I'm guessing there is a reason you cannot just use a mallet / pickaxe type of setup?
Hahahahahahahahahahahahahahaaaa. No.
Pickaxes are for hard ground but not concrete and a mallet would work on a brick wall with a chisel but not on concrete . . . a 10lb sledge would do a pretty good job of breaking it up but I avoided this for two reasons - (i) With the ceiling height in the garage relatively low, it'd be impossible to get a full swing and (ii) I didn't want to risk shattering the slab beyond the partition wall (the bit that's staying).
Can you not just cut it where it starts to go into the garage floor and redirect it into the garden? Maybe a new pond?
I could, but with the extension to the garage, the two sheds AND the conservatory then ALL dumping on to the (clay) back garden I'd no doubt have flooding issues !!!
The reason why I'm doing this - shortened version ?
O.K, here we go . . . .
When I first moved in I quite quickly extended the garage (MK1) to fit in the Caddy . . . eventually I thought about extending further to *hopefully* park two cars in there . . . trouble was the area behind the garage was quite high, in comparison to the garage floor so It'd mean loads of mud to remove, skips, mega-effort . . . then I'd be left with a potential flooding issue with water coming off the back garden . . . so I opted to raise the front of the garage with a low-level mezzanine to match the heights. Materials were free and it worked a treat. In order to gain access, the concrete ramps were built (I was never a fan as they looked untidy but they were useful and obviously did a job).
So, moving on, the original garage extension was knocked down and the second one built . . increasing the overall length to just under 35 foot. This length came about as the materials I was using to support the roof were free and that was the length they were . . I eeked every last millimetre out of them but that was it. The other factor was run-off on the roof . . . the longer the extension the lesser angle I'd have had - risking build up of water on the roof.
So, 35 foot it was but, as the build finished it became clear that although I could've fitted 2 Camaros in the garage, I was never going to fit the Caddy plus another . . . . With that in mind I later added the dividing wall between what is now my office/escape area and the main garage (this was done mainly so I could heat the office end without all of the warmth going out the non-insulated roller-shutter door (although I'll never be able to fit a second car in there, I did add double-doors in the dividing wall so I could put a motorbike in the office end, thus future-proofing that part, at least . . . of course, with the concrete ramps gone I'd still need a ramp to get a motorbike in the back but a ramp for a bike can be a lot less substaintial than that for a 5000lb+ Cadillac !!).
Now all up to date, with the Cadillac project looming and knowing there'd be long periods when she'll need moving in and out of the garage with no engine (that of course, with the ramps would be impossible, no matter how many volunteers I had) and with the fact that I'm growing too old to be laying in gravel under a car for 8 hours (plus) a day, I decided to opt for a nice, smooth block paved replacement for the gravel.
During the process the ramps were got rid of (so the Caddy could be more easily rolled in and out) . . . the knock on effect was that I could remove the low-level mezzanine I put in in 2006 but that would only give 16 foot at the lower level . . . I needed to remove another 3 foot of the slab I put in for the second garage extension or the Caddy wouldn't fit.
And that is where (and why) we are now !