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F <br /> i <br /> -,� 3 SAMPLING AND ANALYSIS PLAN <br /> { ` The primary objective of the field investigation described in this sampling and analysis <br /> plan is to gather the data necessary to characterize the lateral and vertical extent of soil <br /> contamination and evaluate groundwater quality in the vicinity of the former Disco <br /> underground tank pit- <br /> i <br /> 31 OVERVIEW OF FIELD INVESTIGATION <br /> The following types of subsurface samr''zs will be collected: soil-gas, soil, and ground- <br /> water. Figure 3-1 shows proposed sampling locations. Before implementing the field <br /> ' sampling plan, CH2M HILL will perform the following tasks: <br /> • Obtain necessary drilling and well installation permits as required. j <br /> • Obtain utility clearances through Underground Service Alert (USA). <br /> Ia <br /> . .1 SOIL-GAS SURVEY <br /> r <br /> The purpose of the soil-gas.survey.is to cost effectively delineate the lateral extent of <br /> the contamination. Soil-gas sampling is a viable option for contamination delineation <br /> due to the volatility of various gasoline constituents. The soil-gas survey results will <br /> "- ' standing of lateral contamination migration. This, in <br /> qualitatively improve the under <br /> turn,may help identify the most effective soil boring locations. Soil-gas sampling in the <br /> former tank pit excavation may also help to identify the vertical extent of contamina- <br /> tion. <br /> { <br /> 1't Figure 3-1 presents the areas where fourteen soil-gas-samples will he taken. The <br /> sample depths will occur between 7.and 20 feet below ground surface (bgs). Prelimi- <br /> nary analytical data will be available at the completion of each clay's work. The soil-gas <br /> samples will be analyzed for volatile Total Petroleum Hydrocarbons (TPH) and ben- <br /> zene, toluene, ethyl benzene, and xylenes {BTEX}. <br /> 3.1.2 SUBSURFACE SOIL SAMPLES <br /> Subsurface soil sarnples.wi11 be collected from seven soil borings. The soil borings will <br /> be drilled to a maximum depth that contamination is evident (drilling will occur to <br /> minimum depth of 44 feet bgs). Soil samples will be collected at 5-foot intervals. The <br /> approximate planned locations of the borings are shown on Figure 3-1. The locations <br /> may be adjusted based on the results of the soil-gas survey. The objective is to obtain <br /> samples from within the area presumed to be contaminated (the tank pit) and to iden- <br /> t,: tify the limits of contamination vertically and laterally. <br /> SF0316041WP1007.31 3-1 <br />