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COLORADO LEGACY LAND <br /> included in the"suspect"data)which also show elevated concentrations (compared to the rest of the post- 20 mg/1 may well be outliers,yet it was not as'suspect'as the concentrations greater than 25 mg/l.In any case,our best <br /> 2012 data provided)? explanation is that the'suspect data'is consistent with RO concentrate and not just for the uranium concentrations but other <br /> parameters as well. <br /> 25c Please include data collected since September 2020. Revised as requested. <br /> 25d Please include mine pool levels. CLL has prepared a chart(Figure E-7)as requested in comment#19;when the mine pool elevations are displayed on Figure E-4 <br /> the figure becomes too cluttered and is difficult to read. <br /> 26 The Division has the following comments regarding Figure E-4: Please see responses to specific comments below. Please note that the figure numbers have changed,and Figure E-4 is now <br /> Figure E-5. <br /> 26a Please explain why this figure includes two data points for molybdenum concentrations prior to November The figure has been revised to include the missing 2012 uranium concentrations. <br /> 2012,whereas this data is not available for uranium 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 2.0 mg/I even after the first in-situ treatment.It is <br /> 26b above 3.0 mg/L?If so,how does the operator explain the data points within the same timeframe(not reasonable to suspect outliers when the concentrations are more than double that of historical concentrations.The one <br /> included in the"suspect"data)which also show elevated concentrations (compared to the rest of the data concentration in 2017 greater than 2.0 mg/I may well be an outlier,yet it was not as'suspect'as the concentrations greater than <br /> provided)? 4.0 m 1. <br /> 26c Please include data collected since September 2020. Revised as requested. <br /> 26d Please include mine pool levels. CLL has prepared a chart(Figure E-7)as requested in comment#19;when the mine pool elevations are displayed on Figure E-5 <br /> the figure becomes too cluttered and is difficult to read. <br /> 27 The Division has the following comments regarding Figure E-5: Please see responses to specific comments below. Please note that the figure numbers have changed,and Figure E-5 is now <br /> Figure E-6. <br /> 27a Please explain why the linear regression method was chosen for this analysis.Would another method, Please see the response to comment#17.In addition,the Mann-Kendall trend test is used to evaluate statistically significant <br /> perhaps the Mann-Kendall test be more appropriate for the type of data being analyzed? trends at specific confidence levels.The linear regressions herein were used to present a visual trend. <br /> 27b Please include additional tick marks on the vertical and horizontal axes to make it easier to determine the The figure has been revised to include additional concentration and time units. <br /> concentration and sample date for the data points. <br /> 27c Please expand this analysis to include data collected since September 2020. Revised as requested. <br /> 28 The Division has the following comments regarding Appendix 1-Conceptual Site Model: Please see responses to individual comments below. <br /> 28a This Conceptual Site Model(CSM)is dated November 2018.Please provide an updated CSM that Revised as requested Ensero has prepared a revised CSM (Appendix 1) dated December 2021. <br /> incorporates the data collected since that time and reflects current conditions and site knowledge. <br /> Because no page/slide numbers are provided in the CSM,the Division will refer to the slide title for its Revised as requested,the Ensero CSM has numbered slides. <br /> 28b comments.However,the operator is encouraged to add page/slide numbers to the CSM for future <br /> reference and revision). <br /> On the slide titled"A Brief History",the operator might consider updating the timeline to include This slide provides the historical context of mining operations,however,where dates are available,the subsequent slides that <br /> 28c significant events that have occurred at the site since mining ceased (e.g.,mine pool pumped down 150 feet describe reclamation activities have been annotated with dates and technical revision numbers. <br /> below Steve Level,new RO water treatment plant brought online,new 60-hp pumpinstalled). <br /> On the slide titled"Key Reclamation Issues",in the list of Current Issues,the operator includes"hydraulic Previous studies regarding the hydraulic connection between the mine pool and Ralston creek are documented in the EPP <br /> connection(s)between the mine workings and Ralston Creek".Please explain what studies have been done (Technical Revision 23,Attachment B Schwartzwalder Mine Environmental Protection Plan [Whetstone Associates Inc.,2016]), <br /> to investigate this issue.Additionally,please explain what is meant by the Future Issues"Non-tributary which states"Ralston Creek does not appear to be in strong hydraulic connection with the Schwartzwalder Mine based on stream <br /> water potential"and"Potential for using mine pool for long-term storage". flow rates,mine pumping rates,and isotopic comparison of mine water and surface water". <br /> The text referring to"non-tributary water potential"refers to developing a water right to deep bedrock water stored in the <br /> 28d flooded mine workings.If these waters were determined to be"non-tributary water"then CLL may choose to develop a water <br /> right. This is a complex issue and is ongoing. <br /> The term"Potential for using mine pool for long-term storage"refers to creating storage for refill water in the mine pool so that <br /> the WTP only needs to be operated for 6 months or less. At the time this CSM was presented in 2018,CLL had not yet installed <br /> the 60-HP pump and headframe. The storage that CLL has created in the mine pool since 2018 is summarized in Table E-3 as <br /> "feet gained". This reclamation issue has been resolved as documented by the summary data in Table E-3 and corresponding <br /> text. <br /> On the slide titled"Infiltration",the data presented is from 1978-2005.Please update this slide to The infiltration data presented are representative of the site because the Schwartzwalder Mine was an underground mine,and <br /> 28e incorporate more recent data. the surface expressions are largely undisturbed or reclaimed. These data are useful in communicating and conceptualizing the <br /> h draulic mechanism,however a more recent site-specific value will not change the interpretation or understanding of the CSM. <br /> PAGE 9 OF 35 <br />