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amec— <br /> A <br /> pair of deeper onsite wells (M-25C1 and M-25C2) was installed in 1999 to depths of 158.5 <br /> and 186.5 feet bgs, respectively, and depth-discrete groundwater samples were conducted <br /> (IT, 1999). In August and December 2005, Geomatrix Consultants, Inc. (Geomatrix) advanced <br /> 18 Cone Penetrometer Test (CPT) borings to depths of approximately 120 feet bgs to further <br /> define the shallow stratigraphy and collect depth-discrete groundwater data (Geomatrix, 2006). <br /> Depth-discrete groundwater sampling conducted by Geomatrix in 2005 comprised 54 <br /> groundwater samples at 18 locations, including 5 locations west of the Site in the parking lot <br /> across Industrial Avenue (Figure 3). The results of this sampling program indicated substantial <br /> stratification of COCs with depth, with the highest concentrations of TCE (>1,000 pg/L up to <br /> 7,800 pg/L) reported for samples collected between 40 and 57 feet bgs. In May 2007, ECM <br /> advanced seven soil borings to depths of up to 55 feet bgs for collection of soil and <br /> groundwater samples (ECM, 2007). These results further delineated the distribution of TCE, <br /> showing high concentrations of TCE in groundwater did not extent north of the site boundary. <br /> 3.1.5 Remedial Actions <br /> Remedial actions performed at and near the Site include soil vapor extraction (SVE), <br /> groundwater extraction and treatment, and pilot tests of in situ bioremediation and chemical <br /> oxidation. Based on the results of the 1994 Feasibility Study (FS; RUST, 1994b), groundwater <br /> extraction and treatment was recommended as the remedy for groundwater; in situ biological <br /> treatment was also considered to be feasible but more difficult to implement. Since the original <br /> 1994 FS, difficulties associated with disposal of extracted groundwater have made this <br /> recommended technology less desirable, whereas recent site characterization information <br /> (Section 3.4.2) and technological developments since 1994 may imply that in situ remediation <br /> technologies are less difficult to implement, and perhaps more desirable than groundwater <br /> extraction and treatment, as discussed in the Revised Feasibility Study, to be submitted to the <br /> Water Board by ECM, on behalf of Nestle, in conjunction with this SCM report submittal. <br /> Soil Vapor Extraction <br /> Soil vapor extraction was conducted from 1988 to 1994 sequentially at eight vapor extraction <br /> locations (VE-1 through VE-8; Figure 3) using a mobile treatment unit (RUST, 1994c; Weiss, <br /> 1995b). Generally, average SVE volumetric air flow rates ranged from 125 to 250 cubic feet <br /> per minute per vapor extraction well (cfm; RUST, 1994c). <br /> • January 1988 — May 1988: SVE was conducted at VE-4, located near the former <br /> Decaffeination Building; VE-4 was screened from 7 — 37 feet bgs. Initial <br /> concentrations of TCE were as high as 72 pg/L in influent vapor extracted from this <br /> location; vapor concentrations decreased to 6.6 pg/L by May 1988. Approximately <br /> 26.8 pounds of TCE were removed during 123 days of operation of VE-4 (RUST, <br /> 1994c). <br /> AMEC Geomatrix, Inc. <br /> I:\Doc_Safe\9000s\9837.005\4000 REGULATORY\SCM_01.30.09\1_text\SCM Report Final.doc 13 <br />