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S <br /> y�KLEINFELDER <br /> 3. An submersible pump was lowered to the approximate midpoint of the static <br /> water level apd well bottom, and used to purge a minimum of five well <br /> volumes. <br /> 4. As an indicator of sufficient purging, field parameters (electrical <br /> conductivity, pH, temperature) were periodically measured. Purging was <br /> °^ continued until consecutive stable readings were achieved. <br /> 5. Water samples were collected in appropriate laboratory-supplied sample <br /> containers using a Teflon bailer. Samples were immediately placed in an <br /> iced cooler and delivered to the laboratory under strict chain-of-custody <br /> control. Copies of the chain-of-custodies are included.in Appendix B. <br /> 6. Before sampling each well,all sampling equipment,including the water level <br /> indicator, submersible pump, and Teflon bailer were decontaminated in a <br /> detergent wash and a high-pressure steam rinse. <br /> Thi; water samples were submitted to Chemwest Analytical Laboratories for analysis of <br /> volatile aromatic hydrocarbons by EPA Method 602 and total petroleum hydrocarbons <br /> (TPH)by Gas Chromatography using a flame ionization detector(GC-FID). On the most <br /> recent (May 1988) sampling round, one blind duplicate collected from MW-1 and one <br /> sample blank were also submitted to Chemwest with the primary samples. A triplicate <br /> sample from MW-1 was submitted to Enseco/California Analytical Laboratories for <br /> 4�r <br /> interlaboratory quality assurance quality control. The analytical results for each sampling <br /> round are presented in Section 4. <br /> 3.3 SOIL SAMPLING <br /> On January 29, 1988, confirmation soil boring B-17 was drilled between the vapor <br /> extraction well, EX-1, and soil boring B-8 (Plate 4) to collect sail samples from the vadase <br /> zone. This location was selected because the highest hydrocarbon concentrations observed <br /> in previous investigations were detected in samples from B-8 and EX-1. <br /> 113-88-908 6 <br />