Laserfiche WebLink
2012 Semiannual Groundwater Monitoring and Evaluation Report <br /> Full-Scale In Situ Hexavalent Chromium Reduction Treatment Implementation <br /> Former Marley Cooling Tower Site, Stockton,California October 2012 <br /> 9.0 ACTIVITIES PLANNED THROUGH 2012 <br /> The following activities are planned through 2012: <br /> • Groundwater monitoring and sampling will continue quarterly. The next sampling event <br /> is anticipated in July 2012. <br /> • The list of wells and analytes may be reduced with DTSC and CVRWQCB concurrence <br /> based on the successful and lasting reduction in Cr and Cr+6 concentrations in the 2008 <br /> and 2010 in situ treatment area. <br /> • Groundwater data evaluation will continue through 2012, including the use of the <br /> decision logic diagram (Figure 5). <br /> • The effect of the full-scale (2008) and supplemental injection (2010) programs will be <br /> monitored. If data from upcoming quarterly sampling events indicate Cr concentrations <br /> have decreased to below the established WQO (50 µg/L), recommendations may be made <br /> to shut down groundwater extraction wells. <br /> • Additional supplemental injections will be executed in the South Yard during the third <br /> quarter 2012. Third quarter 2012 sampling has been conducted prior to the start of <br /> supplemental injections, including the sampling of MW-363. The supplemental injection <br /> will be implemented in accordance with the Final Work Plan for Focused Supplemental <br /> Hexavalent Chromium Reduction as Part of the In Situ Remedial Action Plan Amendment <br /> Activities (MWH, 2012). <br /> MWH. <br /> 9-1 <br />