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2020 GROUNDWATER MONITORING REPORT <br />arcadis.com 5 <br />2 GROUNDWATER SAMPLING ACTIVITIES <br />This section discusses the groundwater sample collection methods, and sample handling and chain of <br />custody procedures. Groundwater sampling was conducted at monitoring wells MW-7, MW-12, and MW- <br />13 (Figure 2) on March 11, 2020. <br />Groundwater sampling activities included measurement of the depth to groundwater and depth to well <br />bottom at monitoring wells MW-7, MW-9, MW-11, MW-12, MW-13, DP-1, and NP-1; and piezometers P-2 <br />and P-3. Depth to groundwater was measured using an electronic water level indicator. Depth to <br />groundwater and well bottom was measured prior to purging and sampling monitoring wells MW-7, MW- <br />12, and MW-13. <br />The groundwater samples were collected in accordance with the groundwater monitoring protocol set <br />forth in the GMP (BBL 2002). Prior to collecting the groundwater samples, these monitoring wells were <br />purged using a disposable Teflon® bailer. In general, three well volumes in each well were removed <br />before collecting a water sample. However, due to the slow recharge in MW-7 it was not possible to purge <br />three well volumes from MW-7 within a reasonable period of time. MW-7 was purged dry and left to <br />recharge prior to collecting the sample. The field water quality parameters in wells MW-12 and MW-13, <br />including temperature, pH, and specific conductivity were stable (i.e., less than a 10 percent change <br />between readings) after three well volumes and samples for laboratory analysis were subsequently <br />collected from each well using the disposable bailer. One duplicate sample was collected from MW-12. <br />Samples were placed directly into laboratory-supplied containers and kept on ice in a cooler. Copies of <br />the groundwater sampling forms are included in Appendix C. <br />The unfiltered groundwater samples were then shipped to ACZ Laboratories, Inc. (ACZ) located in <br />Steamboat Springs, Colorado. The samples were submitted for analysis of metals (iron, manganese, <br />potassium, and sodium), total dissolved solids (TDS), and sulfate. The samples collected for dissolved <br />analytes were lab filtered upon receipt at the laboratory. In addition, temperature, pH, and specific <br />conductivity were measured in the field. <br /> <br />