UAR/PROP 65 FILE 3 - Laserfiche WebLink

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I GA-ROVERS Mr. Michael Infurna & ASSOCIATES November 26, 2008 southern portion of the site. The highest levels of gasoline constituents are detected in wells RW4A, MW-5R and MW-18. These data are as expected since the gasoline release at this site occurred from the former USTs in the southeastern comer of the site. Wells MW-2 and MW46 provide delineation in the northern portion of the site as these wells typically contain only MTBE and at levels which are below the MTBE MCL. Well MW-7 contains MTBE levels slightly higher than those of MW-2, but MW-7 is located 50 feet northwest of MW-2 and further away from the former USTs than MW-2. We will continue to monitor the MTBE concentration in MW-7, but based on groundwater flow direction and the low levels of MTBE observed in MW-2 it may be that the MTBE in MW-7 does not originate from the Shell site. Wells MW-8 and MW-15 provide delineation along the western side of the site. Both of these wells currently have MTBE levels below the MCL and low levels of other gasoline constituents. Downgradient (southwest) of theses wells is located MW-9 which typically does not contain any gasoline constituents. MW-9 has contained low levels of MTBE, but never above the MCL. MW-9 is located on the southern side of Country Club Boulevard. Wells MW-10 and MW-11 are also located on the southern side of Country Club Boulevard, further east than MW-9. These wells also typically do not contain any gasoline constituents except low levels of MTBE, below the MCL. Wells MW-9, MW-10, and MW-11 provide plume delineation southwest, south and southeast of the site. In addition wells MW-10 and MW-11 are located between the site and the offsite domestic wells. These two wells serve as sentry wells for the site to assure the plume is not migrating toward the domestic wells. An additional sentry well (MW44) is located approximately 670 feet southeast of the site and is screened in the deep zone, which is also the same zone the closest domestic well is screened in. As mentioned above, this well has contained sporadic detections of MTBE below the MCL for MTBE. Perimeter wells MW-3, MW4, and MW-6 provide plume delineation east, and northeast of the site. These wells typically do not contain gasoline constituents other than MTBE, and in the last year at levels near or below the MCL for MTBE. In summary, the existing well network provides adequate plume delineation for this site and is particularly protective of the domestic wells located southeast of the subject site. Groundwater flow direction is typically toward the southwest which means the domestic wells are located crossgradient from the site. Based on the current and historical data for this site there appears to be little or not threat to the domestic wells southeast of the subject site. 240783 10 - Near Worldwide Engineering, Environmental, Construction, and IT Services