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Fourth Quarter 2001 Groundwater Monitoring and Sampling Report-CAO#5-00-707,Stockton,CA January 15,2002 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 Groundwater extracted and used by San Joaquin Delta College to irrigate its campus This report has been prepared in accordance with the quarterly reporting requirements outlined in the CAO As required by the CAO, each quarterly report shall include • Groundwater analysis results for Total Petroleum Hydrocarbons as gasoline (TPH-G) by modified EPA Method 8015, and benzene, toluene, ethylbenzene, total xylenes (BTEX), methyl tert-butyl ether (MTBE), tert-butyl alcohol (TBA), di-isopropyl ether(DIPE), ethyl tert-butyl ether(ETBE), tert-amyl methyl ether (TAME), 1,2-dichloroethane (1,2-DCA), ethylene dibromide (EDB), ethanol, and methanol by EPA Method 8260B • Groundwater elevation contour maps (shallow and deep) • Groundwater flow diagram to document historic flow directions and magnitude • Hydrographs for representative shallow and deep monitoring wells • Pollutant concentration contour maps for TPH-G and benzene (shallow and deep) • Tabular listing of all monitoring well details • Tabular results of current sampling data completed during the previous quarter • Groundwater purge data sheets o Narrative describing the work presented in the report, including methodology, conclusions, and recommendations o Data documenting disposal of investigation derived wastes FIELD INVESTIGATION Groundwater Monitoring and Sampling On December 2, 2001, prior to purging or sampling activities, depth measurements to fluid levels were obtained by GR from all monitoring wells associated with the Wards and Unocal (MW-1 through MW-27, AS-26) sites No free-product was detected in any of the wells The top of casing elevations, depth to groundwater and groundwater elevations are summarized in Table I On December 2 through 4, 2001, groundwater samples were col cted by GR from all groundwater monitoring wells associated with the Wards and Unocal sites All fief work was conducted in accordance with GR's Standard Operating Procedure — Groundwater Sampling which is included in Appendix A The data collected for each well is included in Appendix B J L 7 T«.call p water -'as trancnorti-d by C;R to the Tosco— San Francisco Area Refinery AS icq=C,Wu Uy 1J 11V1 a1, purge water i w f J in Rodeo, California C 240022 01-001 3