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4 . 1.0 INTRODUCTION Upgradient Environmental Consultants (Upgradient) assumed the responsibility for assessment and monitoring of groundwater contamination at the Dallies Trucking facility in Stockton, California in September, 1994 The assessment was completed in late 1996, and Upgradient submitted a Problem Assessment Report in November of that year In the first quarter of 1997, Mr Steve Sasson of the San Joaquin County Department of Environmental Health approved the PAR and recommended that a Corrective Action Plan be prepared Although he assumed that groundwater monitoring would continue on a quarterly basis,he did not specifically request it in his letter Due to this misunderstanding, Gillies Trucking did not authorize Upgradient to continue groundwater monitoring or prepare a Corrective Action Plan until contacted by Mr Sasson in late October of 1997 The purpose of this report is to present the results of the 4th quarter monitoring, which took place on November 21 2.0 BACKGROUND INFORMATION The project site is located at 3931 Newton Road, in an industrial area on the northeast outskirts of Stockton near U S Highway 99 The location of the site is shown in Figure 1, and the site facilities are shown in Figure 2. Originally agricultural property, the site was developed as a commercial truck terminal in 1973 The property occupies an area of about 3 5 acres • Topography in the area is generally flat, although the project site is elevated several feet above the adjacent parcels There is a maintenance building and office fronting Newton Road, with a large, unpaved storage yard/parking lot in the rear A diesel and gasoline fueling facility, consisting of two underground storage tanks (UST's), was formerly present on the east side of the storage yard (Figure 2) This facility was removed in 1989 and replaced with an above-ground fueling facility, which is located to the west of the abandoned facility 3.0 MONITORING PROCEDURES Upon arrival at the site, Upgradient personnel opened all six wells and allowed well pressures to equalize with atmospheric pressure before measuring water depths The depth to groundwater in each well was measured with a Solinst water level meter and the measurements were recorded on the Well Monitor Report (Appendix A) A Grundfos Readi-flo 2 groundwater pump was then used to purge 8 gallons from well GT-6 and 7 gallons from GT-9 During purging, pH, temperature, and conductivity were measured at 2-gallon intervals, and purging was discontinued when these parameters stabilized Because the top of the screened interval in wells GT-1, 2, and 3 was approximately 12 feet below the static water level, Mr Sasson requested Upgradient to purge between 20 and 25 gallons from these wells in an attempt to reach formation water beyond the well bore The pump was decontaminated with TSP solution between wells Because of slow recharge and binding of the pump against the well casing, GT-5 was hand-bailed with a disposable bailer, 2