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Report-Groundwater Inves..6ation First Student Bus Facility(Former A.W. Hayes Facility) 2005 Navy Drive—Stockton, CA A. FINDING THE LOCATION OF MONITORING WELL MW-2 On November 12, 2008, KR Environmental conducted a visit to the Site to determine the locations of the four (4) monitoring wells, and to re-develop the four (4) wells. Monitoring wells MW-1, MW-3 and MW-4 were successfully located in the gravel surfaces in which the wells were installed. According to Plate 2 provided in the Ramcon June 22, 2004 Summary Report, MW-2 should have been located in the gravel driveway located approximately 40 feet west of the existing covered concrete slab and wash rack located on the west side of the shop building, and approximately 30 feet west of MW-4. Our inspection of the driveway in which MW-2 was installed revealed that this surface was no longer gravel, but had been re-surfaced with asphalt. According to personnel of First Student Bus Facility (Site occupants), this driveway was re-surfaced with asphalt approximately two years ago (2006), and that MW-2 was most likely covered over with asphalt. B. RE-DEVELOPMENT OF GROUNDWATER MONITORING WELLS On November 12, 2008, the three (3) existing monitoring wells (MW-1, MW-3 and MW- 4) were re-developed to improve well yield by removing fine materials from the well casing, filter pack and boring annulus/formation interface. The fine materials were removed, and the soil grains aligned in the formation surrounding the well screen, thereby increasing porosity and hydraulic conductivity. The wells were purged by hand bailing to remove the fine suspended solids. The purging was continued until the groundwater was sand/silt-free and water clarity, temperature, pH, and conductivity had been stabilized. Approximately ten casing volumes (30 gallons) of groundwater were purged from monitoring wells MW-1 and MW-3, and approximately ten casing volumes (60 gallons) of water was purged from monitoring well MW-4 during development. The wells were purged using a new, disposable bailer for each well. Groundwater removed from all three (3) monitoring wells was cloudy (grayish mud) and odorless. Neither floating product nor oily sheens were observed in the groundwater removed from MW-1, MW-3, or MW-4. A summary of purge volumes, pH, electrical conductivity, (NTUs) and temperature measurements made during well development purging activities are presented below in Table 1. Copies of the Well Monitoring Data Sheets for development purging are included in Appendix A. 3