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2022-01-14_REVISION - M1977300
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2022-01-14_REVISION - M1977300
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Last modified
1/20/2025 4:40:33 AM
Creation date
1/18/2022 8:12:35 AM
Metadata
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Template:
DRMS Permit Index
Permit No
M1977300
IBM Index Class Name
Revision
Doc Date
1/14/2022
Doc Name Note
Response to Secondary Adequacy Review
Doc Name
Adequacy Review Response #2
From
Colorado Legacy Land
To
DRMS
Type & Sequence
AM6
Email Name
AME
MAC
Media Type
D
Archive
No
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COLORADO LEGACY LAND <br /> mine pool rises.The regulatory limit for the mine pool is to remain 150-feet below the Steve-level adit. CLLs transducer is <br /> accurately r cording and reporting compliance with this limit. <br /> On page 15,the operator states"On the basis of historical refill trends,once the mine pool is dewatered at Yes,the operator is referring to data presented on Figure E-1. This text has been revised for clarity. These data are in good <br /> the end of the operating season,the natural groundwater recharge will take approximately six months agreement with the historical refill trends and mine pool volumes presented in Section 8 Groundwater of the EPP(Technical <br /> before the mine pool approaches the regulatory limit".In discussing"historical refill trends",is the Revision 23,Attachment B Schwartzwalder Mine Environmental Protection Plan [Whetstone Associates Inc.,2016])which <br /> operator referring to the data presented on Figure E-1,which shows mine pool levels from January 2018 to discussed refill trends during mining operations (Section 8.b.iii.3.Mine Inflow During Operations)and after mining operations <br /> April 2021?At what point after the 2012 Board Order,was the mine pool pumped down at least 150 feet (Section 8.b.iii.4.Mine Flooding After Operations). <br /> below Steve Level?Did this occur prior to the September 2013 flooding?Does the operator have sufficient <br /> data to predict how the mine pool might be affected by a significant precipitation event such as what CLL does not know the exact date that Cotter dewatered the mine to below the regulatory limit,but we understand from Cotter's <br /> 11 occurred in September 2013? records in was in Fall 2017.CLL is not aware of any transducer data from 2013. CLL became the operator of the Schwartzwalder <br /> Mine in March of 2018 and does not have access to the previous Operators records other than those submitted to DRMS with the <br /> permit file that are public record. <br /> While the mine flows did show seasonality during the operating period(Section 5.2,Whetstone,2007)the seasonal variation was <br /> between 180 and 209 gpm,which is evidence of minor and indirect connection of surface water to the mine pool. The Whetstone <br /> report indicated a range of 0-28.7 gpm of precipitation-linked recharge,while the mine pool was pumped down far deeper than <br /> current conditions —2000 feet below Steve in 1995-1999 vs. 150-400 feet below Steve in 2018-2021 . <br /> On page 16,the operator discusses how chemical stabilization of the mine pool has been accomplished The precipitated metals are insoluble,dense,and will sink to the bottom of the mine pool.The mine shaft/mine pool is acting as a <br /> through in-situ treatments,which are designed to create a sulfate-reducing environment for the reduction long-term in-situ bioreactor in which a reducing environment will be maintained such that the precipitates remain insoluble.The <br /> of soluble uranium species to insoluble uranium species.The reducing environment is essential for the raising and lower of the mine pool will not have an effect on the precipitates at the bottom of the mine pool.It is not expected that <br /> reduction of U(VI)to U(IV)to immobilize uranium and the precipitation of iron sulfides.In addition to the precipitates will adsorb to the wall rock in any meaningful fashion based on the formation of the metal sulfides and tendency to <br /> formation of insoluble uranium species,trace metals may coprecipitate with or adsorb on the surfaces of precipitate rather than adsorb. Further,the mine water has been maintained in a chemically reducing form by the sealing of the <br /> the iron sulfides.Please describe what happens to the precipitates that occur due to the in-situ treatments. mine,the avoidance of ventilation,and the in-situ treatments,such that the mine water is routinely>0 millivolts.This avoidance <br /> Is it expected that these precipitates sink downward in the mine pool?Could the repeated raising and of bulk oxidation processes is shown in stable TDS concentrations in the mine water,unchanged in the last 4 years compared to <br /> 12 lowering of the mine pool hundreds of feet cause the precipitates (e.g.,adsorbed to wall rock)to re- the initial filling period. <br /> dissolve into the mine pool?Could the RO reject brine injected into the mine pool have any effect on the <br /> results of the in-situ treatments? While a limited amount of're-dissolving'of metal sulfides in the mine pool is possible since the mine is not 100%sealed,the <br /> population of sulfate reducing bacteria(SRB)that maintains the reducing environment will aid in the re-formation of metal <br /> sulfides and reprecipitation of other reduced metals precipitates such as uraninite.Since the mine pool is not being pumped <br /> during in-situ treatments,there is no RO reject brine being introduced back into the mine pool during the in-situ treatment <br /> period.As shown on the figures,there is a rebound in metal concentrations after in-situ treatments in the subsequent year for a <br /> few constituents but on the whole the mine pool chemistry is stable. <br /> The Division has the following comments regarding Table E-1-Observed Groundwater Gradients; The mine pool elevation data shown in Table E-1 are average daily elevations that correspond to the specific sample dates for <br /> MW-15 and MW-18. Because these wells were not sampled in Q1 and Q2 of 2019,the mine pool elevation data is not listed in <br /> 13 <br /> Please explain why there is no mine pool elevation data available for Q1 and Q2 of 2019. Table E-1. <br /> Figure E-1 includes mine pool levels going back to January 2018.Why was this data not included on Table <br /> E-1to compare with water levels from wells MW-15 and MW-18? <br /> On page 19,the operator states"The in-situ treatment was interrupted by a 1,000-year rainfall event in The text refers to prohibited access for large semi-trucks to the site and thus to maintain in-situ treatment.Mine pool levels can <br /> September 2013 that prohibited access to the Schwartzwalder mine from September 2013 until the be monitored remotely at all times and most likely were monitored during this period.However,CLL was not involved with the <br /> summer of 2015".Were mine pool levels monitored during this time?Since water quality data for the mine mine at this point and cannot state for certain exactly what transpired during this period. CLL understands that the limited <br /> pool is presented for this period on Figures E-3 and E-4,it would appear the site could be accessed for access may have been accomplished during this time with all-terrain vehicles or similar in order to collect water samples from <br /> 14 water quality sampling during this time.This would imply that access to the mine was not"prohibited", the mine.In the event that Glencoe Valley Road is not accessible,there is another access point through White Ranch Open space <br /> and that some limited access may have been available.Please explain and/or correct this discrepancy. which we are aware was used in 2015 to perform limited in situ treatment. <br /> Additionally,please describe how the operator would handle an extended access-limiting/prohibiting <br /> event in the future.If Glencoe Valley Road was not available,could the site be accessed any other way?Can <br /> mine pool levels be monitored remotely? <br /> On page 20,the operator states"there was not a significant decrease in uranium concentrations after the The absence of a significant decrease in uranium concentrations during the last in-situ treatment was an anomaly as evidence by <br /> 15 2020 in-situ treatment as was seen in the previous in-situ treatments".The operator then lists some factors the previous treatments.Upon further reflection,we believe that adding waste rock into the mine as a result of reclamation may <br /> that may have contributed to these results.Does the operator expect there will be a point at which also have contributed to this increase of uranium in the mine pool,but we are not fully satisfied with any explanation because <br /> continued in-situ treatments is expected to have little to no effect on uranium concentrations in the mine there were multiple variables during the 2020 season. The in-situ treatments have actually resulted in a sustained reducing <br /> PAGE 5 OF 35 <br />
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