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' Results of CPT Investigation and Work Plan Cleanup and Abatement Order No 5-00-707 EAI Project No 1232 1.0 INTRODUCTION On September 8, 2000, the California Regional Water Quality Control Board, Central Valley Region (RWQCB) issued Cleanup and Abatement Order No 5-00-707 (the CAO) to Union Oil Company of California (Unocal), Montgomery Ward, LLC (Wards), Surry California Limited Partnership, and Stone Brothers and Associates General Partnership, for the properties located at 5400 Pacific Avenue and 5606 Pacific Avenue, Stockton, California The CAO requested ' the responsible parties to investigate and clean up petroleum hydrocarbons released from the underground storage tank (UST) systems formerly located on 5400 Pacific Avenue and 5606 Pacific Avenue, and stated that discharges from these two properties have impacted ground ' water extracted from the Robinhood Irrigation Well (RIW) and used by San Joaquin Delta College to irrigate its campus (see Figure 1) The RIW was taken out of service by the RWQCB in August 2000 On October 13, 2000, Environmental Audit, Inc (EAI), on behalf of Unocal and Wards, submitted to the RWCB a report entitled "Supplemental Investigation Report, Problem ' Assessment Report, and Work Plan, Cleanup and Abatement Order No 5-00-707, Montgomery Ward Auto Service Center and Former Unocal Site, 5400 and 5606 Pacific Avenue, Stockton, California" (hereinafter referred to as "the SIR/PAR Report" (see EAI, 2000B) The SIR/PAR Report summarized existing hydrogeologicaI conditions related to the Wards and Unocal sites, assessed the extent petroleum hydrocarbon impact at the two sites, and proposed additional work to define the extent of impact at the Unocal site and to investigate the lateral and vertical extent of contamination from Unocal and Wards towards to RIW On October 27, 2000, the RWQCB forwarded a letter approving only the Cone Penetrometer ' Test (CPT) soundings around the RIW to provide data on the lateral and vertical extent of contamination from Unocal and Wards towards to R1W, with the understanding that the information obtained from completing the CPT work would be used to determine additional well locations on the Unocal and Wards sites required to define the vertical extent of ground water impact beneath these sites ' This report provides information on ' • The results of the CPT work completed to define the lateral and vertical extent of contamination around the RIW • Proposed well locations on the Unocal and Ward's sites to define the vertical extent of impact beneath these two sites, and as requested by the RWQCB, a deep well near the RIW for future monitoring purposes EAI was retained by Wards and Unocal to prepare this report This report was prepared following Tri-Regional Board staff "Recommendations for Preliminary Investigation and Evaluation of Underground Tank Sites," including Appendix A "Reports " BS 1232P WFLLS WP -1- ENVIRONMENTAL AUDIT, INC.,