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The following sampling procedures will be followed to ensure that water levels and quality can be reliably compared from well to well and from sampling event to sampling event and that the data are reproducible. This section also outlines the laboratory analyses required for each groundwater sample. 5.1 Sampling Protocols 5.1.1 Monitoring Wells MW -001A, MW -002, and MW -003. Following is the protocol _ that will be followed for groundwater sampling at MW -001A, MW -002, and MW -003. Note that ; r' MW -001A will be checked for water during each sampling event, and groundwater samples of this ( G- -- `'" v well will be taken only if there is water in the well. 1 Q 2E. , k xe 4 V IX / , . -- ®✓ T D, • Measure the depth to groundwater from the top of the casing using an electric well probe and engineer's scale. \k rfs- X ` • • SECTION 5 SAMPLING PROCEDURES AND ANALYSIS Purge a minimum of three casing volumes. A bailer or a peristaltic pump will be used to purge the wells. The well purge water will be discharged and allowed to infiltrate into the soil or flow in a nearby arroyo. Record field water quality measurements in the field notebook at the start of purge p and after removing the first, second, and third casing volumes. Field water quality measurements include pH, specific conductance /electrical conductivity (SC /EC), and temperature. • Collect the groundwater sample using a bailer or peristaltic pump and fill all laboratory- prepared containers assigned to the well. • Submit e groundwater sa les ACZ Laboratories and Reservoirs Environmental Services for analysis. 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 whether the well is operational (pump installed) or not. 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 P: \Data \GEN \F -S -P -T \22421 \Pecmrtnng \Snpulanon Response \Groundwater Sampling Plan \Condition 1 Groundwater Sampling Plan 2_28_03.doc 7