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SECTION 3 <br /> Summary of Field Methodology <br /> This section summarizes the field and analytical methods followed during this focused field <br /> investigation. The reader is referred to the Work Plan(CH2M HILL, 1999) for specific field <br /> methodology details such as sample collection procedures and handling,and equipment <br /> decontamination procedures. <br /> 3.1 Drilling and Sampling Methodology <br /> 3.1.1 Cone Penetrometer Testing (CPT) <br /> All borings installed during this field investigation were installed using a CPT direct push <br /> drill rig. CPT lithologic logging was conducted using a standard electronic piezocone <br /> (CPTU). CPTU measurements of cone bearing,sleeve friction,and dynamic pore water <br /> pressure were recorded at 5 cm intervals for the entire length of each boring. <br /> CPT borings were installed at 15 locations on and around the Disco site. Five borings (CPT-1 <br /> through CPT-5)were installed within the former tank and pump area,nine borings(CPT-6 <br /> through CPT-13,and CPT-15)were installed downgradient of the former tank and pump <br /> area,and one boring(CPT-14)was installed cross-gradient,as shown in Figure 2. CPT logs <br /> were obtained in each of the borings to a depth of approximately 130 to 150 feet below <br /> ground surface (bgs),with the exception of CPT-15. Drilling refusal was met at the location <br /> of CPT-1 at 89 feet bgs during CPT logging prior to attaining the target depth of 150 feet bgs. <br /> One additional attempt(CPT-1A) to complete the boring to 150 feet bgs was made by <br /> moving a short distance from the original location. Refusal was again encountered at 95 feet <br /> bgs. <br /> PHS/EHD boring permits(#021331 and#021328)were obtained prior to beginning <br /> fieldwork. All boring locations were marked prior to drilling activities and Underground <br /> Service Alert(USA)was notified. California Department of Transportation(CalTrans) <br /> encroachment permits(No. 1099-6SV-1022;and 1000-6SV-0128)were obtained prior to <br /> beginning fieldwork on the shoulder area of Highway 4. <br /> 3.1.2 Soil and Grab Groundwater Sampling <br /> Adjacent to each of the CPT borings,additional borings were installed to obtain soil and <br /> grab groundwater samples. These borings were completed using direct push methods that <br /> are compatible with the CPT sampling rig, as described below.The exact sampling depths <br /> were determined in the field by the onsite field geologist based on the CPT lithologic logs. <br /> Groundwater samples were collected at significant changes in lithology and focused on <br /> permeable,coarse-grained units. <br /> Sol! Sampling <br /> Soil samples were collected using a piston-type sampler. The sampling tool is pushed in the <br /> 1. 'closed'position to the desired sample interval. The inner cone tip portion of the sampler is <br /> then retracted approximately 12-inches,leaving a hollow soil sampler containing two inner <br /> SPOWT REPORT I.DOCI00670036 3-1 <br /> t <br />