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March 7, 2019 | Page A-1 File No. 0504-119-01 <br />APPENDIX A <br />FIELD METHODS <br />General <br />Groundwater conditions at the Kittitas County Lower Shop in Ellensburg, Washington were monitored on <br />January 30, 2019, by measuring depth to groundwater and sampling groundwater in monitoring wells MW-1 <br />through MW-6. Field methods generally were performed in compliance with the project Work Plan <br />assessment procedures. <br />Groundwater Elevations <br />The static depth to groundwater was measured using a Solinst Model Interface Probe. Measurements were <br />referenced to the north side of the surveyed top-of-casing in each well monument. Groundwater elevations <br />were calculated by subtracting the depth to water measurement from the surveyed well casing elevation <br />and are referenced to the North American Vertical Datum of 1988 (NAVD 88). The probe of the water level <br />indicator was decontaminated after use with a detergent wash, followed by two distilled water rinses. <br />Depths to groundwater measured in the monitoring wells in January 2019 are summarized in Table 1; <br />measurements from this event and two prior events are tabulated in Table A-1. The corresponding <br />groundwater elevations in January 2019 are summarized in Table 1 and shown in Figure 2. <br />Low-Flow Sampling Procedures <br />Groundwater sampling was performed consistent with the United States Environmental Protection Agency’s <br />(EPA’s) low-flow groundwater sampling procedure, as described by EPA (2017). Monitoring wells were <br />purged using a peristaltic pump equipped and disposable tubing. During purging activities, water quality <br />parameters, including pH, conductivity, temperature, turbidity, ORP and DO, were measured using a YSI Pro <br />multi-parameter meter equipped with a flow-through cell; measurements were recorded approximately <br />every 3 minutes. The meter calibration was verified at the beginning of each work day consistent with <br />manufacturer recommendations prior to purging and sampling activities. <br />Groundwater samples were collected after: (1) water quality parameters had stabilized; or (2) a maximum <br />purge time of at least 30 minutes was achieved. During purging and sampling, the purge rate was not <br />allowed to exceed 500 milliliters per minute. Water quality parameter stabilization criteria include the <br />following: <br />■ Turbidity: ±10 percent for values greater than 5 NTU; <br />■ DO: ±10 percent for values greater than 0.5 milligrams per liter; <br />■ Conductivity: ±3 percent; <br />■ pH: ±0.1 unit; <br />■ Temperature: ±3 percent; and <br />■ ORP: ±10 millivolts. <br />After groundwater quality stabilization criteria were reached, the pump’s discharge tubing was <br />disconnected from the flow-through cell, and groundwater samples were collected for analysis.