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Geosyntec° <br /> consultants <br /> 3. WELL INSTALLATION <br /> This section describes the new monitoring well proposed to be installed at RRI in 2024. <br /> As discussed above in Section 1, one new groundwater monitoring well is proposed to be <br /> installed south of the Site 49 Central Area and west of the UST 817B Central Area to define the <br /> extent of petroleum hydrocarbons west of the former UST and vinyl chloride south of Site 49. <br /> The locations and screen intervals for the proposed monitoring well is shown on Figure 4 and <br /> described in Table 2. <br /> 3.1 New Monitoring Well Installations <br /> Monitoring well installation activities will be conducted in accordance with the SOP in <br /> Appendix A. The SOP was previously included in the DTSC- and CVRWQCB-approved 2018 <br /> GMWP (Geosyntec, 2018). All new monitoring wells installed at RRI since 2018 have been <br /> installed in accordance with the SOP. The well construction design details included in the SOP <br /> and in Table 2 are based on the hydrogeologic conceptual site model (CSM) and lithology <br /> encountered at RRI. <br /> 4. GROUNDWATER MONITORING PROGRAM <br /> This section describes the proposed groundwater monitoring program for 2024 at RRI. Pending <br /> DTSC and CVRWQCB approval of this 2024 GMWP, the groundwater monitoring event will be <br /> conducted in the third quarter when concentrations of VOCs have historically been the highest <br /> and the wells at RRI are generally the most accessible (Geosyntec, 2018, 2023). <br /> 4.1 Field Inspection and Depth to Water <br /> Groundwater levels at RRI will be gauged to evaluate groundwater flow directions and gradients. <br /> The wells and piezometers proposed to be gauged in 2024 are listed in Table 3 and were in good <br /> condition the last time they were inspected. The wells and piezometers proposed to be gauged <br /> will be located and visually inspected and the condition will be recorded on a field data sheet. If <br /> the well or piezometer is in good condition, the depth to water and total well depth will be <br /> measured using a water level meter and recorded on a field data sheet with the date and time the <br /> measurement was taken. The wells and piezometers will be gauged within a period of a few <br /> days. <br /> 4.2 Selection of Monitoring Wells for Sampling <br /> Figure 4 show the wells selected for sampling and the constituents each well is proposed to be <br /> sampled for. The wells were selected to meet the objectives described in Section 1.6. The 2024 <br /> sampling plan is provided in Table 3. <br /> Following the initial phase of remediation in the Landfill Area, as described in the Remedial <br /> Action Plan for Soil,Landfill Area (DTSC and CVRWQCB, 2021), construction of the Stockton <br /> Soda Bulk Export terminal will begin, which is currently expected to commence in the third <br /> quarter of 2024 and estimated to continue over approximately two years. Due to on-going soil <br /> remedy and construction efforts in the Landfill Area, only wells and piezometers that were last <br /> RRI 2024 Groundwater Monitoring Work Plan 12 June 13,2024 <br />