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1� COLORADO LEGACY LAND <br /> 22b On average,how long does it take to bring the water treatment plant and pump back online? Every winter,the water treatment plant is shut down and operators implement a series of"winterization"precautions to prevent <br /> equipment damage.The average amount of time to bring the plant online in the spring is one week. <br /> Please provide more details on how the mine pool levels are monitored throughout the year,and what kind The mine pool elevation is monitored with a pressure transducer that is installed at an elevation of 354.4 feet below the Steve <br /> of alert system(s)are in place. Level.The pressure transducer sends a signal that is processed by a WebMaster Controller.The controller can be accessed <br /> 22c remotely at all times.The controller sends daily data log for review by operators.The mine pool elevation has never been <br /> observed to increase in rates that would warrant the use of an alarm system,but the controller is programed to send operators <br /> an alarm when water levels reach 170 feet below the Steve Level. <br /> 22d Is the 25-hp pump still maintained in the Steve Adit as a potential back-up in the event the 60-hp pump is Yes,the pump is still installed in the shaft and could be put back in operations with less than 2 days notice. <br /> not functional? <br /> 22e How will an"increasing trend"in dissolved uranium concentrations in the mine pool be determined for in- CLL would propose to use the Mann-Kendall trend test to evaluate statically significant trends in the uranium concentrations. <br /> situ treatments? <br /> The Division has the following comments regarding Figure E-1: Revised as requested. <br /> a) Please update this graph to include data collected since March or April of 2021. <br /> 23 b) Please adjust the mine pool elevations prior to October 8,2020 to conform with the transducer <br /> recalibration. <br /> c) Please indicate times the water treatment plant was online and offline. <br /> d) Please include the dates that in-situ treatments were performed. <br /> 24 The Division has the following comments regarding Figure E-2: Please see responses to specific comments below. Please note that the figure numbers have changed,and Figure E-2 is now <br /> Fi ure E-3a and Figure E-3b. <br /> This figure depicts the backfill slurry(RO reject brine)as filling the bottom of Shafts#1 and#2 and Figure E-3a is a rendition of the first in-situ treatment in 2013 and not meant to accurately portray the nuances requested in the <br /> partially filling drifts connected to these shafts.Does the operator have any idea how the backfill slurry is comment.Considering that the workings are perpendicular to the vertical shafts,it is unlikely the backfill slurry gets deposited <br /> actually deposited in the mine workings?Is there a chance the slurry could be filling or partially filling into the workings,therefore,the water treatment operations and pumping are not likely to be affected.For clarity,the"backfill <br /> 24a upper workings rather than sinking to deeper portions of the mine?If so,how would this impact the water slurry"has some suspended solids associated with the addition of barium chloride forming barium sulfate,and during the <br /> pumping and treating operations?Could this scenario result in an isolated mine pool which can no longer addition of in-situ reagents such as molasses,it is denser than RO concentrate,however it doesn't have enough solids to create <br /> be properly sampled or treated?Could this scenario result in contaminated groundwater being redirected isolation and filling of mine workings with solids. CLL has shown the groundwater gradient is from the creek to the mine not vice <br /> toward Ralston Creek? versa so there is no contaminated groundwater being redirected toward Ralston Creek.It is unlikely that an isolated mine pool <br /> would be formed.The sampling of the existing mine pool is most likely representative of existing conditions. <br /> Please describe all water treatment and management infrastructure installed inside the Schwartzwalder There is a 60HP pump installed through the Jeffery Air Shaft,a 25 HP pump installed through the Steve Adit,a transducer <br /> Mine.Will all existing infrastructure remain for final reclamation?How frequently must this infrastructure installed through the Steve Adit,and a pipe (which is also used for the backfill slurry)that is used for in-situ treatment through <br /> 24b be inspected and repaired/replaced? the Steve Adit that discharges at the 1,100 level.The 60HP pump is used seasonally and can be brought to surface for repair and <br /> maintenance via a wench/headframe. The 25 HP is not in use(it hangs dry in the mine)but was left in place as a backup. The <br /> transducer and in-situ piping was most recently inspected in 2020. These do not have any mechanical parts,so they are not <br /> subject to a routine maintenance schedule. Repairs are made on an as-needed basis. <br /> Please provide additional details on the process for injecting the RO reject brine into the mine,including The RO reject brine,which is immediately dosed with Barium Chloride,is stored in the Backfill Slurry(BFS)tank.The BFS tank <br /> whether the brine is immediately injected into the mine after the treatment process,or temporarily stored has a maximum capacity of 20,000 gallons,but during normal operation,the tank is only filled with 15,000 gallons before being <br /> 24c at the surface.If the brine is temporarily stored at the surface,please specify where it is stored,the pumped into the mine.The tank typically cycles between 4 hours of filling and 2 hours of pumping down to a volume of 5,000 <br /> approximate maximum volume that is stored at the surface at any given time,and the average length of Gallons.The BFS tank sits in a lined secondary containment area. During in-situ treatment,the BFS is amended with the in-situ <br /> time it is stored at the surface prior to being injected into the mine. rea ents and dosed into the mine in such a way to promote mixing within the mine. <br /> Does the operator have an emergency plan for disposing of the RO reject brine in the event the In the event that the disposal piping was not functional,the WTP would be shut down so that operators could repair the line. As <br /> 24d infrastructure used to transport this waste to the mine workings is not functional,but pumping must described above the BFS tank has sufficient capacity to store RO reject brine prior to disposal. If necessary,both the Steve and the <br /> continue? Pierce levels and the Sunshine access area could all become alternative injection locations on a temporary basis. <br /> 25 The Division has the following comments regarding Figure E-3: Please see responses to specific comments below. Please note that the figure numbers have changed,and Figure E-3 is now <br /> Figure E-4. <br /> Please explain the increased variation between total and dissolved uranium concentrations observed in CLL does not have a definitive explanation for this variability at this time as it may relate to the analyses of the samples.However, <br /> 25a data collected from 2017 to 2020 compared with the closer values observed in the data from 2013 to 2015. the takeaway from Figure E-4 is that except for the 2017'suspect data',the uranium concentrations have decreased since the <br /> concentrations reported in 2012 prior to the in-situ treatments,which is the reason for the decrease in concentrations. <br /> Please explain how the"suspect"data was chosen.Was this selection based on the data points plotting The suspect data was chosen based on the historical data,which did not exceed 25 mg/1 even after the first in-situ treatment.In <br /> 25b above 25 mg/L?If so,how does the operator explain the data points within the same timeframe(not fact,after the first in-situ treatment,the uranium concentrations remained below 10 mg/l.It is reasonable to suspect outliers <br /> when the concentrations are more than double that of historical concentrations.The other concentrations in 2017 greater than <br /> PAGE 8 OF 35 <br />