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i SOIL SAMPLING AND BOREHOLE DRILLING OPERATIONS I To determine the concentration of gasoline and/or gasoline constituents remaining in the sort E at the terminus of the gasoline tank excavation that was proposed in the Soil Remediation Proposal of 3 October 1989 for the Fabricare site and implemented in April 1990, one boring ` will be completed to a depth of 28 feet through the fill material At this point, one soil sample k will be collected. See Figure 7 for the location of the proposed sort boring f Boreholes will be sampled at a depth of every 5 feet for those designated for monitoring well construction The boreholes will be drilled and sampled using a truck mounted drilling rig, f and minimum 6-inch diameter hollow-stem augers The soil samples will be collected from the boreholes for laboratory analyses using the MOSS sampling system or a modified California split spoon sampler fitted with three 2-inch X 6-inch brass liners If the MOSS sampling system is used, then a split spoon sampler fitted with three 2 5-inch X 6-inch brass liners will be utilized and the boreholes will be continuously sampled. Auger flytes and other tools used in the borehole drilling and sampling operations will be thoroughly steam cleaned before initial use and between drilling and sampling subsequent boreholes to minimize cross contaminating the boreholes The modified California sampling tube and brass liners will be washed in a mixture of Liqui-Nox and clear water, rinsed in clear water, rinsed in distilled water, rinsed in deionized water, and allowed to air dry prior to their initial use, and prior to ' subsequent use downhole The use of phosphate based cleaners, such as TSP, will not be I allowed due to the documented laboratory analyses interference effects caused by the phosphate compounds in these types of cleaners If the California modified sampler is used, then soil samples for laboratory analyses will be collected by advancing the borehole to the desired sampling increment and lowering the modified California sampler through the hollow- stem auger string to the bottom of the borehole The sampler will then be advanced ahead of • the auger string using a 140-pound hammer or by hydraulically pushing the sampler. The r1fab-W.12-t) Page 25