COMPLIANCE INFO - Laserfiche WebLink

Home Browse Search

Stantec L & M OPERABLE UNIT- FOURTH QUARTER AND ANNUAL 2012 SITE STATUS, REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT Groundwater Monitoring and Sampling February 1, 2013 • TPHd and TPHo by Environmental Protection Agency (EPA) Method 8015M (Varies per MRP) • TPHg; benzene, toluene, ethylbenzene, and total xylenes (collectively BTEX); and fuel oxygenates (MtBE and TBA) by EPA Method 8260B (Varies per MRP) • Dissolved Arsenic by EPA 6000/7000 Series (during third quarter and in A-Zone wells only per MRP) Groundwater samples were not collected at the UOU and MOU in City of Stockton's wells during 4Q12. Volatile organic compounds, semi-volatile organic compounds, and additional dissolved metals were discontinued from the monitoring and sampling plan during the 2Q12 in accordance with the MRP No. R5-2012-0805. Monitoring well construction details are presented in Table 2. Groundwater elevation and analytical data are presented in Tables 3 and 4. Historical analytical data are presented in Appendix D. Certified laboratory analytical reports, Stantec Lab Validation forms, COC documentation, and field data sheets for 4Q12 monitoring and sampling event performed by Stantec are presented in Appendix E. Gauging data provided by Wallace-Kuhl for the City of Stockton in UOU and MOU wells are included in Appendix F. Electronic Deliverable Format (EDF) upload confirmations for the 4Q12 L&M OU monitoring and sampling event are presented in Appendix G. 2.3 FOURTH QUARTER 2012 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 2.89 ft below mean sea level (MSL) in well MW-3 to 1.85 ft above MSL in well MW-23 (Table 3 and Figure 2). Groundwater gradient during 4Q12 was calculated for two sections of the site (central and eastern). Along the central portion of the site, groundwater flow direction was to the east with an approximate hydraulic gradient of 0.008 foot per foot (ft/ft). In the eastern part of the site, groundwater flow direction was to the south-southwest with an approximate hydraulic gradient of 0.02 ft/ft. Historical gradient data are summarized in Table 5; vertical gradients are summarized in Table 6. A groundwater elevation contour map of the October 15, 2012 monitoring event is included as Figure 2. 2.3.2 Shallow Zone Groundwater Quality Data During 4Q12, groundwater samples were collected from 4 shallow zone wells between October 15 and 17, 2012 (Table 1). Groundwater analytical results are presented in Table 4, and are summarized below. TPHg, TPHd, TPHo, benzene, MtBE, and TBA isoconcentration contour maps are attached as Figures 3 through 8, respectively. Certified laboratory analytical reports for the L&M OU samples are included in Appendix E. In addition, Lab Validation Forms are I:\Tidewater\TW Stockton(P2A)\QMRs\2012\4Q12-Ann ual\4Q12 and Annual QSSR QRSR QMR Stockton_FINAL.doc 2.2