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RBC.INC. ID:303-698-9241 FEH 19'98 14:52 No .007 P.08 Work Plan for Alluvial Groundwater Characterization, Big Elk Mine adrienBrown Drilling and Completing 3/4-inch Wells The 3/4-inch monitoring wells will be installed using push technology, according to the Standard Operating Procedures (SOP) attached. Au:ordirtg !o geologic logs from monitoring wells installed in the alluvium at the Yoast mine, located to the east of the Big Elk Project area, the alluvium is typically 40 feet deep end consists of silty clay, silty sand, end silty gravel. The drill rig capable of this installation is relatively lightweight, and will caust minimal disturbance. The sampling tubes will be pushed to refusal, at the alluvium/bedrock contact. Geologic samples will be collected in 4-foot intervals, in 1.75-inch diamMer p)astic sample tubes. The samples will be logged according to standard gcologie nomenclature. Samples will not be retained. The wells will be completed using flush-threaded, 0.75-inch ID, 10-slot PV(;, with a natural filter pack. Wells will generally be soreened from 20-40 feet below ground surface, although the final decision as to screen placement will be made by the on-site hydrogeologist, The well completion will consist of e »ntura] filter pack, with a surface seal. The surface completion will consist of a 4-inch diameter area] surface casing, with locking aluminum cap. This casing will be set 2.5-3 feet into a concrete monument, and will extend 2-2.5 feet above ground surface. The surface casing will be painted, and the well ID will he painted or stamped on the casing or will be curved into the concrete monument. Any wells which exhibit artesian or flowing artesian head conditions will be sealed and pressurized to avoid damage by freezing. Wells will be re-pressurized monthly, after routine water level monitoring, during the winter months. Well Development Both the 2-inch and 3/4-inch wells will be developed by surging and pumping, The 2-inch wells will be developed using a weighted 2-itteh surge block on a teflon cable, followed by pumping with n Citundfos submersible pump. the 3/4-inch diameter wells will be developed using a 3/4-inch surge block, attached to 3/R-inch rigid pipe. The wells will be surged using the surge block and pumped using a foot valve to remove fines from the well scrccrt and fornradon immediately near the screen. Water quality parameters, including temperature, pH, conductivity, and turbidity, will he monitored during well development. Wells will be developed until field parameters stabilize and the discharge water is visibly clear. Development will achieve the following results: • Rectify drilling effects, including clogging, smearing, or wntpaetiott of formation materials ¢t borehole wall; • Rectify drilling el'L'ects on hydraulic conductivity (such as localised zones of lower hydraulic conductivity); and Prolaet 74690.980208 8