Beginning in November 2006, the Marriott Hotel in Schaumburg, IL underwent a major renovation including upgrades to every one of their 400 guest rooms. One of the most significant upgrades was the replacement of all of the heating and air conditioning units with more efficient models. But a problem was quickly uncovered with this plan – the new HVAC units required five pipes where the old had used three, and there was not enough space in the existing sleeves for two additional pipes. Complicating matters further was the realization that the elevated floors of the hotel were all post-tensioned, and the PT cables would need to be precisely located before any holes could be drilled.

Ground Penetrating Radar Systems was brought in to solve this problem and allow hundreds of holes to be safely drilled through the post-tensioned slabs. GPRS was able to locate the cables running alongside the existing sleeves and identify areas in which it was safe to drill, and all of the holes were able to be drilled without cables being hit. During renovations to the hotel’s lobby and restaurants, GPRS located conduits, rebar, and PT cables to allow many more holes to be drilled safely.

Concrete scanning with GPR for the purposes of locating post-tension cables, rebar, and embedded electrical conduits is a common application for GPRS. We plot the locations of the steel or conduit directly onto the concrete surface, in order for the drilling to be completed successfully without damaging a PT cable or shutting down electrical service.

Nathan Machel runs GPRS operations in Chicago. He can be reached at 847-514-2277 or by email at nathan.machel@gp-radar.com.