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Groundwater Assessment Report ARCO Facility No 2186 Stockton,California Page 3 Delta field verified the locations and operational status of these wells The wells 400 feet northwest and 900 feet northeast are owned by the City of Stockton, and are used to irrigate Oak Park The well situated 1,800 feet northwest of the site is located at St Mark's Church The Pinnacle survey identified three wells at this site Further information regarding the actual number and use of the wells at St Mark's Church could not be verified The well situated 400 feet northwest of the ARCO station appears to be the Oak Park well identified in the Pinnacle survey SCOPE OF WORK The primary objective of this investigation was to further assess the lateral and vertical extent of petroleum hydrocarbon impact to groundwater offsite To accomplish this objective, the following activities were conducted • Advanced three exploratory soil borings to approximately 80 feet below ground surface (bgs), converting the soil borings to 2-inch diameter groundwater monitoring wells (MW-5, MW-6, and MW-7), • Collected soil samples every five feet for lithologic description, field screening, and possible laboratory analyses, • Developed and sampled the groundwater monitoring wells, and • Surveyed the elevation and horizontal coordinates of the top of casing of each monitoring and vapor extraction well Subsurface Characterization Prior to implementation of field activities, Delta obtained an access agreement from the City of Stockton to install two monitoring wells in Oak Park An encroachment permit was obtained from the City of Stockton Public Works Department, and a revocable permit was obtained from the City of Stockton Transportation Department to install one monitoring well in the American Street public right-of-way Permits to advance the soil borings and construct the monitoring wells were obtained from San Joaquin County PHS/EHD Underground Service Alert, ARCO, the City of Stockton Transportation Department, the City of Stockton Parks and Recreation Department, and San Joaquin County PHS/EHD were notified 48 hours prior to beginning work activities Delta's Field Practices and Procedures and included in Appendix A Copies of the permits and State of California Well Completion Reports are included in Appendix B A Delta geologist was onsite to oversee Woodward Drilling Company of Rio Vista, California complete the drilling activities on August 13 and 14, 2001 All work was conducted under the direct supervision of a State of California Registered Geologist The P\ARCO\2186\REPORTS\2186report doc