WEBVTT

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>> Thank you. Appreciate you
getting us kicked off today. Is

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it we have a very exciting topic
to discuss today and an
excellent

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presenter but I'm glad everyone
is joining. As my slides

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are loading, G did not say who I
am. I am Michelle Mahoney, I
work

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in EPA Superfund office in the
same office as Jean actually.

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We're just the different
branches.

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I work on technology transfer
and technology assessment for
cleaning

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up mining sites. And I manage
the content that is on the

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slide here, this website where
we have lots

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of information on all of the
webinars we have done.

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This is part of the series, and
as you see on the

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slide here, there are links
where you can go to view

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all the archives of previous
webinars, and we started

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this back in 2012. so there's
quite a few out there about

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you can also get information on
cleanup technologies and other
meetings

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going on around the world. So I
would encourage you all to visit

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this webpage.

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So today as part of a series as
we

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said. And this is a list of some
of the archives that we have
from

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past seminars.

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Here is the direct link to get
that list of archives. So if
you're

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interested in seeing what else
we have presented in the past,
please

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check it out because it you will
find some very useful topics
presented

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over the years. And if anyone
has any suggestions for future
topics

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are speakers, please feel free
to get in touch

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with me. The goal is to do a
mining related webinar on CLU-IN
every

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quarter, that is four per year.

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If you have any suggestions or
respond with the feedback that
Jean

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shares with you at the end of
this webinar Brooke like I said,
I'm

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very excited about today's
topic. The title is
considerations

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for bulkheading training mine
tunnels.

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During this webinar we are going
to address

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underground bulkheads and
present specific examples on the
EPA region

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eight where they have done
simple kit installations and
water quality

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changes, including the de Niro
title, the Pennsylvania mind and
Captain

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Jack Mill site. We have three

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presenters today, and we are
very fortunate they are all in
the room

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together interacting. The first
presenter is Chistoph Goss. Is a

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principal at Deere & Ault
consultants in Longmont
Colorado. 's practice

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includes tunneling, underground
mine design and

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underground rehabilitation.

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For pretty much 20 years he has
been

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working on a variety of
abandoned mines and water
tunnels, evaluating

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and support rehabilitation and
bulkheads.

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Were very glad to have him here
as a presenter. The second

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presenter today or one of the
presenters today is Joy Jenkins.
She is the

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remedial project manager in EPA
region

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eight office. She has worked as
a consulting environmental
engineer

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prior to joining EPA, and joy is
the RPM for Captain

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Jack Mill and Nelson tunnel in
Colorado and the mine in

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South Dakota. And the third
presenter we have today

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is Jeff Graves. Jeff has been
with

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the state of Colorado for 18
years where he has designed and
implemented

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to numerous my

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reclamation projects for the
state of Colorado as a senior
project

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manager but we are very excited
to have all three presenters,
and

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with that I'm going to turn it
over to them to present the
topic

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today.

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>> We are really glad to be here
today. This is definitely a
topic

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that's important to all of us
here. We have had

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a chance to work together on
various projects and now we get
to talk

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about them, and share the
information with everyone. For
those of you

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with that [ Indiscernible ]
October

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9 talk, this presentation will
be similar. This is an extended
version

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of that.

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Don't give up in the first
couple of minutes. We will add
more stuff.

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And then go and sub other
examples. So talking here

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today about bulkheading
considerations for mining
drainage

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back so a quick outline of the
presentation.

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Just a little bit about how to
hard

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rock mining. If people come from
different backgrounds just to
give

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you an idea of what is it about
and why we're even here. Talk

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about what bulkhead actually is.

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Bulkhead design is going to be a
topic here. Bulkhead risks, real

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and not so real. In the real
important thing

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about how to integrate a
bulkhead into your site plan.

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[ Indiscernible ] care and
feeding. So we will start with
the

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geology because that is the
source of everything. You are
probably

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on audit sites with problems
because there is a mind there.
Why?'s that

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is the geometry but we have a
typical example of how we can

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get metals into the ground. You
have

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some kind of magma source down
deep, and it is hot and moose
material

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a. You get fractures in the
rock.

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You then have different gases
and fluids that come up through
the

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rock, in those gases and fluids
have different metals

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inside the book as the metals
get up into all these fractures
in the

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ground, the pressure goes down,
the temperature goes down these

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metals come out and pile up on
the sides of these cracks.

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We have enough metal that
collects in the increased
cracks,

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you have a called a vein,
actually worth mining. We

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will be using some underground
mining technology here today. So
I did

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want to bring a few things up
here to everybody. Let's take a
look

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at a couple things.

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Everybody knows about tunnels.
Okay, it is a hole in the ground
that

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makes one side to the other.
Will be using the

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term added ace tunnel that
doesn't make it all the way to
the other

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side back in comparison, a shaft
is a vertical opening into the
underground.

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From the other side your that
vein that you saw inside the
mountain?'s

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that is this guy right here.
With your mining around

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a vein, you have or drifts
underneath,

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and your stokes so where mining
into the minds. So when you hear

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some terms from that, that is
something we are talking about.
Let's talk

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about what happens in an area
before mining, one of these
mountainous

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areas. We have a lot of
mountains and here. We have some
faults that

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are veins. They have enough
metal in

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them and what you've got is
these different groundwater
compartments

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in the ground. That will be kind
of the base. This happens

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before mining. They find the
outcrop of

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that vein right there and say
this is terrific, I'm going to
mine in

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this. All right. So you see we
have

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adit coming in horizontally and
Chasse going down and people are

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mining the veins, life is good.

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Then you get down deeper and
then you hit the water. And life
stops

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being so good because water is
really hard to

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deal with. It is messy to work
a, you have to pump it out, and
that

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gets really expensive. What to
do?'s

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what happens is you get a couple
of minds that you get together
and

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they drive a drainage tunnel
down below their workings, down
as deep

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as they were trying to go, and
this thing is terrific because,
as you

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can see, the groundwater has now
drained all the way down, the
mine

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is dry. You can connect your
minds to this drainage tunnel so
now instead

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of hauling the

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ore out, you can double down the
main shaft and carry it out the

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tunnel and life is really good.
So all is right in this picture

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except maybe the AMD over there.
Got to keep that one

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in mind. Because what happens is
at some point every mine

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plays out. I always love hearing
the stories about different mine

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sites about the great riches in
the ground and

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what was a conspiracy, why was
the mine shut down and the
reality is

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it ran out of the good stuff. So
you say

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see you and you leave the area.

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And of course no problem, all
you have is water leaking out
through

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the drainage tunnel you built,
and you know

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what cracks now you have a whole
bunch of

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my here is a picture of what it
looks like a typical day.

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All right.

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The post mining evaluation.
First question of course is, you
know,

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you've got this old training
mine.

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First question is the drain the
problem for water quality?

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if it is a problem you have two
general

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solutions, you can keep on
training the mountain --
draining

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the mountain in perpetuity.

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Another option in some cases
would be to install underground
dams,

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what we call bulkheads. These go
into the water and they

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tend to improve water quality
because it is letting

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oxidation in the minds you
flooded the

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mine workings, the pirate long
terms

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[ Indiscernible ] but what we
will be talking about

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here today in this talk is how
you really need a very

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detailed evaluation of all the
mine workings. The regional
Hydra

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knowledge a, you really need to
know about what is going on,
what

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can happen so bulkhead would be
nothing to consider. This you
really

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need to know the site to see if
it is the right thing. You also

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need to have all your
preliminary information, water
chemistry prior

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to bulkheading so you have to
look for changes. Here is

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what happens if you do put in

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bulkheads, the key thing to
determine is how high will the
groundwater

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table go.

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That is a key parameter because
how many of my

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levels are going to flood
collects the

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what is pressure going to be on
the bulkheads. Are

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you going to impact the other
minds, active or inactive, known
and the

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unknown ones and

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overall the feasibility. In some
cases, if you got maybe two
openings

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and the rest doesn't feel, could
be a real good option. If you've

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got 30 different mines all
entering the same vein,

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don't bother.

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It is not a one-size-fits-all
kind of Weber County figure out
what

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the water table was? a good
starting point it's a

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start with whatever the
pre-money groundwater table was,
that is where

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it is wonderful with any kind of
old mining records showing when

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the encounter was water.

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Typically the best way to know
this is whenever they started
driving

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the drainage tunnel, that is
when you're not going to drive

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a drainage tunnel before that.
Some information is available
and sometimes

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not. You start off with your
water levels,

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but then you have to work on
that more because you no longer
have

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the same ground he had before
picking up all these openings
underground,

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the ones that flow differently
through places, very high
permeability going

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three big opening. But not only
flow-through

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the actual mine workings, you
also have fault permeability.
With most

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faults they tend to have some
course

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gravel material in the middle
and clay on the side. That means
that

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along the fault it has to be
very permeable. Whereas across
them they

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tend to be very image permeable.
If you line

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out that there you made a whole
bunch of holes through these
veins

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and they are very permeable. So
that is going to change the

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groundwater system.

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[ Indiscernible ] so the
bulkheads are in place but the
groundwater

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has gone back up to some level
so similar to

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before, but there are no longer
my compartments. More of a
general

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ground level water here. You
also see down below know
[ Indiscernible ]

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being produced, up top AMD is
still a bit of a problem.

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Okay. So let's Exley talk about
what a bulkhead

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is. A bulkhead is an engineered
concrete plug that

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is designed to hold that water
for a long-term. It is it used

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in mines and hydroelectric
projects.

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Here's a couple of different
cartoon designs of the basic
concepts. There

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is a thinner slab keyed into the
walls of the topic you

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have a tapered plug that looks
like a cork in the middle. And
that a

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parallel plug that is just kind
of a long rectangular

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plug that just runs right along

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the surface. So here is a more
detailed view here looking over
here

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in profile. Of what a bulkhead
may or may not look like.

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So we have the mine pool on the
right, we have the error

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side on the left. A couple
things to point out. You know,
you

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need to put these into good
ground. You improve the ground

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a bit right where your. First
thing you do is move any loose
or broken

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or weathered rock around you.

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That you put up your ground
support and bolts and things in
place. Next

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thing, we do most of our, I
recommend, is that you

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put a big grout curtain in
place.

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A big grout rain, drill 20 foot
holes and a ring pattern

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around your to help intersect
the other joints in the area and
grout

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them up and make them less
permeable. Again, we're trying

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to limit the amount all more
water going past the bulkhead
through

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the ground. That you have the
rest, you have the concrete

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in place. You do have your main
water line

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through their and then also very
important a sampling pipe

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that you see over

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here at the top it allows you to
check the pressure behind the
bulkhead,

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take water samples and all that
kind of stuff. Here is the

355
00:16:31.067 --> 00:16:36.000
same bulkhead, you see it here
and a couple a section

356
00:16:36.000 --> 00:16:41.067
of use. Views. Over here on the
left we have a grout

357
00:16:41.067 --> 00:16:46.067
ring pattern. That is like your
big cut off key in the middle to

358
00:16:46.067 --> 00:16:50.067
keep water from flowing through
the formation around your

359
00:16:50.067 --> 00:16:56.067
bulkhead. That over here on the
right we have got a

360
00:16:56.067 --> 00:17:00.067
contact grouting. What you have,
these are shorter grout

361
00:17:00.067 --> 00:17:04.067
holes that are designed to grout
the interface between the rock
and

362
00:17:04.067 --> 00:17:07.067
the concrete placed in the
bulkhead.

363
00:17:07.067 --> 00:17:09.067
And so, these are shorter holes,
just kind of go through the

364
00:17:09.067 --> 00:17:14.067
interface they are. And
typically you will combine that
with a chemical

365
00:17:14.067 --> 00:17:20.067
grout ring as well. What is not

366
00:17:20.067 --> 00:17:26.067
a bulkhead. A lot of this work,
you

367
00:17:26.067 --> 00:17:28.067
know, people imagine all kinds
of things that

368
00:17:28.067 --> 00:17:32.000
they talk about bulkheads
failing minds and that. A lot of
times that

369
00:17:32.000 --> 00:17:36.000
is not really the case. So this
right here is a collapsed
portal,

370
00:17:36.000 --> 00:17:41.067
not a bulkhead. This writer is a
collapsed

371
00:17:41.067 --> 00:17:47.067
tunnel, again, not a bulkhead.
This is a bulkhead.

372
00:17:47.067 --> 00:17:51.067
This is a very nice bulkhead.
Nice good solid concrete.

373
00:17:51.067 --> 00:17:55.067
You can see the remains of some
of the contact grout to the
there.

374
00:17:55.067 --> 00:17:58.067
A lovely valve on the for but
this looks like before you

375
00:17:58.067 --> 00:17:59.067
have any water pressure behind
it.

376
00:17:59.067 --> 00:18:03.067
This is a bulkhead some years
after you have had water behind
it. You

377
00:18:03.067 --> 00:18:11.067
can see this bulkhead is before
-- performing perfect fine, but

378
00:18:11.067 --> 00:18:16.067
when you -- the water makes its
way and you have dripping in
general

379
00:18:16.067 --> 00:18:21.067
mine scrunch right there behind
you. All right. So bulkhead

380
00:18:21.067 --> 00:18:25.067
placement. In general, it is
going to be similar deep in the
my

381
00:18:25.067 --> 00:18:29.067
because you need to have a deep
enough under good ground cover.

382
00:18:29.067 --> 00:18:31.067
Those near the portal have all
the water drained right out
through

383
00:18:31.067 --> 00:18:37.067
the stuff in the front. That is
good ground. You don't want have

384
00:18:37.067 --> 00:18:40.067
fractured broken up ground,
sometimes there are solid pairs,
so you can

385
00:18:40.067 --> 00:18:45.067
have a pressure step down as you
go through

386
00:18:45.067 --> 00:18:48.067
the area. And you start at the
lowest levels of the minds and
move up

387
00:18:48.067 --> 00:18:53.067
to plug all levels that are
going to be inundated. That
includes all

388
00:18:53.067 --> 00:18:58.067
the areas better
[ Indiscernible ] they

389
00:18:58.067 --> 00:19:06.067
can be can connected in
different ways,

390
00:19:06.067 --> 00:19:08.067
Hydro geologically in the same
vein or through drill holes
through

391
00:19:08.067 --> 00:19:12.067
different minds but it is
interesting what kind of
exciting connections

392
00:19:12.067 --> 00:19:14.067
you find in these places. So you
have to understand not just the

393
00:19:14.067 --> 00:19:17.067
my layouts, but also the
hydrogeology and the extent of
the impacted area.

394
00:19:17.067 --> 00:19:21.067
And of course the important
thing is, don't stop halfway.
You can

395
00:19:21.067 --> 00:19:25.067
effectively drain the amount
the, flood up the mountain, if
you do

396
00:19:25.067 --> 00:19:31.067
it halfway, it is going to cause
problems. So here's a

397
00:19:31.067 --> 00:19:37.067
project that you will be seen
again here. A quick

398
00:19:37.067 --> 00:19:41.067
plan view of the cap to Jack. It
illustrates

399
00:19:41.067 --> 00:19:47.067
some considerations for placing
a bulkhead. So when you

400
00:19:47.067 --> 00:19:51.067
look at a map like this, you
see, okay, all kinds

401
00:19:51.067 --> 00:19:56.067
of intersections of background,
probably not a

402
00:19:56.067 --> 00:20:00.067
good spot. Here we have a
collapsed any bypass tunnel.
Again, not a

403
00:20:00.067 --> 00:20:06.067
real good spot. This right here
is

404
00:20:06.067 --> 00:20:07.067
probably a pretty good spot.

405
00:20:07.067 --> 00:20:12.067
The share they are showing right
here actually happens to be, I
think

406
00:20:12.067 --> 00:20:17.067
the haying wall of the

407
00:20:17.067 --> 00:20:22.067
vein, and that is something
that, depending on how open it
is, that

408
00:20:22.067 --> 00:20:28.067
you may be able to mine up in
area, grout up and be able to

409
00:20:28.067 --> 00:20:32.000
hold it pretty well.

410
00:20:32.000 --> 00:20:35.000
You have to know where to place
it. next things for bulkhead
design.

411
00:20:35.000 --> 00:20:36.000
Let's get into more details
here.

412
00:20:36.000 --> 00:20:45.067
First of all, there is a
question of, constructibility.
Can you access

413
00:20:45.067 --> 00:20:49.067
the area? do you have to drive
bypass tunnel question back how
do you

414
00:20:49.067 --> 00:20:52.067
get in there. How do you get to
both

415
00:20:52.067 --> 00:20:55.067
sides. Had to get out after you
build it? what materials are
available

416
00:20:55.067 --> 00:21:01.067
to build the. What you need
quick [ SIRENS ]

417
00:21:01.067 --> 00:21:10.067
how do you get the stuff in.
Temporary

418
00:21:10.067 --> 00:21:13.067
water diversion. You are dealing
with the site that is draining,

419
00:21:13.067 --> 00:21:15.067
so there's going to be water
coming out you. How do you
effectively

420
00:21:15.067 --> 00:21:20.067
deal with that water while you
construct this

421
00:21:20.067 --> 00:21:23.067
beautiful bulkhead? next piping
and valves. This is an area,
Paul

422
00:21:23.067 --> 00:21:26.067
Chelstad to be signed by people
who are really into mining and
geology

423
00:21:26.067 --> 00:21:35.000
and stuff and there also
[ Indiscernible ] but

424
00:21:35.000 --> 00:21:42.067
there is a matter of piping the
valves.

425
00:21:42.067 --> 00:21:45.067
I don't find it exciting at all
proportionally I work with
people

426
00:21:45.067 --> 00:21:48.067
who do, so there things I need
to hand over to people like
that. First

427
00:21:48.067 --> 00:21:51.067
thing is, compatible pressure
ratings.

428
00:21:51.067 --> 00:21:57.067
If you design a bulkhead for
1000 psi, that is terrific.

429
00:21:57.067 --> 00:22:01.067
If you put 150 psi valve on a,
that is going

430
00:22:01.067 --> 00:22:07.067
to be a lot less terrific and
kind of awkward. So make sure

431
00:22:07.067 --> 00:22:11.067
that whatever valving You have
is compatible with what

432
00:22:11.067 --> 00:22:17.067
[ Indiscernible ] as soon as you
go up 150 psi the cost for
valves get

433
00:22:17.067 --> 00:22:20.067
really high.

434
00:22:20.067 --> 00:22:28.067
What materials? same as steel.
Other big question

435
00:22:28.067 --> 00:22:37.000
is, discharge. Is a regular
discharge plan? if your plan is
to close

436
00:22:37.000 --> 00:22:39.000
it up and unless something goes
horribly wrong never open it
again,

437
00:22:39.000 --> 00:22:41.000
you maybe find with a simple
pipe and valve in their you are.
You

438
00:22:41.000 --> 00:22:46.000
can probably discharge regularly
perhaps because it is

439
00:22:46.000 --> 00:22:49.000
a temporary stormwater, then you
need more detailed design about

440
00:22:49.000 --> 00:22:52.000
how to open and keep things
open, and in some cases, if
there is a

441
00:22:52.000 --> 00:22:57.000
certain flow you have to keep,
you have to design it for
specific

442
00:22:57.000 --> 00:23:06.000
flow rates to avoid cavitation
and other problems.

443
00:23:06.000 --> 00:23:09.000
Testing pipes.

444
00:23:09.000 --> 00:23:12.000
The small diameter pipe to take
water samples

445
00:23:12.000 --> 00:23:18.000
from and test the water pressure
behind

446
00:23:18.000 --> 00:23:21.000
your bulkhead.

447
00:23:21.000 --> 00:23:23.000
Next a bulkhead design is to
consider all the different
failure

448
00:23:23.000 --> 00:23:29.000
modes, and then how do you
effectively design for those
with safety.

449
00:23:29.000 --> 00:23:31.934
Hydraulic jacking. That is where
the water

450
00:23:31.934 --> 00:23:38.000
pressure opens up the joints in
the rock. It may

451
00:23:38.000 --> 00:23:42.000
be that the rock had some
fractures and

452
00:23:42.000 --> 00:23:46.000
things in it, but they're pretty
close, water doesn't really get

453
00:23:46.000 --> 00:23:49.000
through. Is the water pressure
buildup, after a certain

454
00:23:49.000 --> 00:23:52.000
point those joints open up and
all of a sudden instead of it
being

455
00:23:52.000 --> 00:23:55.000
a tiny hairline joint, it is
only open maybe a couple of
millimeters

456
00:23:55.000 --> 00:23:56.000
and it let's a lot of water
through.

457
00:23:56.000 --> 00:23:59.000
So that is what you're trying to
avoid. How to avoid hydraulic
jacking.

458
00:23:59.000 --> 00:24:04.000
You have to locate your bulkhead
at a high enough cover. You

459
00:24:04.000 --> 00:24:07.000
have to understand the ground
stresses and know what the
pressures are

460
00:24:07.000 --> 00:24:13.000
inside the ground. A lot of
times you can do that with
[ Indiscernible ]

461
00:24:13.000 --> 00:24:16.000
packer testing. That is what the
guys in the photo are doing.

462
00:24:16.000 --> 00:24:21.000
You drill a borehole and
pressurize a certain section of
that, and you

463
00:24:21.000 --> 00:24:25.000
measure how much water it takes
under certain pressures and

464
00:24:25.000 --> 00:24:29.000
essentially once you hit that
radical point, all of the sudden
your flowrates

465
00:24:29.000 --> 00:24:33.000
really go up. So that is an
important thing to know. Again,

466
00:24:33.000 --> 00:24:38.067
if you design a bulkhead for
1000 psi but a 200 psi rock

467
00:24:38.067 --> 00:24:42.067
opens up around it, that is not
going

468
00:24:42.067 --> 00:24:45.067
to work. Perimeter sure failure
along the tunnel. This could be

469
00:24:45.067 --> 00:24:49.067
the bulkhead zipping right along
the rock interface. Probably

470
00:24:49.067 --> 00:24:54.067
not realistic, but kind of
exciting to think about really.
So how do

471
00:24:54.067 --> 00:24:58.067
you avoid having your beautiful
bulkhead go skidding down

472
00:24:58.067 --> 00:25:04.067
the tunnel? you have nice rough
walls, the court

473
00:25:04.067 --> 00:25:07.067
shape is [ Indiscernible ] as is
on the

474
00:25:07.067 --> 00:25:13.067
samples, rock bolts in the rock
that tied to your steel

475
00:25:13.067 --> 00:25:19.067
enforcing. And grouting up the
interface between the rock in

476
00:25:19.067 --> 00:25:22.067
the bulkhead.

477
00:25:22.067 --> 00:25:24.067
Another exciting way to feel a
bulkhead in structural

478
00:25:24.067 --> 00:25:27.067
failure but that is when the
actual bulkhead fails to the
concrete either

479
00:25:27.067 --> 00:25:32.000
by bending or sharing and
breaking the actual concrete
apart. You fix

480
00:25:32.000 --> 00:25:37.067
this by making your bulkhead
long enough, using a proper
size, reinforcing

481
00:25:37.067 --> 00:25:41.067
steel, using right quality of
concrete. What

482
00:25:41.067 --> 00:25:45.067
is more of an issue
[ Indiscernible ] what you can
get, you can

483
00:25:45.067 --> 00:25:51.067
get water hammer effect just
like you would in a pie. If
you've got

484
00:25:51.067 --> 00:25:54.067
-- pipe. If you have earthquake
conditions but that is the
biggest

485
00:25:54.067 --> 00:26:00.067
load you would be likely to get
on a structure.

486
00:26:00.067 --> 00:26:04.067
Especially in California, that
is a design consideration

487
00:26:04.067 --> 00:26:09.067
to have. Already. Another
failure of load would be
concrete degradation.

488
00:26:09.067 --> 00:26:14.067
Acidic mine water and concrete

489
00:26:14.067 --> 00:26:17.067
is made of calcium carbonate. So
the acidity can break down the
concrete

490
00:26:17.067 --> 00:26:21.067
entered into a great mush. So
how do you deal with that? you
have

491
00:26:21.067 --> 00:26:26.067
some sacrificial thickness. You
figure

492
00:26:26.067 --> 00:26:29.067
the first bit at the bulkhead
will degrade. No problem. Make
it longer.

493
00:26:29.067 --> 00:26:33.000
That is easy to another thing is
to reduce the permeability. Some

494
00:26:33.000 --> 00:26:37.067
is just done with a mixed design
with

495
00:26:37.067 --> 00:26:40.067
enough status and pace and in
some cases people have used some
other

496
00:26:40.067 --> 00:26:41.834
admixtures that reduce the

497
00:26:41.834 --> 00:26:45.067
permeability within the
concrete. Those are also

498
00:26:45.067 --> 00:26:50.067
good options. You want to use a
type two slash

499
00:26:50.067 --> 00:26:54.067
five cement that is highly
sulfide resistant. And also
substituting

500
00:26:54.067 --> 00:26:59.067
some of your cement for fly ash
because that doesn't react with

501
00:26:59.067 --> 00:27:04.067
acidic water at all. And then,
another nicely to do short-term

502
00:27:04.067 --> 00:27:08.067
is play some lime upstream so
why your concrete is caring, you
are

503
00:27:08.067 --> 00:27:14.067
able to bring the pH up quite a
bit. Okay.

504
00:27:14.067 --> 00:27:20.067
Seepage of piping. Seepage of
piping is excessive seepage past

505
00:27:20.067 --> 00:27:24.067
the plug that is where you're
most likely to have

506
00:27:24.067 --> 00:27:28.067
failure but by failure we may
need it is not holding back

507
00:27:28.067 --> 00:27:31.067
the water as nice as we would
like, or the worst case would

508
00:27:31.067 --> 00:27:37.067
be an actual piping failure
where you have water starts
flowing through

509
00:27:37.067 --> 00:27:40.067
an opening, and it takes a
little bit of matériel

510
00:27:40.067 --> 00:27:43.067
and then more water starts
flowing at and it makes bigger
chunks of

511
00:27:43.067 --> 00:27:48.067
material which makes more water
flow

512
00:27:48.067 --> 00:27:51.067
out which brings up more chunks
of material. You see where we
are

513
00:27:51.067 --> 00:27:53.067
going, and all the sudden you
have an opening that is very
large and

514
00:27:53.067 --> 00:27:58.067
you have an uncontrolled flow of
water and life stinks.

515
00:27:58.067 --> 00:28:03.067
So that is an important thing
design against. How do you do
that

516
00:28:03.067 --> 00:28:09.067
cracks -- question back, that is
a geology. Do

517
00:28:09.067 --> 00:28:12.067
good geologic mapping.
Fireplaces that

518
00:28:12.067 --> 00:28:18.067
would give you the first
runaround the bulkhead. The
grout

519
00:28:18.067 --> 00:28:22.067
ring that you saw. Trying to
make the whole

520
00:28:22.067 --> 00:28:25.067
formation less permeable.

521
00:28:25.067 --> 00:28:29.067
Big crowds between the contact
-- grout between the contact

522
00:28:29.067 --> 00:28:34.000
and the bulkhead. Another thing
is it's making the plug long
enough.

523
00:28:34.000 --> 00:28:38.067
If you guys [ Indiscernible ]
flow that you have

524
00:28:38.067 --> 00:28:42.067
to draw, the longer structure
is, the

525
00:28:42.067 --> 00:28:46.067
longer the pressure of the
upstream side

526
00:28:46.067 --> 00:28:50.067
has to dissipate through the
zero pressure on the other side.
That

527
00:28:50.067 --> 00:28:55.067
is another key point. Nice long
structure but

528
00:28:55.067 --> 00:28:58.067
that of course, postinstallation
monitoring. You

529
00:28:58.067 --> 00:29:05.067
may have done a great job in
designing a long bulkhead and
mapped all the

530
00:29:05.067 --> 00:29:09.067
joints and grouted up and life
is good, but

531
00:29:09.067 --> 00:29:11.067
you know, there's always unknown
things, they're going to be
joints

532
00:29:11.067 --> 00:29:14.067
that you didn't see before the
suddenly appear. Joy said to do
not think

533
00:29:14.067 --> 00:29:18.067
were connected to the line pool
actually are. Is pretty common
to

534
00:29:18.067 --> 00:29:23.067
have to do some additional
grouting after a bulkhead
installation,

535
00:29:23.067 --> 00:29:28.067
maybe along a bigger joint maybe
around the bulkhead again or
even

536
00:29:28.067 --> 00:29:34.000
extend it. in the picture over
here on the right you guys can

537
00:29:34.000 --> 00:29:39.067
see the grout Packers from a
grout ring, and then here on the
slide,

538
00:29:39.067 --> 00:29:45.067
this right here along with
beautiful for work made

539
00:29:45.067 --> 00:29:51.067
by minors, you see over here the
bigger tubes

540
00:29:51.067 --> 00:29:58.067
are your content grout tubes
that go

541
00:29:58.067 --> 00:30:02.067
back through six or eight feet
or so through the concrete rock
interface,

542
00:30:02.067 --> 00:30:07.067
and then you also got some
tubes, some valves up in here

543
00:30:07.067 --> 00:30:13.067
that go to the, in this case a
chemical

544
00:30:13.067 --> 00:30:20.067
grouting ring. Okay. Bulkhead
this. This

545
00:30:20.067 --> 00:30:27.067
is fun. -- Miss the if you could
list some

546
00:30:27.067 --> 00:30:32.000
of the ones you of her because
those are always fun to

547
00:30:32.000 --> 00:30:37.067
talk about we will be the
MythBusters here for the last
part of the talk.

548
00:30:37.067 --> 00:30:42.067
That will be cool.

549
00:30:42.067 --> 00:30:45.067
So first, bulkheads are the
right solution for every minds
eye. No.

550
00:30:45.067 --> 00:30:49.067
If the ground is to permeable or
there too many openings, not a
good

551
00:30:49.067 --> 00:30:54.067
choice. Next, bulkheads will
eliminate all my water

552
00:30:54.067 --> 00:31:00.067
drainage. No. They reduce the
flows by a lot, 90%,

553
00:31:00.067 --> 00:31:04.067
maybe more, if You have got 1000
GPM of water coming

554
00:31:04.067 --> 00:31:10.067
out of your tunnel, you can
probably knock

555
00:31:10.067 --> 00:31:15.067
it down to 50. 100 GPM are so,
but it is not going

556
00:31:15.067 --> 00:31:21.067
to be perfectly dry. The next is
particularly popular. And

557
00:31:21.067 --> 00:31:24.067
sometimes, unfortunately, just a
necessity given funding and
ownership

558
00:31:24.067 --> 00:31:28.067
and so on. Bulkheads can be
installed and forgotten.

559
00:31:28.067 --> 00:31:32.000
Their maintenance-free. They do
need regular inspection

560
00:31:32.000 --> 00:31:37.067
and monitoring. Can always be
done realistically cracks not

561
00:31:37.067 --> 00:31:40.067
necessarily --? not necessarily.

562
00:31:40.067 --> 00:31:46.067
Another fun one is bulkheads
only affect individual

563
00:31:46.067 --> 00:31:51.067
minds -- mine mints -- if I
would [ Indiscernible ] my

564
00:31:51.067 --> 00:31:56.067
solution out to close it is to
bulkhead it up I am

565
00:31:56.067 --> 00:32:02.067
okay with paying for bulkhead
for my own mind. I

566
00:32:02.067 --> 00:32:08.067
am not [ Indiscernible ] who
actually stole a bunch of my ore

567
00:32:08.067 --> 00:32:11.067
anyway. But realistically
bulkheads have to

568
00:32:11.067 --> 00:32:14.067
be part of the holistic
solution.

569
00:32:14.067 --> 00:32:23.067
For the whole mindset, all the
area, whatever minds

570
00:32:23.067 --> 00:32:25.067
are connected, you have to deal
with that whole thing because
all

571
00:32:25.067 --> 00:32:31.067
these others can be connected
directly or through the

572
00:32:31.067 --> 00:32:33.000
natural fractures.

573
00:32:33.000 --> 00:32:39.000
Lastly to talk about, bulkheads
always improve water quality.

574
00:32:39.000 --> 00:32:43.000
This is typically yes.

575
00:32:43.000 --> 00:32:49.000
Most cases. They reduce the
amount of oxygen, the pirate --

576
00:32:49.000 --> 00:32:56.000
pyrite reactions. But water
quality tends to decrease

577
00:32:56.000 --> 00:33:01.000
as the salt immobilizes,
particularly earlier in workings
or temporary

578
00:33:01.000 --> 00:33:08.000
storage that can be a problem.

579
00:33:08.000 --> 00:33:11.000
Bulkhead risks, real and
imagined it let's go to the
imagine one for

580
00:33:11.000 --> 00:33:14.000
us because there a lot more fun.

581
00:33:14.000 --> 00:33:18.000
You put in the bulkhead, the
water piles up behind up until
it squirts

582
00:33:18.000 --> 00:33:19.000
up the top of the peak.

583
00:33:19.000 --> 00:33:23.000
No, it will go back to something
like the groundwater level it
was

584
00:33:23.000 --> 00:33:28.000
at before. Another fun one is
that the bulkhead concrete
shoots explosively

585
00:33:28.000 --> 00:33:32.934
like a cannon. That would be
very exciting,

586
00:33:32.934 --> 00:33:38.000
very neat, not realistic. But
kind of fun to think

587
00:33:38.000 --> 00:33:43.000
about. Let's talk about the real
risks. Leakage past the bulkhead

588
00:33:43.000 --> 00:33:46.000
it requires initial routing or

589
00:33:46.000 --> 00:33:53.000
second baldhead water flows out
of other mine workings, the
known

590
00:33:53.000 --> 00:33:56.000
and unknown, the flow suddenly
comes in or you may think all is
well

591
00:33:56.000 --> 00:34:02.000
and all the sudden you see
orange water coming

592
00:34:02.000 --> 00:34:09.000
out from trees or a pile of

593
00:34:09.000 --> 00:34:12.000
avalanche debris. Seeps develop
in the surrounding area per the

594
00:34:12.000 --> 00:34:20.000
water is pressured up in will
seep out somewhere.

595
00:34:20.000 --> 00:34:22.000
Here's another one. Water
seeping pass bulkhead still
requires some

596
00:34:22.000 --> 00:34:25.000
form of treatment. What a
bummer.

597
00:34:25.000 --> 00:34:30.000
The good thing is, if we go back
to the example

598
00:34:30.000 --> 00:34:33.000
about 1000 GPM of water flowing
out, you are looking at an
active

599
00:34:33.000 --> 00:34:39.067
water treatment plant. If you
knock that down to

600
00:34:39.067 --> 00:34:41.067
50 GPM, now you're in the realm
of some

601
00:34:41.067 --> 00:34:46.067
potentially more passive
treatments, which is a lot
cheaper and easier

602
00:34:46.067 --> 00:34:47.067
to work with.

603
00:34:47.067 --> 00:34:50.067
The real risk is the piping
failure around the bulkhead. If
the water

604
00:34:50.067 --> 00:34:55.067
makes its way around, that can
be a problem, and of course, the
liability

605
00:34:55.067 --> 00:35:01.067
for flooding adjacent mines

606
00:35:01.067 --> 00:35:07.067
Mac back -- last section is how
to integrate

607
00:35:07.067 --> 00:35:11.067
a bulkhead into the site plan.
Some of

608
00:35:11.067 --> 00:35:17.067
the bulkheads are really just
one component of the

609
00:35:17.067 --> 00:35:18.634
site solution. You use them in

610
00:35:18.634 --> 00:35:21.067
conjunction with other
monitoring and sampling

611
00:35:21.067 --> 00:35:25.067
on the site. If the flow comes
up in different places,'s dream

612
00:35:25.067 --> 00:35:31.067
gauges, ponds, distance from
other

613
00:35:31.067 --> 00:35:36.000
mines. Potentially still with
treatment plans if that

614
00:35:36.000 --> 00:35:42.067
is needed. And bulkheads can be
used really in different ways

615
00:35:42.067 --> 00:35:46.067
in different mine sites if he
integrate them in. There's

616
00:35:46.067 --> 00:35:51.067
a great quote from a talk I with
that recently and I can't
remember

617
00:35:51.067 --> 00:35:55.067
the author, but he said, if it
were free and available

618
00:35:55.067 --> 00:36:01.067
on Monday, what would you do
with it. so that is

619
00:36:01.067 --> 00:36:04.067
really a big question to ask
yourself. If it were free and
available

620
00:36:04.067 --> 00:36:13.067
on Monday, what would you do
with the bulkhead?

621
00:36:13.067 --> 00:36:16.067
so that is something to keep in
mind. Let's see how we can use

622
00:36:16.067 --> 00:36:17.067
the bulkhead in different ways.

623
00:36:17.067 --> 00:36:18.067
You can work as a flow control
structure.

624
00:36:18.067 --> 00:36:21.067
Full control structure is of the
where you're not trying to keep

625
00:36:21.067 --> 00:36:23.067
all the water inside the
mountain, perhaps you're keeping
the mountain

626
00:36:23.067 --> 00:36:28.067
drained and maybe whatever
treatment system

627
00:36:28.067 --> 00:36:32.000
you have, you just normal flows
but you have problems with
surges

628
00:36:32.000 --> 00:36:37.067
as the mind burps and sends
material out. So by putting

629
00:36:37.067 --> 00:36:43.067
a flow can stroll -- flow
control structure a thin had or
over glorified

630
00:36:43.067 --> 00:36:46.067
steel door, you could then
adjust the flows to whatever

631
00:36:46.067 --> 00:36:49.067
your treatment system can
handle.

632
00:36:49.067 --> 00:36:54.067
So that is nice. These do
require regular cleaning

633
00:36:54.067 --> 00:36:57.067
and maintenance. Temporary
storage.

634
00:36:57.067 --> 00:37:01.067
You may have a mine site where
the ground

635
00:37:01.067 --> 00:37:04.067
is so broken up that if you
[ Indiscernible ] water too long

636
00:37:04.067 --> 00:37:08.067
it leaks out it is not usable.
But again, your think about your
whole

637
00:37:08.067 --> 00:37:12.067
mine site and maybe are treating
the water maybe only a very
limited

638
00:37:12.067 --> 00:37:16.067
storage for water on the site so
the option could be that you
store

639
00:37:16.067 --> 00:37:22.067
water underground for part of
the season or you treat other

640
00:37:22.067 --> 00:37:25.067
service water in the critical
areas, and that if

641
00:37:25.067 --> 00:37:27.067
one level gets high enough,
inside the mountain and starts
to dribble

642
00:37:27.067 --> 00:37:31.067
out, the new drawdown the water
entry that. So you're actually
using

643
00:37:31.067 --> 00:37:37.067
underground storage almost like
a second reservoir.

644
00:37:37.067 --> 00:37:39.067
Or perhaps, the in situ
treatment you're able

645
00:37:39.067 --> 00:37:42.067
to do that you treated inside
the mountain and the release
that after

646
00:37:42.067 --> 00:37:46.067
the water is clean, that could
be another option. Another
option

647
00:37:46.067 --> 00:37:49.067
of course is the permanent seal.

648
00:37:49.067 --> 00:37:56.067
It returns the groundwater to
pre-grouting conditions. You
treat

649
00:37:56.067 --> 00:38:00.067
the seeps passive, you monitor
the bulkhead regulate. The
condition

650
00:38:00.067 --> 00:38:03.067
of the bulkhead, the head behind
a, how the grout is behaving

651
00:38:03.067 --> 00:38:07.067
and perhaps to combine that with
with some in

652
00:38:07.067 --> 00:38:14.067
situ treatment. Last section on
the post

653
00:38:14.067 --> 00:38:17.067
bulkhead installation. So
keeping permanent access to the
bulkhead

654
00:38:17.067 --> 00:38:23.067
for monitoring. You need to be
looking for seepage asked the
bulkhead and

655
00:38:23.067 --> 00:38:26.067
see if it becomes a problem.

656
00:38:26.067 --> 00:38:30.067
You look how you design the
bulkhead. You design for some
water

657
00:38:30.067 --> 00:38:34.000
level. If you designed it for
1000 psi, you have 800 behind
it,

658
00:38:34.000 --> 00:38:38.067
that is just fine. If You have
1200 behind a, that is less fine
and

659
00:38:38.067 --> 00:38:42.067
you may need to put in a second
bulkhead or extend the one that

660
00:38:42.067 --> 00:38:50.067
you have. You want to develop
and execute a proper

661
00:38:50.067 --> 00:38:53.067
monitoring plan to close your
bulkhead, just like with the
dam, closing

662
00:38:53.067 --> 00:38:57.067
it up and just walk away is not
a good

663
00:38:57.067 --> 00:39:01.067
plan. You need to have, you need
to have a good baseline of all
the

664
00:39:01.067 --> 00:39:03.067
flows in different areas and
monitor how fast the bulkhead is
coming

665
00:39:03.067 --> 00:39:07.067
up, in many cases you want to
check the bulkhead pressure up
to a certain

666
00:39:07.067 --> 00:39:11.067
level. And then wait and see if
it becomes a problem, the may be

667
00:39:11.067 --> 00:39:16.067
taken up 50 fever example, take
up another

668
00:39:16.067 --> 00:39:19.067
100 feet, give it a month or
something to check, maybe a
little further

669
00:39:19.067 --> 00:39:27.067
print so those are things to
look at the

670
00:39:27.067 --> 00:39:30.067
have to look for changes in
water chemistry per calendar
baseline

671
00:39:30.067 --> 00:39:33.000
change with the bulkhead coming
in their pick what is happening

672
00:39:33.000 --> 00:39:37.067
with surrounding mines. Increase
and decrease the, what is
happening

673
00:39:37.067 --> 00:39:45.067
to the streams in the area
collects that --?

674
00:39:45.067 --> 00:39:50.067
actual bulkhead inspection and
evaluation. You need to take a
look

675
00:39:50.067 --> 00:39:53.067
at the condition of the actual
concrete base. The condition of

676
00:39:53.067 --> 00:39:57.067
the valves of the pipes and the
stuff in there, the condition of

677
00:39:57.067 --> 00:40:02.067
the instruments you may have
behind their. Looking for
there's

678
00:40:02.067 --> 00:40:08.067
concentrated flows around the
bulkhead to see if that is
becoming

679
00:40:08.067 --> 00:40:13.067
a problem. If you're looking for
any kind of

680
00:40:13.067 --> 00:40:16.067
concentrated flows. Even
downstream in the bulkhead.
Again, there may

681
00:40:16.067 --> 00:40:20.067
be one of those joints that you
didn't think, [ Indiscernible ]

682
00:40:20.067 --> 00:40:24.067
it happens. And then of course
you check edition of the

683
00:40:24.067 --> 00:40:28.067
ground support to keep access
open to the bulkhead.

684
00:40:28.067 --> 00:40:30.067
You may need to go in the
regular basis, to clean out the
drainage

685
00:40:30.067 --> 00:40:36.000
ditch. You may need to install
new bolts or

686
00:40:36.000 --> 00:40:52.067
new supports.

687
00:41:27.067 --> 00:41:33.000
And -- so, I have

688
00:41:33.000 --> 00:41:38.067
some concluding thoughts due to
the cost of indefinite

689
00:41:38.067 --> 00:41:44.067
treatment it. bulkheads should
at least be considered on

690
00:41:44.067 --> 00:41:47.067
draining underground mine
solutions.

691
00:41:47.067 --> 00:41:53.067
It should be considered. The
regional and local geology, that
is key

692
00:41:53.067 --> 00:41:58.067
for evaluating if and where to
install bulkheads.

693
00:41:58.067 --> 00:42:03.067
You really have to,

694
00:42:03.067 --> 00:42:06.067
you know, once you know the
general area, you then have to
do the bulkhead

695
00:42:06.067 --> 00:42:08.067
designed to take a close look at
the local area and potential
seepage.

696
00:42:08.067 --> 00:42:14.067
If the bulkhead remains open, do
keep in mind that

697
00:42:14.067 --> 00:42:17.067
[ Indiscernible ] it is nothing
you necessarily want to

698
00:42:17.067 --> 00:42:21.067
pressurize up, they can still
serve as regulate flow

699
00:42:21.067 --> 00:42:25.067
and limit the damage from burps
and stuff. Whatever seepage you

700
00:42:25.067 --> 00:42:30.067
get past the bulkhead are coming
out of other seeps

701
00:42:30.067 --> 00:42:34.000
in the area may still be a big
improvement over groundwater
quality.

702
00:42:34.000 --> 00:42:37.000
So the fact you're not able to
totally seal something off does
not mean

703
00:42:37.000 --> 00:42:40.000
that it was not effective. And
of course bulkheads can be
combined

704
00:42:40.000 --> 00:42:47.000
with in situ treatment or other
treatment plans. If you more
concluding

705
00:42:47.000 --> 00:42:50.000
thoughts but bulkheads may or
may not be the right solution
for your

706
00:42:50.000 --> 00:42:52.000
site. Definitely not a
one-size-fits-all.

707
00:42:52.000 --> 00:42:58.000
You should only install after
very significant study and
design. Adjacent

708
00:42:58.000 --> 00:43:02.000
mines may be affected and that
would be a problem for you. And

709
00:43:02.000 --> 00:43:08.000
monitoring and maintenance are
needed after installation as
much

710
00:43:08.000 --> 00:43:11.000
as possible.

711
00:43:11.000 --> 00:43:16.000
With that, I can open it up to
questions from

712
00:43:16.000 --> 00:43:25.000
the audience. And then we will
move on to other speakers.

713
00:43:25.000 --> 00:43:27.000
>> Wonderful. We did get a
number of questions coming

714
00:43:27.000 --> 00:43:30.000
in as you were speaking and I
want to remind the participants
that

715
00:43:30.000 --> 00:43:34.934
they can continue to submit
questions using the Q&A

716
00:43:34.934 --> 00:43:38.000
pod. While we are waiting for
more questions, let's ask the
few that

717
00:43:38.000 --> 00:43:41.000
have come in. One person wants
to know if you can talk about
the range

718
00:43:41.000 --> 00:43:46.000
of flow rates you have addressed
with bulkheads.

719
00:43:46.000 --> 00:43:52.000
>> I mean, actually the

720
00:43:52.000 --> 00:43:57.000
highest flows I have been aware
of on design was

721
00:43:57.000 --> 00:44:03.000
maybe 2500. 2000 to begin with.
And then

722
00:44:03.000 --> 00:44:08.000
another one to look at, they had
a flow rate of

723
00:44:08.000 --> 00:44:14.000
about 1 1/2 GPM which led to the
big question

724
00:44:14.000 --> 00:44:18.000
of, you really want this? and
often the answer is not

725
00:44:18.000 --> 00:44:21.000
really.

726
00:44:21.000 --> 00:44:26.000
>> Considering these are used on
dam

727
00:44:26.000 --> 00:44:28.000
projects, a lot of times you
have significant head. So in
flow rates.

728
00:44:28.000 --> 00:44:34.000
It can run across the entire
spectrum in terms of

729
00:44:34.000 --> 00:44:37.067
flow rate.

730
00:44:37.067 --> 00:44:42.067
>> Okay.

731
00:44:42.067 --> 00:44:46.067
Another question, this
participant makes a statement
about criteria

732
00:44:46.067 --> 00:44:50.067
to decide how long to monitor a
bulkhead

733
00:44:50.067 --> 00:44:55.067
to arrive at a stable pool or
stable pool conditions. While

734
00:44:55.067 --> 00:45:01.067
site Pacific, what are some of
the factors you would consider
and try

735
00:45:01.067 --> 00:45:10.067
to arrive at that stable pool?

736
00:45:10.067 --> 00:45:12.067
>> Yeah, I mean, I guess Jeff --

737
00:45:12.067 --> 00:45:17.067
>> This is Jeff Graves. I will
show in a couple of the case
studies

738
00:45:17.067 --> 00:45:23.067
coming up pretty good slides
that establish how quickly

739
00:45:23.067 --> 00:45:25.067
a bulkhead reaches a relatively
steady state condition.

740
00:45:25.067 --> 00:45:29.067
I think will be pretty obvious
and based on that, it certainly
is site-specific

741
00:45:29.067 --> 00:45:35.000
in terms of how long it takes,
but in at least two examples

742
00:45:35.000 --> 00:45:39.067
I'm going to show, it is

743
00:45:39.067 --> 00:45:42.067
typically established a
steady-state condition within a
couple of months

744
00:45:42.067 --> 00:45:47.067
to a year. So once you have gone
through a full hydrologic cycle.

745
00:45:47.067 --> 00:45:52.067
You get a pretty good idea as to
what that final

746
00:45:52.067 --> 00:45:57.067
bulkhead or flow elevation is
going to be as a result of

747
00:45:57.067 --> 00:46:01.067
the bulkhead. Okay, great. With
that I think it might be good to

748
00:46:01.067 --> 00:46:05.067
move on to some of the site
examples in the next
presentation at this

749
00:46:05.067 --> 00:46:11.067
point. While letting
participants any more questions
as you

750
00:46:11.067 --> 00:46:23.067
are talking.

751
00:46:23.067 --> 00:46:24.067
Such

752
00:46:24.067 --> 00:46:30.067
>> This is Jeff Graves. I'm
going to be covering a couple of
bulkhead

753
00:46:30.067 --> 00:46:35.000
case studies. Actually, we have
quite a few bulkheads that

754
00:46:35.000 --> 00:46:40.067
the state is been involved in
here in Colorado. I just chose

755
00:46:40.067 --> 00:46:43.067
two of the sightseer. The first
site we're going to be talking
about

756
00:46:43.067 --> 00:46:50.067
is the Dinero Tunnel bulkhead
located it in Lake County
Colorado practice

757
00:46:50.067 --> 00:46:55.067
is installed in 2009. So we have
a pretty good post bulkhead data

758
00:46:55.067 --> 00:46:59.067
set to go over.

759
00:46:59.067 --> 00:47:01.067
Then I will also be talking
about a number bulkheads that
were installed

760
00:47:01.067 --> 00:47:05.067
at the Pennsylvania mine in
Summit County. There are
actually three

761
00:47:05.067 --> 00:47:09.067
constructed at that site. Will
cover a little bit regarding

762
00:47:09.067 --> 00:47:16.067
the reasoning behind having
three different bulkheads and
the

763
00:47:16.067 --> 00:47:18.067
site-specific conditions. Okay.

764
00:47:18.067 --> 00:47:22.067
We will start off with the
Dinero Tunnel. You've got some
obviously

765
00:47:22.067 --> 00:47:31.067
lovely and attractive AMD at
this

766
00:47:31.067 --> 00:47:33.000
mine site.

767
00:47:33.000 --> 00:47:36.000
Just trying to find the pointer.

768
00:47:36.000 --> 00:47:41.067
There we go. So you can see

769
00:47:41.067 --> 00:47:44.067
the large iron discharge, the
portal is located right about
their, and

770
00:47:44.067 --> 00:47:49.067
then you have waste rock pile
sitting in the wetland just
below the site,

771
00:47:49.067 --> 00:47:51.067
and in the photo on the right is
kind of a picture just outside
the

772
00:47:51.067 --> 00:47:57.067
portal and you can see obviously
significant precipitation of
iron

773
00:47:57.067 --> 00:48:06.067
hydroxide and all kinds of
bacterial use discussed earlier.

774
00:48:06.067 --> 00:48:10.067
Lovely photo. A little bit of
information regarding

775
00:48:10.067 --> 00:48:15.067
the setting. The Dinero Tunnel
is located in the Sugarloaf mind
district,

776
00:48:15.067 --> 00:48:19.067
in that area. This whole area
right

777
00:48:19.067 --> 00:48:25.067
in here located just kind of
south of turquoise Lake outside

778
00:48:25.067 --> 00:48:29.067
of Leadville. Most of the money
took place here in the late
1880s

779
00:48:29.067 --> 00:48:35.000
to the early 1900s. They
produced

780
00:48:35.000 --> 00:48:38.067
silver, gold, led, zinc, pretty
typical for most of the hard

781
00:48:38.067 --> 00:48:41.067
rock mining district here in
Colorado.

782
00:48:41.067 --> 00:48:45.067
The mining was located in large
granitic intrusion that

783
00:48:45.067 --> 00:48:50.067
had a number of small narrow
veins that were in place

784
00:48:50.067 --> 00:48:53.067
based on some tertiary
intrusions into that area.

785
00:48:53.067 --> 00:48:59.067
So you have got these fractures
and the majority

786
00:48:59.067 --> 00:49:05.067
of the ore was in that area in
that

787
00:49:05.067 --> 00:49:08.067
granitic intrusion. So the
Dinero Tunnel area based on some
of the

788
00:49:08.067 --> 00:49:14.067
water sampling that was done
accounts for about 75% of

789
00:49:14.067 --> 00:49:17.067
the magazines and zinc --
manganese zinc loading to the

790
00:49:17.067 --> 00:49:21.067
lake for which is this creek
right here, late

791
00:49:21.067 --> 00:49:27.067
for Creek which feeds into the
Arkansas River Park this area
right in here

792
00:49:27.067 --> 00:49:33.000
accounted for the majority of
the metals loading into the
lower

793
00:49:33.000 --> 00:49:39.067
leg fork -- Lake Fork Creek on
their. As you can see here,
here's

794
00:49:39.067 --> 00:49:44.067
a close-up over in here of a
site in the boxed area

795
00:49:44.067 --> 00:49:49.067
over there. A couple of the
Dinero Tunnel discharged onto
those waste

796
00:49:49.067 --> 00:49:55.067
piles and to Sugarloaf golf and
it's into

797
00:49:55.067 --> 00:49:57.067
the water wetland and loading
from the and other drainages

798
00:49:57.067 --> 00:50:02.067
around there in the tunnels. On
the next slide, you

799
00:50:02.067 --> 00:50:05.067
can kind of see a little more
defined photo of where those
drainage tunnels

800
00:50:05.067 --> 00:50:08.067
were. So this is part of what
was discussed in terms of
getting a

801
00:50:08.067 --> 00:50:12.067
good sense of what the overall
geology and

802
00:50:12.067 --> 00:50:16.067
kind of mind working system is
within the area to get a better
understanding

803
00:50:16.067 --> 00:50:22.067
of how potential bulkheading my
impact other areas. Within

804
00:50:22.067 --> 00:50:25.067
the Sugarloaf mining district
you have a number of drainage

805
00:50:25.067 --> 00:50:34.000
tunnels. The majority of those
tunnels were driven kind of to
the

806
00:50:34.000 --> 00:50:37.067
northwest to ore bodies backup
in here. Originally

807
00:50:37.067 --> 00:50:42.067
those were mind through shafts
back in here and then eventually

808
00:50:42.067 --> 00:50:46.067
they countered the water table
and needed to drain that area.
Probably

809
00:50:46.067 --> 00:50:51.067
the biggest drainage tunnel in
the area area is the Dinero
Tunnel.

810
00:50:51.067 --> 00:50:57.067
There couple of others in the
area but this one drained the

811
00:50:57.067 --> 00:51:03.067
majority of this ore body back
in here. A

812
00:51:03.067 --> 00:51:08.067
lot going on the list the same.
So with any investigation

813
00:51:08.067 --> 00:51:12.067
that might result in putting in
a bulkhead,

814
00:51:12.067 --> 00:51:14.067
there is pretty significant
baseline water quality sampling
that needs

815
00:51:14.067 --> 00:51:18.067
to occur in the area. This is
not only to establish what the
existing

816
00:51:18.067 --> 00:51:23.067
loads are and whether or not
even looking at

817
00:51:23.067 --> 00:51:26.067
a bulkhead at one of the tunnels
would deal with the majority of

818
00:51:26.067 --> 00:51:31.067
the problem, but it is also just
to establish the baseline to
understand

819
00:51:31.067 --> 00:51:35.000
what happens after you install
that bulkhead so you get some
kind

820
00:51:35.000 --> 00:51:39.067
of sense is as to how it
actually impacts the groundwater
system within

821
00:51:39.067 --> 00:51:42.067
the region. And so, with the
Dinero

822
00:51:42.067 --> 00:51:46.067
Tunnel there was a pretty
significant effort made to
establish a number

823
00:51:46.067 --> 00:51:48.067
of water quality sampling
locations.

824
00:51:48.067 --> 00:51:54.067
Some of these are historic
springs with the area. Some of

825
00:51:54.067 --> 00:52:00.067
them are drainage tunnels, and
some of these are just year's

826
00:52:00.067 --> 00:52:03.067
official creeks and runoff
areas.

827
00:52:03.067 --> 00:52:05.067
Federal helps to establish that
baseline to either build the
case

828
00:52:05.067 --> 00:52:14.067
that the bulkhead is working or
not working or successful or

829
00:52:14.067 --> 00:52:16.067
marginally successful.

830
00:52:16.067 --> 00:52:18.067
So we will do a little bit of
site-specific stuff here. Tunnel
conditions. As

831
00:52:18.067 --> 00:52:23.067
you can see in the photo in the
lower left, you kind of see the

832
00:52:23.067 --> 00:52:25.067
iron hydroxide mark down here,
and that is indicative

833
00:52:25.067 --> 00:52:30.067
of the fact that elevations
within that tunnel or the

834
00:52:30.067 --> 00:52:34.000
mine pool very quite a bit and
probably ended up with some kind
of blowout

835
00:52:34.000 --> 00:52:36.000
in the past where he had water
backed up to the elevation,

836
00:52:36.000 --> 00:52:42.000
and then suddenly released.
There his historic evidence of
water being

837
00:52:42.000 --> 00:52:48.000
impounded and released. We did a
tunnel investigation in 2005
which

838
00:52:48.000 --> 00:52:52.000
required quite a bit of
underground rehab,

839
00:52:52.000 --> 00:52:54.000
and that is a big part of doing
any of these tunnel
investigations.

840
00:52:54.000 --> 00:52:57.000
Kind of a pretty significant
cost is establishing safe enough
working

841
00:52:57.000 --> 00:53:03.000
conditions to gather the data
needed to be able to decide

842
00:53:03.000 --> 00:53:05.000
if a bulkhead is even an option.
So we

843
00:53:05.000 --> 00:53:10.000
did a good bit of underground
rehab to access areas of the
tunnel to

844
00:53:10.000 --> 00:53:15.000
get a better sense of what the
underground plumbing was. You
can see over on

845
00:53:15.000 --> 00:53:18.000
the right slide doing that
underground

846
00:53:18.000 --> 00:53:22.000
investigation usually results in
a pretty big mess when you're
walking

847
00:53:22.000 --> 00:53:25.000
around inside their. You get
quite a bit of release

848
00:53:25.000 --> 00:53:30.000
of iron hydroxide it fully at
the site we had a number of
ponds downstream

849
00:53:30.000 --> 00:53:35.934
we were able to address that
iron hydroxide we were inside
mucking

850
00:53:35.934 --> 00:53:40.000
around. But it can be pretty
challenging just to do the
investigation component

851
00:53:40.000 --> 00:53:44.000
of any of these sites. Sometimes
actually the underground

852
00:53:44.000 --> 00:53:48.000
rehab becomes more expensive
than the actual

853
00:53:48.000 --> 00:53:53.000
bulkhead installation. At this
site based on the initial

854
00:53:53.000 --> 00:53:58.000
work we did to do
investigations, we decided that
this might

855
00:53:58.000 --> 00:54:00.000
be a great site for a bulkhead.

856
00:54:00.000 --> 00:54:06.000
So based on a number the
criteria that was talked about
in

857
00:54:06.000 --> 00:54:10.000
terms of making a significant
overburden to reduce the
potential for Hydro

858
00:54:10.000 --> 00:54:16.000
jacking or fracking, we selected
a bulkhead location that was
about

859
00:54:16.000 --> 00:54:22.000
1250 feet from the portal. So
here

860
00:54:22.000 --> 00:54:26.000
is the Dinero portal over here.
We did

861
00:54:26.000 --> 00:54:28.000
exploration all the way back to
where we are prevented from
exploring

862
00:54:28.000 --> 00:54:31.067
further based on a cave-in. And
them based on the geology and
the

863
00:54:31.067 --> 00:54:36.000
fractures within that area and
the required head, required
overburden

864
00:54:36.000 --> 00:54:40.067
we would need. That assistance
is right

865
00:54:40.067 --> 00:54:41.067
here based on the potential
pressure.

866
00:54:41.067 --> 00:54:46.067
We selected a spot at about 1250
feet from

867
00:54:46.067 --> 00:54:50.067
the portal. That design had we
have there is 680 feet with
really based

868
00:54:50.067 --> 00:54:56.067
on this Dinero shaft over here
which would be

869
00:54:56.067 --> 00:55:02.067
the next discharge location.

870
00:55:02.067 --> 00:55:05.067
So typically that design has the
function of, if you

871
00:55:05.067 --> 00:55:11.067
were to backwater up, where
would water just discharge
naturally

872
00:55:11.067 --> 00:55:13.067
if the -- at the next elevation
and that Dinero

873
00:55:13.067 --> 00:55:16.067
shaft would be the pressure
relief valve if we were to
exceed that

874
00:55:16.067 --> 00:55:20.067
design pressure. And so that
Dinero shaft guided the actual
680 feet

875
00:55:20.067 --> 00:55:23.067
of design had as part of that
bulkhead placement. And so, we
decided

876
00:55:23.067 --> 00:55:30.067
on a 15 foot thick reinforced
concrete parallel plug. There
are a couple

877
00:55:30.067 --> 00:55:34.000
of different methodologies for
bulkhead design based on the

878
00:55:34.000 --> 00:55:40.067
design head, the rock editions
at the site, the

879
00:55:40.067 --> 00:55:45.067
amount of roughness along the
sides

880
00:55:45.067 --> 00:55:52.067
of that, we decided that a
parallel plug would be
sufficient if it was

881
00:55:52.067 --> 00:55:57.067
15 feet thick to resist any of
the thrust created by that 680
feet

882
00:55:57.067 --> 00:56:02.067
of head. I covered a little bit
of this, but one of the big
questions

883
00:56:02.067 --> 00:56:05.067
is why choose a bulkhead at the
site. And really one of the

884
00:56:05.067 --> 00:56:09.067
first reasons for choosing a
bulkhead is cost-effective flow
control.

885
00:56:09.067 --> 00:56:15.067
Bulkheads really allow you to
prevent those burps or sudden
surges that

886
00:56:15.067 --> 00:56:19.067
result in downstream water
quality impacts. So very
cost-effective

887
00:56:19.067 --> 00:56:22.067
doing that. At this site we knew
we did not have the

888
00:56:22.067 --> 00:56:28.067
funding or really the desire to
put in a permanent

889
00:56:28.067 --> 00:56:33.000
water treatment plan

890
00:56:33.000 --> 00:56:35.000
at the spot. And so, bulkheads
to provide an alternative to
water

891
00:56:35.000 --> 00:56:37.067
treatment. It is one way to try
and reduce loading without
having

892
00:56:37.067 --> 00:56:40.067
to put in a water treatment
plan.

893
00:56:40.067 --> 00:56:46.067
At the site we knew we had
pretty limited mine working
connectivity.

894
00:56:46.067 --> 00:56:49.067
We knew if we trapped up water,
at least we didn't have a lot of

895
00:56:49.067 --> 00:56:54.067
other workings connected to this
mine. In the crosscut tunnel
scenario,

896
00:56:54.067 --> 00:56:57.067
something to think about with
respect to where

897
00:56:57.067 --> 00:57:03.067
you place the bulkhead and what
the surrounding geology looks

898
00:57:03.067 --> 00:57:07.067
like dark one of the terms in
mining is a

899
00:57:07.067 --> 00:57:09.067
draft, and usually those dress
are horizontal workings driven
on structure.

900
00:57:09.067 --> 00:57:12.067
The crosscut is a tunnel that's
driven oftentimes perpendicular

901
00:57:12.067 --> 00:57:18.067
or at least oblique to the
dominant structural pattern
within

902
00:57:18.067 --> 00:57:21.067
the rock. And so, typically if
you got a crosscut,

903
00:57:21.067 --> 00:57:25.067
putting a bulkhead in that
location is good because most of
your fractures

904
00:57:25.067 --> 00:57:29.067
are running perpendicular, or at
least are dominant fractures

905
00:57:29.067 --> 00:57:32.000
are running perpendicular to the
actual mine working spec and

906
00:57:32.000 --> 00:57:36.000
and then it also provides an
opportunity to reduce oxygen
interaction with

907
00:57:36.000 --> 00:57:40.067
those sulfites. So here are some
photos

908
00:57:40.067 --> 00:57:41.067
a general bulkhead construction.

909
00:57:41.067 --> 00:57:45.067
This is actually the Dinero
bulkheads construction photos.
You can kind

910
00:57:45.067 --> 00:57:51.067
of see the upper left the
initial construction

911
00:57:51.067 --> 00:57:53.067
purposes construction at a
copper damper when you're

912
00:57:53.067 --> 00:57:56.067
constructing that bulkhead,
you've got to do with the water
still going

913
00:57:56.067 --> 00:57:59.067
through that location. You don't
shut the water off while you're

914
00:57:59.067 --> 00:58:00.067
working to put the bulkhead in.

915
00:58:00.067 --> 00:58:04.067
So you've got to capture the
water upgraded and get it
through your

916
00:58:04.067 --> 00:58:12.067
bulkhead location so you can
construct your for work and put
in

917
00:58:12.067 --> 00:58:14.067
your concrete. These are general
form construction, building the

918
00:58:14.067 --> 00:58:17.067
inner and outer forms you're
going to pump your concrete
into. You

919
00:58:17.067 --> 00:58:22.067
see this is kind of a completed
inside face of the

920
00:58:22.067 --> 00:58:25.067
waterside bulkhead. Actually
that is the air side bulkhead
because

921
00:58:25.067 --> 00:58:30.067
you can see up here in the upper
portion the grout tubes that
Christoph

922
00:58:30.067 --> 00:58:35.000
has spoken about. That is the
inside face of the air side

923
00:58:35.000 --> 00:58:38.067
of that bulkhead. And then you
can see down here what

924
00:58:38.067 --> 00:58:41.067
is required in terms of floor
cleanout.

925
00:58:41.067 --> 00:58:45.067
Typically through the mining
process, the actual driving of
that

926
00:58:45.067 --> 00:58:48.067
drift result in a pretty
irregular floor that have to be
completely

927
00:58:48.067 --> 00:58:56.067
cleaned out, and you may have a
floor that has 2 to 3

928
00:58:56.067 --> 00:58:59.067
feet of backfill material that
than the mind track was laid on.
So it

929
00:58:59.067 --> 00:59:01.067
does require significant amount
of cleaning to actually get good

930
00:59:01.067 --> 00:59:06.067
contact with solid rock all the
way around that bulkhead. So
here's

931
00:59:06.067 --> 00:59:10.067
a picture where the concrete is
being pumped into

932
00:59:10.067 --> 00:59:14.067
the mine. The papers down here,
and here's the final

933
00:59:14.067 --> 00:59:18.067
product. Christoph also
mentioned the pressure gauge. So
this had

934
00:59:18.067 --> 00:59:22.067
not only the discharge line, but
then

935
00:59:22.067 --> 00:59:28.067
we also had a separate
three-quarter inch line to
monitor pressure and

936
00:59:28.067 --> 00:59:31.067
to conduct sampling

937
00:59:31.067 --> 00:59:35.000
>> And so, somebody asked
earlier a question

938
00:59:35.000 --> 00:59:37.067
regarding my pool elevation and
when you reach that steady-state

939
00:59:37.067 --> 00:59:43.067
condition. So this is pressure
monitoring at the Dinero Tunnel
mind pool

940
00:59:43.067 --> 00:59:47.067
at the bulkhead face over the
course of

941
00:59:47.067 --> 00:59:50.067
the last 10 years. As you can
see, we achieved relatively
steady-state

942
00:59:50.067 --> 00:59:57.067
conditions pretty quickly. About
a year. Roughly a year to

943
00:59:57.067 --> 01:00:01.067
get those steady-state
conditions up in here. And then
it tends to

944
01:00:01.067 --> 01:00:04.067
fluctuate based on the
hydrographs. But we have

945
01:00:04.067 --> 01:00:07.067
peak elevations and then some
troughs are here, and remains
relatively

946
01:00:07.067 --> 01:00:13.067
consistent along that kind of
time period in

947
01:00:13.067 --> 01:00:15.067
terms of what the actual head
is. And this is

948
01:00:15.067 --> 01:00:20.067
had on the site, not pressure,
it is not 400 feet a

949
01:00:20.067 --> 01:00:25.067
head. A little bit of
post-bulkhead data.

950
01:00:25.067 --> 01:00:27.067
This shows some interesting
things.

951
01:00:27.067 --> 01:00:30.067
One thing I will note on here is
we did sampling at the site or
USGS

952
01:00:30.067 --> 01:00:36.000
did sampling kind of for the
large group at

953
01:00:36.000 --> 01:00:41.067
the site. Initially in June 2006
was kind of the baseline data,
and

954
01:00:41.067 --> 01:00:45.067
then we sampled the next three
years. And the three sites

955
01:00:45.067 --> 01:00:50.067
that are shown on here, one of
the Dinero Tunnel discharge, we
have

956
01:00:50.067 --> 01:00:56.067
a downstream location here, then

957
01:00:56.067 --> 01:00:58.067
[ Indiscernible ] is the
farthest downstream location

958
01:00:58.067 --> 01:01:01.067
which I don't want to call it a
compliance point, but that is
where

959
01:01:01.067 --> 01:01:05.067
we are trying to establish
better water quality. As you can
see on

960
01:01:05.067 --> 01:01:08.067
here, each one of the sampling
locations, and he was he

961
01:01:08.067 --> 01:01:13.067
discharge, pH, totals and
concentration, and then total
zinc load. Some encouraging

962
01:01:13.067 --> 01:01:15.067
things we saw.

963
01:01:15.067 --> 01:01:18.067
We roughly had at the Dinero
Tunnel a reduction which is not
surprising

964
01:01:18.067 --> 01:01:24.067
considering we pretty much shut
off the flow reduce the flow
significantly

965
01:01:24.067 --> 01:01:29.067
back and then we also saw some
downstream improvements

966
01:01:29.067 --> 01:01:35.000
in both pH. So we had pre-pH
condition 3.7

967
01:01:35.000 --> 01:01:39.067
and saw nearly a unit, a full
unit of pH increase downstream.

968
01:01:39.067 --> 01:01:48.067
That is pretty significant. We
also saw zinc loads

969
01:01:48.067 --> 01:01:49.067
decrease downstream.

970
01:01:49.067 --> 01:01:53.067
There were some anomalies that
occurred in 2011. and I was a
pretty big

971
01:01:53.067 --> 01:01:55.067
snow year, so with it we also
had some downstream influence
from other

972
01:01:55.067 --> 01:01:59.067
sites within the watershed that
were more surface

973
01:01:59.067 --> 01:02:04.067
related, but there could've been
a

974
01:02:04.067 --> 01:02:08.067
component of mine pull the
impact of water quality during
that time

975
01:02:08.067 --> 01:02:12.067
too. As you can see, it does
show improvement. One thing I
don't have

976
01:02:12.067 --> 01:02:19.067
on here and I believe USGS is
going to publish

977
01:02:19.067 --> 01:02:21.067
a paper here in the next year or
so that discusses some long-term

978
01:02:21.067 --> 01:02:26.067
monitoring they've done. They
did some additional sampling at
the

979
01:02:26.067 --> 01:02:31.067
site between 2015 and 2018

980
01:02:31.067 --> 01:02:33.000
that kind of confuses the
picture a little bit. We don't
see quite

981
01:02:33.000 --> 01:02:38.000
the improvement over the long
term that we saw initially. So
you have

982
01:02:38.000 --> 01:02:41.000
to wait for that data to come
out.

983
01:02:41.000 --> 01:02:44.000
One of the impacts we did see
was out of that water table

984
01:02:44.000 --> 01:02:46.000
rose within the region based on
having the tunnel plugged, with

985
01:02:46.000 --> 01:02:50.000
on increase of discharge at one
of the adjacent mine sites

986
01:02:50.000 --> 01:02:56.000
but this is something Christoph
mentioned that

987
01:02:56.000 --> 01:02:58.000
can happen. Here is the Nelson
tunnel right

988
01:02:58.000 --> 01:03:00.000
over here. Is the Dinero Tunnel.

989
01:03:00.000 --> 01:03:04.000
This whole area back here is now
flooded up to 400 feet above
where

990
01:03:04.000 --> 01:03:07.000
it was prior to the bulkhead,
and we started seeing

991
01:03:07.000 --> 01:03:11.000
significant increase in
discharge at the Nelson tunnel.

992
01:03:11.000 --> 01:03:16.000
So the upper left photo is
pretty bulkhead, and then you
can see the

993
01:03:16.000 --> 01:03:20.000
bottom left photo is about four
years following

994
01:03:20.000 --> 01:03:28.000
bulkhead installation. Pretty
significant change in discharge
at the Nelson

995
01:03:28.000 --> 01:03:30.000
tunnel location. And so we
definitely saw what we think is

996
01:03:30.000 --> 01:03:33.934
an impact as a result of having
a regionally raised water table.

997
01:03:33.934 --> 01:03:38.000
And what we think is what is
going on as you can see I have
highlighted

998
01:03:38.000 --> 01:03:42.000
here and read a large geologic
structure that runs kind of this

999
01:03:42.000 --> 01:03:48.000
direction from the northwest to
the southeast and the Dinero
Tunnel

1000
01:03:48.000 --> 01:03:52.000
actually accesses, and the
majority of the mine workings
are on that

1001
01:03:52.000 --> 01:03:57.000
geologic structure here. The
hypothesis is the regional water
table raised

1002
01:03:57.000 --> 01:04:02.000
and now is kind of utilizing
that fault

1003
01:04:02.000 --> 01:04:06.000
zone as a conduit that Christoph
mentioned that can function

1004
01:04:06.000 --> 01:04:09.000
as carrying water down to the
Nelson tunnel where it
eventually discharges.

1005
01:04:09.000 --> 01:04:15.000
So it is an impact that we think
is a result of

1006
01:04:15.000 --> 01:04:18.000
having that mine pool raised
significantly.

1007
01:04:18.000 --> 01:04:22.000
Here is data the bears that
connection out. A little bit

1008
01:04:22.000 --> 01:04:26.000
of a comp located slide, but
these are other sampling
locations, and

1009
01:04:26.000 --> 01:04:32.000
so little Sugarloaf is kind of

1010
01:04:32.000 --> 01:04:34.000
this zone right here.

1011
01:04:34.000 --> 01:04:38.067
This is Sugarloaf. Dinero Tunnel
did not discharge into a, this
is

1012
01:04:38.067 --> 01:04:43.067
an adjacent surface Gulch. And
what you

1013
01:04:43.067 --> 01:04:47.067
will see, these are some
sampling locations in their. You
will

1014
01:04:47.067 --> 01:04:53.067
see pre-bulkhead, obviously the
zinc concentration

1015
01:04:53.067 --> 01:04:57.067
really high. All the adjacent
discharge locations, is in
concentrations

1016
01:04:57.067 --> 01:04:58.067
pretty low.

1017
01:04:58.067 --> 01:05:02.067
What we saw following bulkhead
installation and valve closure
in 2009 with what

1018
01:05:02.067 --> 01:05:07.067
appears to be an increase in
adjacent discharge locations.

1019
01:05:07.067 --> 01:05:10.067
So the Nelson tunnel is here in
these upside down purple

1020
01:05:10.067 --> 01:05:15.067
triangles. You can see a general
trend in the upward direction
for

1021
01:05:15.067 --> 01:05:22.067
zinc concentration, then also in
Sugarloaf Gulch your see the
same

1022
01:05:22.067 --> 01:05:25.067
kind of trend on the start
their. So we do see what appears

1023
01:05:25.067 --> 01:05:31.067
to be an interaction between the
mind pool and adjacent surface
water

1024
01:05:31.067 --> 01:05:34.000
discharge and other mine
workings. But so far, at least

1025
01:05:34.000 --> 01:05:40.067
in the data we have available at
this point, there is still a
downstream

1026
01:05:40.067 --> 01:05:45.067
improvement in load, but it is
not as great as we were

1027
01:05:45.067 --> 01:05:48.067
hoping for. So a little bit of a
summary of Dinero bulkhead
results

1028
01:05:48.067 --> 01:05:52.067
back I always like to keep in
mind what the purpose of that

1029
01:05:52.067 --> 01:05:56.067
bulkhead was in terms of
evaluating success or failure.
One of the purposes

1030
01:05:56.067 --> 01:06:00.067
was to reduce or eliminate
blowout surge events,

1031
01:06:00.067 --> 01:06:03.067
and the successfully did that.
We did reduce discharge at the
portal,

1032
01:06:03.067 --> 01:06:09.067
and then also reduced downstream
loading of most

1033
01:06:09.067 --> 01:06:13.067
metals but it is a little

1034
01:06:13.067 --> 01:06:16.067
bit of a mixed picture proximity
new data may not bear that out
completely,

1035
01:06:16.067 --> 01:06:19.067
but we certainly did not
decrease water quality
downstream. Which

1036
01:06:19.067 --> 01:06:25.067
is not seeing as much of a
decrease in water quality we
were

1037
01:06:25.067 --> 01:06:29.067
hoping for. Or an increase in
water quality we were hoping for

1038
01:06:29.067 --> 01:06:35.000
but we did see an increase the
flow at the Nelson tunnel which

1039
01:06:35.000 --> 01:06:38.067
wasn't unexpected, but we were
hoping that it would not have
had as significant

1040
01:06:38.067 --> 01:06:45.067
of an impact. And then we also
saw increased loading in
Sugarloaf Gulch

1041
01:06:45.067 --> 01:06:47.067
with the -- which at this point
is not offset the downstream
improvement,

1042
01:06:47.067 --> 01:06:52.067
but it is something we are
keeping an eye on. Kind of that
long-term

1043
01:06:52.067 --> 01:06:56.067
impact is still unknown. And
that

1044
01:06:56.067 --> 01:06:59.067
is a bit they will bulkheads. A
lot of times it takes a long
time

1045
01:06:59.067 --> 01:07:01.067
to understand the full impacts
to the groundwater system
surrounding

1046
01:07:01.067 --> 01:07:04.067
the bulkhead the next one we
will touch on is the
Pennsylvania mine.

1047
01:07:04.067 --> 01:07:09.067
You can see if some other lovely
photos of AMD discharge across.

1048
01:07:09.067 --> 01:07:11.067
We installed a flume
pre-investigation to get

1049
01:07:11.067 --> 01:07:15.067
an understanding of what flow
rates were at

1050
01:07:15.067 --> 01:07:19.067
the site. The photo on the right
you can see where the discharge

1051
01:07:19.067 --> 01:07:22.067
from the Porter actually meets
the receiving stream and then
you have

1052
01:07:22.067 --> 01:07:27.067
precipitation and iron hydroxide
and aluminum

1053
01:07:27.067 --> 01:07:32.000
hydroxide downstream. So setting
here. Very similar to the Dinero

1054
01:07:32.000 --> 01:07:37.067
site. You have got a large, I

1055
01:07:37.067 --> 01:07:40.067
think I will show in the next
slide the geology pick but you
have a

1056
01:07:40.067 --> 01:07:46.067
lot of mine sets around here we
established a lot of

1057
01:07:46.067 --> 01:07:50.067
monitoring locations. But it is
located

1058
01:07:50.067 --> 01:07:53.067
in the upper regions of Peru
Creek just outside of Keystone.
Here's

1059
01:07:53.067 --> 01:07:55.067
a Keystone ski area over here.
Based on the data we collected,
the Pennsylvania

1060
01:07:55.067 --> 01:08:04.067
mine is a single largest
man-made metals contributor

1061
01:08:04.067 --> 01:08:07.067
to the snake River at about
40.000 pounds of zinc per year
perks a

1062
01:08:07.067 --> 01:08:13.067
huge loader. And that is borne
out down here in

1063
01:08:13.067 --> 01:08:15.067
the lower tables here. This is
looking at zinc load from
upstream above

1064
01:08:15.067 --> 01:08:16.067
the Pennsylvania mine to
downstream.

1065
01:08:16.067 --> 01:08:18.067
And you can see significant
increase pretty much all the
metals concentrations

1066
01:08:18.067 --> 01:08:23.067
above and below the Pennsylvania
mines. Establish

1067
01:08:23.067 --> 01:08:28.067
pretty well this is the bad
actor within the watershed. So
as with

1068
01:08:28.067 --> 01:08:33.000
the Dinero Tunnel, you've got a
situation where you've got a
large

1069
01:08:33.000 --> 01:08:40.067
geologic stock here and in place
stock

1070
01:08:40.067 --> 01:08:43.067
called the Montezuma stock in
they have mineralization along
the margins.

1071
01:08:43.067 --> 01:08:45.067
Also a shear zone over here the
did have significant
mineralization

1072
01:08:45.067 --> 01:08:49.067
too. A lot of hydrothermal
alteration in the surrounding
rock which does

1073
01:08:49.067 --> 01:08:51.067
influence how well we can
establish the success of that

1074
01:08:51.067 --> 01:08:59.067
bulkhead because there is a lot
of natural loading going on
within

1075
01:08:59.067 --> 01:09:02.067
this watershed.

1076
01:09:02.067 --> 01:09:04.067
History of the mine site. The
photo on the left, here

1077
01:09:04.067 --> 01:09:08.067
is the cross-section of what it
looks like and then here is a
plan

1078
01:09:08.067 --> 01:09:13.067
view looking down at it here.
Originally discovered in 1879.
It

1079
01:09:13.067 --> 01:09:22.067
was mind until the 1950s for
both gold and silver. They had
six

1080
01:09:22.067 --> 01:09:24.067
main levels, a through F and sub
levels in between. And a lot of

1081
01:09:24.067 --> 01:09:28.067
scoping between those levels. So
pretty open in the upper
workings.

1082
01:09:28.067 --> 01:09:31.067
There was a decent producer,
mostly silver, not a huge
producer. So

1083
01:09:31.067 --> 01:09:36.000
not one of the biggest sites,
but since it was driven as a
drainage

1084
01:09:36.000 --> 01:09:40.067
tunnel, pretty significant
impact

1085
01:09:40.067 --> 01:09:43.067
in the local watershed. One of
the challenges we had in
evaluating

1086
01:09:43.067 --> 01:09:45.067
the site is initially all the
portals into those working for
actually

1087
01:09:45.067 --> 01:09:50.067
collapsed.'s we did some
interesting investigative
techniques to establish

1088
01:09:50.067 --> 01:09:54.067
the underground flow system and
how things are connected

1089
01:09:54.067 --> 01:10:00.067
based on doing some tracer
studies and

1090
01:10:00.067 --> 01:10:04.067
isotope analysis. So here is a
site picture. We're sitting

1091
01:10:04.067 --> 01:10:10.067
at about 11.000 feet here. So
pretty high up in

1092
01:10:10.067 --> 01:10:13.067
the watershed. This is a trace
of the vein system where it

1093
01:10:13.067 --> 01:10:17.067
is exposed on surface and you
can see the two main levels, the
drainage

1094
01:10:17.067 --> 01:10:21.067
tunnel and then you have another
main entry level, the sea level

1095
01:10:21.067 --> 01:10:26.067
appear which is about 270 feet
above the F level

1096
01:10:26.067 --> 01:10:28.067
and then here is Peru Creek down
here where the earlier photo

1097
01:10:28.067 --> 01:10:30.067
was with the discharge
intercept.

1098
01:10:30.067 --> 01:10:34.000
You can also see a number of
what are collapsed scope syrup
on

1099
01:10:34.000 --> 01:10:38.067
the surface. Mining actually all
the way to the surface and it is

1100
01:10:38.067 --> 01:10:43.067
probably collecting surface
runoff and snowmelt and
challenging it

1101
01:10:43.067 --> 01:10:46.067
-- channeling it into
[ Indiscernible ] as I

1102
01:10:46.067 --> 01:10:49.067
mentioned, the portals were
collapsed and we had to do a
significant amount

1103
01:10:49.067 --> 01:10:55.067
of portal and undergrad rehab at
the site. We excavated the

1104
01:10:55.067 --> 01:10:58.067
portal, installed a good bit of
ground support and put

1105
01:10:58.067 --> 01:11:03.067
in a large 12 foot culvert to
allow access into

1106
01:11:03.067 --> 01:11:07.067
those workings. Here are before
and after pictures down here on

1107
01:11:07.067 --> 01:11:10.067
the bottom of the amount of
rehab done underground just to
provide

1108
01:11:10.067 --> 01:11:14.067
safe access. This is at the main
junction with

1109
01:11:14.067 --> 01:11:18.067
the vein, before with the timber
and all the iron hydroxide and
then

1110
01:11:18.067 --> 01:11:22.067
you can see what that looks like
after we did rehab. So pretty

1111
01:11:22.067 --> 01:11:28.067
significant effort is rehab and
pretty expensive. So we did a
good

1112
01:11:28.067 --> 01:11:33.000
bit of underground
characterization to establish
what is going on with

1113
01:11:33.000 --> 01:11:37.067
the plumbing system underground.
Obviously these

1114
01:11:37.067 --> 01:11:41.067
are not quantitative, but we're
pretty good water in

1115
01:11:41.067 --> 01:11:47.067
certain locations. And we had
very bad water and

1116
01:11:47.067 --> 01:11:50.067
other locations. I won't get
into too much of the detail in
terms

1117
01:11:50.067 --> 01:11:53.067
of why that is going on, but the
majority of it is, this is the
main

1118
01:11:53.067 --> 01:11:57.067
fault structure here were most
of the mineralization occurred,
and

1119
01:11:57.067 --> 01:11:59.067
the water that moves down that
fault structure through the
upper workings

1120
01:11:59.067 --> 01:12:08.067
is pretty bad because it has
been moving through a good bit

1121
01:12:08.067 --> 01:12:11.067
of sulfite ore. This is a cross
got driven all the way to
intercept

1122
01:12:11.067 --> 01:12:18.067
other veins so they didn't
really have nearly the same kind
of intersect

1123
01:12:18.067 --> 01:12:21.067
with an ore body in the secular
pick we had two zones with

1124
01:12:21.067 --> 01:12:25.067
water coming into the site. This
is a cross got tunnel as I
mentioned.

1125
01:12:25.067 --> 01:12:28.067
So could be conducive to having
a bulkhead, just based on the
natural

1126
01:12:28.067 --> 01:12:33.000
trend of the geologic structures
in

1127
01:12:33.000 --> 01:12:35.000
that area. So we did a good bit
of water sampling. You can see
what

1128
01:12:35.000 --> 01:12:40.000
the inside of that mind working
looks like after we got it

1129
01:12:40.000 --> 01:12:46.000
cleaned out. So why choose a
bulkhead at

1130
01:12:46.000 --> 01:12:49.000
the site?

1131
01:12:49.000 --> 01:12:51.000
a lot of the same reasons we
chose at the Dinero site. One of
the biggest

1132
01:12:51.000 --> 01:12:53.000
being cost-effective flow
control.

1133
01:12:53.000 --> 01:12:55.000
At the site we have had pretty
significant search and blowout
events in the

1134
01:12:55.000 --> 01:13:04.000
past. Typical flow of the sites
up to about a maximum of

1135
01:13:04.000 --> 01:13:06.000
150 GPM at the peak of the
hydrographs, but there were

1136
01:13:06.000 --> 01:13:14.000
certain occasions following
rainfall where we had a peak
flow of over

1137
01:13:14.000 --> 01:13:21.000
1 1/2 CFS. So we wanted at least
a

1138
01:13:21.000 --> 01:13:23.000
minimum to be able to control
flow.

1139
01:13:23.000 --> 01:13:25.000
And then also a lot of the
things I mentioned before, same
credit

1140
01:13:25.000 --> 01:13:28.000
they've, alternative to water
treatment but we're not going to
build a water

1141
01:13:28.000 --> 01:13:31.000
treatment plant here. At a
pretty simple mine in terms of
connectivity.

1142
01:13:31.000 --> 01:13:34.934
So we did build two bulkheads at
the site. One back along the
crosscut

1143
01:13:34.934 --> 01:13:36.934
here. I showed a pretty
significant water inflow back
here. And then

1144
01:13:36.934 --> 01:13:43.000
we also built an outer bulkhead
to capture the water

1145
01:13:43.000 --> 01:13:46.000
flowing down that drift through
here. One of

1146
01:13:46.000 --> 01:13:50.000
the challenges we have is we
don't have a lot of rock cover
here because

1147
01:13:50.000 --> 01:13:51.000
we're not very far back in the
tunnel.

1148
01:13:51.000 --> 01:13:55.000
This outer bulkhead is only
about 275 feet from the portal,
and we

1149
01:13:55.000 --> 01:13:58.000
only have a little over 100 feet
of cover at that location. Which

1150
01:13:58.000 --> 01:14:02.000
is really why we try to step the
pressure down with two bulkheads

1151
01:14:02.000 --> 01:14:08.000
at this site. So we built the
first bulkhead appear in 2014.

1152
01:14:08.000 --> 01:14:12.000
impounded water, and eventually
rotted off all the connections
within

1153
01:14:12.000 --> 01:14:17.000
the bulkhead, and then pour the
second bulkhead downstream as
kind

1154
01:14:17.000 --> 01:14:23.000
of a step down to capture the
remaining flow, and then also
step

1155
01:14:23.000 --> 01:14:27.000
that pressure down. So you can
see the basics with respect to
design

1156
01:14:27.000 --> 01:14:32.000
on those bulkheads. The

1157
01:14:32.000 --> 01:14:34.000
just couple pictures a bulkhead
construction. I won't spend too

1158
01:14:34.000 --> 01:14:37.067
much time on these big you can
look through general process. It
is pretty

1159
01:14:37.067 --> 01:14:44.067
much the same in each one of the
sites. Establishing your air
side

1160
01:14:44.067 --> 01:14:49.067
and waterside formwork and then
putting underground pipes and
all

1161
01:14:49.067 --> 01:14:54.067
the insides, inner workings of
your bulkhead. And that here is
construction

1162
01:14:54.067 --> 01:14:59.067
a bulkhead number two. Very
similar situation. Like I
mentioned,

1163
01:14:59.067 --> 01:15:02.067
it is always a challenge to get
that floor cleaned out, and that

1164
01:15:02.067 --> 01:15:04.067
is one of the critical points,
getting the floor completely
clean so you

1165
01:15:04.067 --> 01:15:11.067
have good contact with your wall
rock. Okay. Quick here on what
our

1166
01:15:11.067 --> 01:15:16.067
pressures are on the bulkhead.
This time period,

1167
01:15:16.067 --> 01:15:18.067
and at the site we actually
installed pressure transducers

1168
01:15:18.067 --> 01:15:21.067
with data loggers on the
backside of the bulkhead so we
could have

1169
01:15:21.067 --> 01:15:24.067
real time pressure all year
long.

1170
01:15:24.067 --> 01:15:27.067
And have that recorded pixel
records pressure twice daily on

1171
01:15:27.067 --> 01:15:36.000
both of these bulkheads. And we
also establish a flume out

1172
01:15:36.000 --> 01:15:40.067
front the safe slow right at the
same time

1173
01:15:40.067 --> 01:15:44.067
the bulk rate monitors pressure
per this is for 2014 on the way

1174
01:15:44.067 --> 01:15:46.067
to 2018% over the last four
years Brooke you can see
steady-state

1175
01:15:46.067 --> 01:15:51.067
at the inner bulkhead actually
took two seasons to establish.
First

1176
01:15:51.067 --> 01:15:55.067
season it made it up to this
pressure, and the drop-down

1177
01:15:55.067 --> 01:16:00.067
over the summer, and then we
established what appears to be a
steady-state

1178
01:16:00.067 --> 01:16:05.067
pressure because it pretty much
meets the peaks on all these and

1179
01:16:05.067 --> 01:16:08.067
easy a similar trend in terms of
dewatering from the bulkhead

1180
01:16:08.067 --> 01:16:13.067
over the course of the year pick
we had a

1181
01:16:13.067 --> 01:16:16.067
similar situation on the inner
bulkhead where establish, or the
outer bulkhead

1182
01:16:16.067 --> 01:16:19.067
were established pressure the
first year, and that we have
pretty steady-state

1183
01:16:19.067 --> 01:16:22.067
pressure. So a lot of gaps in
here.

1184
01:16:22.067 --> 01:16:24.067
We've had issues keeping the
batteries powered at that
elevation

1185
01:16:24.067 --> 01:16:27.067
considering the temperatures
over the winter and the fact
that we

1186
01:16:27.067 --> 01:16:32.000
can't access the site. Out of
six months out of the

1187
01:16:32.000 --> 01:16:36.000
year. That we have got pretty
good data. You fully see a flow,
increase

1188
01:16:36.000 --> 01:16:39.067
in flow rate at the portal based
on an increase

1189
01:16:39.067 --> 01:16:43.067
in pressure behind those
bulkheads, but this flowrate
right here

1190
01:16:43.067 --> 01:16:47.067
actually reflects a significant
reduction over what we had
prior.

1191
01:16:47.067 --> 01:16:53.067
So even the P are about a third
of what they been otherwise

1192
01:16:53.067 --> 01:16:55.067
in a very short lasting.

1193
01:16:55.067 --> 01:17:01.067
Very temporal. But we also
suspect that that steady-state
is a function

1194
01:17:01.067 --> 01:17:03.067
of bedrock contacted we're
actually getting discharge from
the mind

1195
01:17:03.067 --> 01:17:08.067
pull into that contact and then
down through the blue via. It
never

1196
01:17:08.067 --> 01:17:11.067
actually surfaces.

1197
01:17:11.067 --> 01:17:16.067
Bulkhead results. So these are

1198
01:17:16.067 --> 01:17:17.067
bulkhead results for pH and
think.

1199
01:17:17.067 --> 01:17:22.067
Here in the red you will see
pre-bulkhead data. This is
looking from upstream

1200
01:17:22.067 --> 01:17:26.067
near the Pennsylvania mind
downstream to the snake River
which is

1201
01:17:26.067 --> 01:17:31.067
about 6000 meters downstream.
You can see what it looks like,
a pretty

1202
01:17:31.067 --> 01:17:34.000
good trained, very low pH part
of the bulkhead

1203
01:17:34.000 --> 01:17:37.067
in each of the subsequent years
we actually have an increase a
bulkhead

1204
01:17:37.067 --> 01:17:42.067
directly downstream. We tend to
lose that as we have other
sections

1205
01:17:42.067 --> 01:17:46.067
or other streams the discharge
into the Peru Creek the

1206
01:17:46.067 --> 01:17:50.067
pretty significant background
load, not related to

1207
01:17:50.067 --> 01:17:54.067
my name. Just the natural
geology. So we are not seeing

1208
01:17:54.067 --> 01:17:57.067
a significant improvement all
the

1209
01:17:57.067 --> 01:17:59.067
way downstream as we would hope,
but the fully as a result of the

1210
01:17:59.067 --> 01:18:03.067
bulkhead with the improvement
within the local watershed. Same
situation

1211
01:18:03.067 --> 01:18:09.067
for think. This was Inc.
pre-bulkhead, here is Inc.
following

1212
01:18:09.067 --> 01:18:11.067
bulkhead closure. We do see a
reduction.

1213
01:18:11.067 --> 01:18:15.067
Not necessarily as big as we
would like. The interesting
thing here

1214
01:18:15.067 --> 01:18:21.067
is reducing a pretty significant
increase over in

1215
01:18:21.067 --> 01:18:23.067
this area.

1216
01:18:23.067 --> 01:18:26.067
This is part of downstream that
we don't think it is connected
to

1217
01:18:26.067 --> 01:18:28.067
the mind pool. This is more a
function of the local geology
and inputs

1218
01:18:28.067 --> 01:18:34.000
from other tributaries that come
into

1219
01:18:34.000 --> 01:18:36.000
Peru Creek.

1220
01:18:36.000 --> 01:18:39.067
So it didn't improve water
quality as far downstream as we
hoped, but

1221
01:18:39.067 --> 01:18:42.067
we did see at least a local
improvement in the watershed. So
here is some

1222
01:18:42.067 --> 01:18:47.067
loading numbers. You can see
these are all

1223
01:18:47.067 --> 01:18:51.067
post bulkhead construction as
compared to the 20.000 or 2009
baseline.

1224
01:18:51.067 --> 01:18:54.067
You can see pretty consistent
load reductions

1225
01:18:54.067 --> 01:18:57.067
across the board for most
metals.

1226
01:18:57.067 --> 01:19:02.067
Some obviously a bigger
improvement,

1227
01:19:02.067 --> 01:19:05.067
somewhere, 33% zinc is not as
much as we hoped. But some of
the other

1228
01:19:05.067 --> 01:19:10.067
three had pretty significant
improvements in terms of total
low downstream.

1229
01:19:10.067 --> 01:19:13.067
So relatively happy with the
results, but it is somewhat
mixed

1230
01:19:13.067 --> 01:19:22.067
and we will see over time what
we actually get. So

1231
01:19:22.067 --> 01:19:26.067
pen mine results,

1232
01:19:26.067 --> 01:19:29.067
illuminate a portal blowout or
surge events. Reduced surface
discharge

1233
01:19:29.067 --> 01:19:32.000
of the mine portal. Reduced
downstream of loading of most
metals Eberly

1234
01:19:32.000 --> 01:19:34.000
reduce long time ago when M by
installing bulkheads that are
somewhat walk

1235
01:19:34.000 --> 01:19:38.067
away provocatively completely
walk away because Christoph
would not

1236
01:19:38.067 --> 01:19:40.067
let me, but at least there are
situations where we don't have

1237
01:19:40.067 --> 01:19:47.067
to do as much active work on the
site. We do have some

1238
01:19:47.067 --> 01:19:51.067
increased flow at a spring

1239
01:19:51.067 --> 01:19:53.067
above the mine portal. We will
see what happens over time but
as I

1240
01:19:53.067 --> 01:19:55.067
mentioned with bulkheads, it is
really a long-term monitoring
situation

1241
01:19:55.067 --> 01:19:57.067
to understand those full
impacts.

1242
01:19:57.067 --> 01:20:03.067
That is all I have. Any
questions from the audience
cracks

1243
01:20:03.067 --> 01:20:07.067
>> --?

1244
01:20:07.067 --> 01:20:11.067
>> Yes. Yes. What as well
related to some of the
statements

1245
01:20:11.067 --> 01:20:17.067
you just made. So

1246
01:20:17.067 --> 01:20:21.067
when ace that goes in and
installs the bulkhead

1247
01:20:21.067 --> 01:20:24.067
and an abandoned mine in there's
remaining discharge of water,
how

1248
01:20:24.067 --> 01:20:29.067
is the water discharge dealt
with and also, is there a
permanent --

1249
01:20:29.067 --> 01:20:31.067
a permit required Quek

1250
01:20:31.067 --> 01:20:35.000
>> That is a good question, and
potentially yes on the permit
required.

1251
01:20:35.000 --> 01:20:38.067
At this point in time as part of
a long-term situation

1252
01:20:38.067 --> 01:20:43.067
where we are monitoring what
does impacts are going to be and
whether

1253
01:20:43.067 --> 01:20:47.067
or not there is going to need to
be, whether there is going to be

1254
01:20:47.067 --> 01:20:51.067
a need for some kind of
long-term

1255
01:20:51.067 --> 01:20:54.067
passive treatment, and that is
one of the things that Christoph
discussed,

1256
01:20:54.067 --> 01:20:57.067
now that the flow is reduced, we
have a much broader spectrum of

1257
01:20:57.067 --> 01:21:03.067
passive treatment options that
we can

1258
01:21:03.067 --> 01:21:06.067
look at at the site, so that was
somewhat contemplated

1259
01:21:06.067 --> 01:21:11.067
based on the fact that we knew
we were not going to get all

1260
01:21:11.067 --> 01:21:14.067
the flow addressed, and so
passive is one of those options,
but we

1261
01:21:14.067 --> 01:21:17.067
really need to have a good
understanding of kind of what
the long-term impact

1262
01:21:17.067 --> 01:21:23.067
and flow rate is going to be. So
that is

1263
01:21:23.067 --> 01:21:24.067
a challenge.

1264
01:21:24.067 --> 01:21:28.067
>> Okay. Another question that
was specific

1265
01:21:28.067 --> 01:21:33.000
to the Dinero Nelson groundwater
interaction, this person states

1266
01:21:33.000 --> 01:21:37.067
that it is an example of how
long to monitor for stable

1267
01:21:37.067 --> 01:21:42.067
system related to a bulkhead,
and the person states

1268
01:21:42.067 --> 01:21:46.067
that oftentimes the bulkhead is
the first step towards the
decision

1269
01:21:46.067 --> 01:21:47.067
related to future water
treatment.

1270
01:21:47.067 --> 01:21:52.067
This person is just wondering,
how long do you wait for a
bulkhead

1271
01:21:52.067 --> 01:21:56.067
to settle out within a range of
chemistry,

1272
01:21:56.067 --> 01:22:02.067
pressures, discharges before
asking the question, is the

1273
01:22:02.067 --> 01:22:08.067
next step do we now need to
consider

1274
01:22:08.067 --> 01:22:09.067
water treatment?

1275
01:22:09.067 --> 01:22:13.067
I don't want to cop out by
saying it is site specific, but
I think

1276
01:22:13.067 --> 01:22:17.067
of some of the slides that I
showed you can see in terms of
pressure

1277
01:22:17.067 --> 01:22:21.067
and mind pool a pretty good
sense of

1278
01:22:21.067 --> 01:22:24.067
when it has reached a
steady-state condition. That
does somewhat very.

1279
01:22:24.067 --> 01:22:27.067
But it looks like it was about 1
to 3 years on both sides. At
Dinero

1280
01:22:27.067 --> 01:22:33.000
it did take four years really to
begin to see impacts in the
adjacent

1281
01:22:33.000 --> 01:22:37.000
mind tunnel and within the
adjacent

1282
01:22:37.000 --> 01:22:41.000
receiving streams. But it is so
site-specific in terms of how
quickly

1283
01:22:41.000 --> 01:22:46.000
you know that impact, which is
why this monitoring component is

1284
01:22:46.000 --> 01:22:51.000
so critical in being able to
establish a longer-term
monitoring plan at

1285
01:22:51.000 --> 01:22:54.000
the site, but most of the sites,
we are monitoring at least,
hoping

1286
01:22:54.000 --> 01:22:58.000
to monitor at least 10 years to
get some sense of what those
impacts

1287
01:22:58.000 --> 01:23:03.000
are, but it is so site-specific
based on the geology and the
workings

1288
01:23:03.000 --> 01:23:08.000
and how connected they are.

1289
01:23:08.000 --> 01:23:12.000
>>. That make sense. I think we
should move on to Joy and then
we

1290
01:23:12.000 --> 01:23:16.000
can continue with more questions
than answers after she shows us

1291
01:23:16.000 --> 01:23:23.000
her talk.

1292
01:23:23.000 --> 01:23:28.000
>> Okay.

1293
01:23:28.000 --> 01:23:31.934
Thank you. I am Joy Jenkins with
EPA in Region 8. I am a

1294
01:23:31.934 --> 01:23:35.934
remedial project manager in the
Superfund program. We're going
to

1295
01:23:35.934 --> 01:23:41.000
go through another case study.
And this one is about the big

1296
01:23:41.000 --> 01:23:45.000
five tunnel, in the big five in
tunnel treatment system at the
Captain

1297
01:23:45.000 --> 01:23:51.000
Jack mill Superfund site.

1298
01:23:51.000 --> 01:23:56.000
First I will go through some
background insight history. Will
talk

1299
01:23:56.000 --> 01:24:00.000
about the mine water remedy, the
concepts and features of that
remedy,

1300
01:24:00.000 --> 01:24:03.000
will go over result of that
initial operation, and then a
little

1301
01:24:03.000 --> 01:24:06.000
foreshadowing, we will talk
about the problem-solving we
have to do

1302
01:24:06.000 --> 01:24:11.000
because conditions did not react
as we anticipated. And then the

1303
01:24:11.000 --> 01:24:17.000
next steps for continuing to
work

1304
01:24:17.000 --> 01:24:24.000
on effective implementation of
our remedy. So

1305
01:24:24.000 --> 01:24:29.000
this is a Superfund site.
National priority list site. The
site was

1306
01:24:29.000 --> 01:24:32.000
gold and silver mining and
milling area. Activity started
in

1307
01:24:32.000 --> 01:24:37.067
the 1860s, and actually went
intermittently to as recently as
1992. The most

1308
01:24:37.067 --> 01:24:43.067
recent mining and milling in the
area was

1309
01:24:43.067 --> 01:24:48.067
sort of a small shop of two guys
and a shovel sort of

1310
01:24:48.067 --> 01:24:51.067
situation. And they were asked
to cease and desist by the state
in

1311
01:24:51.067 --> 01:24:57.067
1992. So the elevation of the
site is about

1312
01:24:57.067 --> 01:25:01.067
8500 feet to 9000 feet above sea
level. A pretty small area. And

1313
01:25:01.067 --> 01:25:05.067
the major features of the site
spam less than a mile to a

1314
01:25:05.067 --> 01:25:11.067
mile and a half. The big five
tunnel, in this case

1315
01:25:11.067 --> 01:25:16.067
is the drainage into the creek.
Tunnels tend to have

1316
01:25:16.067 --> 01:25:21.067
two openings and adits only have
one,

1317
01:25:21.067 --> 01:25:25.067
however the miners often need a
structure or tunnel if they were

1318
01:25:25.067 --> 01:25:30.067
using it for ore haulage or

1319
01:25:30.067 --> 01:25:33.000
drainage, so a lot of the maps
will call something a tunnel
even when

1320
01:25:33.000 --> 01:25:35.000
technically it is an adits. EPA
and communicating with folks in

1321
01:25:35.000 --> 01:25:39.067
the surroundings, we often use
that word interchangeably. So

1322
01:25:39.067 --> 01:25:46.067
you engineers don't criticize me
when using adits. The main
contaminants

1323
01:25:46.067 --> 01:25:50.067
of concern here are Cavium,
copper, Mac

1324
01:25:50.067 --> 01:25:51.601
Minis and think that there is

1325
01:25:51.601 --> 01:25:54.067
variability in the
concentrations and seasonal

1326
01:25:54.067 --> 01:25:58.067
variability, and we also had
variability in the pH range for

1327
01:25:58.067 --> 01:26:04.067
the maximum low part of the
remedy was about 2.6. and some

1328
01:26:04.067 --> 01:26:08.067
seasonal changes with high pH of
about 4.5. So

1329
01:26:08.067 --> 01:26:13.067
generally we thought the citable
actively low flows, a baseball
of

1330
01:26:13.067 --> 01:26:17.067
22 maybe 40 gallons per minute
with a peak seasonal spring

1331
01:26:17.067 --> 01:26:25.067
run off low just up to 160
gallons per minute. So

1332
01:26:25.067 --> 01:26:29.067
this site is really close to
Denver where the EPA region
eight office

1333
01:26:29.067 --> 01:26:32.000
is as well as our state partner,
Colorado Department

1334
01:26:32.000 --> 01:26:35.000
of Public health and the
environment.

1335
01:26:35.000 --> 01:26:38.067
We both sit in Denver, this site
is a little less than

1336
01:26:38.067 --> 01:26:42.067
50 miles away. It is near the
small town of Ward, historic
mining town

1337
01:26:42.067 --> 01:26:48.067
as well. And so this looked like
a great opportunity for a
location

1338
01:26:48.067 --> 01:26:54.067
to implement a novel treatment
technology. So we will

1339
01:26:54.067 --> 01:26:58.067
go through what that technology
is. The record of decision for
the

1340
01:26:58.067 --> 01:27:04.067
site was decided in 2008 and

1341
01:27:04.067 --> 01:27:08.067
included an in situ or in tunnel
treatment system to treat

1342
01:27:08.067 --> 01:27:14.067
that drainage water. The concept
here was

1343
01:27:14.067 --> 01:27:17.067
to submerge the mineral zones in
order to minimize

1344
01:27:17.067 --> 01:27:20.067
the contact with oxygen by
impounding water behind an
engineered bulkhead.

1345
01:27:20.067 --> 01:27:24.067
As we all know, oxygen diffuses
much more slowly through water
than

1346
01:27:24.067 --> 01:27:27.067
it does through air, and my
chemistry background

1347
01:27:27.067 --> 01:27:30.067
from undergrad makes me want to
put in an equation. This is our

1348
01:27:30.067 --> 01:27:36.000
generalized equation for acid
mine drainage generation. You
get pyrite

1349
01:27:36.000 --> 01:27:40.067
and mix it with oxygen and water
and come out with fair Diane --

1350
01:27:40.067 --> 01:27:45.067
ferric iron and a lot of so fax
it -- so fast it

1351
01:27:45.067 --> 01:27:49.067
--'s of uric acid about the
remedy concept also included the
ability

1352
01:27:49.067 --> 01:27:55.067
to neutralize the impounded mine
pool water. The objective here

1353
01:27:55.067 --> 01:27:59.067
again with the same idea, use
the pH increase to help slow

1354
01:27:59.067 --> 01:28:03.067
that oxidation, slow those
bleaching reactions and reduce
the metal solubility

1355
01:28:03.067 --> 01:28:07.067
in general. The remedy included
a circulation provision

1356
01:28:07.067 --> 01:28:12.067
an option to add organic carbon
to potentially drive biological

1357
01:28:12.067 --> 01:28:17.067
sulfate reduction to sulfide
generation and sulfide

1358
01:28:17.067 --> 01:28:19.067
metals precipitation. So I will
go through some of the details
of

1359
01:28:19.067 --> 01:28:24.067
the components. This included a
concrete bulkhead with a

1360
01:28:24.067 --> 01:28:28.067
stainless deal piping in Val
systems the water to be released
to manage

1361
01:28:28.067 --> 01:28:32.000
that water level in the mine
pool, there was a

1362
01:28:32.000 --> 01:28:37.067
220 foot section of tunnel that
was packed with gravel size,

1363
01:28:37.067 --> 01:28:43.067
crushed limestone. And this was
located just expected

1364
01:28:43.067 --> 01:28:49.067
to provide initial
neutralization as the mine pool
started to

1365
01:28:49.067 --> 01:28:53.067
develop. The recirculation
system allows, was to allow
water to be

1366
01:28:53.067 --> 01:28:56.067
pumped from just the bulkhead to
a borehole

1367
01:28:56.067 --> 01:29:00.067
intersecting the tunnel of
gradient of approximately 900
feet away.

1368
01:29:00.067 --> 01:29:04.067
And the goal here was to be able
to move, neutralize water from
the

1369
01:29:04.067 --> 01:29:09.067
limestone section or any other
amendments we

1370
01:29:09.067 --> 01:29:13.067
might add to the of gradient
portion of the mine pool that we
could otherwise

1371
01:29:13.067 --> 01:29:15.067
access. Besides through
boreholes.

1372
01:29:15.067 --> 01:29:20.067
This remedy included some
flexibility in the capability to
add liquid

1373
01:29:20.067 --> 01:29:25.067
caustic or sodium hydroxide if
additional neutralization

1374
01:29:25.067 --> 01:29:31.067
was needed. It also has an
option through the same
boreholes to

1375
01:29:31.067 --> 01:29:37.067
add liquid or storied organic
carbon to promote that sulfate

1376
01:29:37.067 --> 01:29:41.067
reduction potentially.

1377
01:29:41.067 --> 01:29:43.067
So the initial operation
strategy, though, was to try to
employ what

1378
01:29:43.067 --> 01:29:45.067
we saw as the simplest method
first, that was perceived to be
flooding,

1379
01:29:45.067 --> 01:29:49.067
that initial limestone
neutralization, and then the
plan was to address

1380
01:29:49.067 --> 01:29:54.067
the system as needed so I will
go through a little bit of the
system

1381
01:29:54.067 --> 01:29:59.067
layout here, over on the
right-hand side of the screen

1382
01:29:59.067 --> 01:30:02.067
we have the creek and up from
that

1383
01:30:02.067 --> 01:30:08.067
there are two settling ponds
that received water from the big
five

1384
01:30:08.067 --> 01:30:13.067
tunnel, and our bulkhead is
located about 600

1385
01:30:13.067 --> 01:30:18.067
feet back from that tunnel
portal. You will remember

1386
01:30:18.067 --> 01:30:24.067
that picture from Christoph
about the various fracture zones
and higher

1387
01:30:24.067 --> 01:30:28.067
permeability areas. So this was
approximately the same area that

1388
01:30:28.067 --> 01:30:34.000
we found have the lease fracture
zones.

1389
01:30:34.000 --> 01:30:38.067
This is a vein here, so we had
to deal with that in our
concrete

1390
01:30:38.067 --> 01:30:40.067
bulkhead design.

1391
01:30:40.067 --> 01:30:47.067
This is our limestone pile. And
then just is this borehole which

1392
01:30:47.067 --> 01:30:51.067
contains the recirculation pump
ticket pumps water through a
varied

1393
01:30:51.067 --> 01:30:55.067
pipeline and delivers the water
back into the tunnel, and

1394
01:30:55.067 --> 01:31:01.067
that is approximately a little
less than 900

1395
01:31:01.067 --> 01:31:09.067
feet away. So these are just
some pictures from remedy
installation.

1396
01:31:09.067 --> 01:31:11.067
This is, before I started this
project I had no idea

1397
01:31:11.067 --> 01:31:15.067
how to get limestone into the
tunnel, but the in tunnel
contractors know

1398
01:31:15.067 --> 01:31:21.067
how to do this sort of work that
they used a mucker to pack

1399
01:31:21.067 --> 01:31:24.067
the suction of tunnel of
limestone and were

1400
01:31:24.067 --> 01:31:26.067
able to get about two feet from
the tunnel ceiling. We felt like

1401
01:31:26.067 --> 01:31:31.067
we got a good amount of
potential alkalinity generation
in

1402
01:31:31.067 --> 01:31:34.000
that tunnel. Will go through a
little bit of the concrete
bulkhead design

1403
01:31:34.000 --> 01:31:38.067
I mentioned it is a little less
than 600 feet of the

1404
01:31:38.067 --> 01:31:43.067
portal. If you can remember back
from to slide to go, that
location

1405
01:31:43.067 --> 01:31:47.067
was also about 200 feet below
ground.

1406
01:31:47.067 --> 01:31:51.067
So that gave a sufficient ground
to above the bulkhead to

1407
01:31:51.067 --> 01:31:54.067
place the bulkhead they are. And
you also remember

1408
01:31:54.067 --> 01:31:58.067
the slide with the three
different types of bulkhead
design. We used

1409
01:31:58.067 --> 01:32:02.067
a slab keyed into the bedrock
here. And our parameters

1410
01:32:02.067 --> 01:32:06.067
here, this bulkhead was design
pretty conservatively for the
conditions.

1411
01:32:06.067 --> 01:32:10.067
We knew that there was

1412
01:32:10.067 --> 01:32:12.067
not only the borehole we
installed, but there was another
shaft that

1413
01:32:12.067 --> 01:32:18.067
have potential connectivity that
was about

1414
01:32:18.067 --> 01:32:23.067
200 feet above the surface of
the shaft and the borehole we
installed

1415
01:32:23.067 --> 01:32:28.067
was 200 feet or so above the
tunnel floor. So that would be
the maximum

1416
01:32:28.067 --> 01:32:32.000
water level here that this mine
pool could

1417
01:32:32.000 --> 01:32:35.000
ever hold. However, we did over
design this or conservatively
design

1418
01:32:35.000 --> 01:32:39.000
this bulkhead, we put in a 15
foot long bulkhead, concrete
bulkhead

1419
01:32:39.000 --> 01:32:43.000
and the key sections were six
feet wide and three

1420
01:32:43.000 --> 01:32:51.000
feet tall. And that keyed in
section goes to circumference of
the bulkhead

1421
01:32:51.000 --> 01:32:54.000
area. This bulkhead includes two
stainless steel pipes, the lower

1422
01:32:54.000 --> 01:32:57.000
pipe is a 12 inch pipe in the
upper pipe that we put towards
the top

1423
01:32:57.000 --> 01:33:01.000
of the bulkhead was only a three
inch pipe, in the idea here was

1424
01:33:01.000 --> 01:33:06.000
that we would use the 12 inch
pipe for any sort of flow
control that

1425
01:33:06.000 --> 01:33:10.000
we want to do in the future and
our three inch pipe would

1426
01:33:10.000 --> 01:33:14.000
be just a backup in case we got
too much sludge buildup at the
lower

1427
01:33:14.000 --> 01:33:18.000
pipe. And you will see in the
construction design we had

1428
01:33:18.000 --> 01:33:21.000
to build, to manage the water
through the bulkhead we

1429
01:33:21.000 --> 01:33:27.000
built a small dam and then put
the piping structure with
perforated

1430
01:33:27.000 --> 01:33:31.000
pipe to direct that water into a
pipe while constructing the
bulkhead

1431
01:33:31.000 --> 01:33:36.934
but so of course once you
construct the bulkhead, that
copper dam and

1432
01:33:36.934 --> 01:33:38.000
perforated pipe is in place now.

1433
01:33:38.000 --> 01:33:42.000
You will never go back and get
it that. So you have to make
sure that

1434
01:33:42.000 --> 01:33:46.000
will work for you in the long
term operation of

1435
01:33:46.000 --> 01:33:49.000
your system. Here are just some
photos to build on some of the
photos

1436
01:33:49.000 --> 01:33:53.000
that Jeff had in his
presentation as well. Here the

1437
01:33:53.000 --> 01:33:59.000
underground crew is injecting
grout, preparing the curtain
grout in

1438
01:33:59.000 --> 01:34:02.000
the bulkhead area.

1439
01:34:02.000 --> 01:34:05.000
The middle picture, here is the
12 inch

1440
01:34:05.000 --> 01:34:11.000
stainless steel pipe. You're
looking at the crew basically
standing

1441
01:34:11.000 --> 01:34:16.000
in the excavated area of the
keyed out area for the future
bulkhead.

1442
01:34:16.000 --> 01:34:20.000
You see the formwork in the back
and that will be the waterside
formwork.

1443
01:34:20.000 --> 01:34:23.000
The upper pipe here. In the far
right picture

1444
01:34:23.000 --> 01:34:28.000
you're looking at the completed
bulkhead, and again, you're
seeing

1445
01:34:28.000 --> 01:34:34.000
some of those contact route
pipelines still in place,

1446
01:34:34.000 --> 01:34:42.067
and then we have our stainless
steel pipes. Speaking of pipes
and

1447
01:34:42.067 --> 01:34:47.067
valving systems, this is the
place for you get your pipe and
valve

1448
01:34:47.067 --> 01:34:50.067
experts on board. In this case,
for this

1449
01:34:50.067 --> 01:34:53.067
particular situation, we knew we
wanted to be able to adjust or
regulate

1450
01:34:53.067 --> 01:34:59.067
flow from the bulkhead pipes.
And as folks in the piping and

1451
01:34:59.067 --> 01:35:05.067
valving system arena know, many
valves are not made for

1452
01:35:05.067 --> 01:35:08.067
flow regulation prepare me for
on and off. If you use them of
flow

1453
01:35:08.067 --> 01:35:12.067
regulation, you can get
cavitation or destruction of
your materials

1454
01:35:12.067 --> 01:35:17.067
in that valve. So the pressure
changes can

1455
01:35:17.067 --> 01:35:22.067
cause us. You have to consider
your long-term maintenance
considerations

1456
01:35:22.067 --> 01:35:25.067
needed to regulate flow.

1457
01:35:25.067 --> 01:35:29.067
So the solution in this case was
to put in, so here

1458
01:35:29.067 --> 01:35:34.000
is the bulkhead over on the
right side. We put

1459
01:35:34.000 --> 01:35:40.067
in primary isolation valves, and
these are primarily to be used
in

1460
01:35:40.067 --> 01:35:47.067
a valve to be used in an off
position. And then we installed

1461
01:35:47.067 --> 01:35:51.067
a secondary flow control,
specialized flow control valve,
in this case

1462
01:35:51.067 --> 01:35:54.067
it is a Fisher flow control
valve. We also

1463
01:35:54.067 --> 01:35:58.067
use piping reduction to be able
to install that flow control
valve

1464
01:35:58.067 --> 01:36:01.067
and be able to knock it down,
the pressure coming from

1465
01:36:01.067 --> 01:36:04.067
the bulkhead to get the flows we
wanted to see out of here. And
so

1466
01:36:04.067 --> 01:36:10.067
this setup allows us to over
time, maintenance might

1467
01:36:10.067 --> 01:36:13.067
be needed, the flow control
valves might

1468
01:36:13.067 --> 01:36:15.067
need to be replaced the
isolation valve let's is easily
replaced the

1469
01:36:15.067 --> 01:36:19.067
flow control valve, pretty good
for future maintenance. All of
these

1470
01:36:19.067 --> 01:36:23.067
parts were for 316 stainless.
And in this

1471
01:36:23.067 --> 01:36:29.067
case we used a conservative
design and did use the 250 psi
isolation

1472
01:36:29.067 --> 01:36:35.000
valve pressure rating. So

1473
01:36:35.000 --> 01:36:39.067
this is just a little bit
brighter picture with the

1474
01:36:39.067 --> 01:36:45.067
completed bulkhead, here is our
lower pipeline, big

1475
01:36:45.067 --> 01:36:48.067
isolation valve, flow control
valve, and then we move from the

1476
01:36:48.067 --> 01:36:54.067
stainless steel into HD PE
piping to convey that water out

1477
01:36:54.067 --> 01:36:58.067
to the portal. And you will see,
Christoph and Jeff both pointed

1478
01:36:58.067 --> 01:37:02.067
out, they're still dripping
water

1479
01:37:02.067 --> 01:37:04.067
after you filled your bulkhead.

1480
01:37:04.067 --> 01:37:05.067
It is often not completely dry.

1481
01:37:05.067 --> 01:37:08.067
So this is new since WaterPik we
were able to manage this a
little

1482
01:37:08.067 --> 01:37:13.067
bit better as we went on. This
is just my best photo I had. So
we

1483
01:37:13.067 --> 01:37:17.067
installed the system. So

1484
01:37:17.067 --> 01:37:19.067
what happened next? we close the
valves in spring of 2018. The
system

1485
01:37:19.067 --> 01:37:22.067
filled pretty fast. Faster than
we anticipated based on what we

1486
01:37:22.067 --> 01:37:23.067
understood the flow rates to be.

1487
01:37:23.067 --> 01:37:29.067
In about four months water level
rose about 160 feet, and

1488
01:37:29.067 --> 01:37:35.000
that was measured by that
borehole adjusting by the
bulkhead,

1489
01:37:35.000 --> 01:37:40.067
the height to the casing was
about 198 feet. So as

1490
01:37:40.067 --> 01:37:44.067
we were watching the real steep
part

1491
01:37:44.067 --> 01:37:48.067
of this curve happen, we started
to get uncomfortable about water

1492
01:37:48.067 --> 01:37:53.067
coming out of the borehole or,
if not there, the shaft not

1493
01:37:53.067 --> 01:37:56.067
too far from this location.

1494
01:37:56.067 --> 01:37:59.067
So we opened the valves in
September 2018 in a controlled
fashion.

1495
01:37:59.067 --> 01:38:04.067
We used our flow regulation to
maintain that water level for a
while. And

1496
01:38:04.067 --> 01:38:10.067
prevent any further increase in
that mine

1497
01:38:10.067 --> 01:38:15.067
pool level. So what happened in
this scenario, at least in

1498
01:38:15.067 --> 01:38:18.067
this timeframe, we had an
assumption that our mine pool
would equal liberate

1499
01:38:18.067 --> 01:38:21.067
with the surroundings. And that
just did not appear to happen.
We

1500
01:38:21.067 --> 01:38:25.067
had other monitoring wells and
none of her other monitoring

1501
01:38:25.067 --> 01:38:34.000
system showed any significant
migration of water into the
nearby

1502
01:38:34.000 --> 01:38:38.067
surrounding ground, nor did we
see it equal liberate

1503
01:38:38.067 --> 01:38:40.067
at a steady level. Not shown on
this graph, but there's a point

1504
01:38:40.067 --> 01:38:43.067
where had to close the valve
again when he saw a steep
increase again

1505
01:38:43.067 --> 01:38:47.067
from this point up. So we didn't
see that equal liberation in
this

1506
01:38:47.067 --> 01:38:50.067
timeframe with any of the
surroundings.

1507
01:38:50.067 --> 01:38:53.067
So we resampling several of our
boreholes, but we have three

1508
01:38:53.067 --> 01:38:59.067
locations where we could sample
WaterPik the key location, we
have

1509
01:38:59.067 --> 01:39:06.067
a borehole about 400 feet inby.
So we had really

1510
01:39:06.067 --> 01:39:11.067
good water quality there. We
were CPH above six

1511
01:39:11.067 --> 01:39:13.067
and low conductivity, seem like
we were getting positive impact

1512
01:39:13.067 --> 01:39:19.067
from the limestone, but we
thought it was anomalous that

1513
01:39:19.067 --> 01:39:23.067
are sample port on her bulkhead
was having

1514
01:39:23.067 --> 01:39:26.067
a lower pH. So we thought we are
just not moving WaterPik we've
got

1515
01:39:26.067 --> 01:39:31.067
some preferential flow paths or
something like that. It turns
out

1516
01:39:31.067 --> 01:39:34.000
that we realized our sampling
techniques of the borehole

1517
01:39:34.000 --> 01:39:38.067
were not keeping up with the
changing water level. So we

1518
01:39:38.067 --> 01:39:40.067
weren't getting a representative
sampling from the boreholes over

1519
01:39:40.067 --> 01:39:45.067
that summer period that we had
the valves closed. So

1520
01:39:45.067 --> 01:39:50.067
to identify specifically what
happened is we

1521
01:39:50.067 --> 01:39:56.067
employed in [ Indiscernible ] pH
probe and drop

1522
01:39:56.067 --> 01:39:59.067
that down the depth of the
borehole taking a reading at

1523
01:39:59.067 --> 01:40:05.067
various intervals and you can
see from the top down we

1524
01:40:05.067 --> 01:40:10.067
got nice above pH 6 water, and
about 60 feet above the floor

1525
01:40:10.067 --> 01:40:12.067
of the bulkhead we had a
significant decline in pH, and
then shot down

1526
01:40:12.067 --> 01:40:17.067
to less than three and the same
story happened, similar story

1527
01:40:17.067 --> 01:40:22.067
with conductivity. Everything
was looking pretty good, then
you get

1528
01:40:22.067 --> 01:40:26.067
this pretty significant decline
in

1529
01:40:26.067 --> 01:40:31.067
the bore you get into this
higher conductivity water
[ Indiscernible ]

1530
01:40:31.067 --> 01:40:35.000
so we saw this really

1531
01:40:35.000 --> 01:40:37.067
significant stratification in
our monitoring boreholes that
the sampling

1532
01:40:37.067 --> 01:40:41.067
technique was not capturing. So
we had thought of water quality

1533
01:40:41.067 --> 01:40:46.067
was much better than it was, and
the other reason we were led

1534
01:40:46.067 --> 01:40:50.067
to believe this is when we first
put in the limestone, we put in

1535
01:40:50.067 --> 01:40:54.067
the bulkhead, we had the valves
open, so it was just a couple of

1536
01:40:54.067 --> 01:40:56.067
feet of water running through
the limestone. That limestone
was giving

1537
01:40:56.067 --> 01:41:02.067
us a really positive impact. At
the we created a

1538
01:41:02.067 --> 01:41:05.067
really nice anoxic line drain in
that situation. Sorrow

1539
01:41:05.067 --> 01:41:07.067
for about a year and a half
while the water was running
through that

1540
01:41:07.067 --> 01:41:10.067
limestone, through open valves,
we had really good water
quality,

1541
01:41:10.067 --> 01:41:15.067
so that made us believe the
results we were seeing in the
tunnel with

1542
01:41:15.067 --> 01:41:17.067
our samplings on the borehole.
What had really happened

1543
01:41:17.067 --> 01:41:21.067
is the water quality had gotten
much worse in

1544
01:41:21.067 --> 01:41:26.067
this time. So the table here on
the left

1545
01:41:26.067 --> 01:41:29.067
side shows the middle column,
the maximum concentration of our
pre-remedy

1546
01:41:29.067 --> 01:41:32.000
conditions from about 2014 to
2016.

1547
01:41:32.000 --> 01:41:41.067
And then the maximum
concentration

1548
01:41:41.067 --> 01:41:44.067
over in this column after the
valve closure

1549
01:41:44.067 --> 01:41:47.067
but this is just one sampling
point that this is an averaged
over type

1550
01:41:47.067 --> 01:41:49.067
it actually picked up the worst
water quality with all. But you

1551
01:41:49.067 --> 01:41:52.067
can see that in that timeframe
of about four months of the
valves

1552
01:41:52.067 --> 01:41:55.067
being closed, we saw order of
magnitude increase in metals in
the water

1553
01:41:55.067 --> 01:42:02.067
and the samples were behind the
bulkhead. So this is surprising

1554
01:42:02.067 --> 01:42:05.067
to us but this was unexpected.
The pH of that particular point
in time

1555
01:42:05.067 --> 01:42:09.067
didn't change that much from the
lowest pH we had seen before. We

1556
01:42:09.067 --> 01:42:13.067
did a subsequently in another
month sample, we did see lower

1557
01:42:13.067 --> 01:42:19.067
pH is in the next following
months, but actually not
consistent with

1558
01:42:19.067 --> 01:42:23.067
worsening metals concentration.
But what we think

1559
01:42:23.067 --> 01:42:27.067
is likely to have happened is
the flushing and dissolution of
acidic

1560
01:42:27.067 --> 01:42:32.000
metal laden salt when the
subsurface is wet. And folks
that work in this

1561
01:42:32.000 --> 01:42:39.000
field, this is not, this is a
typical phenomenon you can

1562
01:42:39.000 --> 01:42:43.000
see whispering flashback over
the winter of snowmelt, trickles
through

1563
01:42:43.000 --> 01:42:51.000
a waste rock pile or ore pile
you can see, you pick up some
acid mine

1564
01:42:51.000 --> 01:42:57.000
drainage. The water evaporates
Saul's,

1565
01:42:57.000 --> 01:43:00.000
salts are evaporated onto the
rock, and then you come through
with your

1566
01:43:00.000 --> 01:43:01.000
spring flush and flush them out.

1567
01:43:01.000 --> 01:43:02.000
This is not an unheard-of
phenomenon.

1568
01:43:02.000 --> 01:43:05.000
But I think what happened here
is the order of magnitude change
was

1569
01:43:05.000 --> 01:43:09.000
really unexpected, and we didn't
have any sort of, we didn't have

1570
01:43:09.000 --> 01:43:13.000
any signal we saw prior to
letting the bulkhead to

1571
01:43:13.000 --> 01:43:16.000
give us indication this would
happen.

1572
01:43:16.000 --> 01:43:22.000
Another question that we have
too is, probably flushing of
these

1573
01:43:22.000 --> 01:43:27.000
salts was a significant

1574
01:43:27.000 --> 01:43:31.000
[ Indiscernible ] but was are
also acid mine drainage
generation still

1575
01:43:31.000 --> 01:43:34.934
occurring while flooding the
tunnel.

1576
01:43:34.934 --> 01:43:38.000
So then we're into
problem-solving mold mood. We
have a mine pool getting

1577
01:43:38.000 --> 01:43:44.000
higher. We have water quality
that is worse than it

1578
01:43:44.000 --> 01:43:46.000
was before.

1579
01:43:46.000 --> 01:43:49.000
And so EPA emergency response
mobilized a temporary external
line treatment

1580
01:43:49.000 --> 01:43:51.000
system to manage the mine pool
level and allow discharge of
treated water.

1581
01:43:51.000 --> 01:43:54.000
Of course, these things happen
in Winter Park so it starts to
snow,

1582
01:43:54.000 --> 01:43:57.000
we were able to, with the
emergency response team and
contractors, were

1583
01:43:57.000 --> 01:44:01.000
able to put in an effective line
treatment system that was able
to

1584
01:44:01.000 --> 01:44:05.000
operate in all sorts of
inclement conditions. Some
additional

1585
01:44:05.000 --> 01:44:09.000
problem-solving we did, we took
the taxability we

1586
01:44:09.000 --> 01:44:13.000
had in the remedy design and
added that liquid sodium
hydroxide,

1587
01:44:13.000 --> 01:44:18.000
25% sodium hydroxide. We added
that into that gradient borehole
that

1588
01:44:18.000 --> 01:44:23.000
was about 900 feet from the
bulkhead. And we

1589
01:44:23.000 --> 01:44:26.000
also increased our recirculation
rate and attempt to mix that
sodium

1590
01:44:26.000 --> 01:44:32.000
hydroxide. We did set up a test
where we took in out of sampler

1591
01:44:32.000 --> 01:44:36.000
at the bulkhead to see if we
could use the sodium

1592
01:44:36.000 --> 01:44:40.067
as a tracer and see how well
that sodium hydroxide was moving

1593
01:44:40.067 --> 01:44:45.067
around. We saw sodium and an
increase in the bulkhead at the
time of testing,

1594
01:44:45.067 --> 01:44:49.067
but we also saw a blob,
technical term, a big puddle

1595
01:44:49.067 --> 01:44:53.067
of sodium hydroxide that sat at
the bottom of the tunnel where
the

1596
01:44:53.067 --> 01:44:58.067
borehole location where we added
it. you can see the graph on the

1597
01:44:58.067 --> 01:45:04.067
right-hand side here, we took
that pH probe and dropped it
down

1598
01:45:04.067 --> 01:45:09.067
intervals, this is a different
scale here in this graph than a
couple

1599
01:45:09.067 --> 01:45:12.067
slides ago. We were consistently
pH 3 down that borehole,

1600
01:45:12.067 --> 01:45:18.067
and then about two feet or so
from the

1601
01:45:18.067 --> 01:45:22.067
tunnel bottom in this particular
instance we

1602
01:45:22.067 --> 01:45:25.067
had a rapid increase of pH but
this one went up to nine. Other
instances

1603
01:45:25.067 --> 01:45:29.067
where we can CPH a 13 from the
sodium hydroxide just pedaling
there. It

1604
01:45:29.067 --> 01:45:35.000
is the same story with the
conductivity. Acid mine

1605
01:45:35.000 --> 01:45:39.067
drainage and then a significant
increase that would

1606
01:45:39.067 --> 01:45:42.067
be indicative of the 25% sodium
hydroxide practice sitting
there.

1607
01:45:42.067 --> 01:45:45.067
This is another interesting
phenomenon.

1608
01:45:45.067 --> 01:45:49.067
With the pH probe on the way up,
the red dots

1609
01:45:49.067 --> 01:45:53.067
are on the way down. Blue dots
on the way up

1610
01:45:53.067 --> 01:45:56.067
I think we were drawing along
some of that sodium hydroxide
with us

1611
01:45:56.067 --> 01:46:01.067
or we just cause the pH probe to
go a little out of whack with
significant

1612
01:46:01.067 --> 01:46:06.067
changes in a dip into sodium
hydroxide. So the recirculation

1613
01:46:06.067 --> 01:46:09.067
system, we seem to have limited
success in mixing in the
scenario.

1614
01:46:09.067 --> 01:46:12.067
This is very different than what
we had seen we had just a couple

1615
01:46:12.067 --> 01:46:16.067
of feet of water in the tunnel.

1616
01:46:16.067 --> 01:46:19.067
Pretty solid plug for when we
did our initial tracer test, but
that

1617
01:46:19.067 --> 01:46:22.067
didn't seem to play out once we
increased the level of water in

1618
01:46:22.067 --> 01:46:26.067
this mind tunnel system. So the
current

1619
01:46:26.067 --> 01:46:29.067
objective is to bring that my
flow back down to historic water
level

1620
01:46:29.067 --> 01:46:38.067
as well as corresponding
historic water quality is

1621
01:46:38.067 --> 01:46:41.067
the hope. The objective is to
buy some time to reevaluate this
in

1622
01:46:41.067 --> 01:46:47.067
tunnel approach. So current
conditions a relatively recent.
We

1623
01:46:47.067 --> 01:46:51.067
did see, this is the same table
I showed you a

1624
01:46:51.067 --> 01:46:57.067
couple slides ago with the
pre-remedy column. The maximum
concentrations

1625
01:46:57.067 --> 01:47:01.067
we saw in the fall of 2018 and
then here's some data from
August 2019.

1626
01:47:01.067 --> 01:47:03.067
So just a few months ago or so.

1627
01:47:03.067 --> 01:47:09.067
So we have seen a real
significant decrease again in
those

1628
01:47:09.067 --> 01:47:13.067
metals concentration. It leads
us to believe this was a
flushing

1629
01:47:13.067 --> 01:47:17.067
of the acidic salt, the middle
column would

1630
01:47:17.067 --> 01:47:22.067
hundred 50 feet in the more
recent sample at 30

1631
01:47:22.067 --> 01:47:25.067
4P feet. So maybe if we would be
able to let the system play out,

1632
01:47:25.067 --> 01:47:28.067
we would see a decrease of those
metals again. But we wanted to
manage

1633
01:47:28.067 --> 01:47:34.000
that mine pool more effectively
and more actively at least in
the

1634
01:47:34.000 --> 01:47:39.067
temporary timeframe. And so, we
also think that maybe our flow
monitoring

1635
01:47:39.067 --> 01:47:43.067
from the past, periodic spot
measurements. You see some

1636
01:47:43.067 --> 01:47:45.067
consistency in you think it is
real consistent but considering

1637
01:47:45.067 --> 01:47:50.067
our variety of treatment rates
we've had to keep increasing to
really

1638
01:47:50.067 --> 01:47:53.067
draw down this mine pool,
possibly either the system

1639
01:47:53.067 --> 01:47:57.067
changed or we really thought the
system flows were lower than
we've

1640
01:47:57.067 --> 01:48:01.067
been able to capture with the
sampling we have done.

1641
01:48:01.067 --> 01:48:08.067
So currently this week or a
guess last week we actually hit
back to

1642
01:48:08.067 --> 01:48:10.067
her historic mine pool level of
less than three feet. Grade
getting

1643
01:48:10.067 --> 01:48:14.067
back to those objectives of
trying to reevaluate

1644
01:48:14.067 --> 01:48:17.067
this in tunnel treatment remedy.

1645
01:48:17.067 --> 01:48:18.634
That is exactly what the next

1646
01:48:18.634 --> 01:48:21.067
steps are. We will be
considering a purchase

1647
01:48:21.067 --> 01:48:26.067
for adding organic carbon to
drive some biological

1648
01:48:26.067 --> 01:48:29.067
sulfate reduction. Will be
looking at reevaluating that
recirculation

1649
01:48:29.067 --> 01:48:33.000
and mixing capabilities in mind
tunnel system. It doesn't seem

1650
01:48:33.000 --> 01:48:36.000
to behave as we would have
anticipated from our initial
studies. We are

1651
01:48:36.000 --> 01:48:45.067
going to be considering what
external treatment needs we need
to have

1652
01:48:45.067 --> 01:48:47.067
on hand while implementing a new
tunnel

1653
01:48:47.067 --> 01:48:51.067
treatment system in the
situation, particularly with
that understanding

1654
01:48:51.067 --> 01:48:54.067
that we are not getting a really
quick equilibration of this

1655
01:48:54.067 --> 01:48:57.067
water with his surroundings and
we do have that risk of water
coming

1656
01:48:57.067 --> 01:49:03.067
out of a shaft or our own
boreholes, but

1657
01:49:03.067 --> 01:49:06.067
the mineshaft that may be
connected, we don't have a great

1658
01:49:06.067 --> 01:49:09.067
ability to plug off water there.

1659
01:49:09.067 --> 01:49:16.067
So whoops I put this funny
picture on the right-hand

1660
01:49:16.067 --> 01:49:18.067
side here. Right at the end of
the tunnel for acid mine

1661
01:49:18.067 --> 01:49:22.067
drainage water sources but
because of the long-term cost
that the octave

1662
01:49:22.067 --> 01:49:30.067
water treatment has for mining
companies, for taxpayers,
federal and

1663
01:49:30.067 --> 01:49:36.000
state government. Both EPA
interstate partners think that
it is worse

1664
01:49:36.000 --> 01:49:39.067
-- worth the cost savings of
internal

1665
01:49:39.067 --> 01:49:43.067
treatment over external
treatment that we're continuing
to work on

1666
01:49:43.067 --> 01:49:45.067
this in tunnel treatment concept
and trying to

1667
01:49:45.067 --> 01:49:50.067
deal with these challenges that
were presented, in this case, to

1668
01:49:50.067 --> 01:49:55.067
try to get an effective in
tunnel treatment process in
place. This

1669
01:49:55.067 --> 01:49:58.067
also gives us this experience at
the

1670
01:49:58.067 --> 01:50:04.067
site in the amount of sampling
we did collect, it does give us
an

1671
01:50:04.067 --> 01:50:06.067
opportunity to use forensics to
create a predictive tool for
trying

1672
01:50:06.067 --> 01:50:10.067
to understand how water quality
changes upon flooding in the
future,

1673
01:50:10.067 --> 01:50:13.067
and so we will be looking back
at what information we have at
the

1674
01:50:13.067 --> 01:50:17.067
site that we can wrap into
looking to be predictive to use
at

1675
01:50:17.067 --> 01:50:24.067
other sites. We will be working
on developing a geochemical
model

1676
01:50:24.067 --> 01:50:27.067
using existing data here as well
as some

1677
01:50:27.067 --> 01:50:30.067
additional sulfur isotope
sampling we plan to do to
determine if that

1678
01:50:30.067 --> 01:50:34.000
dissolution of acidic salt was
the main contributor of

1679
01:50:34.000 --> 01:50:43.067
these metals. Increasing
concentration, or if there is

1680
01:50:43.067 --> 01:50:45.067
[ Indiscernible ] pyrite
oxidation that was a significant

1681
01:50:45.067 --> 01:50:48.067
driver to the increase in metals
concentration. We will also be
looking

1682
01:50:48.067 --> 01:50:52.067
for a closer examination of the
information we had about
mineralogy,

1683
01:50:52.067 --> 01:50:57.067
porosity and flow paths to
provide predictive information
for other

1684
01:50:57.067 --> 01:51:01.067
sites. And I would like to use

1685
01:51:01.067 --> 01:51:06.067
this as a tool to look at
pre-flooding differences between
high and low

1686
01:51:06.067 --> 01:51:08.067
flow conditions for pH and
metals concentrations and see if

1687
01:51:08.067 --> 01:51:13.067
those could be indicative of
changes that may occur

1688
01:51:13.067 --> 01:51:16.067
upon flooding. Ideally, I see
this as, if we were able to get
sufficient

1689
01:51:16.067 --> 01:51:20.067
data from other sites, where we
had the pre-and post flooding
water

1690
01:51:20.067 --> 01:51:26.067
quality conditions, can we use
that information

1691
01:51:26.067 --> 01:51:29.067
to get some predictive tools
together.

1692
01:51:29.067 --> 01:51:32.000
So if you are in possession of
that data I would like to share,
we can

1693
01:51:32.000 --> 01:51:36.000
work on how we might put some
information together to look at
how these

1694
01:51:36.000 --> 01:51:41.067
mind tunnels behave after
flooding perform what we
might've known before

1695
01:51:41.067 --> 01:51:45.067
hand. So to wrap up the
presentations today.

1696
01:51:45.067 --> 01:51:49.067
We have gotcha some concluding
thoughts and questions, to
sitting on some

1697
01:51:49.067 --> 01:51:55.067
of the points that one of the
three of us have

1698
01:51:55.067 --> 01:51:59.067
spoken about for all of us spoke
about so far.

1699
01:51:59.067 --> 01:52:01.067
At the the big thing you see
with these case studies is, not
all mine

1700
01:52:01.067 --> 01:52:04.067
sites are the same. Solution
doesn't fit all. They might all
behave a

1701
01:52:04.067 --> 01:52:06.067
little differently after you put
in a bulkhead. The idea of
characterizing

1702
01:52:06.067 --> 01:52:11.067
the mine system and surrounding
areas to the extent feasible
including

1703
01:52:11.067 --> 01:52:16.067
groundwater and mine system
hydrology, geology mineralogy.

1704
01:52:16.067 --> 01:52:20.067
All of your existing water
quality loading from the tunnel

1705
01:52:20.067 --> 01:52:24.067
itself, but also from the
watershed and the nearby areas
that could

1706
01:52:24.067 --> 01:52:30.067
be impacted by your bulkhead,
both positively

1707
01:52:30.067 --> 01:52:33.000
and negatively. Another concept
we brought up today is
establishing

1708
01:52:33.000 --> 01:52:34.000
reasonable goals for that
bulkhead.

1709
01:52:34.000 --> 01:52:42.000
Are you trying to just do flow
control that is preventing herbs
or

1710
01:52:42.000 --> 01:52:44.000
sudden releases collects are
using it for temporary storage
that may

1711
01:52:44.000 --> 01:52:47.000
be is helping you reduce loading
at certain times or certain
seasons

1712
01:52:47.000 --> 01:52:49.000
or temporary storage to help you
feed into a treatment system
cracks

1713
01:52:49.000 --> 01:52:54.000
in --? are you really trying to
plug a pathway completely back
so

1714
01:52:54.000 --> 01:52:57.000
water may come out somewhere
else, determine if that

1715
01:52:57.000 --> 01:52:59.000
is going to be good a bad thing.

1716
01:52:59.000 --> 01:53:02.000
Maybe it is going to come into
play that is were easy to manage
than

1717
01:53:02.000 --> 01:53:06.000
the current exit location from
the mountain but were in the
watershed

1718
01:53:06.000 --> 01:53:09.000
you try to reduce metals? are
there other lines of

1719
01:53:09.000 --> 01:53:13.000
evidence that you can predict
what the water quality changes
are going

1720
01:53:13.000 --> 01:53:16.000
to be after flooding? I think
that is the place I like to look
into

1721
01:53:16.000 --> 01:53:21.000
more thoroughly, and will those
lower or controlled flows that
you

1722
01:53:21.000 --> 01:53:25.000
might have on a valve bulkhead
or the

1723
01:53:25.000 --> 01:53:28.000
book had the sense water
somewhere else, is that going to

1724
01:53:28.000 --> 01:53:31.934
help you put in a passive
treatment and make that were of
a

1725
01:53:31.934 --> 01:53:34.934
feasible option. Maintenance is
generally required, so thick
about

1726
01:53:34.934 --> 01:53:39.000
that as you're doing your
design, what maintenance are you
going to

1727
01:53:39.000 --> 01:53:42.000
require, what the long-term fate
of the bulkhead

1728
01:53:42.000 --> 01:53:46.000
is going to be. And overall,
bulkhead effectiveness may
require years

1729
01:53:46.000 --> 01:53:49.000
to establish. This is been a
question that some of the
participants have

1730
01:53:49.000 --> 01:53:52.000
asked, how long will it take.
And like Jeff indicated, it is
site-specific.

1731
01:53:52.000 --> 01:53:56.000
So those are just some concepts
we had. Thanks

1732
01:53:56.000 --> 01:53:59.000
for your attention today. We
appreciate the opportunity to
present this

1733
01:53:59.000 --> 01:54:06.000
information. I think we have a
very few minutes for

1734
01:54:06.000 --> 01:54:08.000
questions.

1735
01:54:08.000 --> 01:54:13.000
>> Thank you very much brick a
lot of great information shared
and

1736
01:54:13.000 --> 01:54:19.000
lots of questions coming in.
Let's see if we can take a
couple of

1737
01:54:19.000 --> 01:54:21.000
them here. Somewhat had a very
specific question wanted

1738
01:54:21.000 --> 01:54:26.000
to know about what was the rock
site at the bulkhead and how
much

1739
01:54:26.000 --> 01:54:34.000
grout was needed in the grout
curtain. Because that specific

1740
01:54:34.000 --> 01:54:38.067
to Captain Jack?

1741
01:54:38.067 --> 01:54:41.067
>> I don't have that handy in my
head. But feel free to use my

1742
01:54:41.067 --> 01:54:46.067
contact information, and I can
provide that information.

1743
01:54:46.067 --> 01:54:50.067
>> Great. We're going to compile
all the questions and share them

1744
01:54:50.067 --> 01:54:51.067
with you guys, the speakers.

1745
01:54:51.067 --> 01:54:56.067
Because we are not going to get
all of them today. So the
opportunity

1746
01:54:56.067 --> 01:55:01.067
to respond back to them. We did
get a number of

1747
01:55:01.067 --> 01:55:04.067
questions related to cost. I was
wondering if you

1748
01:55:04.067 --> 01:55:08.067
guys wanted to talk about how
much putting in some of these
systems

1749
01:55:08.067 --> 01:55:11.067
has cost.

1750
01:55:11.067 --> 01:55:15.067
Some of the specifics people
asked, if you could provide a
discussion

1751
01:55:15.067 --> 01:55:19.067
on cost for the investigation,
opening

1752
01:55:19.067 --> 01:55:24.067
the workings, placing the
bulkhead, and things like

1753
01:55:24.067 --> 01:55:27.067
that.

1754
01:55:27.067 --> 01:55:31.067
>> This is Jeff. I can speak to
the Pennsylvania mine in terms

1755
01:55:31.067 --> 01:55:36.000
of what the total cost were. We
spent probably two or three
years

1756
01:55:36.000 --> 01:55:40.067
doing investigations of the
site, and that evolved drilling,
some

1757
01:55:40.067 --> 01:55:47.067
tracer testing, and then we put
in those bulkheads on the lower

1758
01:55:47.067 --> 01:55:49.067
tunnel and actually in upper
bulkhead on one of the upper
tunneled. And

1759
01:55:49.067 --> 01:55:55.067
I think including investigation,
rehab and bulkhead installation,

1760
01:55:55.067 --> 01:56:00.067
we were pushing $2 million
total. And that

1761
01:56:00.067 --> 01:56:03.067
included everything.

1762
01:56:03.067 --> 01:56:06.067
I think I shared it with my
slides with the actual book a

1763
01:56:06.067 --> 01:56:09.067
construction component of that
was.

1764
01:56:09.067 --> 01:56:13.067
Each of the bulkheads we
installed was about $275.000

1765
01:56:13.067 --> 01:56:14.067
to install.

1766
01:56:14.067 --> 01:56:18.067
See you can see that the
bulkhead component of that whole
site was

1767
01:56:18.067 --> 01:56:24.067
probably only one third of the
total cost, the investigation
and

1768
01:56:24.067 --> 01:56:27.067
the rehab was the remaining two
thirds.

1769
01:56:27.067 --> 01:56:33.000
>> I think that is pretty
typical on a lot of these

1770
01:56:33.000 --> 01:56:38.067
sites.

1771
01:56:38.067 --> 01:56:43.067
>> Okay. Christoph our joy, did
you want to add anything to that

1772
01:56:43.067 --> 01:56:46.067
quick

1773
01:56:46.067 --> 01:56:47.067
>> --?

1774
01:56:47.067 --> 01:56:48.067
>> Pick

1775
01:56:48.067 --> 01:56:49.067
>> Jeff covered it really well.

1776
01:56:49.067 --> 01:56:53.067
The basic thing is how much
rehab it takes to get to the
actual book

1777
01:56:53.067 --> 01:56:56.067
had placement.

1778
01:56:56.067 --> 01:56:58.067
>> Okay.

1779
01:56:58.067 --> 01:57:05.067
I think one last question I'm
going to ask is a good way to
try to summarize

1780
01:57:05.067 --> 01:57:08.067
some things. This person wants
to know if you could refer us to
some

1781
01:57:08.067 --> 01:57:16.067
of the best information out
there to look at to learn more
about bulkheads

1782
01:57:16.067 --> 01:57:17.067
design.

1783
01:57:17.067 --> 01:57:22.067
>> There's not a whole lot
published to be honest.

1784
01:57:22.067 --> 01:57:27.067
I mean, it is somewhat in-house
but I don't know if that is the

1785
01:57:27.067 --> 01:57:31.067
right term for it. But there are
a couple of different papers. I

1786
01:57:31.067 --> 01:57:33.000
know John Abel was one of the
original kind of guys that came

1787
01:57:33.000 --> 01:57:37.067
up with the process for bulkhead
design, certainly

1788
01:57:37.067 --> 01:57:41.067
for abandoned mind tunnels. I
believe yes and publications out
there.

1789
01:57:41.067 --> 01:57:47.067
Back from the 90s.

1790
01:57:47.067 --> 01:57:50.067
I don't know what you have used
in the past Christoph.

1791
01:57:50.067 --> 01:57:51.067
There are a few publications but
definitely not a clearinghouse
for

1792
01:57:51.067 --> 01:57:52.067
that information.

1793
01:57:52.067 --> 01:57:56.067
>> Right. The most rigorous, the
real studies of bulkheads, that

1794
01:57:56.067 --> 01:58:02.067
took place in the 1950s and
1960s in South Africa. They had
a

1795
01:58:02.067 --> 01:58:06.067
whole lot a very controlled
experiments on

1796
01:58:06.067 --> 01:58:10.067
that with different ground
levels and came up with a design
criteria.

1797
01:58:10.067 --> 01:58:14.067
Those that adopted by the Bureau
of mines in the U.S. in the
early

1798
01:58:14.067 --> 01:58:19.067
80s I think. And then pulled out
more by John Abel, what Jeff

1799
01:58:19.067 --> 01:58:22.067
was talking about.

1800
01:58:22.067 --> 01:58:27.067
>> There's also literature of a
hydroelectric

1801
01:58:27.067 --> 01:58:31.067
project because your
[ Indiscernible ] requires a

1802
01:58:31.067 --> 01:58:36.000
pretty intense [ Indiscernible ]
but a lot

1803
01:58:36.000 --> 01:58:38.067
of this, a lot of it is very
site-specific.

1804
01:58:38.067 --> 01:58:41.067
A unique design. It is all
custom.

1805
01:58:41.067 --> 01:58:44.067
Not here is your standard
bulkhead, throw it

1806
01:58:44.067 --> 01:58:47.067
in there.

1807
01:58:47.067 --> 01:58:51.067
>> Okay. Great. I think that now
we

1808
01:58:51.067 --> 01:58:54.067
can add the archive of this
webinar to the list of
references that people

1809
01:58:54.067 --> 01:58:57.067
can use to learn more about
bulkheads.

1810
01:58:57.067 --> 01:59:01.067
I want to thank all of you,
Christoph, Jeff

1811
01:59:01.067 --> 01:59:08.067
and Joy, for an excellent
presentation but I was not only
seeing comments

1812
01:59:08.067 --> 01:59:10.067
of gratitude within the webinar,
but people were sending me
private

1813
01:59:10.067 --> 01:59:14.067
messages saying how wonderful
this was's. Thank you for taking
the

1814
01:59:14.067 --> 01:59:17.067
time and share your knowledge.
It is very appreciated

1815
01:59:17.067 --> 01:59:21.067
and I know people will be
watching this archive over and
over Brooke's

1816
01:59:21.067 --> 01:59:23.067
a thank you so much. With that,
I would to turn

1817
01:59:23.067 --> 01:59:25.067
it over to Jean.

1818
01:59:25.067 --> 01:59:27.067
>> Thank you so very much
Michelle.

1819
01:59:27.067 --> 01:59:33.000
I'm going to walk through a few
quick reminders. For those of
you

1820
01:59:33.000 --> 01:59:36.000
that found this to be an
informative seminar, I will
remind everyone

1821
01:59:36.000 --> 01:59:38.067
that we have webinars like this
advertised on the cleanup
information

1822
01:59:38.067 --> 01:59:44.067
network as well as a variety of
other resources for mining
sites.

1823
01:59:44.067 --> 01:59:48.067
So I encourage you to visit us
on CLU-IN.org or sign up

1824
01:59:48.067 --> 01:59:57.067
for a monthly news later the
goes out on the first of

1825
01:59:57.067 --> 01:59:59.067
each month. For those of you who
are looking for copies of the
presentation

1826
01:59:59.067 --> 02:00:02.067
materials, we already have this
posted under the resources link.

1827
02:00:02.067 --> 02:00:06.067
It is on the middle right of
your screen right now under
related URLs.

1828
02:00:06.067 --> 02:00:09.067
I also included a under the Q&A
window pick you can click on

1829
02:00:09.067 --> 02:00:11.067
either one of those links to
browse to the page and actually
download

1830
02:00:11.067 --> 02:00:15.067
the materials. Contact
information for presenters and
organizers is

1831
02:00:15.067 --> 02:00:19.067
also available on the seminar
homepage, but

1832
02:00:19.067 --> 02:00:22.067
as Michelle noted, will be
compiling these questions are
working to get

1833
02:00:22.067 --> 02:00:24.067
them to the instructors so we
can try to get additional
follow-up

1834
02:00:24.067 --> 02:00:28.067
with each of you. We will ask
ask -- each of you to fill out
our online

1835
02:00:28.067 --> 02:00:32.000
feedback form to let us know
what you thought in terms of
materials

1836
02:00:32.000 --> 02:00:35.000
and the content that was
presented today. What are the
most

1837
02:00:35.000 --> 02:00:37.067
frequent questions I get is a
session moderator is if we offer
credit

1838
02:00:37.067 --> 02:00:43.067
hours or certificates. We don't
issue CEU or PDH, but you can
get

1839
02:00:43.067 --> 02:00:45.067
a participation certificate
after you submit feedback for
the

1840
02:00:45.067 --> 02:00:50.067
session. So if you follow the
link on your related URLs or in
the Q&A

1841
02:00:50.067 --> 02:00:53.067
window, fill out the form and
submit feedback make

1842
02:00:53.067 --> 02:00:59.067
sure to check the box at the
very bottom of

1843
02:00:59.067 --> 02:01:02.067
the seminar pick a song to enter
your email address correctly

1844
02:01:02.067 --> 02:01:04.067
on therefore, as soon as you
submit that, you will be to have
access

1845
02:01:04.067 --> 02:01:09.067
to a certificate that looks
something like this that you can
print

1846
02:01:09.067 --> 02:01:12.067
out or save for your records
procurement dissipated in a
group in today's

1847
02:01:12.067 --> 02:01:15.067
webinar, each person in the room
can actually fill out that
feedback

1848
02:01:15.067 --> 02:01:19.067
form on their own to get their
own certificate. Even if you
didn't

1849
02:01:19.067 --> 02:01:21.067
each individually register I
will ask

1850
02:01:21.067 --> 02:01:24.067
those of you who did sign up, if
you share the room with others,

1851
02:01:24.067 --> 02:01:26.067
please be sure to share the
feedback form with your
colleagues so they

1852
02:01:26.067 --> 02:01:31.067
can get their own certificate
and give us their thoughts on
the session

1853
02:01:31.067 --> 02:01:35.000
as well. As Michelle noted, this
webinar

1854
02:01:35.000 --> 02:01:37.067
and a series of mining events
we've been hosting has been
recorded and

1855
02:01:37.067 --> 02:01:40.067
will be available for on-demand
playback in approximately one
week

1856
02:01:40.067 --> 02:01:42.067
for all the registers will get
an email as soon as that archive
is

1857
02:01:42.067 --> 02:01:45.067
available. With that, I will
echo the thanks to everyone who
joined

1858
02:01:45.067 --> 02:01:48.067
us as well as those of you
stayed on for a few additional
extra minutes

1859
02:01:48.067 --> 02:01:50.067
here to close things out. We
will go head to formally
conclude the

1860
02:01:50.067 --> 02:01:55.067
live broadcast. Vicki you can so
very much for joining us.