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tl <br /> 4 <br /> The approximate planned locations of the borings are shown on Figure 3-1. The loca- <br /> tions may be adjusted based on the results of the soil-gas survey. The objective is to <br /> obtain samples from within the area presumed to be contaminated and to identify the <br /> limits of contamination vertically and laterally. <br /> 3.1.4 GROUNDWATER SAMPLES <br /> Figure 3-1 shows the location of the groundwater 'monitoring well (MW-EMG-1). The <br /> well will be completed directly beneath the former location of the gasoline tank. A bail <br /> test will be performed to provide data on aquifer transmissivity, and two groundwater <br /> samples will be collected from the monitoring well. <br /> In order to prevent boring through contaminated soil and still obtain a groundwater <br /> sample directly beneath the gasoline tank, a. slant boring is proposed for Monitoring <br /> Well MW-EMG-I. A schematic of this slanted monitoring well is shown on Figure 3-2. <br /> Monitoring well installation procedures and well design specif;cations are described in <br /> Section 4.3. <br /> Analytical results of the soil samples taken from and below the former gasoline tank <br /> excavation will be reviewed before the monitoring we'1 is drilled. If the results indicate <br /> that the soil contamination level is too low to .rause cross-contamination of to <br /> groundwater during drilling, then Monitoring Well M'W-EMG-1 will be drilled vertically <br /> through the former location of the gasoline tank. <br /> 3.2 SAMPLING METHODOLOGIES <br /> 3.2.1 SOIL-GAS SAMPLING <br /> + Soil-gas sampling probes will be inserted between depths of 7 and 20 feet below grade. <br /> All analyses of the samples will be performed onsite using a mobile laboratory <br /> equipped with a gas chromatograph. <br /> 3.2.2 SOIL SAMPLING <br /> Boreholes will be drilled using a hollow-stem continuous-flight augering method. The <br /> auger size to be used is 8-inch outside diameter (dD). Samples will be collected at 5- <br /> foot vertical intervals using a split-spoon sampler lined with brass sleeves. Soil sam- <br /> pling procedures are presented in detail in Section 4.3. <br /> The samples from each boring will be submitted for chemical analysis as described in <br /> Section 3.3. <br /> After sampling, each borehole will be filled to the surface with grout. <br /> SF0316051wP1003.51 3-3 <br />