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C4069kat T"h4ics Inc. `"W Page 4 Work Plan—Additional Site Characterization Marci's Property Project No. 770.2 October 25,2001 2.2.1 Groundwater Sampling Procedure Before sampling is attempted, the wells will be sounded for depth to water and then a clear disposable bailer will be used to determine if floating product is present. The wells will be purged of at least 3 well volumes of stagnant water using a submersible pump, a dedicated Waterra pump or a stainless steel bailer. Purging will continue until the temperature, conductivity, and pH of the groundwater has stabilized (<10% variation between three readings) indicating that formation water representative of aquifer conditions entering the well is being sampled. These water quality parameters are measured at intervals of each well volume purged. A stainless steel bailer, disposable plastic bailer or dedicated Waterra pump will be used to collect each sample. Care will be taken to minimize sample agitation from the initial filling of the bailer to the transfer of the sample to the VOA vial and glass amber liter bottles. Once the sample container is filled and capped, the bottle will be inverted, tapped, and checked for headspace bubbles. The sample container is identified and labeled with a unique designation, inserted into foam holders and placed in an ice chest cooled to 4°C for transport to the laboratory. All non-disposable sampling equipment will be decontaminated using a steam cleaner before and between uses. The effectiveness of the decontamination procedure is ensured by using the following quality control measures: • Disposable gloves will be used by the technician to collect all samples and will be changed with each sampling event. • A bailer blank for each well will be collected prior to sampling by filling the decontaminated stainless steel bailer with water (provided by the laboratory) and then filling a VOA vial (provided by the laboratory) using the same procedures for actual sample collection. Bailer blanks for each sample, along with a field blank (prepared from water provided by the laboratory poured into a VOA vial on site) will accompany the samples to the laboratory �., and serve as checks against cross contamination. A chain of custody document, listing all samples collected, accompanies the samples from field to laboratory, thereby providing a means to track their movement and ensure their integrity. All water purged from each monitoring well and not used as a sample, will be placed in a 55 6. gallon DOT approved container, properly labeled and stored on site until its proper disposition can be arranged. 2.2.2 Groundwater Sample Analyses Groundwater samples from each well will be submitted to Sherwood Labs of Hilmar, California (Department of Health Services Certification No. 1400) for the following analyses: V