I need to cut a hole in a basement concrete floor in a house that I own so I
can put in a sump pump.

I know how to do all of the sump pump stuff, but I'm not sure if there are
any tricks to cutting the hole in the concrete. The concrete seems *very*
hard (it sort seems like it's a finer texture and much harder to chip at or
break than most concrete). I have tried drilling into this concrete in the
past with a concrete drill bit and it seemed to go nowhere.

The main thing I want to avoid is creating a crack in the concrete while
chipping or cutting out the opening. So, I'm wondering if I could buy some
kind of one-time-use circular saw blade and cut grooves around the perimeter
of the hole where the concrete would break/crack instead of the
breaks/cracks extending outward past the opening.

I know this is somewhat vague, but any thoughts, suggestions, or ideas would
certainly be appreciated.