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COLORADO LEGACY LAND <br /> TECHCNIAL REVESION 27,RESPONSE TO COMMENTS: <br /> Comment 1:The Operator is proposing to sample the various groundwater sumps as an aggregate sample,rather <br /> than as individual samples,as has been the past practice.The Division is concerned that by sampling the sumps <br /> in aggregate,it may prevent the detection of trends in the alluvial groundwater quality.Please provide a technical <br /> justification for changing the sampling methodology on the groundwater sumps. <br /> Response: The true test of successful reclamation will be determined when Ralston Creek can naturally flow across <br /> the property. This is a cumulative and binary criterion. Individually sampling the sumps does not contribute to <br /> evaluating this criterion. Furthermore, one or more of the sumps may be removed during excavation work, and <br /> ultimately all of the sumps onsite will be removed during reclamation. Trends in alluvial groundwater quality will <br /> continue to be monitored bygroundwater wells upgradient and downgradient of the sumps onsite. Analytical data <br /> obtained by sampling groundwater monitoring wells are more representative of environmental site conditions, <br /> whereas sump water is influenced by the dewatering pumps. For these reasons a cumulative `Sumps"sample is <br /> recommended to monitor the chemical concentration and geochemical properties of the sump capture system. <br /> Comment 2:The new submersible pump location will require the installation of a 5"High Density Polyethylene <br /> Pipe.The pipe will convey untreated water from the mine pool to the water treatment plant.As required by Rule <br /> 6.4.21(7)(e), describe any release response procedures, redundancies, and "backup" measures necessary, <br /> appropriate,and economically reasonable to control,prevent and mitigate releases of the toxic materials from <br /> the containment facility(pipeline) outside the permit area during reclamation operations. <br /> Response: As part of the automation design an emergency shut down will be programmed to control the new mine <br /> pump without operator intervention. The emergency condition will be initiated from two inputs that will be wired <br /> directly to the mine pump Programable Logic Control(PLC)and correspond directly with the mine pump effluent <br /> line process. The designed inputs will relay back to the PLC, data that is indicative of a properly controlled system <br /> and adequate flowing water. The first input will be a pressure reading transducer that will be installed at the well <br /> head/vent shaft head and will register an operational pressure.Should the pressure deviate due to lack of water in <br /> the line the mine pump will go into a shutdown situation. The second operational constraint will be determined from <br /> a flow meter that will be installed to monitor the collection tank inletflow rate. Should the flow rate drop to a value <br /> that is less than what is required for system operation the pump will go into a shutdown situation. <br /> In addition to the direct emergency shut down associated with mine pump process,an indirect emergency control <br /> will be latched to the Mine Pump operation by using the reverse osmosis (RO) system shutdown. Due to input <br /> programming that is used to control the RO integral PLCs, both RO skids will completely shut down if the overall <br /> Water Treatment Plant system parameters fall outside of proper operational criteria. The two key indicators are <br /> Low pressure and High pressure.Although this feature is dedicated to preserve the RO equipment it will be used to <br /> protect all other Water Treatment equipment and spill potential by controlling the mine pump PLC run command. <br /> In this scenario,feed water loss will be demonstrated by a rapid decrease in pressure and this will trigger the mine <br /> pump to shutdown. <br /> The proposed emergency controls are similar to the automation design that is currently in place on both 10 <br /> horsepower(HP)and 25 HP pumps. The conceptual design for the Automation controls has proved successful in real <br /> time application in both quarterly testing and in real time shut down situations.As part of the commissioning plan <br /> for the 60 HP pump all safety mechanisms will assessed by real world tests and once confirmed for proper operation <br /> then the system will be used. <br /> To address a line spill that could potentially occur outside of the permitted area,the operator proposes installing a <br /> secondary containment around the mine water effluent pipe. The primary 5-inch HDPE will be installed inside of a <br /> larger diameter 8-inch HDPE pipe and then routed to the collection tank secondary containment In the event of a <br /> line rupture the untreated mine water will be controlled by the 8-inch containment line into the tank battery <br /> containment located on the mesa and to the immediate east of the RO water treatment plant The quantity of water <br /> will be limited to a single water column due to the emergency shut down programming that is described in the <br /> previous paragraphs. <br /> PAGE 2 OF 3 <br />