what is a ground water well, thats the a very traditional method used to in collecting water where the other sources of water or rivers are far away, if u wanna know a lot more about more technical detail and kids of wells used for ground water.
firstly you'll need is good form-work to preppier the cylinder part of it, so what was used is a steel framing with 1.2meter (4 feet) in diameter and 1.2m (4FT) in height as in the pic shown, this type of shuttering or form work has two parts init, external shuttering and internal shuttering. all the steel shuttering is bolted together with 9mmx 25mm bolts at each connection, always we have to prepare the internal shuttering first.
after u have carefully prepared the internal shuttering its time to start with the steel work, steel used for vertical is 10mm deformed bar at 150mm spacing, and horizontal as rings its 6mm round bar at spacing of 150mm. since the wall thickness of this well is 120mm, make sure to add a wooden block in between the shuttering before u completely bolts it.
once the steel bars are been handled, insert the cover blocks so that the steel bars wont be touching the form work, what have been used for cover blocks is 35mm small blocks around 2inch by 2 inch, if u wanna knw how to make simple concrete cover blocks visit bigatoll.come, well any how making a cover block is pretty simple.
after u have completed the steel work, concrete cover blocks its time for you to place the external covering for the form work. if you wanna find out how much of concrete needed for 1m3 of concrete visit yd-mv.com this website has a free concrete calculator. now start mixing the concrete in the ratio of 1:2:3. make sure its a bit wet like 60% water, this will help you to get rid if the honey combing that will occur, but dont forget to use a mechanical vibrator, good vibration has to be done after each load of concrete has been poured into this shuttering.
once the concrete has been poured, give the form work 24 hours to dry out, than carefully remove the bolts and remove the shuttering, Always remove internal form work first than external form work, this is because the concrete haven't got its full strength and giving 1 day means its surface is dry. so there will be cracks if u try removing the external first. so keep in mind internal than external. leave the concrete for curing with wool bags till 7 days, so it will reach the peak of strength starts to gain. spray water 2 times a day so that it will keep wet and no thermal crackings occurs.
while the 7 day period is there, use that time to cast a new concrete cylinder part for your well, if you have heavy machinery than it will be a advantage for you, but if u dont u have to wait till the 7 day period is over than to put the form work on top of it to precast a new concrete.
if you have an excavator, excavate the place where you want to keep the well, mark the location of the well, than dig the place till water or more than water, in this case water depth was something like 1.2 meters, since Maldives is a flat land water table is petty high and the island is 1meter above sea level.
when the excavation is done, place the pre caste concrete in side the hole, use a crane or a the excavator, while lifting heavy objects you must be very careful, cos every where there are nut cases running around.
once the well is placed, start another concrete on top of this well with connection the rods or place another concrete cylinder on top of it. once the pieces is placed, start manual excavation from inside of the well, the more soil u remove underneath the concrete, it will slowly starts to sink down, ground water well are sinks like this and its called the sinking method.
in this case YD Works used a mini dredger pump of 4", this pump can suck water with soil, this way some soil underneath the concrete wells will come plus there will be one labor always digging the soil and sand out of it. once the sinking starts try not to stop digging till your done, while your digging the soil around the external surface is been pulled down to your shovel, there will be a gap forming between the external surface and the ground, once that gap is started to from that means its ready to sink, if u get stuck sprey some water to the bottom that way soil erosion will occur giving you more sand to pull up.
top concrete cover plate been laid
Source: Courtesy of YD Works
pre cast concrete cover is 150mm thick and steel of 10mm deformed bar been placed at 150mm spacing both ways, there is an opening of 2ft by 2 ft, a concrete cover has to be made so that no one falls in it, this cover is cast with 6mm steel bar with 80mm spacing T/B.
there you go, now thats a short way on how to build ground water well, now please visit bigatoll.com and find out more other stuff. we would like to thank YD Works for providing us with the pics and detail info on how the work has to be done, bigatoll.com send regards and thanks to YD Works.
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