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2-7 May 1929 Monitoring Well Installation <br /> In May 1999, ASE installed monitoring wells MW-1 through MW-10 at the <br /> site (Figure 3) Monitoring wells MWA through MW-6 are screened <br /> between 9 and 19-feet bgs to monitor the first water-bearing zone <br /> encountered Monitoring wells MW-7 and MW-9 are screened between <br /> 55-feet bgs and 70-feet bgs Monitoring well MW-8 is screened between <br /> 100-feet bgs and 115-feet bgs Monitoring well MW-10 is screened <br /> between 105-feet bgs and 115-feet bgs <br /> Hydrocarbons and/or VOCs were detected in groundwater samples <br /> collected from all ten monitoring wells The highest concentrations <br /> detected were in groundwater samples collected from monitoring wells <br /> MW-5 and MW-6 Both of these wells are screened in the first water- <br /> bearing zone encountered with the bottom of the zone extending to a <br /> depth of no greater than 19-feet bgs Monitoring well MW-5 is located <br /> between the USTs and the pump island near West Yosemite Avenue <br /> Monitoring well MW-6 is located between the USTs and the site building <br /> BTEX concentrations in groundwater samples collected from these two <br /> wells exceeded DHS MCLS for drinking water Benzene concentrations in <br /> groundwater samples collected from monitoring wells MW-7, MW-8 a n d <br /> • MW-9, all screened in deeper zones, also exceeded the DHS MCL f o r <br /> drinking water <br /> The groundwater flow direction in the first zone (shallower than 19-feet <br /> bgs) was to the northwest at a gradient of between 0 008 to 0 01- <br /> feet/foot <br /> 2- 9 August 1999 Qjiarterly Groundwater Monitoring <br /> In August 1999, ASE collected groundwater samples from the site <br /> monitoring wells, as well as the on-site drinking water well Free-floating <br /> hydrocarbons, believed to be gasoline, were present on the groundwater <br /> surface in monitoring well MW-5 A hydrocarbon sheen was present on <br /> the groundwater surface in monitoring well MW-6 The analytical results <br /> from the remaining wells showed a slight decrease from the initial <br /> sampling of these wells The only hydrocarbon concentrations that <br /> exceeded DHS MCLs for drinking water were the toluene, ethyl benzene <br /> and total xylene concentrations in groundwater samples collected from <br /> monitoring well MW-6, and the benzene concentration in groundwater <br /> samples collected from monitoring well MW-7 The groundwater flow <br /> direction in the first zone (shallower than 19-feet bgs) was to the north <br /> and northeast at a gradient of approximately 0 002-feet/foot <br /> Franks One Stop Report — March 2001 <br /> -4- <br />