Need Help With My Bore Hole

Hi all, I don't know if I am at the right place here or not can't sort of work out what category this should be in.
I am getting my own Bore (Water) due to our extended Water problems here in Melbourne, I have ground water at around 20-25 feet and have gone down to about 15 feet with a Post hole digger I have sandy soil after that the hole falls in due to watery sand so I push down a casing 90mm PVC pipe to stop collapsing, but now I have to change the way of going deeper and my thought was of dropping down a approx. length of 3foot 2"galvanized pipe attached to a nylon rope and this pipe when hitting the bottom will go into the watery sand 1 to 3 inches but upon pulling it up I need to have a trap door or something like that to stop the soil from falling out.
As I lift the sand up I push the casing down until I have clean water I know I have good clean ground water here as some of neighbors do have Bores.
Anyone got any ideas on how to construct a device at the end of the pipe to keep the sand in the pipe while pulling it up.
It needs to be strong as it will drop 20 + feet.
My thirsty Plants will love you.

Have you thought of an "Archimides Screw." !

This is a UK site and we don't generally do the same kind of thing

why don't you sink a well?

if the water sand mix is enough you might be able to use a sludge pump,
its like a standard drain pump but with a large inlet on the end to suck up gravel and the like.
suck up the sand in the pipe lower your casing and repeat.
you might also want to drill side holes in the lower end of the pipe to let water enter from the sides for the bottom 2 ft. we call it fracking the pipe a word for side hole punching in the oil fields.

Hi and thank you all.
memor maplin, the Archmides Screw is very interesting I must admit I had never heard about it before I Googled and read about it Wikipedia, my problem would be how to construct one, but it is a very interesting idea and I will try and find more information about it.

John D, yes I do realize that you in the UK are not really into this sort of thing, but John you have many many ingenious people over there who are brilliant in coming up with great ideas and that is what I need. Some of the best engineering has com from the UK, sorry no excuse John.

noseall, sink a well, is not going to work as my ground water is not actually a underground river or artisan I have to have a Spear at the end of a pipe with very fine stainless steel mesh around and the suction pump will suck the water coming trough the sand.

crazycanuck, the ludge pump would work further down from where I am now at this level the sand is not quite wet enough about 2 feet or so before I hit clean water I have very sludgy muddy (clay) stuff and a sludge pump would go through that in no time, but I still have about 3 - 5 feet to go before I get to that.
But that idea with the holes in the pipe at the bottom is actually brilliant I had never thought of that and it would make the sand -water mixture better for the use of a sludge pump.
Again I thank you all for your help so far and please don't stop coming up with ideas.

your pointed spear is called a sand point you keep driving it down and
water is siphoned through went you rest at your final depth.
trouble is you are confined with the size of surface area of the mesh to
your water flow , I presume you want 4 to 7 gallon a minute?
you might rethink to a bigger pipe.
you might also try a hand auger they come in 4,6,8 inch diameters, we use them for fence post drilling and ice boring for fishing in the winter.
although some of the frenchmen still fish in the winter the old way ,
A snowmachine and a fishing line they call it trolling.

Hi and thanks, I have in the meantime found quite a lot of information about my bore hole, especially from a US website by Fred Dungan " Water Well Helpline " a very informative website and by the looks of it sinking bores is very common in the US although it is mainly as you say the pointed Spear is driven into the Ground.but they also do it the other way they call it a Sand Sucker Well.
We actually bore the hole to the water line with a Sand Auger or Post hole digger then lower the casing down and use a Sludger or Bailer or Sandsucker all much the same thing till you get clean water and then lower the Spear down past the casing by a couple of feet.
The 3 foot pipe call it sandsucker that I could not work out how to make to be able to drop the pipe down inside the casing and bring up the sludge is actually quite simple the most popular version is via a Ball Valve at the bottom the sludge and wet sand will enter the pipe when dropped down and when slowly pulling it up by rope the ball will seal the hole and once at the top wash out the sludge and drop it down again by doing this the casing can be lowered more and more it is slow but it works.
My Bore will only be used to water the Garden the Water has to much salinity to be used for drinking water and yes 4 to 10 Gallons is possible
I would be happy with 30 liters a minute.
I am looking forward now to continue with my project.
I will let you know as to the end result.
I thank you all again for your input.

If you wind up in sand I would go a little deeper as the salinity will reduce over time if you have a good flow of water, the sand will flush itself and become a filter reducing the salt.
You might post a question on (in the Garden) asking what fowers are best for salinized soils,or at least what to add to soil to compensate for salt if any.
Good luck from the great white north.

Thank you crazycanuck and I will post back with my progress.

cheers from Downunder

Hi hermie, i am in the same situation, i have started to sink a 100mm caseing into the ground, but i am finding it hard to go any more than about 2 meters, i need something to syphine the sand from the pvc pipe, any suggestions, cheers.