A customer had significant water damage/rot to the base plate in his garage and he wanted me to repair it. See the photos below for my step-by-step process.

Here you can see the severe degradation of the base plate due to water rot.
A piece of the base plate removed shows how severe the damage was.
We made a brace and lifted it using hydraulic jacks so we could support the garage and to provide a way to lift the studs.
We then used a reciprocating saw to cut the old base plate away from the studs. Note that they are lifted from the concrete floor by the brace that we made.
The rotten base plate removed.
The open area is measured for the new base plate.
New base plate installed! It will be secured to the concrete with 1/2 inch anchor bolts.