ARCHIVED REPORTS_XR0012694 - Laserfiche WebLink

Home Browse Search

r t.� i - 3.43 GROUNDWATER SAMPLES Figure 3-1 shows the location of the groundwater monitoring well. The well will be completed directly beneath the former location of the northern tank. A bail test will be performed to provide data on aquifer transmissivity, and two groundwater samples will be collected from the monitoring well. In order to prevent boring through contaminated soil and still obtain a groundwater sample directly beneath the tank pit, a slant boring is proposed for Monitoring Well MW-DIS-1. A schematic of this slanted monitoring well is shown on Figure 3-2. Monitoring well installation procedures and well design specifications are described in Section 4.3. Analytical results of the soil samples taken from and below the former tank pit will be reviewed before the monitoring well is drilled. If the results indicate that the soil contamination level is too low to cause cross-contamination of groundwater during drilling, then Monitoring Well MW-DIS-1 will be drilled vertically through the former location of the northernmost tank. 3.2 SAMPLING METHODOLOGIES -�, 3.2.1 SOIL-GAS SAMPLING Soil-gas sampling probes will be inserted between depths of 7 and 20 feet below grade. All analyses of the samples will be performed onsite using a mobile laboratory equipped with a gas chromatograph. 3.2.2 SOIL SAMPLING ' Boreholes will be drilled using a hollow-stem continuous-flight augering method. The auger size to be used is 8-inch outside diameter (OD). Samples will be collected at 5- foot vertical intervals using a split-spoon sampler lined with brass sleeves. Soil sampling piccedures are presented in detail in Section 4.3. The samples from each boring will be submitted for chemical analysis as described in Section 3.3. Each borehole, upon the completion of sampling,will be filled to the sur- face with grout. After sampling, each borehole will be filled to the surface with grout. i sF031,,04\W?W7s1 3-3