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Mr.M. Scott Mansholt—CEMC Annual 2009 Groundwater Monitoring and Sampling Report April 3,2009 US Can-Welty Road Page 5 of 5 QUALITY ASSURANCE/QUALITY CONTROL All field procedures were conducted in accordance with SAIC's quality assurance/quality control procedures4. SAIC's evaluation concluded that all analytical data are usable as qualified for the purpose of determining chemical concentrations in groundwater at the site. Qualified data with applicable reason codes are shown in Table C-1 of Attachment C. Analytical data collected in support of this investigation are considered precise, accurate, representative, complete, and comparable, and they may be used for their intended purposes unless noted otherwise. CONCLUSIONS AND RECOMMENDATIONS The annual 2009 groundwater monitoring and sampling event was conducted on February 11, 2009. Approximately 0.06 gallon of SPO was removed from MW-1; no measureable amount was observed in MW-2. SPO has been observed intermittently in MW-1 and MW-2 since 1999, with a combined total of 0.51 gallon of product removed from both wells to date. The groundwater sample collected from MW-3 reported a TPHd concentration of 3,000 µg/L, above the WQO and ESL of 100 µg/L. Several PAHs were also detected in excess of their respective screening levels. The TPHd and PAH analyte concentrations detected in MW-3 during the 2009 sampling event are essentially of the same magnitude as the detections reported for this well in 2008, 2006, and 2005. The historical and current data indicate that petroleum hydrocarbon concentrations in groundwater in MW-3 are stable. SAIC recommends the following based on the above conclusions: • Discontinue monitoring and oleophilic sock replacement in wells MW-1 and MW-2, which over 10 years have yielded only minor amounts of SPO in proportion to the cost of SPO recovery efforts. • Discontinue sampling of MW-3. This well is not a perimeter well, and provides no additional information regarding water quality. MW-3 has indicated no significant changes in petroleum hydrocarbon concentrations since 2005. • Properly destroy wells MW-1 through MW-3. 4. SAIL,2007. Quality Assurance and Quality Control Sample Collection,Handling,and Analysis. April(Update).