ARCHIVED REPORTS_HISTORICAL GROUNDWATER ELEVATIONS & ANALYTICAL RESULTS (3)

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Ms. Amy Terrell 31 October 2008 ' Page 5 ' presented in Figure 9. Ammonia was detected at a concentration of 41 mg/L in MW-7, which was significantly less than the 680 mg/L detected in MW-6R • Since August 2006, MW-3 has only had detections above the reporting limits for TON and ammonia. Historical results for these COCs are presented in Figure 7. This well is ' outside the area of any pilot treatment areas. o Historically, TON and ammonia concentrations at MW-3 show seasonal ' variability with an overall decreasing trend since groundwater monitoring began at the Site. Downgradient=MW-5 Well MW-5 is located approximately 430 feet east of the Site in the Welty Road right-of-way, ' across the street from the off-site Expanded Pilot Test plot. COC concentrations detected at MW-5 are generally lower compared to on-site wells. Historical results for MW-5 are presented ' in Figure 10. • TON and ammonia were detected in the sample collected from MW-5 at concentrations ' of 3.8 and 0.28 mg/L, respectively. • 1,2-DCP concentrations have fluctuated with an overall decreasing trend since 2005 and a ' concentration of 3.0 µg/L during the August 2008 monitoring event. • EDB and 1,2,3-TCP were detected in MW-5 during the August 2008 sampling event at ' concentrations less than 1 µg/L. DBCP concentrations remain non-detect. ' OA/OC Review Geosyntec conducted a quality assurance/quality control (QA/QC) review of the analytical data from Calscience. Data were reviewed for completeness, accuracy, precision, sample contamination, conformance with holding times, and detection limits within acceptable ranges. Results of the review indicate the data are of acceptable quality. ' P:\PRJ2003REM\WFS\VER\VERG\3Q08\Report Text\3Q08 Report WFS-VER.doc ' engineers I scientists I innovators