ARCHIVED REPORTS_WELL ABANDONMENT, SOIL AND GROUNDWATER INVESTIGATION REPORT 2009

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APPENDIX C: FIELD AND SAMPLING METHODS CA DRILLING C.1.1 Well Destruction On August 7 and 8, 2008, Science Applications International Corporation (SAIC) supervised RSI Drilling (C57#802334) in the proper destruction of monitoring wells MW-4 and MW-5. The condition of each well was inspected prior to destruction. The total depth of each well was measured and compared to the well construction details. Hand-auger borings were advanced in compliance with SAIC Environmental Health and Safety Procedure 130, "Subsurface Hazard Avoidance" around the perimeter of each well to 8 feet below ground surface (bgs)to confirm the absence of utilities or other subsurface obstructions. The wells were overdrilled using a Geoprobe° 6620DT track-mounted drill rig equipped with 8.75-inch, hollow-stem augers. The boreholes were backfilled with neat cement using a tremie pipe from total depth to ground surface. A representative of the San Joaquin County Environment Health Department (SJCEHD) was on-site during a portion of each well destruction to ensure that proper procedures were utilized. C.1.2 Soil and Groundwater Investigation On August 11 to 18, 2008, November 17 to 25, 2008, and March 3 to 5, 2009, SAIC supervised RSI Drilling in the advancement of 27 soil borings (SB-18 through SB-30 including SB-2413, and SB-32 through SB-43) at the locations shown on Figure 2. The borings were advanced to ' depths ranging from 10 to 88 feet bgs. In accordance with the approach prescribed in the Technical Approach to Site Evaluation and Decision Making, Old Valley Pipeline Sites (Geomatrix Consultants, Inc., 2005), and to the extent practicable, SAIC attempted to collect soil samples from the target depth, or in the event of contamination, from the most-affected soil interval. The completion of soil borings generally conformed to SAIC Field Technical Procedure [FTP] No. 525, "Soil Sampling Using an Auger." j All borings (with the exception of SB-31, which was advanced to 10 feet bgs using a hand auger) were advanced using a Geoprobe 6620DT direct-push drill rig equipped with 2.25 inch- diameter dual-tube rods along with a continuous coring device used to collect soil samples. Dual-tube tooling was selected to provide a seal when sampling through saturated soils and to facilitate the installation of pre-packed well screens as explained in section C.3. The samples were screened with photo-ionization detection equipment, using procedures consistent with SAIC FTP No. 750, "Field Measurement Procedures—Organic Vapor Detection," to detect the presence of residual petroleum in soil. The soil was logged in general accordance to the Unified Soil Classification System as presented in American Society for Testing and Materials (ASTM) 2488-90 under the supervision of a California Professional Geologist. Other information was entered into field logbooks to document where, when, how, and from whom any vital project information was obtained, using procedures described in SAIC FTP No. 1215, "Use of Field Logbooks." Each open borehole was plugged and abandoned following completion of the soil borings according to SJCEHD requirements. C-1 From Science to Solutions