COMPLIANCE INFO_PRE 2019 - Laserfiche WebLink

Home Browse Search

Mr. Eric Jenks -2- 9 September 2015 Groundwater Extraction and Treatment (GETS); Enhanced In Situ Bioremediation (EISB); In Situ Chemical Oxidation; and In Situ Reduction as potential applicable technologies. Based on the alternative evaluation, Wilbur-Ellis proposes EISB as the preferred removal alternative for groundwater at the Site. This alternative involves in situ reduction of Site COCs within the shallow and deeper targeted areas using EISB. On 18 June 2015, Wilbur-Ellis, their consultants Geosyntec, and the Central Valley Water Board staff met to discuss the RAW. In the meeting, the staff concurred with the general approach of the proposed scope of work and its implementation. The Central Valley Water Board staff has the following comments on the subject RAW. Our comments and a response to our comments may be incorporated into the public record during the public comment period. 1. EISB Treatability Study and Well Receptor Survey: Staff concurs with the conclusions of the EISB treatability study. 2. Proposed implementation approach and schedule: The Central Valley Water Board staff concur with implementing the selected remedial alternative of EISB. Re-injecting amended groundwater would require this removal action to be enrolled in the Waste Discharge Requirements (WDRs). Wilbur-Ellis may apply for a General Order for In-Situ Groundwater Remediation and Discharge of Treated Groundwater to Land R5-2015-0012 (General Order). A Notice of Intent (NOI) is needed in order to prepare a Notice of Applicability (NOA) under the General Order. As part of the NOA, a new monitoring and reporting program (MRP) will be issued to comply with the WDRs specifications. Please note, Site-wide groundwater monitoring shall be continued according to the MRP No. R5-2010-0803, 3. Targeted Areas and proposed implementation approach: The RAW proposes to implement the EISB in the shallow target area through a bio-barrier approach which involves a shallow horizontal injection well spanning across the shallow target area and positioned perpendicular to groundwater flow. In the deeper target area, where there are higher COC concentrations, EISB approach involves delivery of electron donor to the deeper target area via a temporarily and intermittently-operated groundwater recirculation system. The Central Valley Water Board concur with the targeted areas and the proposed depths. 4. As part of phase 1 of EISB, the RAW proposes to install one injection well (IW-A) and one nearby groundwater well MW-A in the deeper groundwater zone. Staff concur with the proposed screen interval targeting range of 70-85 feet bgs for the monitoring well MW-A. However, given the downward vertical gradients known to exist in this area, and the screen interval of injection well IW-A (70-85 ft bgs), it is also important to monitor the deeper section of the coarse grained unit beneath the Site. Therefore Wilbur-Ellis needs to propose additional monitoring of the deeper groundwater. An existing deeper groundwater monitoring well may be used to satisfy this condition. 5. The proposed deeper monitoring well MW-A is located approximately 10 feet downgradient of the injection well IW-A. For compliance monitoring just one groundwater well is not sufficient. Wilbur-Ellis needs to monitor at least one upgradient well (from the injection well) and one well each in treatment zone, transition zone and the compliance zone, respectively. Treatment KARL E. LONGLEV ScD, P.E., CHAIR I PAMELA C. CREEDON P.E., BCEE, EXECUTIVE OFFICER 11020 Sun Center Drive#200.Rancho Cordova,CA 95670 1 www.waterboards.ca.gov/centralvalley C1 RECYC.LEO RARER