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lances. Then we inject the iron-rich water. In
the future, we will be using several rows of
lances that will move along canals or roads
like a roller with the aim of installing a large
sheet of bog iron beneath the surface.’
Rolling in the deep
Then it was time to prove that the idea
actually worked on a large scale. The team
of researchers tested the 'roller' in a trial
with three tons of injection material in a
2.5-metre-deep, 40-square-metre container
in the laboratory in Delft. The engineering
firm Hektec designed a special plant for
making the mixtures and injecting the right
amounts into the ground.
There was also an opportunity to conduct
tests in natural conditions when a pond
had to be enlarged in the Veluwe area of the
Netherlands. The researchers wanted to
show that you can do this by extending the
impermeable layer below the pond using bog
iron.
Those experiments identified a new
challenge: you can’t, of course, see anything
below the ground. Marco de Kleine and
his team therefore designed a monitoring
system to watch the injection of bog iron.
‘We can now pinpoint the location and the
spread of the new bog iron. So we know
immediately whether the job has been done
right.’
Application
The team is now waiting to put the idea into
practice. There are numerous possibilities.
Flows of groundwater into construction pits
can be reduced. Bog iron can also be used
to deepen canals and roads. Injecting bog
iron is more environmentally friendly than
sodium silicate and water glass and it may,
depending on the situation, be significantly
cheaper than traditional sheet piling.
Wim de Lange gives an example: ‘Let's say
a canal has to be made wider and deeper
to accommodate larger and taller ships. If
you don't want to replace all the bridges,
you have to lower the water level. But then
the groundwater level will be lower on either
side of the canal. Homes and nature areas
alongside may subside or dry up and that is
certainly not a good idea. We think bog iron
could be a great option here.’
More information:
The development of bog iron in the test set-up.