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6.4.7 Exhibit G — Water Information <br />Past drilling and logging of holes on this property by others reveal that the top of <br />the alluvial groundwater occurs at an average of 6 -7 ft below natural ground <br />surface. Shale, at an average depth of 16 feet on this site, defines the bottom of <br />the alluvial aquifer. The mining operation is to be a dry operation, meaning that <br />dewatering trenches will be constructed at the toes of the pit slopes to prevent <br />accumulation of groundwater in the pit excavations. Water will flow through the <br />dewatering trenches to sumps located at the lowest point of the trench, where <br />pumps are to be set. The predicted maximum dewatering rate is 300 -500 gallons <br />per minute. Mine dewatering effluent will be pumped from discharge points to <br />Boulder Creek. <br />A complete search of all State Engineer's well records and a thorough search on <br />the ground and with aerial photography have shown that no alluvial wells exist <br />within 600 ft of the limits of mining. There are no nearby wells or significant <br />bodies of water that are expected to be adversely impacted by the operational <br />dewatering. Depletions to Boulder Creek will occur due to water taken with the <br />mined product, usage for dust control (0.1 acre - feet/month), and evaporative <br />loss. Impacts to Boulder Creek are addressed and compensated for by the <br />Substitute Water Supply Plan. Replacement water will come from a fully <br />consumable lease agreement with the City of Louisville via Coal Creek. Please <br />refer to the Substitute Water Supply Plan (SSP) submitted to the State <br />Engineer's Office for further detail. ASCI is in the process of updating the SSP to <br />reflect the current mine plan. <br />Backfilling of Cell 2 with shale may cause an increase in water table elevations to <br />the east of the permit boundary. For the purpose of monitoring water levels prior <br />to shale placement and following shale placement, monitor wells shall be <br />installed. The locations of the wells are shown in Exhibits C -2 and F. <br />With regard to the potential effects to water quality due to placement of shale in <br />the alluvial aquifer, a TCLP (Toxicity Characteristic Leaching Procedure) for <br />RCRA metals analysis was performed by Colorado Analytical Labs using EPA <br />approved methods. The sample was composed of a composite of shale material <br />from various sample points for each of the 3 stockpiles. Iron (1.15 mg /I), Lead <br />(0.0023 mg /I) and Manganese (0.95 mg /I) were the only metals detected in the <br />extract. Each of the detected metal concentrations is well below the leachate <br />reference concentrations defined by the CDPHE Hazardous Materials and Waste <br />Division. The analysis is contained herein. <br />All of the Turnpike permit area is contained within the currently defined FEMA <br />floodplain boundary of Boulder Creek. This floodplain boundary is currently <br />undergoing a LOMR (Letter of Map Revision) process that will remove most of <br />the area within the permit area from the floodplain that contains the shale <br />stockpiles and would be elevated above the current grade if the Altemative <br />Reclamation Plan were to be implemented. ASCI is participating in the LOMR <br />process based on the Alternative Reclamation Plan possibility. Following is a <br />letter written by the consultant working for ASCI and the Town of Erie outlining <br />the current status of the LOMR process in the permit area. <br />Turnpike Mining Resource M-2004-009-AM-2 <br />Regular 112 Amendment <br />