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GPR Concrete Scanning Before Trenching in Markham, Ontario

gpr concrete scanning

Cutting a plumbing trench in a commercial slab isn’t hard. Cutting it without hitting power, conduit, or existing lines is the part that can stop the whole job.

This project in Markham, Ontario started the right way: gpr concrete scanning first, markings on the floor, a route adjustment to avoid a conflict—then trench cutting and removal.

gpr concrete scanning

Project overview

A contractor had a planned trench route for a new plumbing pipeline inside a commercial unit. Our scope was full support from “confirm the route” to “hand the plumber a clean trench”:

  • GPR concrete scanning along the trench corridor
  • Field markings and route recommendations
  • A written summary with photos for documentation
  • Then trench cutting + concrete removal (disposal handled by the contractor)
gpr concrete scanning


Site details and quantities

  • Location: Markham, Ontario
  • Trench route scanned: ~120 linear feet
  • Trench width: typically 1 ft, with sections up to 2 ft
  • Slab thickness: ~8 inches
  • Crew: 2 people
  • GPR equipment: GSSI LTX platform
gpr concrete scanning


The challenges

Commercial slabs carry surprises—especially in tenant-improvement spaces:

  • Power and conduit that don’t match the “ideal” plan
  • Existing plumbing and low-voltage runs (fire alarm, security, comms)
  • Reinforcement (rebar + mesh) affecting cut strategy and breakout
  • Owner/building management needing documentation to show the work was planned and executed safely
gpr concrete scanning


Our GPR concrete scanning process

We kept it simple and field-focused—because the scan is only useful if the cutting crew can act on it.

  1. Scan the full corridor (not just spot checks)
    Trenching is linear, so risk is linear. We scanned the full planned route.
  2. Identify hazards and conflicts
    We checked for electrical, existing lines, and reinforcement patterns that could create a bad day once cutting starts.
  3. Mark the slab clearly
    Findings were marked directly on the concrete so the route was visible and usable on the floor—not trapped in someone’s phone.
  4. Adjust the route when the scan says “no”
    We detected a power line conflict in the original path. We coordinated with the contractor and recommended a route adjustment so trenching could proceed without guessing.
gpr concrete scanning


Trench cutting and removal

Once the corridor was confirmed, our team returned for the execution phase:

  • Wet trench cutting inside the unit to control dust and keep the work area manageable
  • Concrete removal from the trench so the plumber had a clean corridor to work with
  • Disposal was completed by the contractor (separate from our scope)

Documentation delivered

The owner needed proof that the slab was checked and that the route was validated before cutting. We provided a written summary with photos documenting:

  • what was scanned,
  • what was identified/marked,
  • and what route change was made to avoid the conflict.
gpr concrete scanning


Result

  • A safe trench corridor confirmed by gpr concrete scanning
  • A route adjustment made before cutting—not after a hit
  • Clear floor markings that supported the cut plan
  • A clean trench handed off to the plumber, with documentation for the owner/building management

GPR Concrete Scanning Before Trenching — FAQ

Answers about commercial slab scanning, trench route changes, and pre-cut safety in Markham, Ontario.

GPR concrete scanning is a non-destructive method used to check what is inside and below a concrete slab before cutting or coring. On this Markham commercial unit, it was needed to verify the planned trench route, locate hidden hazards, and make sure the plumbing trench could be cut safely without damaging embedded utilities.

We scanned for electrical lines, conduits, existing plumbing-related elements, rebar, wire mesh, and other concealed risks inside the slab and immediately below it. The goal was to identify anything that could interfere with trench cutting or create a safety issue during the work.

Yes. During the scan, we identified a power line conflict in the original trench path. Based on that finding, we recommended a route adjustment so the trench could be cut more safely and with lower risk of damaging embedded electrical infrastructure.

Our team scanned approximately 120 linear feet of trench route. Most of the trench was planned at 1 foot wide, with some sections widened to 2 feet depending on the plumbing layout and site conditions.

After the scan, floor markings, and route adjustment, DRM completed the trench cutting and concrete removal. The concrete disposal itself was handled separately by the contractor. This gave the plumber a ready trench path while keeping responsibilities clearly defined.

Yes. We provided a written summary with photos as an official documentation package. This helped the contractor and owner show that the work had been reviewed properly and that the trenching plan was adjusted based on actual slab conditions.

Because trench cutting without scanning can lead to damaged power lines, broken conduit, delays, safety issues, and extra costs. GPR scanning reduces uncertainty before cutting begins, helps avoid unnecessary risk, and gives the contractor a safer, more informed path forward.