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Work Plan for the Former Two 20,000-Gallon USTs Location at Stockton AASF California Army National Guard based on field/sampling conditions and access issues,adjustment to the boring locations may be required for completion.All five borings will be placed surrounding the two former 20,000-gallon USTs location.The borings will be numbered in the field as drilling occurs,with the first boring drilled adjacent to the two former 20,000-gallon USTs location. The first boring will be continuously cored and logged(Section 9.1.31 of the QAPP)to allow for correct sample placement and representation of the area's lithology. The remainder of the borings will be drilled and sampled using a split-spoon sampler every 5 feet beginning at 5 feet,and logged to also allow for correct sample placement and lithological representation. In addition,if evidence of soil impacts is present during drilling,soil samples may be collected at any depth interval where hydrocarbon odors or soil discoloration are present.If evidence of soil and/or groundwater impacts are observed during the drilling of the first five borings,the contingency borings may be drilled/sampled using the same procedures used for the first five borehole locations to determine the extent of impacts that can be attributed to the two former 20,000-gallon USTs.A minimum of two soil samples and one groundwater grab sample will be submitted for analysis. 6.4 To collect soil samples using the HSA drilling method,the pilot bit is removed and,if necessary, the inside of the hollow stem is cleaned out. Soil samples will be obtained by lowering a split-spoon sampler,fitted with stainless steel or brass sleeves attached to the drill rods or wire-line to the bottom of the borehole.The split-spoon sampler will be driven into the undisturbed formation with a 140-pound hammer repeatedly dropped from a height of approximately 30 inches. The number of hammer drops required to collect 6 inches of samples will be recorded to provide qualitative information regarding the density of the material encountered. The nominal sample size will be either 1.5 or 2.5 inches inside diameter, 18 inches in length,and manufactured of stainless steel or brass. Three 6-inch long stainless steel or brass liners will be used inside the split-spoon samplers. Upon sample retrieval,the split-spoon sampler will be opened,soil materials will be inspected and lithologically logged,and plastic caps with Teflon liners will be secured to each end of the stainless steel or brass liners to be used for chemical analysis. The quantity of analyses to be performed will determine how many of the three liners will be submitted to the laboratory for analysis. 6.5 Groundwater samples will be collected using one of three possible methods:through the open augers,installing temporary casing/screen,or using HydroPunch or similar technology. If drilling conditions allow(i.e.,no heaving sands),URS will attempt to collect a groundwater grab sample through the open augers by slowing lowering a decontaminated or disposal bailer through the open augers into groundwater.If URS is unable to collect the groundwater samples through the open augers,temporary well casing/screen may be set.After the boring has been advanced to the desired depth,a temporary 5-foot(I-to 2-inch diameter)polyvinyl chloride(PVC)screen with blank casing above will be placed into the borehole. The screen will be located at the desired sample depth and left in place for two or more hours to allow the groundwater in the temporary well to settle and re- equilibrate. After the temporary well(casing)has been in place for two or more hours,a decontaminated or disposable bailer will be lowered into the temporary well to retrieve the groundwater sample.After groundwater sampling is completed,the well(casing)will be removed from the borehole. 6.6 HydroPunch may also be used if the samples cannot be collected through the open borehole.The HydroPunch is a groundwater sampling tool that allows collection of water samples from precise depths without installation of an MW. The HydroPunch 11 sampler has a 2-inch outside diameter and is 5 feet in length.A disposable polypropylene or PVC screen(5 feet long) is attached to a disposable tip.The screen and internal parts of the tool are sealed from the exterior by an O-ring seal at the base of the cone when the tool is in the closed position. The screen and cone will be inserted into the body KAWprocess\0025 MCA ARNG\Stockton AASF WP\FINAL\WP text.doc 8 June 2007