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1.0 INTRODUCTION , The project site is located in an industrial area on the northeast outskirts of Stockton near U S Highway 99 (Figure 1) Originally agricultural property, the site was developed as a commercial truck terminal in 1973 A diesel and gasoline fueling facility, consisting of two underground storage tanks (UST's), was formerly present on the south side of the storage yard (Figure 2) This facility was removed in 1989, and evidence of soil contamination was discovered Several thousand cubic yards of contaminated soil were removed from the UST excavation in 1990 and treated using above-ground enhanced bioremediation methods, and several phases of drilling have been completed since then to investigate the extent of groundwater contamination and residual soil contamination Ten new monitoring wells, most of which were screened in two aquifers, were installed within the past year and have been monitored and sampled for approximately one year Based on the results, the extent and magnitude of groundwater contamination were fully delineated as of the second quarter of this year In order to completely define the extent of soil contamination and model the fate and transport of the contaminants, six additional borings were drilled this quarter and additional samples were obtained for laboratory analysis This report presents the fate and transport model and the results of groundwater monitoring for the third quarter of 2005 2.0 PROCEDURES 2.1 Drilling and Sampling In accordance with the work plan submitted as Chapter 6 0 in the First Quarter 2005 Report Upgradient Environmental Consultants supervised the drilling of borings GT-22 through GT-27 in August 2005 V &W Drilling utilized a Mobile Drill B-61 hollow-stem auger drilling rig to drill and sample the borings on August 8 and 9 The borings were drilled through the contaminated Modesto Formation into the slightly contaminated Riverbank Formation, and samples were collected in brass sample tubes at 5-foot intervals through the contaminated zone Borings near the source of the contamination (the former underground storage tank facility) were terminated at a depth of 70 feet, and borings that were located farther from the source were terminated at 55 of 60 feet More than 70 samples were collected,and described in the field by a Registered California f Geologist and thirty-two samples were preserved in a cooled ice chest for later laboratory analysis Boring logs were prepared for each boring, and were used to update and modify previously constructed cross sections through the site The logs are in Appendix A, the laboratory report is in Appendix B, and a summary of the analytical data is in Table I When completed, the borings were backfilled with neat cement and the drill cuttings were added to the existing stockpile of soil on the south side of the site 2 2 Groundwater Monitoring The quarterly monitoring event was done on October 6 The welds were opened and the static water level was allowed to equilibrate with atmospheric pressare before the depth to standing water was measured The wells were then pumped to purge them of standing water before groundwater samples were collected Depth measurements and purge data were recorded on the Well Monitor • Report (Appendix C) and then transferred to Table 2 The samples were collected in