Pacific Southwest, Region 9: Superfund
Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations
Purity Oil Sales, Inc.
EPA #: CAD980736151
City: 1/2 mile south of Fresno
Congressional District: 19
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Description and History
NPL Listing History
NPL Status: Final
Proposed Date: 12/30/82
Final Date: 09/08/83
The approximately 7-acre Purity Oil Sales Inc. site operated as a used oil reprocessing facility from 1934 until 1974. Oil and by-products from the refining process were collected, stored in sumps and storage tanks, and disposed of on-site in sludge pits. Waste oil sludge was used by local farmers for dust control or buried in on-site unlined pits and ponds. Contamination problems resulted from the improper storage and disposal of wastes, and numerous surface spills which occurred during site operations. In 1973, Purity Oil began to empty and backfill the waste pits. Although the waste pits were backfilled with construction debris, there is no evidence that the pits were emptied. In 1976, a fire at the site destroyed the main warehouse building and adjacent equipment. The remaining equipment was removed from the site, and the area was partially regraded. Seven aboveground steel tanks were left on site. The tanks are believed to have been used to store oil prior to reprocessing and during the acidification process. One of the tanks had an exterior asbestos coating. Although the tanks were not leaking severely, all of the tanks were rusting. All buildings and tanks have been removed from the site, and the site has been fenced. By 1982, the site was abandoned. Approximately 225 residents lived in an adjacent trailer park until October 2000. The Fresno Aquifer, designated as a sole source aquifer, provides water for municipal, industrial, and agricultural purposes, as well as for a number of private wells. A number of properties in the area were affected and are now served by the Fresno and Malaga water districts. The site is located in the San Joaquin River drainage basin, and the San Joaquin River is 12 miles north of the site.
Contaminants and Risks
- Surface Water
- Soil and Sludges
Groundwater is contaminated with various volatile organic compounds (VOCs) and heavy metals including iron and manganese. Sediment samples taken from the North Central Canal indicated the presence of lead. Soils are contaminated with phenols, polychlorinated biphenyls (PCBs), pesticides, oil and grease, VOCs, and heavy metals including lead, copper, and zinc. The contaminants identified in tank samples include PCBs, pesticides, and heavy metals including lead and zinc. Direct contact with contaminated soils may present a health threat; however, the potential for direct contact with soils was eliminated by capping the soils, which was completed in 2008. Other potential health threats include the use of contaminated groundwater by adjacent users. No current use of groundwater for human consumption occurs in the area.
Who is Involved
This site is being addressed through Federal, State, and potentially responsible parties' actions.
Investigation and Cleanup Activities
This site is being addressed in three stages: initial actions and two long-term remedial phases focusing on cleanup of the groundwater and tanks, and soil.
Initial Actions: During 1984, several potentially hazardous sections of the site near the trailer park were covered with concrete to reduce potential human contact with site wastes. In 1985, the EPA staged and sampled drums, sampled pits and the area surrounding them, and transported the waste for disposal at an approved hazardous waste disposal facility. Approximately 1,800 cubic yards of hazardous materials from two waste pits and numerous surface seeps were shipped for disposal, and 25,000 gallons of liquids from an aboveground tank were removed. Sludge from the pits was solidified, and the pits were excavated and backfilled. In 1987, the EPA removed an additional 33,000 gallons of oil and water from an on-site tank. The site was completely fenced in 1987.
Groundwater and Tanks: The EPA selected final remedies for cleanup of the tanks that include removing and disposing of remaining contaminated wastes in the tanks; solidifying tank wastes prior to off-site disposal, if necessary; and cleaning, dismantling, and disposing of the tanks off-site. The EPA removed remaining tanks in 1991. The final cleanup remedies to address groundwater contamination include using extraction wells and air stripping technology to remove contaminants from the groundwater, and a process known as "greensand" to filter iron and manganese from the water. The treated groundwater will be disposed of in the North Central Canal. Groundwater is being monitored to verify contaminant cleanup. An alternate water supply has been provided to affected private well users northwest of the site. Treatment of contaminated groundwater began in 1995.
Soil: The EPA conducted an investigation into the nature and extent of soil contamination at the site. The investigation included soil treatability studies which showed that the proposed cleanup plan, which includes soil vapor extraction of contaminants from lower layers of soil, would not adequately address lead contamination. The EPA issued a revised proposed plan for soil cleanup before the final remedy was selected in 1992. The remedy was modified in 1996 to include: enclosing the North Central canal (which traverses the southern part of the site), constructing an impermeable cover (RCRA-equivalent cap) with a soil vapor extraction system over the site, and including the rear market areas in the cleanup. The North Central Canal was enclosed in a reinforced concrete pipe in 1998 to prevent leaching of contaminated water into the soil.
The groundwater remedy was reviewed as part of EPA's Five Year Review in September 2006. The review found that improvements to the groundwater monitoring well network were needed to further define details of the plume's interior. The groundwater remedy will also be evaluated for a change, beginning in 2008. The current pump and treat system has not operated effectively due to a regional decline in the water table. A pilot study for an in-situ treatment of the groundwater source area is planned to begin in August 2008. EPA may later propose a remedy change through a ROD Amendment for groundwater.
Construction of the initial site cover began during October 2000 after the 212 residents from the trailer park were moved into temporary housing. As part of a relocation offer, 22 families living in the trailer park took a cash buy out, and 32 families lived in temporary housing until construction of on permanent housing was completed. All 32 families were moved into permanent single family housing by May 2002. Construction on implementation of the site cover was placed on hold while EPA and the PRPs negotiated an alternate method to handle the onsite soils. During implementation of the cover system, EPA discovered that soil contamination extended onto all of the adjacent properties surrounding the site. In addition, during field implementation the contractor for the PRP was unable to meet various design criteria. Soil located adjacent to Pick a Part and the irrigation canal has been moved back onto the Purity Oil Site. EPA conducted trenching and sampling on the adjacent scrap yard, trailer park and market areas during May and September 2002. EPA selected a revised remedy for the soils at the site in June 2006.
The revised remedy for soils is largely complete, as of July 2008. Acidic sludge from the former Purity operations was mixed with calcium carbonate to neutralize the acidity and develop the necessary soil properties for placement under a cap. These soils were placed in layers, compacted, and then covered with a low-permeability landfill cover. The cover includes a geosynthetic clay liner, geocomposite drainage layer, and a vegetative layer to prevent infiltration of rainfall into the neutralized waste oil sludge and contaminated soil. A soil vapor extraction system will also be installed after the cap is complete to remediate any possible gas vapors from the impacted areas entering future buildings or adjacent properties.
Cleanup Results to Date
By removing hazardous materials and tanks, consolidating and capping contaminated soils, providing alternate water supplies to affected residents, and fencing the site, the EPA has reduced the potential of exposure to contaminated materials at the Purity Oil Sales site while final groundwater and soil cleanup activities are conducted.
The most recent Five-Year Review of the remedy at the Purity Oil Sales site was completed in September 2011. The reviewed determined that the remedy is currently protective of human health and the environment, but recommendations were made to ensure that the remedies are protective
in for the long term. The review noted that the selected remedy for Operable Unit 1 (OU-1) is not operating. EPA anticipates that a new remedy will be selected in an appropriate decision document in 2012. The review also noted deficiencies in the institutional controls for both operable units. At OU-1, the groundwater management zone strategy has not yet been developed. At Operable Unit 2 (OU-2), institutional controls to prevent exposure to contaminated soils have not yet been addressed. The Five-Year Review recommended that institutional control strategies be developed for both OUs. The next review for the site will be completed by September 2016.
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.
Chevron Environmental Management Company
Documents and Reports
Public Information Repositories
The public information repositories for the site are at the following locations:
Fresno County Central Library,
2420 Mariposa Street,
Fresno, CA 93721
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
After Hours (Emergency Response)