ARCHIVED REPORTS_THIRD QUARTER 2011 SITE STATUS, REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT

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Stantec L & M OPERABLE UNIT-THIRD QUARTER 2011 SITE STATUS, REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT Groundwater Monitoring and Sampling October 28, 2011 2.2 LABORATORY ANALYSIS Groundwater monitoring of L&M OU wells during 3Q11 was performed by Stantec. Stantec's standard procedures for groundwater monitoring and sampling are presented in Appendix C. Collected groundwater samples were submitted under chain-of-custody (COC) documentation to Kiff Analytical, a state certified laboratory located in Davis, California and were analyzed for the following: • TPHd and TPHo by Environmental Protection Agency (EPA) Method 8015M • TPHg; benzene, toluene, ethylbenzene, and total xylenes (collectively BTEX); fuel oxygenates (MtBE, di-isopropyl ether [DIPE], ethyl tertiary butyl ether [EtBE], TBA, tertiary amyl methyl ether [TAME], methanol, and ethanol); and volatile organic compounds (VOCs) by EPA Method 8260B • Semi-volatile organic compounds (SVOCs) by EPA Method 8270C • Dissolved metals by EPA 6000/7000 Series (during first and third quarters only per the MRP) Groundwater samples were not collected at the UOU and MOU in city of Stockton's wells during 3Q11. Monitoring well construction details are presented in Table 2. Groundwater elevation and analytical data are presented in Tables 3 through 7. Certified laboratory analytical reports, Stantec Lab Validation forms, COC documentation, and field data sheets for 3Q11 monitoring and sampling event performed by Stantec are presented in Appendix D. Gauging data provided by Wallace-Kuhl for the city of Stockton in UOU and MOU wells are included in Appendix E. Electronic Deliverable Format (EDF) upload confirmations for the 3Q11 L&M OU monitoring and sampling event are presented in Appendix F. 2.3 THIRD QUARTER 2011 SHALLOW GROUNDWATER RESULTS 2.3.1 Shallow Zone Groundwater Gradient Groundwater elevations for shallow zone wells at the L&M OU, MOU, and UOU, ranged from 1.74 ft below mean sea level (MSL) in well MW-3 to 5.41 ft above MSL in well MW-30 (Table 3 and Figure 2). Groundwater gradient during 3Q11 was calculated for two sections of the site (north and southwest). Along the northern portion of the site, groundwater flow direction was to the south-southwest with an approximate hydraulic gradient of 0.007 foot per foot (ft/ft). In the southwestern part of the site, groundwater flow direction was to the northeast with an approximate hydraulic gradient of 0.012 ft/ft. Historical gradient data are summarized in Table 8; vertical gradients are summarized in Table 9. A groundwater elevation contour map of the July 18, 2011 monitoring event is included as Figure 2. I:\Tidewater\TW Stockton(P2A)\QMRs\2011\3Q11\3011 QSSR QRSR QMR Stockton_FINAL.doc 2.2