Query on crushed PVC casing

PVC casing crushed

Dear IWP

We have dug a borewell upto 420 feet and put a 30 stage 1.5 submersible pump (KHB) at a depth of 400 feet. As the moter stopped working, we tried to pull out the motor and learned that the casing was crushed. The casing was of a plasto company which is considered to be a good company.What is the best solution for the future now?

We would like to add that upto 170 feet, there is very hard rock strata and from 170 till 420 feet its very soft. Kindly suggest the best solution.