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The CRWQCB required preparation and submittal of a detailed work plan for soil removal, <br /> and a long-term monitoring plan including new monitoring wells <br /> During June 1990, soil excavation was conducted in the former area of the two USTs <br /> Excavations were completed to 26 feet below grade at the former 10,000-gallon diesel tank, <br /> and 22 feet below grade at the location of the former 500-gallon waste-oil tank Excavation <br /> of impacted soil and construction of the on-site bioremediation treatment cell was <br /> conducted The excavation was backfilled with clean silty-sand from a local quarry, and <br /> capped with asphalt Approximately 3100 cubic yards of soil and associated material <br /> disposed An additional 160 cubic yards was excavated and removed from the area of a <br /> fuel pipeline during the summer of 1991 <br /> As b required CB three dr <br /> q Y the CRW Q y monitoring welts were abandoned, and four new <br /> 1 wells were installed during July 1990 <br /> In January 1994, the PHS-EHD defined a soil cleanup level of 100 ppm Quarterly <br /> groundwater monitoring was required until cleanup would be deemed adequate On <br /> August 1, 1994, a Draft Amended Request for Closure was issued to PHS-EHD A five-year <br /> monitoring program followed by closure was suggested, with the condition that <br /> groundwater levels remain lower than 50 feet below surface level A Technical Evaluation <br /> prepared by D&M in November 1994, which provided an assessment of soil remediation <br /> options <br /> 1 In March 1995, the PHS-EHD required the continuation of quarterly water level monitoring, <br /> annual monitoring well sampling, and submittal of a work plan for the installation of a soil <br /> remediation option, as described in the Technical Report A soil and groundwater <br /> investigation was conducted in May 1995, and included the installation of two soil borings <br /> and one groundwater well In July 1995, Dames & Moore issued an Evaluation of <br /> Hydrocarbon Mobility report, which included an assessment of hydrocarbon mobility No <br /> further remedial action was recommended <br /> A 5-year groundwater monitoring plan was submitted to the PHS- <br /> EHD in December 1995, <br /> which was approved by the PHS-EHD in March 1996 In August 1998, the PHS-EHD <br /> indicated that the 5-year monitoring program is no longer a valid approach to closure, <br /> because rising water levels may be approaching impacted soil Further investigation and <br /> documentation were required, including the installation of new monitoring wells, and <br /> quarterly groundwater monitoring for one year <br /> DAMES&MOURE 2 J WFPWP0Rn9911_01 doc <br />