|
INTRODUCTION
TO WATER TREATMENT & ABSTRACTION |
Borehole
construction
Artesian boreholes
Wells
A typical well head
Borehole construction
Boreholes are drilled to allow us to extract water
generally
this water will require a certain amount of treatment before it is fit for drinking
the pictures further down
the page are of a borehole that is so clean it requires very little treatment.
Many boreholes will require treatment using filters,
settling tanks, chlorination
& pH correction
Borehole construction
In its simplest form the construction will go something as described
below
A hole is drilled into the ground generally with a diameter of at
least 300 mm
A lining is inserted into the hole & the lower part of
the lining where the water intake is situated is packed with gravel.
The
gravel acts as a type of filter media & also prevents sand from being sucked
into the well when the pump is running.
The upper part of the well is packed
with grout to seal the outside of the borehole shaft & to pack the well.
Finally a concrete slab is added to the top of the well to prevent ingress of
pollutants & seal the well head.
A borehole pump will be lowered into
the hole on a steel or cast pipe, Alternativly & now more commonly a pump
will be attached to a Wellmaster
pipe.
Wellmaster pipe
is flexible (like a very thick hosepipe) & is easier & quicker to remove
if the pump needs replacing.
The Pictures below show a
borehole being lifted (left) please notice the solid pipe that fits into the
borehole lining the picture on the right shows the pump.
You will also notice
the amount of water coming from the well head this is because this borehole
is artesian please see below
for details on artesian wells
ARTESIAN
BOREHOLES
Artesian flow is created because the borehole
is drilled at a lower level than the underground rivers from which we extract
our water.
The well shown in the picture above is capable of
delivering in excess of 50 litres per second without a pump.
Wells
The picture below shows wells pumping into a settling tank
prior to filtration
chlorine is injected as the water enters the tank to kill
any undesirable elements
Click
her for pictures of a typical well head
