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pH <br />Conductivity at 25 °C <br />Total Dissolved <br />Solids <br />Bicarbonate (HCO )° <br />Calcium (Ca +2 <br />Magnesium (Mg +2)D <br />Ammonia (NH <br />Nitrate <br />Phosphate (PO4 as P) <br />Sodium (Na + ) D <br />Sulfate (SO4 <br />Arsenic (As) <br />Iron (Fe) <br />Lead (Pb) <br />Manganese (Mn) <br />Mercury (Hg) <br />Selenium (Se) <br />Zinc (Zn) <br />D = Dissolved <br />TD = Total Dissolved <br />T = Total <br />TR = Total Recoverable <br />• <br />• <br />RULE 4 PERFORMANCE STANDARDS <br />11. A -8 - Located in the West Fork of Good Spring Creek alluvium, this site represents the condition <br />up- gradient of South Taylor mining activities. <br />For the alluvial groundwater wells, water levels and field water - quality parameters (Temperature, <br />Water Level, pH and Conductivity) will be measured quarterly, samples for laboratory analysis <br />will be collected annually during the second quarter utilizing the paramaters listed below. <br />Annual Groundwater Laboratory Parameters <br />Prior to mining at Lower Wilson, the following three alluvial groundwater monitoring sites will <br />be added to the sampling schedule: <br />1. MW -95 -01 — Located in the Wilson Creek alluvium, this site represents the upstream, <br />undisturbed background conditions of the alluvial aquifer. <br />2. MW -05 -03 — Located in the Wilson Creek and unnamed drainage alluvium, this site <br />represents alluvial groundwater quality immediately downgradient from Lower <br />Wilson. <br />3. MW -95 -02 — Located in the Wilson Creek alluvium, this site represents the <br />downgradient conditions below Lower Wilson and the proposed haul road. <br />Groundwater, Fill Piezometers - The West Pit Fill piezometer will be monitored quarterly for <br />water levels. After mining, two additional piezometers will be installed into the toes of East <br />Taylor Fill and West Taylor Fill as described in Exhibit 21 Item 1. These piezometers will be <br />added to the monitoring program. <br />A future spoil water monitoring well will be drilled (and water quality monitored) as identified on <br />Map 41B in the reclaimed Collom Lite Pit area to monitor and measure the potential development <br />of a spoil aquifer. This location represents the lowest point in the proposed Collom Lite Pit. <br />Points of Compliance - <br />POINTS OF COMPLIANCE - WATER MONITORING, RIO TINTO COLOWYO MINE <br />MEEKER, COLORADO <br />Prepared by Brant A. Dennis, C.P.G. <br />March 2009 <br />When dealing with point of compliance monitoring of ground water in a mining area, the <br />monitoring is dependent on a continuous, non - perched ground water layer /zone that can be <br />monitored, the geologic and structural conditions, and the topography. Currently at the Colowyo <br />Mine (CM), Meeker, Colorado, where mining started over 30 years ago, the mining zone in both <br />the East and West Pits has not encountered any significant shallow or deep ground water, except <br />Couom - Rule 4, Page 16 Revision Date: 8/5/11 <br />Revision No.: PR -03 <br />