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SECTION 3 SUMMARY OF FIELD METHODOLOGY I the sampling device using a small diameter bailer and transferred to appropriate sample i containers,placed in ziplock bags,and placed in an ice-filled cooler. All groundwater samples were analyzed for TPH-gas and BTEX by EPA Method 8015/8020, oxygenates(MTBE,TAME,DIPE,ETBA,and TBA), 1,2-dichloroethane (1,2-DCA),and 1,2-dibromoethane (EDB)by EPA Method 8260,by Chromolab,Inc.,located in Pleasanton, California. 3.2 Monitoring Wells 3.2.1 Monitoring Well Installation Six monitoring wells were installed during this field investigation downgradient and cross- gradient to the site (Figure 4). Four wells were installed to depths of 90 to 1.10 feet bgs (MW-DIS-11 through MW-DIS-14). Two deeper wells were installed to depths of 145 and 165 feet bgs (MW-DIS-11D and MW-DIS-14D). One well was drilled using mud-rotary drilling methods (MW-DIS-11D),and all others were drilled using hollow-stem auger drilling methods.Soil samples for lithologic description were collected at 5-foot intervals i. from ground surface to approximately 80 feet bgs and continuously below 80 feet bgs. All new and existing wells at the DISCO site were resurveyed using GeoTracker standards by Kjeldsen,Sinnock&Neudeck,Inc., of Stockton California.Northing and Easting are NAD 83 State Plane Coordinates,from GPS. The elevation is based on City of Stockton Reference Benchmark#170(elevation 21.60 NGVD 29);City of Stockton Vertical Control Datum November 1996 Adjustment(revised March 2000). Elevation values were approximately 1.15 feet lower than the previous survey elevations. Information regarding the previous the survey vertical control datum is absent. Survey information is included in Appendix D 3.2.2 Groundwater Sampling All newly installed wells were developed via swabbing,surging,bailing and pumping. Groundwater samples were collected by from each well by DelTech Geotechnical Services. DelTech Field Sampling Sheets are included in Appendix A.Groundwater samples from the newly installed monitoring wells were analyzed for TPH-gas and BTEX by EPA Method 8015/8020,1,2-DCA,and 1,2-dibromoethane (EDB)by EPA Method 8260,by BSK Analytical Laboratories,located in Fresno,California. MW-DIS-11D was also analyzed for oxygenates 1 (MTBE,TAME,D1PE,ETBA,and TBA). r 3.3 Permits Prior to beginning fieldwork, the following City of Stockton,San Joaquin County PHS/EHD,and California State Department of Transportation(CalTrans)permits were obtained: • City of Stockton Encroachment permit#66369 (Control Number 08010A)was obtained i for CPT borings and monitoring wells installed in City of Stockton right-of-way; 1 SFOICPTMW REPORT_KS;DOC*03B7003$ 3-2