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Comment <br />A test pit was excavated west of the excavation to field screen residual contamination in this area; <br />however no information regarding this activity was noted in the report. <br />Response <br />During field excavation activities it became apparent residual petroleum hydrocarbon <br />contamination extended beyond the excavation's western sidewall. Due to the close proximity of <br />monitoring well MW -3 and nearby underground utilities to the excavation, an exploratory test pit <br />was excavated approximate seven feet northwest of the excavation (Figure 3). The test pit <br />dimensions were approximately four by five feet to a depth of approximately 10 feet below <br />ground surface. Flame Ioniation detector (FID) readings ranging from 0 to 70 ppm and <br />petroleum hydrocarbon odors were noted between approximately 3 and 10 feet below grade in the <br />pit. Upon completion of field screening the pit's soil, the pit was immediately backfilled with the <br />excavated material due to safety considerations involving an adjacent 4 -inch high pressure water <br />line in addition to the instability of the cavitating pit sidewalls. <br />Comment <br />Information as to why laboratory detection limits were elevated as noted in the report. <br />Response <br />Higher detection limits are due to dilution factors employed at the laboratory. This is stated on <br />the laboratory data sheets in Attachment II of Smith Environmental's October 24, 1995 Soil <br />Excavation Report. <br />Comment <br />Further information regarding the backfill of the excavation. <br />Response <br />The bottom of the open excavation was lined with a fabric filter liner and backfilled with <br />imported, clean, three quarter -inch crushed rock to the ground surface. Smith Environmental has <br />contacted Goins Environmental Construction (the subcontractor) several times for additional <br />information regarding the backfill material. Upon our receipt, the additional information will be <br />forwarded to your office. <br />PROPOSED SCOPE OF WORK <br />The following scope of work is proposed by Smith Environmental to further delineate residual <br />subsurface petroleum hydrocarbon contamination at the subject site. In brief, the proposed work <br />includes the advancement of six soil borings in the vicinity of the former excavation. <br />150081\SxR-0995.DOC 4 <br />• <br />SNRT <br />