I've finally managed to locate the Eagle Gold Mine HLF Manual
20200127 Eagle Gold HLF OMS Manual V 2020-01 (gov.yk.ca) that contains most everything you need to know about this facility. Thoroughly reading it just answered a whole lot of important questions and unknowns for me. Here's just some of the highlights I gleaned from it so far:
1.) The Eagle HLF actually has it's own In-Heap Pond (located within the HLF at the toe of the HLF) that on average holds about 10.5 million gallons of pregnant solution. (see diagram on Page 21). This In-Heap Pond has electronic monitoring systems that can be read and montored remotely at the ADR. From the site photos I've seen this pond is still intact and didn't breach the pad barrier wall and so if any solution was lost, the ADR plant operator already knows this. And I'm pretty sure if 10.5 million gallons (or other significant volume) of pregnant solution leaked we'd all know about it by now and the Mines Official that was on-site and recently stated that it appeared that any solution that may have spilled from the HLF has been contained wouldn't have made that comment if 10.5 million gallons or anything clsoe to that breached containment.
2.) The HLF Sumps (yes sumps not sump) are located within the In-Heap Pond and consist of a canister type containment casing (a well type of casing it seems) that appears (in the diagram) to be centered within the middle area of the In-Heap Pond (not at the edge near the slide as some including I were lead to believe). And the sumps do not sit at the very base / bottom of the In-Heap Pond but instead are raised so that in order for solution to enter the sump canister the solution that flows down the leach pad and into the In-Heap Pond itself must be occuring and initially flowing into the In-Heap Pond, otherwise the pond level would eventually be just at or lower than the top of the sump canister and solution won't flow into the canister and therefore pumping to the ADR plant would stop. The sump canister also has sensors built into it that can be monitored remotely by the ADR Plant operator and the canister accessed for maintenance as needed, So again, they already know if the sump canister is containing or is losing pregnant solution. So were the sumps and canister swept away with the slide? Not likely if they are located in the center of the In-Heap Pond and the pond is still there.
3.) There is / was a 400 meter overland pipe that connected to the sumps pumps, with a 2,070 m3/hr maximum capacity for pumping pregnant solution to the ADR Plant which was likely damaged during the slide. That pipe was not visible in any photos I've seen so this is still an unknown. The nominal flow rate in that pipe as stated in the manual is around 1,500 m3/hr so whatever volume of pregnant solution was left in that pipe may have leaked causing contamination unless that pipe is buried in slide material bent but not broken.
4.) Also on Page 21, there are spillways depicted all around the pad and elsewhere that should have largely facilitated containment, in particular the spillway that runs adjacent to the toe area of the HLF and down (west side of toe area) and down to an overflow pond. I believe the temporary dams built by company workers immediately after the slide for containment are just above this spillway.
5.) And then there's the mandatory requirement for an annual independent engineer inspection / assessment of the HLF stability and monitoring systems for HLF movement, etc. prepared and presented to the Yukon Mining Authorities by October 1st of each year!
This document has so much important information about the HLF from design, safety systems, rountine maintenace and emergency procedures and company responsibilities that you best read it for yourself and draw your own conclusions.
Personally, after reading this manual today, I'm now less convinced that this event is anywhere near the environmental 'catastrophe' it is being perceived to be. The safety features and considerations that were built into the Eagle HLF are mind boggling and no doubt way under appreciated until you're actually aware of and understand them. The perception so far is that this is an environmental 'catastrophe', but is it really? I'm willing to wait for the facts and then I'll make a sell, hold or buy more decision. And the more facts I gather the easier and more sound that decision will be.
Hope this info is helpful to the longs here.
HB77