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Mr Mike Infurna <br /> May 26, 2005 S E C ® R <br /> Page 3 <br /> t� <br /> TPHg, benzene, MtBE, and 1,2-DCA generally show a stable or decreasing trend in w <br /> intermediate wells, with the exception of TPHg and MtBE in wells MW-5 and MW-10, and <br /> 1,2-DCA in wells MW-7 and MW-8 <br /> Review of shallow isoconcentration maps indicates that ConocoPhillips has performed <br /> adequate delineation within the shallow zone, except for TPHg, 1,2-DCA, and MtBE to the " <br /> southeast Intermediate isoconcentration maps indicate the following TPHg is delineated <br /> to 100 ppb or below, MtBE and benzene are delineated to below their respective maximum <br /> contaminant levels (MCLs), and 1,2-DCA is not currently delineated Shallow, intermediate, <br /> and deep isoconcentration maps are included as Figures 3 through 15 The MtBE <br /> isoconcentration contour map for the intermediate zone (Figure 10) was revised (Figure 11) <br /> after resampling of well DMW-3 on March 28, 2005 <br /> RECENT QUARTER ACTIVITIES (First Quarter 2005) <br /> • Quarterly groundwater monitoring and sampling performed by TRC on January 12, <br /> 2005 <br /> • Prepared and submitted the quarterly summary report <br /> • Installed deep monitoring wells MW-16 and MW-17 <br /> NEXT QUARTER ACTIVITIES (Second Quarter 2005) <br /> • Perform quarterly groundwater monitoring and sampling (TRC) <br /> • Prepare and submit a quarterly summary report <br /> • Prepare and submit report documenting the installation of wells MW-15, MW-16, <br /> and MW-17 <br /> RECOMMENDATIONS <br /> The site should continue to be monitored and sampled on a quarterly basis to evaluate the <br /> stability of the plume beneath the former 76 Station Joint monitoring and sampling with the <br /> upgradient ARCO station will continue so that regional groundwater flow and chemical <br /> isoconcentration maps can be generated <br /> CHARACTERIZATION/REMEDIAL STATUS <br /> Sod contamination delineated? Yes <br /> Dissolved groundwater delineated? No <br /> Free product delineated? NIA <br /> Current phase of project? AssessmentlMonitornng <br /> Frequency of sampling? Quarter <br /> Soil remediation in progress? No <br /> Anticipated start date? NIA <br /> Anticipated completion date? NIA <br /> Shallow zone groundwater gradient? Regional 0 005ft/ft Northeast <br /> Intermediate zone groundwater gradient? 0 004 ft/ft Northeast <br /> i <br />