Hi. I need to run an interior French drain to my sump in the basement. I'll probably install a new sump, too. I had someone come in to do an estimate, and they said they use a jackhammer instead of saw to minimize dust. I decided I would like to make this a DIY project, but I'm unable to find specific enough information anywhere online about removing the existing concrete floor. I have two concerns:

1. Do I need to precut/score a line maybe 12" away from the wall with a diamond saw so that I can jackhammer up to this line, or can I just roughly jackhammer out the 12" channel? I don't want to crack the floor beyond the 12", but it would save a step and a lot of mess if I don't need the saw. It's a bit of a long run to cut.

2. My floor is "concreted" right up to the walls with no gap like you see on newer floors. How can I be sure I won't damage the cinder blocks at floor level? Will the concrete just break away from the wall with maybe a tap from a sledge hammer?

Thanks for any help.

Dan