Time-delay in installing pump in borewell in Bangalore, Karnataka - Need advice on related issues

Is there a time duration (which is safe) within which the Borewell Pump has to be installed?

We installed a borewell (6.5") about a month back with 45 ft Steel and 38 ft PVC casing. Now when we are trying to put the submersible pump it is not going beyond 80 ft. The guys says there could be silt. Total depth drilled is 185 ft and the water was stuck at 115 ft. There was no loose soil after we hit the rock at 38 ft of drilling. We stay in Banglore North.

Purushottam Muralidhar