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CONESTO M-ROVERS <br /> &ASSOCIATES -. <br /> -A Chevron site is located immediately�north-,'of the site. A review of the analytical data.from <br /> Chevron well MW-4, the closest�well'to the Shell site;'shows that it has a history of declining <br /> MTBE concentrations dating back to 2002. It is likely the MTBE:detected in'this well originates. _ <br /> from the Chevron site, as it-appears they had a release event sometime during 1999 (free product <br /> - had been detected in Chevron-well MW-4 at that time) �''Subsequent.to'that, there were elevated - <br /> TPHg, TPHd, and MTBE detections in well MW-4: In contrast, TPHg have rarely been detected <br /> at the Shell site. "Furthermore, the low levels of MTBE detected in that.1well provide a <br /> delineation point between Shell's wells MW-1A and MW-3A,,, i <br /> CHECKLIST OF REQUIRED DATA FOR NO FURTHER ACTION REQUESTS <br /> The site appears to meet the RWQCB-CVR criteria for a low-risk groundwater,designation. The <br /> following are responses ;to the checklist items.contained in.Appendix•A.of the Tri-Regional ' <br /> {k <br /> Board Staff Recommendations for Preliminary Investigation'and,-Evaluation of Underground <br /> Tank Sites,dated April_'16,'2004. <br /> 1. Distance to production wells for municipal, domestic,-agriculture, industry;and other uses <br /> within 2000 feet of the site;; <br /> As noted above, 10 wells were identified during,a_1999 well survey conducted by Cambria.. The <br /> nearest well identified Js adomestic well reportedly located at'the'Chevron-site, north of the <br /> subject site. None of the other identified wells are located'downgradient (northeast) of the site. <br /> Based on this,'it is unlikely that groundwater conditions beneath the site could-impact any water <br /> production wells in the site vicinity. <br /> 2. Site maps, to scale,. of area impacted showing locations of former and existing tank <br /> systems, excavation contours and sample locatiotis; boring and monitoring well elevation <br /> contours,gradients, and nearby surface waters,buildings,streets, and subsurface utilities; - <br /> A vicinity map is included.asFigure 4, and Figures 2 and 3 show site features.�--Figure'.2'shows <br /> _ excavation limits and_,soil sample locations from the UST removal in 1990. Figure 3 shows soil <br /> sample locations from,dispenser upgrades' in 2004, and the locations- of all soil'_borings and <br /> groundwater.monitoring wells at the site. The most recent groundwater contour`map is included <br /> in Attachment A. <br /> 0813 -6 _ <br /> - - <br /> Worldwide Engineering Environmental'Cons ruction end IT Service <br /> S, <br />