When basement floor was poured the capped stub for a shower drain was pushed below the surface and cannot be found by tapping the concrete with a hammer. It's location had been changed from the original plan, and the blueprint with the as-built location is "gone"; However the location is known within a 5' x 5' area and is close to the toilet stub. Is there some tool available that could be used from above the floor to follow the line from the toilet stub to the shower drain stub?
Thanks for any help you can provide.
Don

Ground penetrating radar comes to mind. Check it out at; Ground Penetrating Radar Services (http://www.gp-radar.com/).
As for me, I'd cut me a inspection trench in the area and locate the drain line that way. But wait! When basement floor was poured the capped stub for a shower drain was pushed below the surfaceYou have more of a problem then just a hidden shower raiser. If the entire trap assembly was forced beneath or under the pour then you will have backfall on the drainline. I trust that when you uncover the drain line you will check out the slope. Good luck, Tom