HomeMy Public PortalAbout2018.08.23 Email Hamilton A Midas Gold ProjectFrom:Alan Hamilton
To:BessieJo Wagner
Subject:Midas Gold Project
Date:Thursday, August 23, 2018 2:36:50 PM
Dear Mayor and City Council Members,
After reading Midas’ POO (plan of operations) submitted to the Forest Service there are
several areas of concern that you should be aware of as a river steward. They are:
Groundwater/Surface water impacts.
Metals leaching/release from sulfide bearing ores and;
Acid rock drainage (ARD) from the ore, waste rock and mine
tailings.
Groundwater/Surface water impacts – The POO proposes 3-open pits that will extend to
1000+ feet in depth. During the life of mine this will require extensive dewatering which
will result in dramatic drawdowns in the groundwater (GW) aquifer(s). The aquifer(s) or
GW regime is connected to surface water (i.e. E. Fork of S. Fork of Salmon R.) and the
mine dewatering has a real potential for creating declines in streamflow which negatively
affects fish, habitats and dependent wildlife. The water level declines in GW can also
impact water well owners in the vicinity of the mine. At a minimum, extensive
characterization of the GW regime(s) should be performed to have a grasp of these
potential impacts and possible mitigation methods (i.e. where will the pumped GW be
conveyed to?). GW characterization should include drilling/installation of a monitoring
well network with aquifer testing, water sample collection and analyses. This data should
then be fed into various modeling programs such as a finite element numerical model
which will graphically represent the drawdown in GW over time as well as the number of
years for water levels to equilibrate to pre-mine conditions which can be on the order of
decades or centuries. This doesn’t include the impacts to fish from the proposed .8-mile
diversion tunnel of the E. Fork of S. Fork of Salmon R.
Metals leaching/release from sulfide bearing ores – The suite of metals associated with
this deposit are: antimony, arsenic, cadmium, lead and mercury all of which are toxic to
human health and the environment (i.e. fish killers). During mining, various wastes will be
generated (i.e. tailings and waste rock) that will contain these metals and will be sources
for metals contamination. Their ultimate fate (i.e. management and storage) will be critical
to the potential for their release/leaching into the environment. Because the open pits will
expose the ore zone(s) to ambient conditions there is a potential contaminant source to
GW and surface water. As GW flows through the mine workings and emerges along pit
walls it will more than likely contain high levels of these metals in a dissolved state. If this
metal bearing water reaches surface water or migrates in the subsurface to a water well
then human/environmental exposure is imminent. The company needs to show how
these exposure pathways will be offset or eliminated.
Acid rock drainage (ARD) from the ore, waste rock and mine tailings - Three of the
principal ore minerals: pyrite, arsenopyrite and stibnite are sulfide bearing that generate
acid when disturbed and exposed to ambient conditions(i.e. water and air). Due to this,
extensive geochemical testing of the ore, waste rock and tailings should have been done.
This testing comprises what is called Acid-Base Accounting. Through this process the
acid generating potential of the various lithologies/materials at the proposed mine are
quantified along with necessary neutralization requirements necessary to buffer the
materials acidity. This is important particularly when the proposal to backfill one of the
open pits (Yellow Pine) is performed and materials used will need to neutralize the acidity
of GW that will migrate into the backfilled material. Another concern that doesn’t seem to
be addressed is the fact that the two remaining open pits will not be backfilled and will be
left as pit lakes. Pit lakes under these conditions are notorious for being toxic due to their
high concentrations of dissolved metals and acidity. An example of this is a massive kill
of thousands of Snow Geese in Butte, MT at the Berkeley Pit lake in Nov., 2016 (see link:
https://www.smithsonianmag.com/smart-news/toxic-montana-lakes-kills-hundreds-and-
maybe-thousands-snow-geese-180961356/).
Finally, I wanted to add that Midas is a Canadian mining company that trades as a penny stock
so its financial stability going forward is definitely suspect. I also noticed that only 5-years of
post-mining environmental monitoring is proposed which is minimal at best considering the
decades long legacy of environmental contamination associated with metal mines throughout
the northern and central Rockies.
Thanks,
Alan Hamilton
1046 Valley Rim Rd.
McCall, ID 83638