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Second Quarter 2001 Ground Water Momtonng Report Cleanup and Abatement Order No 5-00-707 CAI Project No 1232 . Between 1992 and 1999, additional soil and ground water investigations associated with the ' Unocal site were conducted Table 1 summarizes the historical ground water testing results for the Unocal site In February 2001, seven new wells (MW-18D, MW-23S, MW-23D, MW-24S, MW-24D, MW- 25S, and MW-25D) were installed to assist in defining the vertical and lateral extent of hydrocarbon impacted ground water at the Unocal site and around the Robinhood Irrigation Well (see Section 1 1 3) For specifics on this work, see the EAI report entitled "Well Installation Report, Unocal Oil Corporation, 5606 Pacific Avenue, Stockton, California, " dated April 6, 2001 1 1 3 Robinhood Irrigation Well RI ' San Joaquin Delta College owns and formerly operated a ground water extraction well identified as "the Robinhood Irrigation Well" (RIW) (a k a Delta College Well) The RIW is located southwest of the intersection of Robinhood Drive and Pacific Avenue (see Figure 1) ' The RIW was installed in 1950 and is reported to be 322 feet deep with perforations in multiple zones beginning at depths as shallow as 40 feet below ground surface (bgs) According to the Water Well DrilIer's Report for the RIW, "no strata were sealed against pollution " ' Ground water from the RIW was foimerly used to irrigate portions of Delta College's campus Ground water monitoring data for the Unocal and Wards sites show that historical pumping of the RIW influenced and changed the natural direction of ground water flow in the area from easterly, to south southwesterly, i e , towards the RIW Sampling of the RIW by Unocal and/or Wards for dissolved petroleum constituents began in 1997 and continued through June 15, 2000 Table I summarizes the results of testing ground water samples from the RIW In August 2000, Delta College students and staff complained of a gasoline odor from the water derived from the RIW As requested by the RWQCB, the RIW was taken out of service as of ' 6 00 AM August 22, 2000 The RWQCB in a letter dated February 26, 2001, requested that the RIW be destroyed On April 27, 2001, the San Joaquin County Public Health Services, Environmental Health Division (PHS-EHD) approved the EAI report entitled "Amended Work Plan for Destruction of Irrigation Well, San Joaquin Delta College —Robinhood Irrigation Well, 5151 Pacific Avenue, Stockton, California, " dated April 26, 2001 1 14 Cleanup and Abatement Order On September 8, 2000, the RWQCB issued CAO No 5-00-707 The CAO requested the responsible parties to investigate and clean up petroleum hydrocarbons from the former UST systems located on the Wards and Unocal sites, and stated that discharges from these two properties have impacted ground water extracted and used by San Joaquin Delta College to 13WM 1232RO151 2 ENVIRONMENTAL AUDIT, INC