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' 26 October 2000 AGE-NC Project No. 98-0466 ' Page 8 of 10 3.2. ANALYTICAL RESULTS OF GROUNDWATER SAMPLES ' One grab ground water sample was collected at a depth of approximately 0 feet bsg from soil boring LP4 located in the leach field area adjacent to the Millwork building. TRPH was detected at a ' concentration of 15 milligrams per liter(mg/1). Total chromium was det cted at a concentration of 1.17 mg/l which exceeds the California Maximum Contaminant Leve (MCL) of 0.05 mg/1 for ' drinking water. The sample was not analyzed for dissolved chromium. Lead in the ground water sample(0.10 mg/1) exceeds the 90`s percentile limit of 0.015 mg/l allowed for drinking water at the tap and exceeds the 0.004 mg/l EPA PRG for tap water. The sample was not filtered prior to ' analysis, so the metals results may included total metals from entrained mineral grains and may not be representative of dissolved metals concentrations. ' Neither PCP nor TCP were detected in the ground water sample. Zinc concentrations in the ground water sample do not exceed environmental guidelines.Formaldehyde at 4.7 mg/l exceeds the Action Level of 1 mg/1 in the ground water sample. tAnalytical results of the grab ground water sample are summarized in Table 2. Copies of the laboratory report (Precision Enviro-Tech Sample IDs AG0627-12A through AG0627-12D) and ' chain-of-custody forms are included in Appendix C. ' 4.0. SUMMARY AND CONCLUSIONS The data gathered from the western ditch area appears to support Kleinfelder's interpretation of ' contaminants originating from the steam cleaning operation flowing into the ditch.Hydrocarbon and metals concentrations appear to decrease with soil depth due to the relative low mobility of motor t oil and metals in fine-grain soil. AGE suspects that the surficial soil in the former steam cleaning area,along the surface runoff route to the ditch,the east ditch margin anbottom are impacted with the motor oil and metals; intuitively,the most impacted area would be in the former steam cleaning ' area itself. Clean-up standards for motor oil in soil have not been established, however, the concentration ' detected in DS1-2 is significant along with the chromium and lead concentrations detected in the sample. ' The concentrations of TRPH (motor oil) detected in soil collected from the leach field area are not believed to be of concern, especially with VOC concentrations at less than detectable levels. Additionally, the consistency or narrow range of TRPH concentrations uggests that these may be ' background concentrations. The concentrations of chromium,lead and formaldehyde detected in the ground water sample from Advanced GeoEnvironmental,Inc.