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5.1.2 Supply Well DW -1. Currently, supply well DW -1 is not active and does not have a submersible pump, pitless unit, or power supply. As construction of the processing facility begins, DW -1 will be put into service. Purging and sampling the well requires different sampling techniques depending on if the well is operational (pump installed). 5.2 Field Observations 5.1.2.1 DW -1 Sampling Protocol — Prior to Permanent Pump Installation. Supply Well DW -1 is a 10 inch diameter well extending to a total depth of 624 feet and is screened across the Dakota aquifer beginning at 514 feet (top). The static head in the well was measured by Leonard Rice and Associates in January 2003 to be approximately 65 feet below the ground surface. Because a large quantity of water would be purged to remove three full well volumes prior to sampling the well, the samplers will use the low stress purging and sampling procedure for the collection of groundwater from monitoring wells developed by the U.S. Environmental Protection Agency Region I (EPA). Sampling by this method captures the water that flows through the well under the natural (or near - natural) hydraulic gradient. A copy of the EPA procedure is provided in Appendix A. 5.1.2.2 DW-1 Sampling Protocol — After Permanent Pump Installation. Once the well is operational and producing water regularly, there will be no need to purge the well prior to sampling. Following are the steps for sampling DW -1 when it is operational. • Measure the depth to groundwater from the top of the casing via air line and /or transducer. • Record field water quality measurements in the field notebook. Field water quality measurements include pH, SC /EC, and temperature. Collect the groundwater sample upstream of the chlorination system at a sample port and fill laboratory- prepared containers assigned to the well. Once in place, the sample port will be inspected by DMG personnel to determine if the port will need to be purged prior to sampling. This sampling plan will be updated once the port is inspected by DMG. • Note and record pumping rate from the flow meter. • Submit the groundwater samples to an EPA - certified laboratory for analysis. Collected sample water will be field - analyzed. Measurements, using portable in -stream meters (YSI or comparable) following EPA - approved standard techniques and equipment calibration procedures, will be made for pH, SC /EC, and temperature. Calibration for: pH and SC /EC will be completed at the start of each day and recorded in the field notebook. P:\ Dan\ GEN\ F- S -P -T\ 22421 \Permttnng \Snpulanon Response \Groundwater Sampling Plan \Condition 1 Groundwater Sampling Plan 3_24_03.doc 8