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A-2 0 GROUNDWATER MONITORING <br /> Groundwater levels were measured and samples were collected from monitoring wells DMW-1, <br /> DMW-2, DMW-3, and DMW-4 on May 13, 1994 Sampling procedures and analytical results are <br /> described in this section <br /> A-2 I SAMPLING PROCEDURES <br /> Prior to sampling a minimum of three casing volumes were purged from each well into DOT- <br /> approved, type 17H 55-gallon drums and stored on site The wells were purged using a two-inch <br /> stainless steel Grundfos Rediflow submersible pump The submersible pump was initially steam cleaned, <br /> then washed in a trisodium phosphate solution, rinsed with potable water, and given a final rinse with <br /> distilled water prior to each use <br /> To ensure that a representative sample of fresh formation water was obtained, electrical <br /> conductivity (EC), pH, temperature, and turbidity were monitored during purging of the wells Purging <br /> was continued until measurements of these parameters were stable, varying by less than 10 percent <br /> Each well was sampled using a disposable polyethylene bailer in a manner which minimized <br /> agitation and exposure of the sample to the atmosphere Groundwater samples were collected in <br /> appropriate glassware provided by the analytical laboratory and stored in an iced cooler In accordance <br /> with Dames & Moore quality assurance and quality control (QA/QC) procedures, one blind duplicate <br /> sample was collected and a travel blank was included with the sample shipment Chain-of-custody <br /> documentation accompanied all groundwater samples through transportation and laboratory analyses <br /> Groundwater samples were submitted to D&M Laboratories, a California Department of Health <br /> Services certified laboratory located in Petaluma, California Samples were analyzed for the following <br /> constituents <br /> r • Total Petroleum Hydrocarbons as Diesel (TPHd, EPA Method 8015) <br /> • Benzene, Toluene, Ethylbenzene, and total Xylenes (BTEX, EPA Method 8020A) <br /> A-2 2 ANALYTICAL RESULTS <br /> No detectable levels of TPH diesel, diesel fuel constituents, or BTEX were detected in <br /> groundwater samples collected in May, 1994 There were also no detections in the travel blank submitted <br /> with the samples Table A-1 provides a summary of all analytical results from monitoring wells at the <br /> site Analytical laboratory reports, chain-of-custody, and field records of water sampling are included <br /> in Appendix B <br /> SAC116 07 A-2 JULY 1994 <br />