Need advice - how to pump water in brittle / loose soil as after some period well is completely filled with soil

Need advice - How to pump water in brittle / loose soil

In our area soil is very brittle. Water is easily available from 50/60 feet but the problem is how to pump the water. After some time (1/2 months) well is getting completely fill with soil and not able to pump water and even recover the motor. We have tried to put casing at 60Ft and pipes with slotted holes. But still the same problem occurs. Can anyone help me for this?