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Golden Wonder Mine Technical Revision <br /> Prepared for LKA International, Inc. <br /> Permit M-1978-091-U G <br /> By Black Creek Hydrology, LLC <br /> June 10,2020 <br /> We were asked by LKA in late 2019 to make an assessment of previous and existing water treatment <br /> systems at the Golden Wonder mine and to propose systems and procedures to bring the site into <br /> permit compliance in an economically efficient and sustainable manner. Due to a late spring thaw in the <br /> area,we were unable to access the site to make the measurements and assessments required to <br /> formulate a new system design until mid May 2020.After examining several options and assessing their <br /> practicality,the following represents our current and most comprehensive recommendations. <br /> Site Conditions and History: <br /> Passive minewater treatment systems at the Golden Wonder mine have historically been challenging <br /> and not entirely effective.The site is remote and there have always been challenges in finding locals <br /> who are willing and capable of doing the job of water sampling.The absence of a continuous electric <br /> power supply limits the types of systems that can be used and sustained economically.Another <br /> challenge is that the elevation of the site is approximately 9,000'and only accessible between late April- <br /> mid May through October after which the limited flow from the mine freezes. Based on several years of <br /> observations,the flow of minewater has never exceeded—2 gpm in the spring and tapers off to less than <br /> 1/10 gpm in late summer and is usually non-existent by end of September.The source of this flow is <br /> groundwater that makes its way through the mountain and mine workings to the lowest exit point in the <br /> mine...the portal at 6 Level.Volume is always weather influenced/dependent. During recent drought <br /> years it was non-existent.As overnight temperatures drop later in the season,this water freezes inside <br /> the mine portal and begins to flow again as weather warms and the ice melts in the spring. <br /> (The inability to make adjustments and modifications,due to low and gradually diminishing flow rates, <br /> were the main contributors to the failure of the previous iron ore slag treatment system to live up to <br /> laboratory results and engineering expectations. This was the 2'approved system installed on the site.) <br /> Surface water from Deadman Gulch(eastern edge of the mine pad)is isolated from all mining features <br /> via a 24" HDPE pipe buried in a limestone filled channel until it empties into a lined sump/weir at the toe <br /> of the mine dump. Here it converges with treated minewater,stormwater from the mine pad and dump, <br /> and minor,low pH,seeps before discharging through the flume and into the gulch. Installed,automated <br /> meters record flow and pH at this point.This has also been the primary sampling point.Surface water <br /> (native flow)from the gulch typically flows at a much higher rate(typically 20-30 gpm)vs.the other <br /> sources(minewater,stormwater and seeps)and then dries up by late summer.Accordingly,it has been <br /> difficult to accurately predict,measure,treat,and sample these combined water sources. <br />