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M-1977-410 <br />Technical Revision 10 <br />April 26, 2022 <br />3 <br /> <br /> <br />Section 2: Water System Timeline and Historical Background <br />From 1975-1995, The Hendricks Mining Company (HMC), installed and tested a treatment system to meet <br />the requirements of discharge permit CO-0032751. HMC constructed three (3) passive-solids settling <br />ponds to manage suspended solids emanating from the Idaho Tunnel/Caribou Mine (Appendix A, <br />locations in Figure 1) one Pond to receive pumped water from the Cross Mine (Pond #1) and one pond <br />(Pond #2) to manage pre-environmental release of treated water from the Cross/Caribou Mines into Coon <br />Track Creek. HMC DRMS approved active treatment mechanism consisted exclusively of lime addition (to <br />buffer any potentially dissolved soluble metal ions at a relatively lower pH) These methods were initially <br />successful and met the water quality standards imposed on the operation at that time; however, <br />subsequent and periodical regulatory mandates lowering of metal concentration compliance standards <br />resulted in inconsistent success of the water treatment system. As a result, HMC tested (1995) the <br />suitability of a gravity-fed absorptive medium treatment option consisting of zeolite, with mixed results, <br />particularly during peak discharge (typically during the spring and summer months). HMC became Calais <br />Resources Colorado (CRC), in 1998 CRC continued treating Cross/Caribou effluent with the approved <br />treatment system consisting exclusively of lime addition and sedimentation. Grand Island Resources LLC <br />(GIR) acquired HMC in 1998water treatment mechanisms remained unchanged and GIR continued with <br />lime addition. <br />GIR has since undertaken several mining-related activities (including, but not limited to underground <br />construction, infrastructure retrofit, dewatering, and geological exploratory drilling) required to achieve <br />GIR objectives advancing a sustainable and actively producing mine. The development and retrofit <br />activities, performed during two (2) 3-month seasons from 2020-2021 stressed the lime addition <br />treatment system resulting in inconsistently meeting permitted water quality standards. GIR immediately <br />engaged internal and external assessments of treatment alternatives in an effort to identify water <br />treatment strategies without the use of chemicals to meet permitted water quality standards going <br />forward during mine development and ore production. <br /> <br />The following general timeline of GIR’s recent activities pertaining to water treatment system upgrades <br />and compliance efforts illustrate GIR’s commitments to regulatory compliance: <br />• August 2020 – reconstructed and re-lined settling ponds 3A, 3B, and 3C with geomembrane <br />(locations in Figure 1) to prevent infiltration and optimize suspended solids settling times <br />(Technical Revision 8) <br />• September 2020-present – conducted underground construction, developing additional sediment <br />management capacity and efficiency; water flow paths were also modified, to reduce sediment <br />concentrations in mine water effluent discharging into the settling ponds system <br />• April-June 2021 – sought alternative water treatment packages/systems, conducted in May 2021 <br />a filtration study (Table 2) to aid in selection of water treatment packages/systems and applicable <br />contractors <br />• July 2021 – GIR contracted OPEL Energy to obtain an ™AmberKleen 1200 mine waste system, and <br />an ™AmberKleen 1250 polishing system. DRMS approved the installation of the OPEL pilot plant,