No direct experience, but if this is below grade and you want to seal out ground water, I have heard good things about this type of seal. There may be other manufacturers of the same type of seal, not sure.
2" 2.375 " od
2.5" 2.875 1/4 " around
There's wet and dry core drills. dry lots of dust, wet a lot cleaner with a shop vac picking up the water, dead on hole. Only used a company to saw cut holes in foundation.
One can rent a diamond core bit and a big papa drill at home cheapo. Or have an irrigation company that cores street curbs for drains come out and do this. Several options here.
Need to look at a couple of you tube videos. Poured concrete diamond core machine and if there's a chance of rebar diamond core goes through it easier. Machine has to anchored to the wall, core bit is water cooled and amp meter that has to be watched to keep it a safe range with the pressure put on it.