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QUARTERLY MONITORING REPORT APRIL 1997 CANEPA S CAR WASH 248 E Park Street Stockton CA Apn1:'I, 1997 3.0 QUARTERLY GROUNDWATER MONITORING - APRI=L, 1997 The work conducted during the quarterly groundwater monitoring was in accordance with the I approved protocol formerly established at the site The scope-of-work presented in the proposal was approved by Mr Ronald Rowe of the PHS/EHD On April 2 and 3, I997, Condor personnel made field observations and collected groundwater samples from the seven (7) monitor wells at the site (see Figure 2, Appendix A for well locations) The order of sampling was MW-2, MW-7, MW-5, MW-1, MW-6, MW-4, and MW-3 All field I equipment was decontaminated in the field with a solution of laboratory-grade, non-phosphate detergent and hydrocarbon-free water and rinsed with hydrocarbon-free water prior to use in each well All field instruments were calibrated to the manufacturer's recommended standards The water level in each well was measured to the nearest 0 01 foot with a standard battery-operated, flat-tape, water- level meter A new, disposable, polyethylene bailer was lowered into each well to collect a field- inspection sample The bailer sample was inspected for floating product, sheen, discoloration and/or ' odor Floating product was not observed in any of the monitor wells during the groundwater sampling However, water levels in the wells were above the top of the well screens A strong petroleum odor was detected in MW-2 and MW-5 Each well was purged with a dedicated bailer until at least three well-casing volumes of water were removed and until the pH, specific conductance, and temperature of the water had stabilized Groundwater Monitoring Field Farms are included in Appendix B Prior to sampling, the water was allowed to recover to at least 80% of the pre-purge water level The purge water was discharged to 55-gallon drums and left on site to await disposal For each well IA groundwater sample was collected with a disposable, one-time-use, polyethylene bailer The sample was transferred to two (2) 40-m1 glass VOA vials fitted with Teflon-lined caps Each vial was inverted and tapped to assure that no air bubbles were present • Each vial was labeled and placed in a cooler chilled with ice and delivered under chain-of-custody procedures to GeoAnalyticaI Laboratories, Inc , in Modesto, California, within 24 hours of sample collection The results of laboratory analyses are discussed in Section 4 2 4 0 INVESTIGATION RESULTS 4 1 Laboratory Analyses IThe groundwater samples were analyzed for total petroleum hydrocarbons, quantified as gasoline (TPH-G) by Method 5030/LUFT and for benzene, toluene, ethyl benzene, and xylene (BTEX) and methyl tertiary butyl ether (MTBE) by EPA Method 602 EPA Method 8260 was used to attempt confirmation of MTBE in the sample from MW-2 The laboratory certificates of analyses and chain- of-custody are located in Appendix C Page -2- Ntwlo', i� CONDOR