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Water Quality Monitoring Report <br />First Quarter 2024 <br />www.arcadis.com <br />Forward Landfill 1Q24 Water Quality Mon Report_05012024 6 <br />Forward Unit <br />QA/QC samples at the Forward Unit included two trip blanks, one field blank, one equipment blank, laboratory <br />method blanks, and one duplicate sample. The method blanks were analyzed for all analytes included in the MRP <br />(RWQCB 2014); equipment, field, and trip blanks were analyzed for VOCs by United States Environmental <br />Protection Agency (USEPA) Method 8260. <br />No organic constituents were detected in the trip blanks. Toluene was measured in one field blank and one <br />equipment blank at estimated trace concentrations of 0.34 J micrograms per liter (µg/L) and 0.30 J µg/L, <br />respectively. No VOCs were measured in the laboratory method blanks analyzed with the groundwater samples. <br />Inorganic constituents (chloride, dissolved barium, dissolved calcium, dissolved magnesium, dissolved sodium, <br />dissolved potassium, and sulfate) were measured at estimated trace concentrations in one or more of the <br />laboratory method blanks analyzed with the groundwater samples. Several samples contained similar reported <br />concentrations of these compounds, which are considered suspected laboratory contaminants. <br />Results from the duplicate groundwater sample collected from monitoring well MW-10 are presented in Table 4, <br />along with the primary results for the well. Comparison of the primary and duplicate results for this well indicates a <br />relative percent difference (RPD) of 20 percent or less for the routine monitoring parameters (i.e., ORP, turbidity, <br />temperature, specific conductance, and pH). Based on evaluation of the laboratory QA/QC data, the laboratory <br />results generated for first quarter 2024 were deemed acceptable, and the water quality samples collected from <br />the Forward Unit are representative of water quality at the Site. <br />Austin Road Unit <br />QA/QC samples at the Austin Road Unit included seven trip blanks, one field blank, one equipment blank, <br />laboratory method blanks, and one duplicate sample. The method blanks were analyzed for all required analytes <br />included in the MRP (RWQCB 2014); equipment, field, and trip blanks were analyzed for VOCs by USEPA <br />Method 8260. <br />No organic constituents were measured in the trip blanks, except for tert-butyl alcohol (TBA) detected in one trip <br />blank at a quantifiable concentration of 36 µg/L. Toluene was measured in one field blank and one equipment <br />blank at quantifiable concentrations of 0.26 J µg/L and 0.27 J µg/L, respectively. No VOCs were measured in the <br />laboratory method blanks analyzed with the groundwater samples. Inorganic constituents (chloride, dissolved <br />calcium, dissolved chromium, dissolved magnesium, dissolved potassium, dissolved sodium, and sulfate) were <br />measured at estimated trace concentrations in one or more of the laboratory method blanks analyzed with the <br />groundwater samples. Several samples contained similar reported concentrations of these compounds, which are <br />considered suspected laboratory contaminants. <br />Results from the duplicate groundwater sample collected from monitoring well AMW-34M are presented in Table <br />8, along with the primary results for the well. Comparison of the primary and duplicate results for this well <br />indicates an RPD of 20 percent or less for the routine monitoring parameters (i.e., ORP, turbidity, temperature, <br />specific conductance, and pH). Based on evaluation of the laboratory QA/QC data, the laboratory results <br />generated for first quarter 2024 were deemed acceptable, and the water quality samples collected from the Austin <br />Road Unit are representative of water quality at the Site.