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Ogden Environmental Services November 19, 1990 Mr. Chris Gable Page 2 Sampling and Analysis Sampling of the three groundwater monitoring wells was performed on October 24, 1990. Prior to sampling, water levels were recorded and the groundwater was observed for the presence of floating product or odor. Stagnant water was removed from the wells by purging a minimum of three casing volumes. To ensure collection of representative samples,Field measured pH,conductivity,and temperature were allowed to stabilize prior to sample collection. Copies of well sampling records are attached with this report. Purging of the wells and collection of the samples was performed with a Teflon bailer. Before and after the sampling of each well,all of the sampling equipment was cleaned with a trisoditun phosphate solution followed by three successive rinses with organic free deionized water. Samples of equipment rinse water (equipment ansate blanks) were collected after decontamination of the bailer and prior to collection of each well sample. The equipment blank samples have been referred to as MW-1-0, MW-2-0, and MW-3-0 in the attached laboratory analytical report. The groundwater samples have been referred to as MW-1-1, MW-2-1 and MW-3-1. Groundwater samples were properly sealed and placed in a cooler with ice prior to transporting to the analytical laboratory Net Pacific, Inc. Proper sample handling and chain-of-custody documentation were maintained during all phases of this study. Groundwater samples collected from the monitoring wells were analyzed for TPH by EPA method 8015 modified for gasoline, BTEX by EPA method 602, TRPH by EPA method 418.1, and total lead by EPA method 7421. Additionally, equipment rinse water samples were collected and analyzed for TPH by EPA method 8015, modified for gasoline and BTEX by EPA method 602. Results Groundwater Gradient. The approximate direction of groundwater flow at the time of sampling was to the east (see Plate 3). The measured hydraulic gradient was 0.002. Chemical Analysis. The results of the groundwater analyses are listed in Table 1. Results of the previous rounds of sampling are also included in this table. No detectable levels of TPH, TRPH, BTEX or total lead were found in any of the groundwater samples collected during the October sampling. Additionally, no detectable levels of TPH gasoline or BTEX were found in the equipment rinse samples (see attached laboratory report). Conclusions No detectable levels of petroleum hydrocarbons have been found in any of the groundwater samples collected adjacent the soil pile at the Stockton Soil Treatment Facility. Trace levels of lead have previously been detected in wells MW-2 and MW-3. These lead concentrations are well below the state established Maximum Contaminant Level (MCL) for drinking water. IWAWP.B McClelland consultants