SITE INFORMATION AND CORRESPONDENCE

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ILL NO . jun 11 =1'3 NO .uzz r.U4 ` 1 RI7( K F RE VIOLA STREH'1' -2- 1+4,J UNE-1"JV5 SAN JQhQUIN COUNTY MUSS?FOP.CLOSURE 1n August 1991,the C cf my directed Nor-Cal to investigate ground water contamination. In response to the County directive,Nor-Cal proposed to resample the monitoring well prior to preparing a work plan for further ground water investigation. Confirmation ground water sampling in August 1991 continued to show low levels of benzene and gasoline. Nor-Cal requested site closure in April 1992,and in May 1992,the County requested Board review and comments regarding the site. Upon receipt and review of reports for the site in July 1992,Board staff concluded that site closure was premature because oxtmmely high concentra- tions of soil contamination remained in place at depths of 16 feet digs and one monitoring well was � not sufficient to investigate ground water.and at least two additional monitoring wells were necessary to detennine the gradient.direction(flue depth to ground water was approximately 70 feet at that tirne). A supply well survey was also needed to determine the threat to water uses. In August 1992,the County sent Nor-Cal a letter requesting a work plan for installation of two additional monitoring wells. In November 1992,the attorney for Nor-Cal,Mr.Pat Middle,agreed to the preparation of a work plan for the additional wells. In April 1993,Nor-Cal submitted a j work plan for over excavation of contaminated soils and in May 1993, 150 cubic yards of contaminated soil was removed. I In July 1993,County staff nrct with Nor-Cal and their consultant and agreed that a Hydropuneh(D drilling and ground water sampling would be perforated. The HydropunchO sample indicat+etl non-detectable concentraticng of BTEX and TP11g. .A ground water sample from the monitoring well indicated 2.1 ppb toluene,0.7 ppb ethylbenzene,and 4.2 ppb xylenes. In August 1993,Nor-Cal again requested closure and the County requested the Board's concurrence. Site closure was rejected by the Board because a survey of nearby supply wells had not been performed and the method for determining ground water gradient direction at the site was not provided to the Board. In July 1994,Nor-C:al's consultant,Resna.reported the locations of nearby wells. In January 1994,the County had requested that Nor-Cal install two additional monitoring wells and in the July 1994 report,Nor-Cal requested closure from the hoard on the grounds that a regional gradient to the northeast had been established from San Joaquin County Flood Control Maps(Spring 1992.Fall 1992, Spring 1993)and concentrations in the monitoring well were below the Maximum Contaminant Levels. The County met with Nor-Cal in November 1994,and requested that two quarters of ground water monitoring be performed. The existing monitoring well was sampled in December 1994 and j February 1995,and the analyses revealed non-detectable levels of uontamination for BTEX and TPHg. The depth to water in December 1994 wm not provided by Nor-Cal,but was 61.25 feet in February 1995. In Agri! 1995,Nor-Cal requested closure from the County. Nor-Cal has not cooperated with County and Board stat f or complied with regulatory directives. Only two quarterly monitoring reports were submitted from August 1991;when requested by the