A Phase I environmental assessment and site characterization was conducted in 1992, identifying both unleaded petroleum hydrocarbons and fuel oxygenates as the primary contaminants on site. These consist of total petroleum hydrocarbons in the gasoline organics range (TPHg), benzene, methyl-tertiary-butyl ether (MTBE), tertiarybutyl alcohol (TBA), tertiary-amyl-methyl-ether (TAME), 1,2 dichloroethane (1,2 DCA), and naphthalene. In 2003, an SVE was installed as the primary remedial method to address these constituents, but questionable and inconsistent data resulted in the system being shut down before the TPHg plume had been remediated. In July of 2007, the City of Merced contracted with Provost and Pritchard Consulting Group (P&P) to complete the ongoing remedial activities. P&P recommended that the SVE system be operated in conjunction with an H2O Engineering Inc. mobile ozone and air sparging unit, which began operation in November 2008. The result has been an 80 percent decrease in key contaminant concentrations within the effected source area after only one year of combined operation.
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