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Well Installation Report San Joaquin County Environmental Health Department February 17, 2006 • Page 4 of 5 The analytical report for both soil samples indicated that the concentrations were below the laboratory reporting limits for petroleum hydrocarbon constituents Well Installations Groundwater monitoring wells MW-18S and MW-18D are constructed of 2-inch diameter, flush- threaded, Schedule 40 PVC casing and the screen intervals are constructed of 0 020-inch slotted PVC casing Monitoring well MW-18S was completed to a total depth of 65 feet bsg, and screened from 50 to 65 feet bsg Monitoring well MW-18D was completed to a total depth of 90 feet bsg and screened from 70 to 90 feet bsg The annular space in each well was filled with No 3 Lonestar sand (filter pack) from the maximum depth drilled to two foot above the top of the well screen A 2-foot thick bentonite seal was placed above the filter pack The annular space above the bentonite seal was filled with cement grout containing up to 5 percent bentonite An 8-inch diameter traffic rated well box was installed to protect the wellhead Well construction diagrams are drawn on the soil boring logs presented in Enclosure B Survevinu of Wells The elevation of a reference point on the newly installed monitoring wells and the ground surface immediately adjacent to the wells were surveyed by an appropriately licensed land surveyor These will be included in the first quarter groundwater monitoring report To comply with State of California Assembly Bill AB2886, Delta requested the surveyor to reference the location of the newly installed wells to the California State Coordinate System using Global Positioning Satellite (GPS) surveying The top- of-casing (TOC) elevation of each monitoring well and ground surface elevation were surveyed relative to • mean sea-level within 0 01-foot Well Development The wells were developed by using a surge block followed by purging with a submersible pump The wells were surged and pumped repeatedly until purge water was relatively sediment free The water generated during development was containerized on site pending evaluation of disposal options A licensed waste hauler will be contracted to dispose of the purge water No groundwater samples were taken at the end of development Samples will be collected during the quarterly groundwater monitoring events Waste Soil and purged groundwater generated by drilling and developing activities were placed in 55 gallon drums and temporarily stored on site Based on the laboratory chemical analyses results, the soil and purged groundwater will be disposed of at appropriate licensed disposal facilities Conclusions and Recommendations The newly installed wells MW-18S and MW-18D were sampled during the fourth quarter, 2005 The analytical results of the groundwater samples collected from both wells indicated low concentrations or concentrations below the laboratory reporting limit Based on these results the petroleum hydrocarbon impact on groundwater has been defined downgradient of the site Based on these results and those from ATC's pilot testing, Delta concurs with ATC's recommendations to install a combination AS/MPE remediation system A summary of quarterly groundwater monitoring analytical results is included as Table 2 Remarks • The recommendations contained in this report represent Delta's professional opinions based upon the currently available information, and are arrived at in accordance with currently acceptable professional standards This report is based upon a specific scope of work requested by the client The Contract W 1RPMS-CAVWorktngTro1ect Files1100966 Stockton 2537 Waterloo RoaNnvestigation