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ceol kalTechnicslac. Page 2 <br /> Additional Site Characterization Work Plan <br /> Project No.770.2 <br /> March 3,2005 <br /> • 2000 to present - quarterly groundwater monitoring & sampling of all site monitoring <br /> wells. <br /> *Pre-2001 data from Wm. J. Hunter& Associates documentation. <br /> V <br /> The data compiled during the course of this investigation indicate that the soil and <br /> groundwater were impacted with diesel range petroleum hydrocarbons. <br /> Geological Technics Inc. (GTI) prepared and submitted a Site Conceptual Model dated <br /> August 23, 2004 to SJC/EHD. SJC/EHD in the letter correspondence dated January 12, 2005 <br /> V <br /> approved the GTI's recommendation to advance seven CPT borings for the additional <br /> subsurface investigations, and directed submittal of a work plan to advance the CPT borings. <br /> However, to further define the site geology/lithology, GTI is recommending one additional <br /> CPT boring. See Figure 3 for proposed CPT boring locations. The following sections <br /> describe the work to be performed to drill the eight(8) CPT boreholes. <br /> 2.0 PROPOSED INVESTIGATION <br /> 1.1 <br /> GTI concluded [Site Conceptual Model (SCM) dated August 23, 2004] that the geological <br /> parameters have not been completely understood with the standard practice of sampling the <br /> soil at five-foot intervals, the lithologic units between borings have not been correlated, and <br /> due to the lack of cross correlation between the individual boreholes, the transport <br /> mechanisms/pathways for contaminant migration have not been determined with confidence. <br /> CPT borings will help to investigate the subsurface conditions for the better understanding of <br /> the site specific geology which will further help to decide effective remedial technology. <br /> 3.0 CONE PENETROMETER TESTING & SAMPLING <br /> The following sections describe CPT technology and the sampling procedures for obtaining <br /> discrete soil and groundwater samples. <br /> 3.1 Cone Penetrometer Testing <br /> CPT uses specialized technology to determine subsurface lithology. It consists of using a <br /> large truck to apply massive force to drive a cone at the head of rods through the subsurface. <br /> Friction, pore water pressure and tip resistance are measured as the cone moves downward <br /> and these values can be correlated to determine the type of soil present. Once this lithologic <br /> information is collected, a second hole is advanced next to the first. The second borehole is <br /> advanced for the purpose of collecting discrete soil and groundwater samples. The depths of <br /> these samples will be selected by GTI staff in the field for optimal site characterization. - Losl' paras rop't <br /> v� ldl s seG4-r 0-YL_i-a�� 6,relh of'if�..i <br /> w t be, ad oA_,�-A 4-P <br /> d�P , 6f q O f?1t "bs� 3 I aS <br />