From 1942-1946 the 22 acres composing what was to become the McColl Superfund Site was a disposal area for petroleum refinery waste. During that period, twelve unlined pits or sumps were dug and filled with an estimated total of 72,600 cubic yards of waste. At the time the waste pits were created, the local area was sparsely populated. Refinery operations took place on land located to the north and northwest of the site. During the 1950s and early 1960s, in an attempt to control site odors, three sumps in the Ramparts area were covered with drilling mud. In the late 1950s, six sumps at the lower end of the property were covered with natural fill materials during the construction of the adjacent Los Coyotes Country Club golf course. Additional soil cover was placed over the upper Ramparts sumps in September 1983. Subsequently residences were built on adjacent land and eventually the golf course expanded to include the closed site. The site initially was brought to the attention of regulatory agencies as a result of odor and health complaints received from residents beginning in July 1978. The site was formally listed on the Superfund NPL in 1982. Since 1982, various investigative and removal actions were initiated to characterize the nature and extent of source and groundwater contaminants and to minimize or eliminate immediate threats to human health and the environment. Over time some of the waste constituents leached from the sumps into underlying perched groundwater and have been transported in the dissolved phase hydraulically downgradient from the sumps. The principal contaminants of concern (COC) are: benzene, tetrahydrothiophenes (THTs), and metals. Following investigations conducted by responsible parties, EPA proposed in 1984 to excavate and dispose of the waste. The State of California was designated the lead agency for the site but was later stopped from implementing the plan by a court injunction. Following the court injunction blocking the state from implementing the excavation, community groups were formed and participated in site-related decisions through the final remedy construction. EPA undertook additional feasibility studies at the site, and, having assumed the lead in 1989, proposed excavation of the waste and incineration. Following public comment and field-testing of the proposed incineration process, EPA re-evaluated the alternatives. In August 1992, EPA published its updated feasibility study, called the Supplemental Re-evaluation of Alternatives II, and proposed to solidify the waste. The plan also identified installation of a Resource Conservation and Recovery Act (RCRA) equivalent closure system, or cap, as a contingency remedy in the event that solidifying the material was determined unfeasible. On September 28, 1995, following extensive testing of solidification, EPA concluded that the technology was not feasible for the site and decided to implement the contingency remedy. The contingency remedy included: (1) constructing a multi-layer cap over the untreated sumps with a gas collection and treatment system to prevent infiltration of water and release of hazardous air emissions; (2) building subsurface cut-off slurry walls around the sumps to prevent migration of water into the waste and outward migration of water soluble and gaseous contaminants; (3) stabilizing steep slopes on the site with retaining walls; (4) and monitoring groundwater. Operations and maintenance of the cap and slurry wall, gas collection and treatment system, and site security would be necessary in perpetuity at the site. These requirements are in the Source Record of Decision signed on June 30, 1993. From September 1993 to April 1996, the responsible parties, known as the McColl Site Group of Oil Companies (MSG), under EPA's oversight, conducted a groundwater investigation. EPA proposed a plan for the groundwater remedy on February 15, 1996. The groundwater remedy required that infiltration of water into the ground be reduced through: (1) redirection of surface water off the site; (2) grading of areas adjacent to the containment system, and (3) lining of on-site drainage channels with low permeability materials. EPA's groundwater remedy is in the Groundwater Record of Decision (ROD) signed on May 15, 1996. Construction activities, performed by MSG with oversight from EPA, began on July 1996 and were completed in November 1997. These activities included the following: · Installation of Subsurface Cut-off Walls · Installation of an Impermeable Cover · Grading to Facilitate Surface Water Control · Erosion Control Measures · Building a Gas Collection & Treatment Plant, and · Golf Course Restoration Activities. Prior to cap construction, two vertical cutoff walls, which serve as subsurface barriers, were installed, one each encircling the Ramparts and Los Coyotes sump areas. Each barrier was constructed using a slurry mixture of soil and bentonite clay. The gas collection systems installed beneath the Los Coyotes and Ramparts cover systems consist of a series of eight-inch mains and four-inch laterals. The Los Coyotes and Ramparts networks are interconnected, and a single blower induces a vacuum to draw the subsurface gases through the above-ground vapor treatment system. The vapor treatment system is located on site at a location due west of Sunny Ridge Drive near its intersection with Rosecrans Ave., and consists of two granular activated carbon (GAC) vessels operated in series. The gas collection and vapor treatment systems are collectively referred to as the Gas Collection and Treatment System (GCTS). Additional components of the remedy beyond physical construction include institutional controls and long term monitoring. Institutional controls have been implemented as part of the source OU remedy. McAuley LCX, the property owner, agreed no further development of the site property, and to record a deed restriction on the Los Coyotes and Ramparts areas. This deed restriction runs with the land and is binding on any potential future owner of the site. On November 13, 1997, EPA and the California DTSC conducted a final inspection of the McColl Superfund Site. EPA determined that construction had been completed according to specifications and the remediation had been successfully implemented. In April 1998, EPA approved the Final Remedial Action Report for the McColl Site. On June 30, 1998, EPA signed the Superfund Closeout Report for the site. The Groundwater ROD specified continued groundwater monitoring to determine whether migration of site related contaminants is taking place off site. For the purposes of monitoring groundwater, there is a network of 20 wells from which hydraulic head and chemistry data may be collected. All wells are located outside of the capped areas as there were to be no perforations of the cap. All site work has been completed, and is being monitored to ensure that the remedy remains protective to human health and the environment. This phase of the process is considered Operation and Maintenance.

Hazardous Ranking Score

42 / 100

A score of 28.5 or higher qualifies a site for the Superfund National Priority List.

Regional Contact

Region 9
Phone: (415) 947-4251

Contact Region



Site Inspection
Preliminary Assessment
Final Listing On NPL

Contaminants & Health Effects

      Endocrine Disrupter
      Reproductive Toxin
      Persistent, bioaccumulative and toxic


        African American
        American Indian and Alaska Native
        Native Hawaiian


        People living
        within a 1 mile radius


        Average Income


        Occupied homes

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