Faliure of Drilled Tube wells in very short period

It is expected that in Jharkhand 15 to 30% Drilled tube wells silted or collapsed in 2 to 3 years and get choked, here UPVC casing pipes are used, it may be due to damage of UPVC casing pipe during insertion in loose formation or non insertion the casing pipe up to 15cm in rock, Or some other reason?