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City of Stockton Draft Amended Report of Waste Discharge (AROWD) <br /> Austin Road Landfill Work Plan <br /> 2. If analytical results from the initial boring for each transect indicates non-detectable <br /> concentrations of PCE,then a subsequent boring will be sited approximately 1,000 <br /> feet upgradient(southward) of the initial boring. If this subsequent boring indicates <br /> detectable concentrations of PCE,then the plume edge is defined as between the two <br /> borings. If the second boring also is non-detect,a third boring will be installed <br /> further upgradient to locate the plume. <br /> 3. All boring locations will be surveyed. <br /> Sample collection will be carried out as described below: <br /> ■ Each boring will be advanced without sample collection to the depth of 10 feet above the <br /> groundwater table,as measured in the field at monitoring wells MW-13 and MW-14 prior to <br /> drilling(this depth is expected to be between 90 and 100 feet below the ground surface). . <br /> Sampling information above the targeted depth is not necessary because of the abundant data <br /> available in the unsaturated zone from previous investigations. <br /> ■ In the initial boring of each transect,discrete groundwater samples for shallow and deep aquifer <br /> units utilizing the Hydropunch®water sampler will be taken as described below. <br /> ■ Also in the initial boring,continuous soil samples will be collected for lithologic logging and <br /> possible laboratory analyses using a 5-foot long,split-barrel,core sampler as described in Section <br /> 2.2.1.3. Laboratory analyses include grain size distribution and total organic carbon content. All <br /> collected soil samples will be retained for future use. <br /> ■ At subsequent boring locations, soil cores will be collected approximately every 10 feet using an <br /> 18-inch split barrel sampler. In addition,up to two groundwater samples will be collected--one <br /> sample from the shallow aquifer zone and one sample from the deep aquifer zone--at depths <br /> which target the highest probable concentrations of PCE. These sampling depths will be <br /> determined based on rapid turn-around analysis of samples collected in the transect°s initial <br /> boring. <br /> ■ Two monitoring well cluster locations will be installed downgradient of the northeast edge of the <br /> plume limit. One well will be completed in the shallow aquifer zone and the other in the deep <br /> aquifer zone. The wells will be constructed as described in Section 2.2.1.3. <br /> Well completion depths and screened depth intervals will be determined based on observed <br /> lithology,results of the depth-discrete groundwater sampling,and other factors,as appropriate. <br /> 2.2.1.2 Sample Collection <br /> The following subsections provide descriptions of the sampling methodologies to be used during the <br /> field portion of this study. An experienced drilling contractor with knowledge of the local geologic <br /> conditions will be selected to provide drilling,well development,and well installation services. The <br /> hollow stem auger drilling rig will be a Central Mine Equipment(CME)-75 or equivalent,capable of <br /> reaching the required depths. <br /> The hollow stem auger will either be a hydraulically or mechanically powered drill rig which <br /> simultaneously rotates and axially advances a hollow stem auger column. Each of the joints between <br /> auger sections will be properly connected. <br /> W:\REPORTS\STOCKTON\AUSTIN\WORKPLAN.DOC Page 5 <br />