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City of Stockton A68109 OIB July 18, 1997 Page A-2 Generally, soil samples selected for analyses typically represent those which the field screening indicated will be most likely to contain the contaminate of concern. In most instances the deepest two samples and/or and sample collected from just above groundwater are selected for analyses. Samples intended for chemical analyses are sealed with Teflon® tape and plastic end caps, labeled, placed on ice, and delivered to a laboratory, along with chain-of-custody documentation. Sail borings may be completed as groundwater monitoring wells, or abandoned by grouting with a sand-cement slurry. Abandonment procedures depend upon the boring depth, depth to groundwater, project objectives, and regulatory requirements. For a boring greater than 15 feet deep, grout is emplaced through the hollow augers which will extend to within 15 feet of the bottom of the boring. If required by the local regulatory agency, grout is emplaced by pumping through a tremie pipe which is extended to within 15 feet of the bottom of the boring. The tremie pipe or augers are withdrawn from the boring in 5-foot increments as the boring fills with grout. SOPS for groundwater monitoring well installation are described in a subsequent paragraph (if pertinent to this investigation). Soil cuttings generated during drilling are containerized in United States Department of Transportation (DOT)-approved drums, or placed on and covered with plastic sheeting, and stored on 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 the cuttings based on the analytical results. Disposal will be the responsibility of the client. A-2 Standard Operating Procedures for Equipment Decontamination: Proper decontamination procedures reduce the potential for: cross-contamination among sample locations; and introduction of contamination from outside sources. Before, during, and following drilling operations, drilling equipment is thoroughly cleaned f !.� using a high pressure hot water (steam) washer. , Steam cleaning condensate will be containerized for later disposal. Generally, disposal will be the client's responsibility. i Sampling equipment and any tools, measuring devices, or other equipment which will contact soil or any media being assessed will be washed in a low-phosphate soap and water solution, and rinsed in clean water before each use. The type of soap used will depend upon project requirements. A-3 Standard Operating Procedures for Sample Handling and Chain-of-Custody: I Records are developed for samples which include: sampling date, sample type, location,job number, name of sampling personnel, and method of preservation. Each sample container is labelled immediately following collection. Chain-of-custody protocol, as described in ! United States Environmental Protection Agency, 1986, Test Methods for Evaluating Solid k