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1 �I <br /> Former 76 Station 4409 S E C ® R Irl <br /> January 27, 2006 <br /> Page 5 <br /> MW-14 had varied between 3 2 pg/L and 18 pg/L until fourth quarter 2005 when a <br /> concentration of 20 pg/L was reported <br /> Review of the C monitoring zone concentrations of TPHg, benzene, and 1,2-DCA at 3,400 <br /> pg/L, 190 pg/L and 3 5 pg/L, respectively, are not delineated MtBE is delineated to less �t <br /> than the reporting limit No concentration trends are apparent in the C monitoring zone <br /> wells because adequate data for determining trends have not been collected However, <br /> during fourth quarter 2005, concentrations were generally low to non-detectable in the 4 <br /> groundwater samples collected from MW-15 and MW-16 At MW-17, concentrations of <br /> TPHg and BTEX in groundwater were less than the concentrations reported during secondq <br /> and third quarters of 2005 Fuel oxygenates have not been detected in groundwater at MW- <br /> 17 , <br /> CHARACTERIZATION STATUS' <br /> Soil contamination delineated? Yes <br /> Dissolved groundwater delineated? No <br /> Free product delineated? NIA <br /> Current phase of protect? Assessment/Monitoring <br /> Frequency of sampling? Quarterly <br /> Soil remediation in progress? No <br /> Anticipated start date? NIA J <br /> Anticipated completion date? NIA <br /> A monitoring zone groundwater gradient? 0 004 ft/ft northeast <br /> B monitoring zone groundwater gradient? 0 004 ftlft northeast <br /> C monitoring zone groundwater gradient? 0 001 ft/ft southeast <br /> NEIGHBORING SITE ACTIVITIES 31 <br /> a, <br /> The upgradient ARCO Service Station, located at 16 East Harding Way, appears to be " <br /> affecting groundwater concentrations within A monitoring zone wells at the ConocoPhillips ,, <br /> site Remediation technology at the ARCO site includes soil vapor extraction, groundwater <br /> extraction, and ozone sparging An off-site ozone sparge system was installed during the <br /> second quarter of 2005 and became operational during third quarter 2005 Certified <br /> laboratory analytical reports, chain-of-custody documentation, and field data sheets for the <br /> ARCO station are included as Attachment D <br /> RECENT SUBMITTALSICORRESPONDENCE <br /> Submitted — Quarterly Summary and Monitoring Report— Third Quarter 2005, dated <br /> October 27, 2005 <br /> Submitted — Results of Vertical Assessment and Updated Site Conceptual Model, dated <br /> October 27, 2005 a� <br /> 6Y� <br /> 1� <br /> ^ ;Z <br /> X <br /> tl, <br /> s <br /> Y <br /> 4409 4Q2005 QSR(CR)doc SECOR International Incorporated <br /> x <br /> i <br />