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<br />North County Recycling Center & Sanitary Landfill Department of Public Works/Solid Waste <br />First Semiannual 2025 Groundwater Monitoring Report ©2025 COUNTY of San Joaquin. All Rights Reserved <br /> 6 <br />3 MONITORING PROGRAM <br />3.1 Groundwater <br />Detection monitoring wells on the northern side of the landfill consist of G-7 and G-8. Detection <br />monitoring wells on the western side of the landfill consist of G-5B, G-9, and G-13. Detection <br />monitoring well G-11 is located on the southern side of the landfill. Detection monitoring wells <br />G-10 and G-14 are located on the eastern side of the landfill. Monitoring well G-12 is considered <br />to be the background well for statistical evaluation. <br />The groundwater well network is shown on Figure 3 and Figure 4. During November and <br />December 2016, groundwater monitoring wells G-7 and G-8 were installed. Monitoring well G-9 <br />was installed in October 2017. Monitoring wells G-5B, G-10, and G-11 were installed in February <br />and March 2018. Monitoring wells G-12, G-13, and G-14 were installed in June 2022. <br />Groundwater samples are collected consistent with the Sampling and Analysis Procedures <br />(Appendix A) and monitored semiannually for the following field parameters: <br /> Elevation (Quarterly) pH <br /> Temperature Turbidity <br /> Dissolved Oxygen (DO) Redox Potential (ORP) <br /> Electrical Conductivity (EC) <br />Groundwater samples are analyzed semiannually for the following monitoring parameters: <br /> VOCs Total Alkalinity <br /> Chloride Total Hardness <br /> Total Dissolved Solids (TDS) Chemical Oxygen Demand (COD) <br />Groundwater samples are analyzed annually for the following monitoring parameters: <br /> Bicarbonate Nitrate-Nitrogen <br /> Sulfate Calcium <br /> Magnesium Potassium <br /> Sodium <br />Groundwater samples are analyzed every 5 years for the following additional constituents of <br />concern (COC): <br /> Semi-volatile Organic Compounds Dissolved Metals <br /> Organophosphorus Pesticides Chlorinated Herbicides <br /> Organochlorine Pesticides Polychlorinated Biphenyls (PCB) <br />The 5-year COCs were last collected during 2023. The next 5-year COC monitoring event will <br />occur in the first semiannual period of 2028.