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a <br /> City of Stockton A68101.02C <br /> February 23, 1996 Page A-2 <br /> instances the deepest two samples and/or and sample collected from just above groundwater <br /> are selected for analyses. Samples intended for chemical analyses are sealed with Teflon <br /> tape and plastic end caps, labeled, placed on ice, and delivered to a laboratory, along with <br /> chain-of-custody documentation. <br /> The soil borings may be completed as groundwater monitoring wells, or abandoned by <br /> grouting with a 6-sack cement slurry containing 3 to 5 percent bentonite or by backfilling <br /> with clean soil. Abandonment procedures depend upon the boring depth, depth to <br /> groundwater, project objectives, and regulatory requirements. For borings greater than 15 <br /> feet deep, grout is emplaced through the hollow augers which will extend to within 15 feet <br /> of the bottom of the boring. if required by the local regulatory agency, grout is emplaced <br /> by pumping through a tremie pipe which extends to within 15 feet of the bottom of the <br /> boring. The tremie pipe or augers are withdrawn from the boring in 10-foot increments as <br /> the boring fills with grout. SOPs for groundwater monitoring well installation are described <br /> in a subsequent paragraph (if pertinent to this investigation). <br /> Soil cuttings generated during drilling are containerized in United States Department of <br /> Transportation (DOT)-approved drums, or placed on and covered with plastic sheeting, and <br /> stored on site in an area inaccessible to the general public. Typically, the stockpiled soil is <br /> characterized by collecting and analyzing composite samples from the stockpile. Twining <br /> can recommend an appropriate method for disposition of the cuttings based on the <br /> analytical results. Disposal will be the responsibility of the client. <br /> A-2 Standard Operating Procedures for E ui ment Decontamination: Proper <br /> decontamination procedures reduce the potential for: cross-contamination among sample <br /> locations; and introduction of contamination from outside sources. <br /> Before, during, and following drilling operations, drilling equipment is thoroughly cleaned <br /> using a high pressure hot water (steam) washer. Well casing, screen, end caps, and <br /> centralizers will also be cleaned using the steam washer. <br /> Steam cleaning condensate will be containerized for later disposal. Generally, disposal will <br /> be the client's responsibility. <br /> Sampling equipment and any tools, measuring devices, or other equipment which will <br /> contact soil, groundwater, or any media being assessed will be washed in a low-phosphate <br /> soap and water solution, and rinsed in clean water before each use. The type of soap used <br /> will depend upon project requirements. <br /> A-3 Standard Operating Procedures for Sample Handlingand Chain-of-Custody: <br /> Records are developed for samples which include: sampling date, sample type, location, job <br /> number, name of sampling personnel, and method of preservation. Each sample container <br /> is labelled immediately following collection. Chain-of-custody protocol, as described in <br /> United States Environmental Protection Agency, 1986, Test Methods for Evaluating Solid <br />