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2905 W Benjamin Holt Drive, Stockton, California March 24, 1994 <br /> . Chevron USA Products Company Page 5 <br /> DOT-approved purge water trailer and transported to the Chevron refinery in Richmond, California for <br /> recycling Following installation, the new wellhead was surveyed for elevation relative to mean sea level <br /> (Appendix D) <br /> 35 Groundwater Monitoring <br /> On January 18, 1994, depth to water in groundwater monitoring wells MW-1 through MW-8 was gauged <br /> from tap-of-casing to determine the static water level and to check for the presence of separate-phase <br /> hydrocarbons (SP) The water level was measured using an ORS Environmental Equipment INTERFACE <br /> PROBETM Well Monitoring System, consisting of a dual optical sensor and electrical conductivity probe, <br /> that distinguishes between water and petroleum products <br /> 36 Groundwater Sampling <br /> Groundwater monitoring and sampling were conducted on January 18, 1994 in accordance with the <br /> quarterly groundwater monitoring and sampling program at the site Prior to sampling, each well was <br /> Mpurged of four well volumes or until pH, conductivity and temperature had stabilized in the purged <br /> groundwater Field data sheets with data recorded prior to sampling are included in Appendix C <br /> Groundwater samples were collected using a teflon sampler cleaned with detergent and distilled water <br /> Distilled water field blanks and sampler rinsate blanks were collected to document ambient conditions <br /> and the cleanliness of the sampler Groundwater samples obtained from each of the eight groundwater <br /> monitoring wells were labeled, placed on ice in an insulated container and delivered under <br /> chain-of-custody manifest to Superior in Martinez, California The groundwater samples were analyzed <br /> for TPH-G and BTEX by EPA methods 5030/8020/modrfied 8015 Purge water generated during the <br /> sampling process was pumped to a DOT-approved purge water trailer and transported to the Chevron <br /> refinery in Richmond, California for recycling <br /> GROUNDWATER <br /> 38315UM RPT �r TECHNOLOGY <br />