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Stantec <br />L & M OPERABLE UNIT- THIRD QUARTER 2010 SITE STATUS, REMEDIAL SUMMARY, <br />AND GROUNDWATER MONITORING REPORT <br />Groundwater Monitoring and Sampling <br />October 27, 2010 <br />2.2 LABORATORY ANALYSIS <br />Groundwater monitoring of L&M OU wells during the third quarter 2010 was performed by <br />Stantec. Stantec's standard procedures for groundwater monitoring and sampling are <br />presented in Appendix B. Collected groundwater samples were submitted under <br />chain -of -custody (COC) documentation to Kiff Analytical, a state certified laboratory located in <br />Davis, California and were analyzed for the following: <br />• TPHd and TPHo by Environmental Protection Agency (EPA) Method 8015M <br />• TPHg; benzene, toluene, ethylbenzene, and total xylenes (BTEX); fuel oxygenates <br />(MtBE, di -isopropyl ether [DIPE], ethyl tertiary butyl ether [EtBE], TBA, tertiary amyl <br />methyl ether [TAME], methanol, and ethanol); and volatile organic compounds (VOCs) <br />by EPA Method 8260B <br />• Semi -volatile organic compounds (SVOCs) by EPA Method 8270C <br />• Dissolved metals by EPA 6000/7000 Series (during first and third quarters only per the <br />MRP) <br />Groundwater samples were not collected at the UOU and MOU in RDA wells during the third <br />quarter 2010. <br />Monitoring well construction details are presented in Table 2. Groundwater elevation and <br />analytical data are presented in Tables 3 through 7. Certified laboratory analytical reports, <br />Stantec Laboratory Validation forms, COC documentation, and field data sheets for the third <br />quarter 2010 monitoring and sampling event performed by Stantec are presented in <br />Appendix C. Gauging data provided by Wallace -Kuhl for the RDA in UOU and MOU wells are <br />included in Appendix D. <br />2.3 THIRD QUARTER 2010 SHALLOW GROUNDWATER RESULTS <br />2.3.1 Shallow Zone Groundwater Gradient <br />Groundwater elevations for shallow zone wells at the L&M OU, MOU, and UOU, ranged from <br />5.09 ft below mean sea level (MSL) in well DPE-6 to 4.68 ft above MSL in well MW -30 (Table 3 <br />and Figure 2). Groundwater flow direction during the third quarter 2010 was observed in two <br />sections of the site (northeast and southwest). Along the northeast portion of the site, <br />groundwater flow direction was to the south-southeast with an approximate hydraulic gradient of <br />0.024 foot per foot (ft/ft). In the southwestern part of the site, groundwater flow direction was to <br />the northeast with an approximate hydraulic gradient of 0.01 ft/ft. Historical gradient data are <br />summarized in Table 8; vertical gradients are summarized in Table 9. A groundwater elevation <br />contour map of the July 19, 2010 monitoring event is included as Figure 2. <br />I:\Tidewater\TW Stockton (Parcel 2A-0415)\Reports\QMR\2010\3010\3010QSSRORSROMR Stockton_FINAL.doc 2.2 <br />