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1 BTEX in Water ' The groundwater samples form MW-1 and MW-3 were reported by the laboratory to contain non-detectable concentrations of BTEX and MTBE. The sample from MW-2 did not contain benzene,toluene or MTBE. ' The sample collected from MW-2 ethylbenzene and total xylenes at concentrations of 120 Ppb and 370 ppb respectively. Naphthalene was detected at a concentration of 230 ppb. TPH-g and BTEX concentrations in groundwater are presented in Figure 5. The laboratory ' results are summarized in Tables 4 and 5. Laboratory reports and Chain-of-Custody forms are included as Appendix B. ' CONCLUSIONS Building Analytics has completed an additional Phase II Subsurface Investigation at the ' above-mentioned site. Based on the data presented in this report,the following summary of findings is presented: • The groundwater flow direction is to the northeast with a hydraulic gradient of 0.0025; TPH-g at levels up to 1,300 ppm and benzene (up to 0.39 ppm) were detected in the soil samples collected from boring B2 at depths between 35 and 55 feet bgs; TPH-g and BTEX were not detected in groundwater samples collected from MW-I or MW-3; • Benzene was not detected in the groundwater sample collected from MW-2; TPH-g (1.6 ppm), ethylbenzene (120 ppm) and xylenes(370 ppm) were detected in the groundwater sample collected from MW-2; ° MTBE was not detected in any of the soil or groundwater samples collected; It is the opinion of Building Analytics that former on-site activities at the Wells Fargo Bank Property located at 49 South Wilson Way have not significantly impacted the subsurface of the site or contributed to the contamination on the adjacent properties for the following reasons: 1. The groundwater depth and flow direction data measured at the Knowles Roek site correspond with those measured at the Wells Fargo site. The regional groundwater flow direction in the area is toward the northeast which corresponds with the flow directions measured at the Wells Fargo and Knowles Roek sites. The groundwater flow direction at the Top Filling Station site differs from the measured flow direction at E the Wells Fargo and Knowles Roek sites by almost 90 degrees. The variations in groundwater flow direction may be from seasonal fluctuations of groundwater elevation and/or anomalous measurements. 2. MTBE has not been detected beneath the Wells Fargo property. The monitoring wells at the Top site with high TPH-g and benzene concentrations also have elevated levels of MTBE. Since the use of MTBE in fuels is relatively recent(widespread use of MTBE began in the 1980's) it appears that the Top Filling Station contaminant plume is also relatively recent and not due to previous activities at 49 South Wilson Way. 10 197046a - Stockton