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No fluids were used during drilling activities. Following completion of drilling, bentonite was <br /> placed in the bottom of each boring All borings were backfilled with neat cement to grade <br /> 4.2 Groundwater <br /> To define the lateral extent of groundwater impact RESNA drilled three deeper soil borings, <br /> completing them as monitoring wells. Well MW i was installed downgradient of the tank pit and <br /> line areas, well MW2 was installed near the product lanes, and well MW3 was installed up- <br /> gradient of the tank pit and product lines. The monitoring wells were completed to depth of <br /> approximately 20 feet below grade, fifteen feet below first water Drilling was conducted under <br /> ' the direct supervision of RFSNA, by Exceltech Drilling, a licensed C57 drilling contractor using <br /> a hollow-stem auger rig. The wells were constructed of 4 inch F480 PVC casing and screen and <br /> ' completed as shown on Figure 3 <br /> r <br /> Drill cuttings were logged continuously for characterization of soil type using the Unified Soil <br /> Classification System. Descriptions of sods encountered and monitoring well construction detail <br /> ' were recorded on well/bonng logs (Appendix H) Soils encountered were monitored by placing <br /> a small amount of representative soil in a sealed container, then measuring the concentration of <br /> ' volatiles collected in the head space of the container with a photoionization detector (PID) <br /> calibrated to the benzene molecule. The values obtained at each measurement point were <br /> ' recorded on the well/bonng logs <br /> The soil sample selected for analysis during the drilling of each monitoring well was collected <br /> at the soil/groundwater interface The samples were collected in brass sleeves using a modified <br /> California split spoon sampler The samples were sealed with teflon tape, a plastic cap, duct <br /> ' tape, then labeled and sealed in a plastic bag The samples were placed on ice in an air tight <br /> cooler and transported to Sequoia Analytical, a State certified laboratory under strict chain-of- <br /> R-012792 LF 4 <br />