Downtown Calgary High-Rise | Multi-Frequency GPR & EM Investigation
Subsurface Engineering
CLIENT
A general contractor in Calgary
TIME
2024
SERVICE
Subsurface Engineering
The Challenge
The site presented several technical challenges:
A reinforced concrete slab with embedded electrical conduits
Underground grade beams beneath the slab
Ground wiring systems and weeping tiles located several feet below grade
Limited tolerance for error due to the structural and operational constraints of a high-rise building
No single method or frequency could reliably detect all targets at varying depths, making a conventional single-antenna scan insufficient for this project.
The Solution
Scantec implemented a multi-frequency GPR and electromagnetic (EM) locating strategy designed to address both shallow and deep subsurface conditions.
400 MHz and 350 MHz GPR (HyperStack® technology) were used to investigate deeper features beneath the slab, successfully locating grade beams, ground wiring systems, and weeping tiles at depths of approximately 4–5 ft.
A Radiodetection RD8000 electromagnetic (EM) locator was used to detect live power and grounding systems that may not be consistently visible using GPR alone.
A 2000 MHz GPR Palm antenna was deployed to provide high-resolution mapping of electrical conduits embedded within the concrete slab, supporting precise cutting and trenching.
All findings were interpreted in real time and also post processed and clearly marked on the slab surface to guide construction activities.
The Outcome
By combining multiple GPR frequencies with EM locating, Scantec was able to define a safe excavation corridor between existing grade beams and utilities. This allowed the general contractor to:
Install the underground pit without cutting into structural elements
Avoid damage to live electrical and grounding systems
Proceed confidently with excavation in a complex downtown environment
This project demonstrates how professional concrete scanning and subsurface utility locating in Calgary can significantly reduce risk, prevent utility strikes, and support safe, efficient construction in high-rise structures.
