Right now we are in a place called DeepStore
which is 150 metres below Cheshire.
DeepStore is a storage facility in a disused part of
an active salt mine. Behind me you can see
lots of timber boxes and these boxes contain
sticks of rock like this what we call core.
We take this core using drilling rigs, we
drill bore holes and extract this from the
ground. What's contained in these boxes is
in effect the basis for all the design of
all the underground structures on Crossrail.
We take these cores and we can describe them,
test them in laboratories, test them in the
bore holes and all of that data together forms
the basis for the designs of our works. So
this is a piece of chalk, this is the material
that the white cliffs of Dover are made out
of and this has come from near Plumstead in
southeast London near the end of the Crossrail
tunnels. So what else do we have, well we
have London clay which is most of the ground
immediately below the surface in central London
and we have some other clays and sands that
sit between the London clay and this white
limestone here in my hand. You can find these
materials all across London but as far as
Crossrail's concerned the route to the west
around Paddington, Bond Street and Tottenham
Court Road is dominated by London clay which
is where our construction is and as we move
further east the London clay thins out and
we progressively move through the Lambeth
group, through the Thanet sands and into the
chalk. So by the time you get all the way
down to the River Thames, Woolwich and Plumstead,
we only have the Thanet sand and this material.
If you laid all of the length of the bore
holes end to end I think it would be something
in the region of 34 kilometres long so that
is three quarters of the length of tunnels
on Crossrail. The qualities of the geological
materials under London that make them good
for tunnelling make them not that great for
long term storage so one of the beauties of
this place is we get quite cool temperatures,
constant temperatures and constant humidities
so it means that these materials will stay
as they are for as long as we need them to
here where as if we were in a warehouse above
ground that wouldn't be the case.
DeepStore is a business, an archive storage business
that has been set up at the working salt mine
in Winsford Cheshire. Mining here originally
started in the 1850s, DeepStore was actually
formed in the late 90s. The site was used
to store some material during World War II.
The mined area is equivalent to 700 football
pitches. All the sort that's extracted from
the Winsford mine is used in de-icing products
for keeping the roads safe in winter. DeepStore
occupies about 10% of the mined void space
here in Winsford which is 150 metres below
the ground and because of the geological conditions
around us, it's created an environment which
has a naturally occurring 55 - 58% relative
humidity and a constant 15°C temperature.
DeepStore has been storing core samples for
Crossrail since March 2011. The most interesting
part about working at DeepStore is the varied
client base that we have and the interest
that has been generated from using this unique
facility. It's been a privilege to work alongside
Crossrail on this project.
