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ATTACHMENT A <br /> FIELD PROCEDURES <br /> Exploratory SoilBorin and monitoring Well Installation <br /> The wells will be drilled using eight-inch diameter hollow-stem <br /> auger drilling equipment and will be logged by a PACIFIC <br /> geologist using the Unified Soil Classification System and <br /> standard geologic techniques. Soil samples for logging and <br /> analysis will be collected at five-foot depth intervals by <br /> advancing a California-modified split-spoon sampler with brass <br /> liners into undisturbed soil beyond the tip of the auger. The <br /> } sampler will be driven a maximum of 18 `:aches, using a 140-pound <br /> hammer with a 30-inch drop. All soil samples will be contained <br /> in brass liners, capped with aluminum foil and plastic end caps, <br /> sealed in glass jars, labeled, and logged onto chain-of-custody r. <br /> documents. samples will be chilled for storage. All downhole <br /> drilling equipment including the split-spoon sampler will be <br /> steam-cleaned between borings. <br /> Soil samples collected at five-foot depth interals will be used <br /> s to perform head-space analyses in the field for volatile organic <br /> 4 compounds. The test procedure involves measuring approximately <br /> 30 grams from an undisturbed soil sample, placing this <br /> ` sub-sample in a clean glass jar, and sealing the jar with <br /> € ! aluminum foil secured under a ring-type threaded lid. The jar <br /> is warmed for approximately twenty minutes, then the foil is <br /> fi pierced and the head-space within the jar is tested for total - <br /> organic vapor, measured in parts per million, with a 1 <br /> photo-ionization detector. The results of these tests will be <br /> recorded on the boring logs. <br /> s <br /> The monitoring wells will be advanced approximately 15 feet into <br /> i the water-bearing zone (while avoiding penetrating a five-foot <br /> thick aquitard, should one be encountered) to a total depth of <br /> approximately 20 to 25 feet. After the maximum depth is <br /> achieved either 2 or 3-inch diameter, flush-threaded, Schedule <br /> 40 PVC casing and 0.020-inch factory-slotted screen will be <br /> installed. The screen will be placed through the entire <br /> saturated section, extending approximately 3 to 4 feet above the <br /> i static water level. A graded sand pack will be placed in the <br /> annular space across the screened interval in each well and will <br /> extend approximately 1/2 to 1 foot above the top of the <br /> screens. A bentonite and concrete seal. will be placed above <br /> the filter pack to the ground surface. A locking cap and { <br /> protective vault box will be installed on the top of each well. <br /> 1i <br /> l <br />