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Building the Modern World: Infrastructure is made of ROCKS

Building the Modern World: Infrastructure is made of ROCKS


I’d like to thank AGI, the sponsors and
fellow presenters and my fellow participants for giving me the
opportunity to talk about some of my favorite things which are rocks for
infrastructure. Rocks are really crucial for infrastructure because one lane one
mile of road takes thirty-eight thousand tons of rock. These sources need to be
local because rocks are very heavy and costly to transport. If you go over 30
miles it doubles the cost of the material so you need a lot where it’s
needed and finally geology impacts the quality
of the roads. I’ll try not to use too much jargon but one expression is
aggregates which are simply stone sand or gravel that are used for construction.
A couple of the resources that I’m using come from U.S. Geological Survey – their
minerals information series, and also the Federal Highway Administration has a
very fancifully titled paper called “Wherefore Art Thou Aggregate Resources
for Highways,” which I use some of their information in this presentation. Also on
the NSSGA website we have an aggregate map which uses some of the USGS
information if you’re interested in aggregates in your state. I love quarries –
I consider them windows to geology. I realize not everyone else has that same
interest, but the process of getting rocks to roads at least at the rock
stage is fairly simple: there’s no chemicals used or produced; basically
naturally-occurring rock is crushed and sorted. The industry is heavily regulated,
there are permits and requirements before, during and after operations. Some
of the questions folks ask particularly if quarries are in their
area are why are there so many, why are they so big, and why are they here? And
the answer to all of these is geology. There are about 10,000 aggregates
operations in the US, and you can see their location on the lower green map
and you can tell that these are located in population centers and also follow
the location of highways and roads. This is because again costs go up
exponentially with distance. Quarries need to be large for safety and
efficiency reasons; equipment and permits are expensive so you need scale; also you
have to have room to have barriers, setbacks, and a terraced entryway for
safety. While stone sand and gravel are common, quality material near where it’s
needed is not. Generally there are four types of aggregates resources, and
their general location is shown in the colorful upper map. Trap rock, which is
the black rock, is volcanic, and tends to be located in the West, namely the
Pacific Northwest. Granite tends to be located in eroded mountain areas and as
shown on the map in green. Unconsolidated or loose sand and gravel tend to be located around river deposits and are shown in yellow, and limestone,
which is the white rock, is located all over the US, but mainly big deposits are
located in the Midwest, the southeast and the southwest. Limestone makes great
roads but also has lots of other uses. You’ve probably eaten this if you’ve had
a Tums, and basically all of the industrial purposes are similar to what
Tums does, which is a neutralization, so it’s used to clean air and scrubbers and
for power plants, and also to treat water and wastewater. All the rocks have
really different properties, and the road mixes or the road construction takes
these into account. So how does a rock turn into a road? Well, first a geologist
looks at U.S. Geological Survey maps and other
information to find a good source of aggregate, then they do extensive testing,
and that is looking for a extensive deposit that is enough for a large, long-use quarry, and also that the properties will go into a mix and make a
good road. A mix is basically a recipe for a road that the state departments
of transportation have developed, and these are based on available sources and
traffic and weather. No one size fits all for a good road – a place like Dallas is
going to have a much different road than rural Maine. There’s extensive research,
testing, and looking at roads’ performance, and geologists work to keep up on these
standards to make sure that they have the good product that goes into a good
road. Basically aggregates make up 80 to 90% of road, whether you’re talking about
asphalt or concrete, so it’s basically the rock plus a glue
to hold it together – in the case of asphalt it’s petroleum, in the case of
concrete it’s cement to hold it together. I’m going to go into land-use
and long-term benefit of quarries, and the first example that I’m going to use
is Luck Stone quarry – if you’re a resident of the DC area or live or work
around DC you’ve probably seen this quarry
it’s just northwest of the Dulles Airport so if you fly in or out you see
this large hole in the ground or if you are a biking enthusiast you might have
used the Old Dominion and Washington bike trail which is a former railroad
which actually bisects the quarry. This quarry they don’t actually know how old
it is – they know that it was in operation before the Civil War, it helped build the
railroad – the former railroad that was the area – as well as all the roads in the
area. You can see from the lower aerial photo that there’s a lot of competing
land use in the area: you have homes to the east
you have farmland and parks to the west, quite close. You have you end up having a
lot of houses built near quarries after the quarry’s in operation because it’s a
lot more economic to build where you have materials nearby but you can see
this may create some problems as the quarry continues to operate. When the
quarry is played out, one of the uses is to become a reservoir and that’s what’s
going to happen with the north part of the quarry – the local community is going
to use this for a reservoir to supply water, and I I believe that my fellow
presenter Brian’s company is helping to work on this. What else can a quarry
become? Well it can become a beautiful park: this is the Boboli Gardens in
Florence – the material was used to help build the buildings and the roads
in the area and now it’s a park. In the US it may become a wildlife habitat or a
golf course. On the top left you have what’s known as the Chambers Bay
championship golf course – this was a quarry for about a hundred years
providing material to help build Seattle. On the right you have the Bellwood
quarry which is located in Atlanta – you might have seen this on TV; it was used
in The Walking Dead and also the movie The Hunger Games. This is a disused
quarry but it’s going to become a reservoir with a million gallons of
water to supply the city of Atlanta. To fill this they’re going to have to
drill through the rock to get to the Chattahoochee River. They need a very
large drill bit to do this and to get the community excited about this project
they had a contest to name the actual drill bit that’s being used, and
the local community voted to name the drill bit after the rapper Killer Mike
and he’s become a really great spokesman for this project. So hopefully through
this quick presentation you’ve seen that rocks are really important for
infrastructure, that geology helps determine the quality of the road (you
really need good rocks to make a good road) and that quarries can perform a
long-term benefit, and I believe all questions will be held to the end – thanks.

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