ARCHIVED REPORTS_ANNUAL 2014 GRAOUNDWATER MONITORING AND SAMPLING REPORT

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Mr.C.Dean Hubbard—Central Valley RWQCB Annual 2014 Groundwater Monitoring and Sampling Report April 29,2014 Alden Park Page 6 of 7 MW-16, MW-18, MW-20, and MW-21 between the second quarter 2013 and April 2014. 1 Approximately 1,498 gallons of SPO/water mixture have been removed from the wells to I date. See Table 6 for a summary of SPO/water thickness measured and cumulative volumes extracted through March 2013. Table 7 presents SPO thickness measurements beginning second quarter 2013. Copies of the field data sheets containing SPO/water measurements are included as Attachment B. OLEOPHILIC SOCK REPLACEMENT Oleophilic socks were installed in MW-5 and MW-21 in 2004 due to the presence of relatively minor amounts of SPO. During the first quarter of 2013, SAIC used an oil- water interface probe to estimate the thickness of the product in MW-5 at approximately ' four inches. Based on the thickness of SPO in the well,this well was added to the vacuum extraction network. The oleophilic sock in MW-21 was inspected during each quarterly event and replaced during the fourth quarter 2013. Between the second quarter 2013 and April 2014, approximately 11 ounces of SPO were extracted from MW-21. Well MW-21 commonly does not exhibit SPO, or exhibits only a hydrocarbon sheen, thus the sock in well MW-21 is not necessarily replaced during each quarterly event. See ' Table 4 for a summary of cumulative volumes extracted. QUALITY ASSURANCE/QUALITY CONTROL All field procedures were conducted in accordance with SAIC's quality assurance/quality ' control procedures4. Leidos' evaluation concludes that all analytical data are usable as qualified for the purpose of determining chemical concentrations in groundwater at the ' Site. Qualified data for this sampling event with the applicable reason codes are provided in Table C-1 of Attachment C. ' Analytical data collected in support of this investigation are considered precise,accurate, representative, complete, and comparable, and may be used as qualified for the intended purposes unless noted otherwise. ' CONCLUSIONS AND RECOMMENDATIONS Groundwater samples were collected on March 28,2014, from MW-4, MW-7 through ' MW-12, and MW-14; SPO extraction was generally performed on a quarterly basis on MW-1, MW-3, MW-5,MW-6, MW-15, MW-16, MW-18, and MW-20. The calculated groundwater elevation and gradient were consistent with historical results. ' Approximately 72 gallons of SPO were removed between the second quarter 2013 through April 2014. TPHd was not detected in any sample collected in the March 2014 sampling event. Naphthalene was the only PAH detected in the groundwater samples, and the low concentrations did not exceed the respective WQOs and/or ESLs. ' 4. SAIL,2007. Quality Assurance and Quality Control Sample Collection,Handling,and Anal sis. A ' g y April(Updated).