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i Attachment 1 Site History �I Recent changes to the existing groundwater monitoring and reporting program (MRP), included the destruction of MW-8, MW-10, MW-11, MW-16, MW-17, MW-21 and MW-20 the installation of eleven two inch A-zone monitoring wells (MW-43A through MW-53A) and the installation of one two inch B- it , zone monitoring well (MW-50B) and revised well name designations to denote the zone in which i each well is screened across ! ' An off-site Investigation was completed in 2002, in the adjacent field to the west and north of the site to further define the off-site hydrocarbons concentrations Each boring was advanced to approximately four feet below the first encountered groundwater Low levels of methyl tertiary butyl ether (MtBE) and TPHd were detected in shallow groundwater samples is On December 28, 2001, a flange on a piping manifold failed and released less than 10 gallons of red dye diesel at the site On January 9, 2002, 15 soil samples were collected in and around the spill area 2-inch diameter borings were advanced to approximately 0 5 to 1 5 feet below ground surface i. (bgs) Groundwater was not encountered during boring activities Borings were backfilled with native soil upon completion of soil sampling ethanol transfer facility was supported b I During July of 2002, construction activities for ane y pp Y environmental sampling and segregation of impacted materials transported off-site for disposal Chevron added facilities to comply with pending fuel additive requirements On July 9, 2002 the pre- {' and post-removal characterization of the soil within the footprint of the ethanol transfer facility ; excavation was performed by installing twenty soil borings in the footprint of the truck transfer area A and in the ethanol pipeline area to pre-characterize the soil for disposal prior to excavation During construction, an environmental scientist provided construction support to Chevron's general a contractor Analytical results from pre-characterization work and visual observations were used to segregate impacted soil from other material A total of 397 tons of soil was removed from the excavated area and transported by Integrated Waste Management Inc (IWM) to Forward Landfill located in Manteca, California On July 10, 2002, monitoring well MW-14 and ISO-GEN test well a, TW-3 were destroyed by Watermark Drilling of Woodland, California, a State-licensed well driller Cleanup and Abatement order No R5-2002-0718 (CAO) was issued on August 15, 2002 As 7 required by the CAO, on January 21 through 29, 2003, Cascade Drilling Incorporated (Cascade) of i Rancho Cordova completed 21 soil borings (NSB-0 through NSB-4, NSB-6 through NSB-15, MW- 61 UA, MW-62UA, MW-63A, MW-64B, and MW-65A) Results and findings of assessment activities are presented in the Site Assessment Report, dated March 5, 2003 k, During March of 2003, a 9,000-gallon transmix (tank ID 1842-6) UST was removed and selected soil samples were collected from the tank pit area Results of soil sampling indicated moderate levels of w petroleum hydrocarbons along the sidewalls of the tank pit SECOR is currently working on conducting assessment activities to delineate the lateral and vertical extent of hydrocarbons Al associated with the UST { � Y 1