WORK PLANS - Laserfiche WebLink

Home Browse Search

Lincoln Center - 2 - 29 August 2019 San Joaquin County I cis-1,2-dichloroethene. The Discharger conducted a pilot test for ISCO of the groundwater during 2013 under General Order No. R5-2008-0149-046. Remedial alternatives, including ISCO, were analyzed in an Engineering Feasibility Study, and the selected alternative was presented in a Remedial Action Plan (RAP). The Discharger submitted a Remedial Design/Remedial Action Work Plan (RD/RA Work Plan)with the NOI to perform full-scale groundwater remediation of VOCs and a Notice of Intent to be covered under General Order No. R5-2015-0012 for the associated activities. Central Valley Water Board staff concurred with the design and proposed work in the RD/RA Work Plan in a 23 October 2015 letter. As proposed in the approved RAP and the RD/RA Work Plan, the project consists of injecting dilute, liquid potassium permanganate over a three-year period across two transects, while simultaneously extracting and treating groundwater from the downgradient area. Following the potassium permanganate injection period, groundwater will continue to be extracted, treated, and injected for an additional five years. Before, during, and after the above-proposed remediation program, the groundwater will be monitored to determine the efficacy of the remediation and to monitor for secondary reaction byproducts. A contingency plan, as outlined below, will be implemented if monitoring indicates exceedance of water quality limitations in downgradient compliance wells or if groundwater in the treatment zone does not show adequately declining concentration of secondary reaction byproducts following the injection phase. No comments were received on the draft Notice of Applicability and MRP during the 30-day public comment period ending on 11 January 2016. The first phase (Phase 1) of ISCO injections along the western side of Pacific Avenue began during October 2016 and are ongoing. Monitoring and reporting has been conducted as required by the MRP and has shown significant decreases in VOC concentrations in downgradient monitoring wells including MW-108A, MW-121A-U, MW-123A-L, MW-128A, Al-U, A2-U, A4-U, A4-L, A5-U, and A5-L. Downgradient groundwater extraction has also removed a significant mass of VOCs, and additional extraction wells were installed in the central portion of the VOC plume during 2019. Groundwater monitoring has also shown an increase in VOC concentrations in the original source area along a former sewer line. In response, LCERT has submitted a work plan to perform ISCO injections at 24 locations along the sewer line to target the vadose zone and underlying groundwater to remediate the remaining VOCs in the source area. The ISCO will be conducted with a potassium permanganate solution as permitted under the previous NOA. Monitoring and Reporting Program: As part of the Order, the Discharger is required to perform groundwater monitoring and reporting in accordance with the attached Monitoring and Reporting Program (MRP) to confirm the extent of the treatment area and efficacy of the treatment, and to verify that no adverse groundwater impacts occur due to ISCO treatment. The MRP includes monitoring requirements for two phases of ISCO (Phase 1 and Phase 2) to be conducted across the two transects. The MRP includes the locations of the injection wells and the extraction wells, and monitoring requirements for treatment zone monitoring wells and compliance zone monitoring wells. Background data will be collected from the compliance zone wells to establish