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i ' Quarterly Monnormg Report April 1998 C—epa s Car Wash • 248E Parti Sr Stay 2Kon CA May 25 1998 Page 2 Groundwater Elevation The average depth to groundwater was approximately 25 8 feet below monitor well measuring points (slightly below the ground surface) The groundwater elevation ranged from 15 70 to 13 67 feet below mean sea level (bmsl) Groundwater elevation contours are shown in Figure 3,Appendix A 3. QUARTERLY GROUNDWATER MONITORING-APRIL 1998 The work conducted during the quarterly groundwater monitoring was in accordance with the approved protocol formerly established at the site The scope-of-work conducted was approved by Mr Ronald Rowe of the PHS/E-HD On April 24, 1998, Condor personnel made field observations and collected groundwater samples from the seven monitor wells at the site (see Figure 2, Appendix A, for well locations) All down-hole field 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 Water levels in the wells were above the top of the well screens, however Petroleum odors were noted 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 Forms 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 • A groundwater sample was collected with a disposable, one-time-use, polyethylene bailer The sample was transferred to two 40-m1 glass VOA vials fitted with Teflon-lined caps Each vial was inverted and tapped to assure that no air bubbles were present I • Each vial was labeled and placed in a cooler chilled with ice and delivered under chain-of- custody procedures to GeoAnalyttcal Laboratories, Inc , in Modesto, California, within 24 hours of sample collection The results of laboratory analyses are discussed in Section 4 2 4. MONITORING RESULTS 4 1 Laboratory Analyses The groundwater samples were analyzed for total petroleum hydrocarbons, quantified as gasoline (TPI1-G) by Method 5030/LUFT and for benzene, toluene, ethyl benzene, and total xylenes (BTEX) by EPA Method 602 ' Methyl tertiary Butyl Ether (MTBE) and gasoline oxygenates/additives were analyzed by EPA Method 8260 The laboratory certificates of analyses and sham-of-custody are located in Appendix C eo Ntiio� �� CONDOR