I think I agree with CeramicTec--- an 1/8" is really nothing.
But for your future jobs, I recommend renting a rotary hammer and chisel bit. They rent here in OK for about $65 per day, or for the whole weekend if you rent after noon on Sat. I have found no way that isn't messy, dusty and annoying. But the rotary hammer is the fastest, just becareful not to dig into the concrete, some marring is okay, but don't aim for China. Keep it on an angle and stay at it. It's less wearing than any manual option, but probably the dirtiest, but for the time it saves it's worth it. Tape off your area, get a good dust mask and get to it.
Professional Amateur &