New garage concrete slab problem

I recently built a new 30' x 16' garage/work shop in my back yard. I built the whole thing except for the foundation, and slab. I couldn't be there when the mason poured the 5" thick concrete floor. Long story short, they poured the floor 4 inches to low, and now every time it rains, water runs into the garage from the driveway.



I have to fix this soon. I have plenty of block wall height to raise the floor. Question: Can I pour a 3" or 4" thick slab over the existing floor, to raise it, or will I have to spend a small fortune to have the slab removed?



Thanks Bill

New garage concrete slab problem