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i GROUNDWATER SAMPLING PROCEDURES The locations of the groundwater monitoring wells and other relevant features are shown on Figure 2 Table 1 summarizes the construction details for all monitoring and co-extraction ' wells related to the site investigation Following groundwater level measurements, groundwater samples were collected on July 8, ' 1999 The following protocol was used in obtaining groundwater samples • Before purging, water levels were measured with an electronic interface tape capable of ' measuring the static water level and hydrocarbon product/water interface in one immersion Before sampling, the wells were purged to replace stagnant water in the well i with fresh aquifer water The wells were purged using either an air diaphragm or submersible pump All wells were purged until dry or until four well-volumes of groundwater were removed The purged water was monitored for temperature, pH and ' conductivity Purging was considered complete when these parameters had stabilized When possible, the wells were sampled after 80 percent or greater recovery Turbidity, dissolved oxygen and oxidation-reduction potential of the samples were also measured ' Appendix A contains copies of the Purge/Sampling Worksheets • To minimize potential cross-contammation between wells, all measuring, purging and sampling equipment was washed in an non-phosphate detergent solution, rinsed with tap water, and then rinsed with distilled water prior to sampling each well ' The sampling procedures for each monitoring well consisted of extracting well water with a clean TeflonTM bailer attached to a clean nylon cord Water collected for analysis of ' TPHg and BTEX was decanted into 40-milliliter glass vials with TeflonTM-lined septa The samples were preserved with hydrochloric acid and acidified to a pH of approximately 2 0 All samples were labeled and placed in a refrigerated cooler with the ' chain-of-custody document Samples transported to the laboratory were analyzed within the specified holding time Samples stored overnight at ATC were refrigerated at a temperature of approximately 4°Celsius iThe groundwater samples were analyzed for TPHg utilizing EPA Method 8015M, for BTEX and MTBE utilizing EPA Test Method 8020 One trip blank was submitted with the samples for analytical quality control • Groundwater produced during purging and sampling was contained in 55-gallon drums ' and tciiipotatily stored at the site i '�