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Michael J. Infurna, Jr., Senior REHS Project 0805-140.003 <br /> May 4, 1998 <br /> Page 2 <br /> economics involved in these cases and be prepared to relay your requests directly to the <br /> cleanup fund should they be deemed excessive by our client. <br /> Concerning the destruction and replacement of well MW-3, this well will be properly <br /> destroyed and permits will be obtained. However, we believe replacing well MW-3 will <br /> serve no useful or beneficial purpose to warrant such expenditures. Monitoring well <br /> MW-2 is located downgradient from MW-3 and is more downgradient from the source <br /> areas than MW-3 and can adequately monitor any potential hydrocarbons released from <br /> the pump islands and product lines. Historically, well MW-3 contained nondetectable to <br /> near nondetectable concentrations of benzene, toluene, ethylbenzene, and xylene <br /> compounds, both prior to and after the water levels rose to above top of screened <br /> intervals, <br /> As you will see in the report for the underground storage tank (UST) removal (Pinnacle, <br /> May 4, 1998), we analyzed 17 soil samples collected from under the product delivery <br /> lines, 8 samples collected from beneath the USTs, and 4 soil samples collected from <br /> beneath the dispensers for oxygenates using EPA Method 8260. Of these 29 soil <br /> samples analyzed, only 1 sample (D4 2.5 ft), collected from beneath the northwestern <br /> dispenser, contained any detectable concentrations of these oxygenates (methyl-tert- <br /> butylether [MTBE], 0.62 milligrams per kilogram). Of 8 stockpile samples also <br /> analyzed for oxygenates using 8260, only 2 had minute amounts (possibly from the <br /> dispenser samples previously mentioned). Based on analysis of these 37 samples, we <br /> have demonstrated that oxygenates have not impacted soil at this site. Additionally, <br /> groundwater samples collected from the historically highest concentration wells with <br /> regards to petroleum hydrocarbon concentrations (wells MW-1 and MW-5 during fourth <br /> quarter 1997 and first quarter 1998 samplings) were analyzed for oxygenates using EPA <br /> Method 8260 and, with the exception to minor amounts of MTBE, were nondetectable <br /> for these compounds. Based on this soil and groundwater analytical data collected from <br /> this site, we request that PHS-EHD not require soil and groundwater samples to be <br /> analyzed for oxygenates using Method 8260. MTBE will continue to be analyzed using <br /> Method 8020 as part of the ongoing monitoring program for the site. The cost difference <br /> for analyzing for 8020 compared to 8260 is extremely significant, and we will request <br /> the UST fund to become directly involved in your requests for the 8260 analyses on such <br /> a large number of samples since ARCO has already gone to the expense to show <br /> oxygenates have not impacted this site. <br /> Your letter requests that vapor wells with groundwater in the casings also be sampled <br /> and analyzed, including analyses for oxygenates using EPA Method 8260. We request <br /> that your agency not require sampling of vapor wells, as these wells were built with large <br /> SACW:\PJO\0805\08051400.3GS-98/pzusmer: I P4ma& <br />