A rather urgent need to replace my oil tank requires that I install an exterior bulkhead cellar door to my home. I'm doing this project myself. I've dug the hole and poured the concrete footings, but now I'm faced with how best to open up the foundation itself. Above grade are cinderblocks, which I'm not worried about. Below grade it is poured concrete, I'm estimating 9 to 10 inches thick.
My first inclination was to rent a gas powered concrete saw, but it only has a 4 1/2" depth of cut. I'd have to cut from both sides, and therein lies the problem. One end of my existing oil tank is in the way on one side of the planned opening, and an interior (non-load bearing) wall is right up where the other side of the opening will be. There's no room to get the saw in there for the interior cuts.
Is it possible to drill a series of holes through the foundation wall with a hammer drill and knock out sections with a sledge? If so, is it advisable?
Any help would be very much appreciated.