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i City of Stockton A68101.02F July 24, 1997 Page 12 TABLE 8 Summary of Groundwater Analytical Results SM Probe Locations SB-1 through SB-7 December 18, 1996 Results in micrograms per liter(a f I-) Loctioa Benzene Toluene EthyhXyleara 11E11E3H benzene 1 SB-1 `� 12.4 83 98.8 67 12.7 5,100 2,500 SB-2 ND ND ND ND 4.8 ND 420 SB-3 ND ND ND ND ND ND 330 SB-4 ND 1.6 3.8 79 7.4 2,800 6,000 SB-5 ✓ 6,500 35,000 4.500 25,000 560 93,000 320,000 SB-6 ND ND ND ND ND ND 450 ILS2-7 590 4,100 1,900 18,000 300 72,000 56,000 MTBE = methyl tertiary-butyl ether TPH-G = total petroleum hydrocarbons -gasoline range constituents 1 TeH-D = total petroleum hydrocarbons-diesel range constituents ND = not detected at or above detection limit for reporting purposes Detection limits for these analyses are reported on the attached laboratory reports. 6.0 EVALUATION ' 6.1 Soil Characterization: Gasoline range constituents were detected in soil samples collected at soil probe locations S134 and S13-5. Diesel range constituents were detected in the soil sample collected at 16 .feet BSG in soil probe location S13-5. Trace concentrations (less than 0:1 mg/kg) of toluene and ethylbenzene were detected in the soil sample collected at 16 feet BSG in soil probe.location SB-7. The greatest concentrations ' of PPCs were detected in the soil sample collected at 16 feet BSG from soil probe location SB-5. PPC impacted soils are present below the current water table level (approximately 10 feet BSG) at soil probe locations S13-4 and S13-5. m extend beneath the foundation of the maintenance shop building in PPC impacted soil may e p g ' the vicinity of soil probe location S13-4. However, based on the fact that PPCs were not detected in the soil samples collected from soil probe location SB-3 and on the relatively light concentrations of PPCs detected to the soil samples collected from soil probe location S13-4, it is likely that concentrations of PPCs in soil attenuate to non-detectable concentrations a short distance south and west of S13-4. Further investigation beneath the foundation of the maintenance shop building does not appear to be warranted.