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} ENVIRONMENTAL SCIENCE& ENGINEERING,'INC. CONCORD, CALIFORNIA OFFICE STANDARD OPERATING PROCEDUREINO.3 FOR GROUND-WATER MONITORING AND SAMPLING FROM MONITORING WELLS Environmental Science & Engineering, Inc:(ESE) typically performs ground-water monitoring at project sites on a quarterly basis. As part of the monitoring program an ESE staff member will first gauge the depth to water and free product (if present) in each well, then collect ground-water samples from each well. Depth to water measurements are taken by lowering an electric fiberglass:tape measure into the well and recording the occurrence of water in feet below a fixed datum set on the top of the well-casing. If free-phase liquid j hydrocarbons(free product)are known or suspected to be present in the well,then an electric oil/water interface probe is used to determine the depth to thetoccurrence of ground-water and the free product in feet below the fixed datum on the top of the well-casing. Depth to water and depth to product measurements are measured and recorded within an accuracy of 0.00546ot. The electric tape and the electric oil/water interface probe are washed with an AlconoxO detergent and tapiwater solution then rinsed with tap water between uses in different wells: Ground-water samples are collected from a'well subsequent to purging a minimum of three to four well-casing volumes of ground water from the well, if the well Bails dry;prior to the removal of the required minimum .. volume, then the samples are collected upon the recovery of the ground water in that well to 80% of its initial static level. Ground water is typically purged from monitoring wells using either a hand:operated positive displacement pump,constructed of polyvinylchloride(PVC);a new(precleaned),disposable polyethylene bailer; or, a variable-flow submersible pump, constructed of stainless steel and Teflon. The hand pumps and the submersible pumps are cleaned between each use with an Alconox®detergent and tap water solution followed by a tap water rinse. During the well purging process.the conductivity,pH and temperature of the ground water are monitored by the ESE staff member. G'iound-water samples.are collected.from the well subsequent to the stabilization of the of the conductivity, pH and temperature of the purge water, and the removal of four well- i casing volumes of ground-water(unless the well bails dry): The parameters are deemed to have stabilized when f two consecutive measurements are within 106 of each.other,for each respective parameter. The temperature, y pH, conductivity and purge volume measurements, and observations of water clarity and sediment content will be documented by the ESE staff member on ESE Ground-Water Sampling Data Forms. Ground-water samples are collected by lowering a new(precleaned),disposable polyethylene bailer into the well using new, disposable nylon cord. The filled bailer is retrieved, emptied, then filled again. The ground water from this bailer is decanted into appropriate laboratory supplied glassware and/or plastic containers(if sample preservatives are required,they are added to the empty�containers at the laboratory prior to the sampling event). The containers are filled carefully so that no&eadspace is present to avoid volatilization of the sample. The filled sample containers are then labeled and placed in a cooler with ice for transport under chain of custody documentation to the designated analyticallaboratory. The ESE staff member will document the time and method of sample collection, and the type of.'sample containers.and preservatives(if any) used These facts will appear on the ESE Ground-Water Sampling Data Forms. ESE will collect a duplicate ground-water sample from one well for every ten wells sampled at each site. The duplicate will be a blind sample(its well designation will be unknown to the laboratory). The ;duplicate sample -is for Quality Assurance and Quality Control (QA/QC) purposes, and providesa check;on ESE sampling procedures and laboratory sample handling procedures. When VOCs are included in the laboratory analyses, ESE will include a trip blank, if required, in the cooler with the ground-water samples for:analysis for the identical VOCs. The trip blank is supplied by the laboratory and consists of deionized water. The trip blank is for QA/QC purposes and provides a check on both ESE and laboratory sample handling and storage procedures. Since disposable bailers are used for sample collection, and are not reused, no equipment blank (rinsate) samples are collected.. F_\ \m \-T3 I