Solid Hardwood, Engineered and Laminate Flooring - high spot in concrete slab

Sorry in advance if this is a rookie question (but I am a rookie when it comes to flooring, and have searched the Web for an answer with no success).

I am starting to install engineered hardwood flooring, glue down over a concrete slab, in a condo on the second floor of a building. Previously it was carpeted.

In one room there is a high spot in the middle of the slab, maybe 1/4 in ch to 1/2 inch high at its highest point. It is about eight inches wide and 18 inches long, and somewhat uneven. I have been able to chip away at the edges on one side (and level out the resulting low spots). But the center of the "hump" is extremely difficult to chip away at, even with hammer and chisel. It also seems, to my untrained eye, like a different substance from the rest of the concrete and patch on the slab. It seems darker and smoother than the surrounding concrete.

So my first question is whether I can and should level out this spot. I am concerned about what might be under there; I don't want to start leveling and hit a pipe or harm the structure of the buliding. My father, who is helping me with this (not a pro either) thinks it could be tar or some other substance sealing a pipe or a leak. I don't know if this makes sense so wanted to ask. If I shoul level the spot, any suggestions on how to do it?

My second question is what to do if this is a spot I shouldn't level. Any suggestions on how to lay the floor over this spot without creating an obvious hump or weakening its structure? Can I level out the rest of the floor nearby so the rise would be more gradual? (I've used leveling compound on small spots around the slab, but don't think you're supposed to use that for large areas).

Any insight any of you could give would be greatly appreciated.

Thanks,
Brian

i don't see why you shouldn't be able to level it. no radiant heat in floor ?
pipes would be deeper than 1/4 - 1/2". it's messy but you could use a 7" side grinder and masonry abrasive disc. it's not that large of an area to fix.

Concrete will need to be flat in order to prevent flooring failure. You can rent a grinder.

Grinder are good for little humps and bumps, but ½" it is easier and much faster, with less dust to take a diamond blade and make rips and cross cuts in the area and using an electric demo hammer chip it out, then use your portland and latex mix to screed(drag a straight edge across). to get it flat, because there will be lower spots now.

Dust control is the big issue regardless of the method chosen.