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u) Gl • 06 March 2002 AGE-NC Project No 01-0865 Page 2 of 9 September 1997 Ground water elevation data at the site indicated that the ground water was being controlled by the active island drainage pumping system adjacent to the site • Quarterly ground water monitoring at the site has been on-going since September 1997 to the present Analytical results of ground water samples collected from September 1997 to present are summarized on Table 2 The inferred ground water flow direction at the site has been consistently toward the southeast • Quarterly surface water sampling of the north and south ends of the drainage ditch (DDN and DDS, respectively) and the east and west ends of the island drainage channel (1DCE and 1DCW) adjacent to the site began in October 1998 Analytical results of surface water samples collected from October 1998 to the present are summarized on Table 2 • Between 11 and 13 September 2000, thirteen soil borings (DP-1 through DP-9, SPA and HP-1 through HP-3)were advanced at the site MTBE was detected in the four-foot sample collected from DP-4 and MTBE and TAME were detected in the eight-foot soil sample collected from DP-5 MTBE was detected in the ground water samples collected from borings DP-1 through DP-6, DP-8,DP-9 and HP-2 at concentrations as high as 37,000 pg/l (DP-5) Additional information and tabulated analytical data from this investigation can be found in the Condor-prepared Soil and Ground water Investigation and Sensitive Receptor Survey Report, dated 02 October 2000 • In September 2000,a sensitive receptor survey was conducted for the site The drainage ditch and island drainage channel are the only potential receptors within a 1,000-foot radius of the site • Ms Margaret Lagono of San Joaquin County PHS-EHD referred the site to the CVRWQCB for oversight by letter to Mr Marty Hartzell of CVRWQCB, dated 05 January 2001 According to Ms Lagono the determination was made that the source of the MTBE contamination was the AST system and not the former UST system In an internal memo dated 29 March 2001, the CVRWQCB concurred with the PHS-EHD decision and transferred the site to the CVRWQCB Site Cleanup Section for further oversight On 02 April 2001, the CVRWQCB issued a letter stating that no further action is required for the former UST system at the site • By letter dated 05 June 2001, Ms Wendy Cohen of CVRWQCB finalized Monitoring and Reporting Program (MRP) No 5-01-0835 and approved Additional Ground Water Investigation Work Plan, dated 07 May 2001, prepared by Condor The MRP describes the ground water monitoring and reporting requirements for the site The work plan was prepared to further investigate the lateral and vertical extent of impacted ground water Ms Cohen also agreed with Condor's recommendation to abandon well MW-1, since it is no longer a necessary monitoring point for the MTBE plume associated with the AST system at the site