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® 3.0 AUSTIN UNIT 3.1 WATER QUALITY MONITORING 3.1.1 Sampling and Laboratory Analyses The Austin Unit's DMP and CAP groundwater monitoring wells and surface water monitoring stations were sampled by BAS on August 28 and 29, 2006. Prior to collection of samples, depth-to-water measurements were recorded in the groundwater monitoring wells on August 28, 2006. Of note, well AMW-5 was not sampled this quarter due to an inoperable pump and well AMW-3 has been buried or destroyed during recent grading activities in the vicinity of well AMW-3. Forward is currently preparing a work plan to abandon both wells. A single sample set was collected from each sampling point and submitted to BC for analysis of the parameters stipulated in RWQCB Order No. R5-2003-0049. Table 2-1 presents the monitoring schedule and summarizes the analytical methods utilized during the current monitoring period. Water quality samples were also analyzed in the field for dissolved oxygen,turbidity, temperature, specific conductance, and pH and recorded on well data sheets. The groundwater monitoring wells, surface water monitoring points, and leachate(sampled monthly)were sampled in accordance with the sampling and analysis procedures detailed in Appendix B. The well data sheets, raw laboratory data, certificates of analyses, and chain-of-custody records related to the sampling program are included in Appendix C. The results of both field and laboratory analyses are summarized in Tables 3-1 through 3-5. 3.1.2 QA/QC Results The QA/QC program completed for the third quarter 2006 water quality monitoring event at the Austin Unit included analyses of three ambient(field)blanks, three trip blanks, three laboratory method blanks, two equipment blanks, and one duplicate sample. The trip, field, and equipment blanks were analyzed for VOCs by EPA Method 8260, while method blanks were analyzed for all of the monitoring parameters and are included with the laboratory data in Appendix C. Trace and/or quantifiable concentrations of VOCs including acetone,bromoform,bromodichloromethane, chloroform, dibromochloromethane,methylene chloride, and t-butyl alcohol were detected in QA/QC ambient,trip, equipment, and method blank samples during the third quarter 2006 monitoring period. Review of the analytical data indicates that bromodichloromethane, bromoform, and dibromochloromethane were detected in several of the primary samples collected, and were flagged as suspected laboratory contaminants. BC was notified about the suspected laboratory contaminants and performed an internal QA/QC investigation which concluded that the suspected laboratory contaminants were the result of contaminated VOA containers. BC has since destroyed all VOA containers from the contaminated batches. n:u003021W—rdA —06.aoc 9 Geologic Associates