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Ms. Meays <br /> June 9, 1992 <br /> Page 3 <br /> residual soil contamination was observed as a narrow band of gray staining at a <br /> depth of eight feet at SW-13 (reference Table 1 and Figure 4, Report of Soil <br /> Remediation, Doane Products Company, February 17, 1992). <br /> The residual soil contamination was left in place at the, time of remediation because <br /> potential instability of the excavation wall immediately below a brick restroom <br /> restricted access. The remedial excavation was backfilled with a drainrock material <br /> to a depth of approximately four feet. A moisture barrier consisting of a single layer <br /> of six mil visqueen plastic was placed above the drain rock and a Class II AB <br /> aggregate subbase material was compacted. to 90 percent relative compzcaon <br /> (minimum) above the moisture barrier. <br /> To determine the areal extent of the remaining residual soil contamination, it is <br /> recommended that a minimum of three hand auger borings be drilled to a depth of <br /> approximately eight feet. One soil sample from each boring obtained at the <br /> unsaturated zone (approximately eight feet in depth) will be analyzed for total <br /> petroleum hydrocarbon as diesel and benzene, toluene, ethylbenzene and xylene. <br /> Upon defining the lateral extent of the residual soil contamination and considering <br /> specific above ground access restrictions, a decision will be made as to-what piece of <br /> equipment would be best suited to remove' the residual soil contamination. Most <br /> likely, a small backhoe or a caisson auger drill rig would be, the most appropriate <br /> equipment for this application. <br /> The excavated residual soil would be added to the existing stockpile soils and <br /> subjected to the disposal/treatment plan discussed above. <br /> This recommended scope of work can be performed at the time that the additional <br /> groundwater monitoring well would be installed. As a consequence, this scope of <br /> work will be added to the well installation workplan. <br /> REVIEW <br /> Upon receiving approval of this general plan from SJCPHS, DPC or its authorized <br /> .technical representative will prepare the necessary workplans and permit <br /> applications required to implement the recommended scope of work. This material <br /> will be submitted to the SJCPHS for review and approval .prior to starting work. <br /> BRUNSING ASSOCIATES, INC. <br /> ow <br /> `�� <br />