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L & M OPERABLE UNIT- FIRST QUARTER 2012 SITE STATUS, REMEDIAL SUMMARY, <br />AND GROUNDWATER MONITORING REPORT <br />Groundwater Monitoring and Sampling <br />April 30, 2012 <br />I:\Tidewater\TW Stockton (P2A)\QMRs\2012\1Q12\1Q12 QSSR QRSR QMR Stockton_FINAL.doc 2.2 <br />2.2 LABORATORY ANALYSIS <br />Groundwater monitoring of L&M OU wells during 1Q12 was performed by Stantec. Stantec’s <br />standard procedures for groundwater monitoring and sampling are presented in Appendix C. <br />Collected groundwater samples were submitted under chain-of-custody (COC) documentation <br />to Kiff Analytical, a state certified laboratory located in Davis, California and were analyzed for <br />the following: <br />TPHd and TPHo by Environmental Protection Agency (EPA) Method 8015M <br />TPHg; benzene, toluene, ethylbenzene, and total xylenes (collectively BTEX); fuel <br />oxygenates (MtBE, di-isopropyl ether [DIPE], ethyl tertiary butyl ether [EtBE], TBA, <br />tertiary amyl methyl ether [TAME], methanol, and ethanol); and volatile organic <br />compounds (VOCs) 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 City of Stockton’s wells <br />during 1Q12. <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 Lab Validation forms, COC documentation, and field data sheets for 1Q12 monitoring <br />and sampling event performed by Stantec are presented in Appendix D. Gauging data provided <br />by Wallace-Kuhl for the City of Stockton in UOU and MOU wells are included in Appendix E. <br />Electronic Deliverable Format (EDF) upload confirmations for the 1Q12 L&M OU monitoring and <br />sampling event are presented in Appendix F. <br />2.3 FIRST QUARTER 2012 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 />3.27 ft below mean sea level (MSL) in well MW-3 to 4.17 ft above MSL in well MW-30 (Table 3 <br />and Figure 2). Groundwater gradient during 1Q12 was calculated for two sections of the Site <br />(north and southwest). Along the northern portion of the Site, groundwater flow direction was to <br />the southwest with an approximate hydraulic gradient of 0.004 foot per foot (ft/ft). In the <br />southwestern part of the Site, groundwater flow direction was to the east-northeast with an <br />approximate hydraulic gradient of 0.01 ft/ft. Historical gradient data are summarized in Table 8; <br />vertical gradients are summarized in Table 9. A groundwater elevation contour map of the <br />January 17, 2012 monitoring event is included as Figure 2.