Re-pull large wires into existing buried conduits

[anbm]

There are (4) 4" existing schedule-40 pvc conduits (buried underground) connecting utility xfmr and building main switchboard. The distance between utility xfmr and bldg. main swbd is around 300 feet. We want to remove existing aluminum wiring in those existing conduits, re-use existing conduits and pull new copper wires (4#600MCM per conduit). Will this can be done and save some cost or better to install all new conduits, wires? Thank you.

 

[texie]

There are (4) 4" existing schedule-40 pvc conduits (buried underground) connecting utility xfmr and building main switchboard. The distance between utility xfmr and bldg. main swbd is around 300 feet. We want to remove existing aluminum wiring in those existing conduits, re-use existing conduits and pull new copper wires (4#600MCM per conduit). Will this can be done and save some cost or better to install all new conduits, wires? Thank you.

I don't see any problem as long as the new conductors don't exceed the fill rules. I think I would be more comfortable pulling a mandrel through before installing the new conductors though, just to prove the integrity of the raceways.