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2021 Groundwater Monitoring Report <br />www.arcadis.com <br />2021 Holcim FINAL GWMR 5 <br />2 Groundwater Sampling Activities <br />This section discusses the groundwater sample collection methods, and sample handling and chain of custody <br />procedures. Groundwater sampling was conducted at monitoring wells MW-7, MW-12, and MW-13 (Figure 2) on <br />March 18, 2021. <br />Groundwater sampling activities included measurement of the depth to groundwater and depth to well bottom at <br />monitoring wells MW-7, MW-9, MW-11, MW-12, MW-13, DP-1, and NP-1; and piezometers P-2 and P-3. Depth to <br />groundwater was measured using an electronic water level indicator. Depth to groundwater and well bottom was <br />measured prior to purging and sampling monitoring wells MW-7, MW-12, and MW-13. <br />The groundwater samples were collected in accordance with the groundwater monitoring protocol set forth in the <br />GMP (BBL 2002). Prior to collecting the groundwater samples, these monitoring wells were purged using a <br />disposable Teflon® bailer. In general, three well volumes in each well were removed before collecting a water <br />sample. However, due to the slow recharge in MW-7 it was not possible to purge three well volumes from MW-7 <br />within a reasonable period of time. MW-7 was purged dry and left to recharge prior to collecting the sample. The <br />field water quality parameters in wells MW-12 and MW-13, including temperature, pH, and specific conductivity <br />were stable (i.e., less than a 10 percent change between readings) after three well volumes and samples for <br />laboratory analysis were subsequently collected from each well using the disposable bailer. One duplicate sample <br />was collected from MW-12. Samples were placed directly into laboratory-supplied containers and kept on ice in a <br />cooler. Copies of the groundwater sampling forms are included in Appendix C. <br />The unfiltered groundwater samples were then shipped to ACZ Laboratories, Inc. (ACZ) located in Steamboat <br />Springs, Colorado. The samples were submitted for analysis of metals (iron, manganese, potassium, and <br />sodium), total dissolved solids (TDS), total suspended solids (TSS), and sulfate. TSS was added to the list of <br />analytes in 2021 to monitor the correlation of concentrations of suspended solids and total iron. The samples <br />collected for dissolved analytes were lab filtered upon receipt at the laboratory. In addition, temperature, pH, and <br />specific conductivity were measured in the field. <br /> <br />