Pacific Southwest, Region 9: Superfund
Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations
EPA #: CAD980498695
Congressional District: 39
Other Names: Ramparts & Los Coyotes Tracts
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Description and History
NPL Listing History
NPL Status: Final
Proposed Date: 12/30/82
Final Date: 09/08/83
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.
Contaminants and Risks
- Soil and Sludges
Prior to cleanup, air, groundwater, and soil on site contained thiophene compounds, which can cause severe odors; sulfur dioxide, which can cause respiratory inflammation when inhaled; and various volatile organic compounds (VOCs), including benzene. The waste contaminating the air, groundwater and soil was very acidic. People could have faced health risks from direct contact with the waste because of its acidic nature. Inhalation of emissions of sulfur dioxide and VOCs from the waste also could pose health threats. Low levels of inorganic chemicals, volatile, and semi-volatile compounds were detected in the regional groundwater. Some of these compounds were also detected in the soil.
Who is Involved
This is being addressed through Federal, State, and potentially responsible parties' actions.
Investigation and Cleanup Activities
Site cleanup is being addressed in three phases: initial actions and two long-term remedial phases focusing on cleanup of soil and waste and groundwater.
Initial Actions: Access to the site was restricted by a fence and a 24 hour security guard. A temporary cap was placed over portions of the site. Waste that seeped to the surface was periodically removed to prevent exposure.
Soil and Waste: In 1984, the EPA selected a cleanup remedy including excavation and disposal of wastes at an approved disposal facility. Groundwater monitoring wells were installed on site and sampled to determine whether the groundwater had been contaminated by the soil. A State court injunction in 1985 stopped the transfer of the contaminated soil. As a result of this injunction, the EPA revised the original study. The EPA issued a proposed plan in 1989 identifying excavation and thermal destruction as the preferred cleanup alternative. The EPA then conducted various treatability studies including rotary kiln incineration, low temperature thermal extraction, solvent extraction, and a trial excavation of the waste. Based on information gained from these studies, in mid-1993, the EPA again chose to revise its plan for cleanup; the EPA selected partial solidification of the tar waste in the sumps with a contingency remedy of RCRA equivalent closure. During 1994 and 1995 pilot and full scale treatability studies were conducted to determine if the solidification of the tar waste was a feasible alternative. In September of 1995, EPA selected the contingency remedy of RCRA equivalent closure for the sump wastes. The contingency remedy included a RCRA equivalent cap over the sumps and a below grade soil bentonite slurry wall around the sumps. The design of the remedy was completed in March 1997.
Groundwater: In the early 1980s, a limited number of monitoring wells were installed on site. Samples from these wells produced no conclusive results. In 1986, the EPA conducted a groundwater investigation. Samples taken during the study indicated that thiophenes may have leached into the groundwater. A more comprehensive groundwater investigation began in 1990 to determine the nature and extent of the contamination and to identify cleanup alternatives. Results of this investigation indicate that while contaminants are entering the perched groundwater, they do not result in significant contamination of the regional aquifer nor do they present a threat to human health or the environment. The perched groundwater is not considered usable because there is not enough water to supply an extraction well. Only very low concentrations of contaminants reached the regional aquifer. Although these compounds caused the groundwater to smell and taste bad, they did not present a threat to human health and the environment. Installation of the cap and slurry wall as described above greatly reduced the rate of contaminant movement. Groundwater adjacent to the site is not used as a source of drinking water.
The construction of the cap and slurry wall were completed in May, 1998. The system for collecting and treating subsurface gases was also completed and is fully functional and operational. Currently it runs intermittently due to the low levels of gases generated beneath the cap. Groundwater is monitored regularly to ensure that site contaminants have not migrated off-site.
A third Five Year Review was completed on September 28, 2012. This review summarized cleanup activities that have taken place and evaluated whether the selected remedy remains protective of human health and the environment. According to Superfund law, if a cleanup action takes more than five years to complete and/or leaves waste in place, the protectiveness of the remedy will be reviewed every five years. The review determined that the remedy is functioning as designed and is protective of human health and the environment. The document is available below.
Cleanup Results to Date
The construction of the cap and slurry wall have been completed. The system for collecting and treating subsurface gases has also been completed and is fully functional and operational. Currently it runs intermittently due to the low levels of gases generated beneath the cap.
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 available.
Documents and Reports
Public Information Repositories
The public information repositories for the site are at the following locations:
Fullerton Public Library, 353 West Commonwealth Avenue,
Fullerton, CA 92632
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
Site Mitigation and Brownfields Reuse Division -- Cypress
5796 Corporate Avenue
Cypress, CA 90630-4732
After Hours (Emergency Response)