today we are drilling a borehole to reach
groundwater, by using air. We are using a small air pump to lift out
the soil from the borehole. Using air we are circulating the drilling
fluid. In this video we will tell you how it's done. First we start our borehole with auger. So now we completed approximately three meters,
from this depth we can start airlifting and then things become a little bit more easy. By using a small air pump we can make manual
drilling a lot faster. [Music] All right now I have to take care not to drop
anything in the borehole. It's a very nice tool, saves you a lot of
effort. [Music] So now we have connected the air hose and
we are ready to connect the air pump on the other side. Now we attach the handle. [Music] Now if we would switch on the pump
we would see fluid flying all around [Music]. [Music] Now the fluid doesn't rise all the
way up to the top because we have lifted the the drill step. If we lower it [Music] So now you see fluid coming out, but anyway
we are making a mess. Sofirst we connect the soak pit. When we put it in this container, the flow
here will be very low so the sand will settle to the bottom and the cleaner water will re-enter
the borehole through this pipe. [Music] [Music] So the drilling is nothing more than moving the drill
stem and the drill head up ,and down and rotating only clockwise. If you rotate counterclockwise the fittings
will unscrew and you will lose part of your drill stem in the hole. We are using this drill head and as you can
see it has sharp teeth to grind the soil loose and it has openings from where the drilling
fluid will enter. Every turn you scrape sand off the bottom
of the hole which will be dissolved in the water and sucked out with the drill fluid,
and sink down in the in the soak pit. [Music] [Music] It's a lot of sand with only a small amount
of water. So even when the flow is very low you can
see that it takes out a lot of sand already. So the deeper you go you can understand that
this is much more easy than to drill it out by hand. To demonstrate what's going on at the bottom
of the borehole we have created a transparent model. We are using the blue hose to inject air in
the transparent drill stem. The air forms bubbles in the drill stem which
will cause an upward lift in the drill stem. Because of this sand and gravel is sucked
into the drill stem and gets transported upwards to the surface. [Music] If we look at the sample we took before you
see that it is more than 50 percent sand and for the rest water. We are now going to switch the drill stems. We have two pieces of one meter and then we
have a lot of pieces of three meter so when we have sunk the one meter pieces into the
ground we change them for our three meter piece [Music] We tape the air hose to the pipe so we won't cut down
the air hose accidentally. If you leave your drill resting on the bottom
of your borehole there's always a risk that it gets stuck. [Music] This is the pump we are going to use. It is an old pump from an airco unit this
type of pumps are easily to obtain in countries with a lot of airco units. Yeah the pump is not made to run continuously
without cooling, so to cool it, to keep it on a low temperature we put it in a bucket
and fill the bucket with water. It can be very dangerous to mix electricity
and water so close so always work safe we in this case we use a earth-volt detection
socket. If we touch a live wire, or anything that
is connected to a live wire, a socket with earth-volt detection will trip and switch
off the power immediately. [Music] When working with electricity in the field,
always take proper safety measurements, also when you're working with a generator. Our compressor emits a little bit of oil in
the air stream. We don't want that because it pollutes the
groundwater, so we use an oil separator made from a bottle. [Music] Air will enter here and it will travel
through the bottle and exit here. We will pack the bottle with steel wool on
which the oil will connect so only clean air leaves the bottle. [Music] We also check the cooling water for the pump. The power is off so it's safe [Music] it's
getting warm like 45 degrees so we change it for cool water [Music] And we can switch it on again. [Music] We are going to mix up some additional drilling
fluid. The drilling fluid is good for three reasons
firstly so we don't lose a lot of drilling fluid into the soil, secondly because it prevents
the borehole from collapsing, and thirdly it makes it much more easy for particles to
get lifted up out of the borehole. In this case we use barasol which is a commercial
product, a biodegradable polymer, but you can use a lot of other things like bentonite
or natural clay as long as it makes the water more thick. As you can see it's very viscous. [Music] [Music] So now we are at four, no when this pipe is
in we are at four meters with the hole diameter of 145 millimeters. But the size of the hole we can change easily
by changing the drill bit, depending on your liking. So the deeper you go the more heavier your
drill the unit will be so in the end it's almost impossible to lift it and hammer it
down all alone, so that's why the hook is, you can attach it to a tower and people can
help you lift it with a rope. But up to 10 meters I can still do it on my
own. We have experimented with different types
of drill heads, like this one, this one, but we ended up with a type mostly like this. You can see the difference between this and
this one, this one is much more pointy. We found this one will cause stones to roll
to the center of the borehole and you will end up crushing them with only the tip. This will take a lot of time and energy and
drilling will go really slow, so we found that this shape will work a lot faster. It is also possible to use PVC drill pipes,
the advantage of using PVC is that it's much cheaper than steel pipes. They have a major disadvantage because of
the turning the PVC couplings will screw tighter and tighter and combined with sand it is very
difficult to release them. They will easily break if you use pliers on
them [Music] Yesterday we stopped at around five meters
and today we will continue and I will mix some new drilling fluid to be well prepared. [Music] [Music] We are now at five meter something, and once
in a while you need to empty your soak pit, because it will be accumulating the soil. We have forgotten to empty the soak pit so
it's quite full now. Normally you would empty it more often. Ah this one is too heavy now. [Music] [Music] It is quite a lot of sand we all drilled it
from the borehole. Now we have to refill the water, the circulation
drilling fluid, and then we're good to start again. It may seem strange that you need a lot of
water to drill well, but the water we reuse so we don't need a
lot of it and it brings the source of water much closer to people's houses. [Music] So we are now at six meters and we
changed, we add another one meter pipe. [Music] [Music] [Music] [Music] [Music] Okay it starts we go a bit heavy now. We are now at almost seven meters and as you
can see the flow becomes higher and higher. With this flow it is possible to take out
gravel and small oebbles. Easily to demonstrate it I will put some marbles
in the borehole and we will catch them at the outlet. Ah, here we have our marble! Ah we found a new marble, it must be ancient. Also we put some marbles in the transparent
setup. You can see that the marbles are easily sucked
in by the strong flow. [Music] So one big advantage of using air
for drilling compared to other methods which use a water pump for drilling, is that with
this method you can increase the diameter of your borehole while maintaining the same
flow. The flow in the drill stems is always equal,
it's not a dependent on the size of your hole. If you are using a water pump then the flow
is reversed, the water will go through the drill stem down and it will flow up in the
annular space. The bigger you make your borehole, the slower
the flow upwards will be when you are using a water pump. When you're using a water pump it will degrade
because you are pumping water with sand and gravel and stones and in the end you need
to maintain and replace pieces. This pump is only pumping clean air so it
doesn't degrade by the sand or the dirt that we are pumping around. Compared to other drilling methods it's not
per se faster, but it's a very efficient and maintenance-free way of circulating the drilling
fluid. So now we have reached almost eight meters,
this is enough for today it's only for demonstration. But normally you would drill until you find
a good layer, which is suitable for water extraction.
