When Underground Scanning Saves Existing Buildings From Damage

Cutting into a slab or coring a wall in an occupied building is the one job where being approximately right is not good enough. What is in the concrete is usually live, structural, or both.

Ground penetrating radar and electromagnetic locating are used before the saw comes out, to mark what is in the slab and what runs beneath it.

What scanning finds before you cut

• Post-tension cables, where cutting one can be a structural event.

• Rebar and mesh, so cores land between the steel rather than through it.

• Conduit in slab, which is frequently live and rarely where the drawings show it.

• Radiant heat tubing, which is invisible until it is cut and flooding.

• Void and disturbed soil under a slab, which explains settlement before the repair is designed.

Where this comes up

Tenant improvements in Seattle and Portland where new plumbing or conduit has to pass through an existing slab. Older commercial buildings in Spokane and Tacoma where the as-builts are decades out of date. Additions and remodels where a footing goes in beside services that are still in use. Historic streetscapes and sidewalks where the surface itself is worth protecting.

What scanning can and cannot tell you

Radar shows changes in the material, not labels. It reliably finds the presence and position of targets, and depth within a tolerance that depends on conditions. It does not tell you a conduit is energised or that a cable is post-tension rather than reinforcing, which is why the interpretation matters as much as the instrument. Moisture content, slab thickness and heavy congestion all affect how deep the signal is useful.

We mark the results on the surface where the work is happening, and can capture them as survey-grade points with RTK collection where the information needs to outlast the job.

For the site process from arrival to marks, see what happens during a private utility locate. Seattle-specific ground conditions are covered in GPR scanning and side sewers in Seattle.

Get the private lines located first

Advanced Underground Utility Locating has been locating private utilities since 2002. We locate the lines 811 will not mark, verify the public marks that were made, and mark public lines that were missed. RTK data collection is available as an option if you want the locate captured as survey-grade points rather than paint.

Spokane, Coeur d'Alene and the Idaho panhandle: 509-710-2621. Seattle, Tacoma and Portland: 509-954-8623. Bend, Medford and northern California: 541-678-0629. Eugene and Roseburg: 541-780-4149. Coos Bay and the Oregon Coast: 541-315-6728. Emergency service is available 24 hours.