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I QUARTERLY MONITORING REPORT AUGUST 1996 CANErPA'S CAR WASH 6210 PactEc Avenue Stockton CA September 11 1996 I3 0 QUARTERLY GROUNDWATER MONITORING - AUGUST, 1996 The work conducted during the quarterly groundwater monitoring was outlined by Condor in ' Proposal for Site Evaluation and Groundwater Monitoring (April 8, 1996) The scope-of-work presented in the proposal was approved by Mr Ronald Rowe of the PHS/EHD ' On August 1, 1996, Condor personnel made field observations and collected groundwater samples from the eight (8) monitor wells at the site (see Figure 2, Appendix A for well locations) In addition, at the request of Mr Rowe, a groundwater sample was also collected trom soil vapor ' extraction well SV-7 The order of sampling was MW-3, MW-5, MW-4, MW-8, MW-1, MW-2, MW- 7, MW-6, and SV-7 All 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 I 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 generally above the top of the well screens in the wells Slight petroleum odors were detected in MW-1, MW-2, ' MW-6, and SV-7 Each well was purged until at least three well-casing volumes of water were removed and until the pH and temperature of the water had stabilized Monitoring of electrical conductance measurements for stabilization was not possible because of a malfunction of the electrical conductance meter 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 (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 Blue Ice and delivered under chain-of-custody procedures to GeoAnalytical 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 The groundwater samples were analyzed for total petroleum hydrocarbons, quantified as ' gasoline (TPH-G) by Method 5030/LUFT, for benzene, toluene, ethyl benzene, and xylene (BTEX) by Page -2- Ntiw �• tiv CONDOR