Bacteria To Neutralize Yucaipa Landfill Pollutants Threatening H2O Supply

By Amanda Frye and Mark Gutglueck
The county’s public works department is gravitating toward using an organic process to remediate the polluting of the local water supply that has manifested at the eastern end of the Central Inland Valley.
That pollution is emanating from the long-defunct Yucaipa landfill, which was closed in 1980. The landfill, located on the southeastern slope of the Crafton Hills, was shuttered after sources of readily available soil to cover the contents of the landfill grew difficult or too expensive to obtain, and the nearby San Timoteo Landfill, which presented a more economically expedient alternative, opened. The Yucaipa landfill was unlined, consisting of approximately 25 acres where refuse was deposited within a surrounding 560-acre parcel along the 34200 block of Oak Glen Road, approximately one mile northeast of the intersection of Oak Glen Road and Yucaipa Boulevard in the city of Yucaipa. It was owned by the County of San Bernardino and operated by the county or a series of its contractors as a Class III municipal solid waste landfill from 1963 to 1980. During its operation, the landfill accepted inert, nonhazardous, municipal, construction/demolition, and agricultural wastes.
In 1981, a two-foot-to-four-foot-thick soil cover was placed over the site, and efforts were made to control surface water runoff and erosion in the area through grading.
Subsequent to the closing of the Yucaipa landfill, new standards relating to phasing refuse facilities out of operation and capping them were introduced by the State of California. At least some of the issues plaguing the site now, 38 years after its closure, stem from the haphazard methods used in shuttering the facility.
Efforts to monitor potential contamination migrating from the site began in earnest eight years after the landfill’ closure with the sinking of four test wells on and around the site. Another more strategically located well was sunk the following year, in 1989. Nothing alarming showed up in the samples drawn from those wells over a nearly-six-year-long period. In March 1994, two further groundwater monitoring wells were installed, along with four soil-pore gas monitoring probes. In October 1994 volatile organic compounds turned up in samples obtained from downgradient groundwater monitoring wells and the county notified the California Regional Water Quality Control Board of a potential contaminant release.
Further efforts to control water runoff were made with the creation of a network of concrete-lined drainage swales and an approximately 1.5-acre sediment retention basin in 1997, together with the construction of a surface-water diversion channel in 2005. The county’s solid waste management district also constructed a landfill gas collection system that began operation in February 2008.
Over the years, 17 additional groundwater monitoring wells were installed to augment the first seven within and in proximity to the site. It was determined that groundwater flow and contaminant transport was being directed to the southwest.
The Yucaipa landfill site is located near the northeastern limits of the Yucaipa Hydro Subarea. Surface water is carried by several drainages in the vicinity of the Yucaipa subbasin, including Oak Glen Creek, Wilson Creek and Gateway Wash. The ground water in that area is utilized for municipal and domestic supply, agricultural supply, industrial service supply, and industrial process supply.
According to Harold Zamora, the chief engineer with San Bernardino County’s Public Works Department, contaminants for the Yucaipa landfill are leaking into the water table, representing a significant risk to the nearby population.
“Groundwater investigations completed by the county’s solid waste management district indicate volatile organic compounds in groundwater are migrating away from areas adjacent to the Yucaipa disposal site. These investigations have included evaluation monitoring program studies to determine the nature and extent of impacts to groundwater, engineering feasibility studies to evaluate and select the most appropriate remedial response to groundwater impacts, and a pilot study to demonstrate the suitability and practical application of the selected corrective action.”
According to Zamora, a study completed by an engineering outfit based in San Bernardino, Geo-Logic Associates, identified chlorinated ethenes, including the solvent tetrachloroethene (PCE) and its breakdown products [trichloroethene (TCE), cis-1,2-dichloroethene (cDCE), and vinyl chloride (VC)] as present in groundwater samples collected downgradient of the Yucaipa landfill. “The measured concentrations at some monitoring wells exceed both the United States Environmental Protection Agency and California Department of Health Services maximum contaminant levels that have been established for these compounds,” the Geo-Logic study states. “These chemicals are suspected human carcinogens that can affect (and damage) several body organs and systems such as the central nervous system, respiratory system, liver, kidneys, and heart, and may cause contact dermatitis of the skin.”
According to Zamora and Geo-Logic, the chemical contamination can be redressed by stimulating the growth of existing bacteria in the groundwater that will feed upon the substances and through the metabolic process neutralize them, rendering the water safe. The effectiveness of that approach was demonstrated in a small scale application of the technology, according to Geo-Logic. “Based on the feasibility analyses and results of the pilot study for corrective action, it is concluded that project objectives could best be met by installing a network of groundwater injection wells to permit delivery of nutrients to naturally-occurring bacteria residing in the subsurface,” according to Geo-Logic. “When stimulated, these bacteria consume and sequentially destroy tetrachloroethene and its daughter products until only the inert compounds of ethene and ethane remain. The pilot study concluded aquifer inoculation with additional bacteria colonies was required to fully mitigate chlorinated ethene impacts to groundwater downgradient of the Yucaipa landfill.”
Potentially impacted by the contamination is the 2,200 household Chapman Heights subdivision and nearby golf course that were constructed after the landfill was shuttered. The City of Redlands also has a water well downstream on Yucaipa Boulevard. There is a public trail and soccer park proximate to the former landfill location. Recently, county workers or contractors have been drilling new vaporizing wells at the site.
At this point, the county public works department and the solid waste management department have put together a remedial action plan to support mitigation of volatile organic compound impacts to groundwater downgradient of the former Yucaipa landfill. The county is making the document available for public inspection at:
Members of the public can attempt to provide comment on the remediation plan by calling Geo-Logic Associates at (909) 383-8728, or Chris Saed with the county’s public works department at (909) 386-8761, Sharon Bishop with the county’s public works division at (909) 386-8629 or Kevin Blakeslee, who is the county’s director of public works, at (909) 387-7906.

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