FIELD DOCUMENTS AND WORK PLANS 2004-2014

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Mr. Siddharth Sewalia and Mr.Martin Hermann Notification of Adjustment to Full-Scale In Situ Treatment Performance Sampling of the North Yard Former Marley Cooling Tower Site Page 2 June 4,2013 and should be maintained until such time that SPX conducts activities that would require full- scale MRP Section II monitoring. Background Two groundwater monitoring programs are being performed in accordance with the MRP, Section I Groundwater Monitoring, referred to as "site-wide groundwater monitoring" and Section II Groundwater Monitoring Upon Initiation of Reductant Solution Injection, referred to as "performance monitoring." When wells are removed from the performance monitoring program, they continue to be sampled under the site-wide groundwater monitoring program. Monitoring well locations are shown on Figure 1. SPX currently operates a groundwater extraction and treatment system with onsite water treatment to contain and remediate groundwater impacted by Cr+6. The cleanup process has been expedited by in situ groundwater remediation through injection of a reductant treatment solution, in accordance with the DTSC- approved Final Remedial Action Plan (RAP) Amendment(MWH Americas, Inc. [MWH],2007). Requested Adjustment to the North Yard Performance Monitoring Program MRP Section II, Groundwater Monitoring Upon Initiation of Reductant Solution Injection (Full- Scale In Situ Treatment) identifies 30 wells in the North Yard that are to be sampled to monitor performance of the in situ groundwater remediation effort when amendment injection is occurring north of the Stockton terminal and eastern rail spur. The 30 wells are presented on Figure 1. Of the 30 wells that are to sampled quarterly for four quarters following an injection event, SPX's evaluation determined that 24 wells should be reverted to MRP Section I monitoring and at SPX's discretion, six wells have been retained for quarterly sampling in the North Yard area in order to continue to track and monitor the chromium plume. The following six wells were selected for continued monitoring due to location within the chromium plume and/or location along the general groundwater flow gradient, moving from the former retort pit toward the southeast: • EW-3—Well is located at the former retort pit, in the Shallow Zone. • MW-213 (I-7)—Well is located downgradient from EW-3, in the Intermediate Zone. • MW-4495 —Well is located downgradient from EW-3 and MW-213, in the Intermediate Zone. • MW-449D—Well is located downgradient from EW-3 and MW-213, in the Intermediate Zone. • MW-4 — Well is located downgradient from EW-3 and down/cross gradient from MW- 213, along the facility boundary, in the Intermediate Zone. • MW-320 — Continue monitoring as a control well, to ascertain if plume migration offsite in the Intermediate Zone is occurring. The following 24 wells were identified as not requiring continued MRP Section II monitoring based on (1) the last set of North Yard groundwater amendment injections occurred in October