4 lbs/day) precipitated the decision to terminate steam injection operations for the monitoring plan to be implemented.
In July 2004, SCE and DTSC agreed on procedures that would demonstrate the successful implementation of remedial measures and achievement of remedial action objectives for both groundwater and soil.
Groundwater treatment plant was in operation from 1984 to 2004. The groundwater treatment plant ceased operation in 2004.
A five year review for SCE was completed in September 2005 and a Covenant to restrict use of property was completed in May 2007.
As noted earlier, cleanup activities were first initiated in 1975, with the installation of extraction wells to remove contaminated groundwater and discharge to POTW. This action was followed by construction of the slurry wall in 1976-77, to prevent further downgradient migration of WTCs in groundwater. Additionally, an on-site water treatment plant (WTP) consisting of filtration and adsorption system was built in 1985 and was successful in removing the chemicals of concern (COC) from the treated groundwater. The WTP was modified with additional filtration and gravity separation in 1987, which optimized plant performance by minimizing hazardous waste generation. The WTP pumped, treated, and discharged an average of 0.36 million gallons per day between 1985 before the construction and operation of the Visalia Steam Remediation Project (VSRP) in March of 1997 when the volume of water treated increased to approximately 0.5 million gallons per day.
The VSRP system consisted of the following elements:
-A steam injection system including four 50,000 lb/hr steam boilers connected to eleven injection wells placed around the periphery of the WTC plume;
-A vacuum extraction system consisting of four vapor and liquid extraction wells, with follow-on liquid and vapor separation, liquid cooling, and vapor and liquid treatment; and
-An ERT and thermocouple-based thermal monitoring array completely surrounding the steam injection-vacuum extraction systems.
The VSRP operated in two phases, between May 1997 and June 2000. Phase 1 operations focused on the intermediate aquifer, with injection and extraction wells screened between 80 and 100 feet bgs. Phase 2 operations began in November 1998 and included steam injection and extraction below the intermediate aquitard, with injection wells screened between 125 and 145 feet bgs. Phase 2 operations continued until June 2000, when a precipitous drop in the rate of removal of WTCs was measured.
Following cessation of the VSRP, the enhanced biological degradation system was installed and operated (SCE, 2001) to augment existing physical processes that were initiated by Dynamic Underground Stripping (DUS) and to encourage natural biological processes to flourish. This system was in operation from June 2000 until March 2004. It included vadose zone bioventing and saturated zone biosparging, coupled with continued groundwater pump-and-treat operation. Construction completion of the enhanced biological degradation system was documented in the 2001 Preliminary Close Out Report (PCOR).
A post-remediation soil investigation of the surface soils was conducted at this site in November 2004. Tetrachlorodibenzo-p-dioxin (TCDD) was detected slightly above the cleanup standards at four locations. As a result of the 2005 Five-Year Review, contaminated surface soil (soil between zero and ten feet below grade) was removed in July 2006 and verified with confirmatory sampling to be below the cleanup standards prescribed in the ROD.
Quarterly groundwater monitoring was conducted from 1985 through June 2007 within, and outside the boundaries of the area subjected to steam remediation operations. Monitoring of extraction wells within and on the edge of the WTC plume was used as a tool to assess the success of WTC removal. Monitoring of offsite wells was conducted to ensure WTCs were not escaping the groundwater extraction system.
Groundwater monitoring data from June 2004 through June 2007 were used to verify that all ROD groundwater cleanup standards had been met. The Remedial Action Completion Report (SCE 2008) documented that the post-remediation groundwater monitoring and soil removal actions performed met the ROD cleanup standards for soil and groundwater. A Remedial Action Report (RA) was signed on May 14, 2009. The final Close Out Report (FCOR) was signed on May 19, 2009.
The Federal Register notice for direct deletion (Direct final deletion notice and Notice of intent to delete) was published on July 27, 2009. A notice was also published in the local newspaper. EPA did not receive any comments. As of August 27, 2009, the Southern California Edison, Visalia Pole Yard Superfund site has been deleted from the National Priorities List (NPL), which is a list of the most hazardous waste sites identified for possible long-term remedial response. The National Contingency Plan (NCP) directs the site deletion process. The NCP states that the deletion of a site from the NPL does not preclude eligibility for future response actions, should future conditions warrant such actions. EPA will conduct subsequent "Five-Year Reviews" to evaluate the continued protectiveness of remedial actions where hazardous substances, pollutants or contaminants remain at a site above levels that allow for unrestricted use. EPA may initiate further action to ensure continued protectiveness at a deleted site, if necessary.
Cleanup Results to Date
During the VSRP operations, the various forms of WTC removal or destruction were documented through continuous monitoring systems and regular volume measurements.
-Free Product recovery
-Free product was recovered from both dissolved air flotation and oil-water separation and transferred to storage tanks where the volume measurements were made. Vapor-phase recovery was measured as both total hydrocarbons and CO2 equivalents of oxidized hydrocarbons via continuous emissions analyzer systems. Liquid phase removal was measured through a total organic carbon analyzer.
Quarterly groundwater monitoring was conducted from 1985 through June 2007 both within, as well as outside, the boundaries of the area subjected to steam remediation operations. Monitoring of extraction wells within and on the edge of the WTC plume was used as a tool to assess the success of WTC removal. Monitoring of offsite wells was conducted to ensure WTCs were not escaping the groundwater extraction system.
Groundwater monitoring data from June 2004 through June 2007 demonstrate that all groundwater cleanup standards have been met.
Demonstration of Attainment of RAP/ROD Cleanup Standards
The Remedial Action Completion Report (SCE, 2008) documents the post-remediation monitoring of groundwater and confirmation of soil removal actions performed to meet the RAP/ROD cleanup standards. The report also includes the demonstration of attainment of groundwater cleanup standards. A Remedial Action Report (RA) was signed on May 14, 2009. The Final Close Out Report (FCOR) was signed on May 19, 2009. A Direct Final Notice to delete the site from NPL was published July 27, 2009 and no comments were received. The Site was deleted from NPL site on August 25, 2009.
The Second Five-Year Review Report, completed in July 21, 2010, found that the remedy remains protective of human health and the environment. For more information, please consult the report in the Technical Documents subsection of the Documents and Reports section below.
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.
Documents and Reports
|05/01/98||New Technology to Speed Clean Up and|
|04/20/10||EPA Begins the Second Five-Year Review of Southern California Edison (SCE), Visalia Pole Yard Superfund Site, Visalia, California|
|05/23/07||Land Use Covenant|
|06/10/94||Record of Decision|
|05/14/09||Remedial Action Report|
|05/19/09||Final Close Out Report|
|07/21/10||Second Five Year Review Report|
Public Meetings: Community involvement activities included the development of a Community Involvement Plan (CIP), prior to initiation of the RI/FS activities. The CIP included development of a community profile and a list of key local contacts. The community profile indicated the surrounding area was mainly businesses that had little interest in the site cleanup activities. Copies of the Draft ROD were made available at the local public library, DTSC and USEPA Region IX Record Center. Notification of the issuance of the Draft ROD was made. A Public Notice was also placed in the local newspaper. A Public Meeting was held in Visalia, California on October 13, 1993, to provide information on the proposed cleanup. There were no members of the public in attendance at the meeting. A meeting was also held with members of the Visalia City Council, to apprise them of the proposed site cleanup activities. The Council members were supportive of the proposed cleanup actions.
Notification to the public of the Federal Register Deletion Notices will be made through a Public Notice in the Visalia Times-Delta newspaper.
Public Information Repositories
The public information repositories for the site are at the following locations:
Tulare County Public Library
200 West Oak Street
Visalia, CA 93291
Sat. 10am-5pm, close Fri. and Sun..
EPA Site Manager
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
8800 Cal Center Drive
Sacramento, CA 95826-3200
After Hours (Emergency Response)