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�r During June 1990, soil excavation was conducted in the former area of the two USTs Excavations were completed to 26. -feet below-grade-at the former 10,000-gallon diesel tank, and 22 feet belo_w_grade at the location of the former 500-gallon waste-oil tank Excavation of impacted soil and construction of the on-site bioremediation treatment cell was conducted The excavation was backfilled with clean silty-sand from a local quarry, and capped with asphalt Approximately 3100 cubic yards of soil and associated material was disposed An additional 160 cubic yards was excavated and removed from the area of a fuel pipeline during the summer of 1991 As required by the CRWQCB, three dry monitoring wells were abandoned, and four new wells were installed during July 1990 ZIn January 1994, the PHS/EHD defined a soil cleanup level of 100 ppm Quarterly groundwater monitoring was required until cleanup would be deemed complete On August 1, 1994, a Draft Amended Request for Closure was issued to PHS/EHD A five- year monitoring program followed by closure was suggested, with the condition that groundwater levels remain lower than 50 feet below surface level A Technical Evaluation was prepared by Dames & Moore in November 1994, which provided an assessment of soil remediation options In March 1995, the PHS/EHD required the continuation of quarterly water level monitoring, annual monitoring well sampling, and submittal of a work plan for the installation of a soil remediation option, as described in the Technical Report A soil and groundwater investigation was conducted in May 1995, and included the installation of two soil borings and one groundwater monitoring well In July 1995, Dames & Moore issued an Evaluation of Hydrocarbon Mobility report, which included an assessment of hydrocarbon mobility No further remedial action was recommended A five-year groundwater monitoring plan was submitted to the PHS/EHD in December 1995, which was approved by the PHS/EHD in March 1996 In August 1998, the PHS/EHD indicated that the,_five-year, monitonng program was no longer a valid approach to closure, becaus nsmg_groundwater levels might be approaching impacted soil Further investigation and documentation were required, including the installation of new monitoring wells, and quarterly groundwater monitonng Two new wells were installed in December 1998, and quarterly monitoring was resumed from December 1998 through March 2001 Site closure was requested again in July 2001 In November 2001, 2 K 1$40191AFP\4Q01_rpt doe