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APPENDIX A THE TWINING LABORATORIES,INC. STANDARD OPERATING PROCEDURES This appendix contains the standard operating procedures used by The Twining Laboratories, Inc. (Twining) in performing investigations. Twining observes these procedures in order to obtain consistent, reliable data. The procedures proposed for use for this investigation include the following. • Direct Push Technology, Soil Sampling • Hand Augering and Soil Sampling • Sample Handling and Chain-of-Custody • Laboratory Quality Assurance/Quality Control (QA/QC) • Photoionization Detector(PID) and Drager Tube Analyses • Performing Head Space Analyses • Equipment Decontamination Standard Operating Procedures for Direct Push Drilling;Soil Sampling: Subsurface assessment permits, if required, are filed with the appropriate regulatory agencies prior to conducting field operations. Field activities are performed under the supervision of a California registered geologist or professional engineer. Sampling equipment is thoroughly cleaned before,during,and after each use according to Twining's "Standard Operating Procedures for Equipment Decontamination." Direct Push (Geoprobe or equivalent)involves the use of small(1.25"to 1.5")steel probes that are hydraulically pushed or hammered into the underlying soil formation to a specified depth. At this depth, the operator may extract a soil core or a groundwater or vapor sample. There are two methods for soil sampling;discrete depth soil sampling and continuous core sampling. For discrete depth soil sampling,the sampler is comprised of a hollow cylindrical tube of hardened steel that measures 2 feet in length. Sample sleeves are available; clear acetate or Teflon sleeves (1.125-inch diameter by 2-foot length screen is used.For a continuous core sample the sampler with the sampling tube is pushed to the appropriate depth to collect the sample then the sampler is withdrawn the sample removed and a new sampling tube is placed in the hole and advanced to collect the next sample section. To collect a discrete soil sample the rod is pushed to the appropriate depth then the rod tip is removed to expose the sampler and then the sampler is pushed to the appropriate depth to collect the sample. The bore holes are abandoned by backfilling with a 6-sack cement slurry containing 3 to 5 percent bentonite,or backfilling with hydrated bentonite. Abandonment procedures depend upon the boring depth, depth to groundwater, project objectives, and regulatory requirements. Soil cuttings generated during direct push operations are stockpiled, depending upon project requirements. Stockpiled soil is containerized in United States Department of Transportation- approved drums, or placed on and covered with plastic sheeting, and stored on the site in an area inaccessible to the general public. Typically,the stockpiled soil is characterized by collecting and analyzing composite samples from the stockpile. Twining can recommend an appropriate method for disposition of stockpiled soil based on the analytical results. Disposal will be the responsibility of the client. Standard Operating Procedures for Hand Augering and Soil Sampling: Subsurface assessment permits, if required, are filed with the appropriate regulatory agencies prior to conducting field operations. Field activities are performed under the supervision of a California registered geologist 1� or professional engineer. Sampling equipment is thoroughly cleaned before,during, and after each use according to Twining's "Standard Operating Procedures for Equipment Decontamination."