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SECTION 3 Summary of Field Methodology This section summarizes the field and analytical methods followed during this focused field investigation.The reader is referred to the Work Plan(CH2M HILL,2000)and Addendum to the Work Plan (CH2M HILL,2001)for specific details such as drilling methodology,well construction procedures,sample collection procedures and handling,and equipment decontamination procedures. All boring locations were marked prior to drilling activities and Underground Service Alert(USA)was notified. 3.1 Cone Penetrometer Testing (CPT) 3.1.1 CPT Installation Borings CPT-18 through CPT-24 were installed using a CPT direct push drill rig.CPT lithologic logging was conducted using a standard electronic piezocone (CPTU). CPTU measurements of cone bearing,sleeve friction,and dynamic pore water pressure were recorded at 5 cm intervals for the entire length of each boring. E During this investigation nine CPT borings were installed downgradient and cross-gradient of the Disco site (Figure 4). Four borings(CPT-18 through CPT-21)were installed on Lafayette Street approximately 500 feet downgradient of the previously installed downgradient borings(CPT-10 through CPT-13 and CPT-15). Four borings (CPT-16,-17,-23 and 24)were installed west of Filbert Street cross-gradient to the previously installed CPT borings.CPT-22 was installed east of previously installed boring CPT-13. CPT logs were obtained in each of the borings to a depth of approximately 130 to 150 feet below ground surface (bgs). PHS/EHD boring permits(#0026832 and#021328)were obtained prior to beginning fieldwork. All boring locations were marked prior to drilling activities and Underground Service Alert(USA)was notified. California Department of Transportation(CalTrans) encroachment permits(No. 1099-6SV-1022;and 1000-6SV-0128)were obtained prior to beginning field work on the shoulder area of Highway 4. 3.1.2 Grab Groundwater Sampling Adjacent to each of the CPT borings,additional borings were installed to obtain grab groundwater samples.These borings were completed using direct push methods that are compatible with the CPT sampling rig, as described below.The exact sampling depths were determined in the field by the onsite field geologist based on the CPT lithologic logs. Groundwater samples were collected at significant changes in lithology and focused on permeable,coarse-grained units. Grab groundwater samples were collected at each boring using a groundwater sampler designed for use with the CPT drill rods. Upon reaching the desired depth for the groundwater sample, the sample tool was pulled back 3 to 4 feet,exposing a temporary } 5-foot long 0.75-inch diameter PVC well screen. Groundwater samples were extracted from i SFOICPTMW_REPORT KS_.DOCIM670036 31