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Following well construction, the wells are developed in accordance with agency protocols by <br /> intermittently surging and bailing the wells. Development is deemed to be sufficient once <br /> pH, conductivity and temperature stabilize to within approximately <_ 0.1, <_ 3%, and <_ 10%, <br /> respectively, or when ten casing volumes have been removed. <br /> Organic Vapor Procedures <br /> Soil samples are collected for analysis in the field for ionizable organic compounds using a <br /> PID with a 10.2 eV lamp. The test procedure involves measuring approximately 30 grams <br /> from an undisturbed soil sample, placing this sub-sample in a ZiplocTM-type bag or in a clean <br /> glass jar, and sealing the jar with aluminum foil secured under a ring-type threaded lid. The <br /> container is warmed for approximately 20 minutes (in the sun); then the head-space within <br /> the container is tested for total organic vapor, measured in parts per million as benzene <br /> (ppm; volume/volume). The instrument is calibrated prior to drilling. The results of the field- <br /> testing are noted on the boring logs. PID readings are useful for indicating relative levels of <br /> contamination, but cannot be used to evaluate petroleum hydrocarbon levels with the <br /> confidence of laboratory analyses. <br /> Equipment Decontamination <br /> Equipment that could potentially contact subsurface media and compromise the integrity of <br /> the samples is carefully decontaminated prior to drilling and sampling. Drill augers and <br /> other large pieces of equipment are decontaminated using high pressure hot water spray. <br /> Samplers, groundwater pumps, liners and other equipment are decontaminated in an <br /> Alconox scrub solution and double rinsed in clean tap water rinse followed by a final distilled <br /> • water rinse. <br /> The rinsate and other wastewater are contained in 55-gallon DOT-approved drums, labeled <br /> (to identify the contents, generation date and project) and stored on-site pending waste <br /> profiling and disposal. <br /> Soil Cuttings and Rinsate/Purge Water <br /> Soil cuttings and rinsate/purge water generated during drilling and sampling are stored on-site <br /> in DOT-approved 55-gallon steel drums pending characterization. A label is affixed to the <br /> drums indicating the contents of the drum, suspected contaminants, date of generation, and <br /> the boring number from which the waste is generated. The drums are removed from the site <br /> by a licensed waste disposal contractor to an appropriate facility for treatment/recycling. <br /> Laboratory Procedures <br /> Selected soil samples were sent under chain-of-custody procedures to a California State- <br /> certified laboratory. The selected soil samples were analyzed for the presence of total <br /> petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, ethylbenzene, and total xylenes <br /> (BTEX), and methyl-tertiary butyl ether (MtBE) using EPA Method 8260B; also, total petroleum <br /> hydrocarbons as diesel (TPHd) using EPA 8015M (Modified). <br /> 32 <br />