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Testing ground conditions

Geotechnical drilling at the Bow River crossing

Testing ground conditions

Prior to main construction of tracks, stations, tunnels and bridges, due diligence work was completed to test ground conditions through a series of geotechnical and environmental borehole drilling exercises.

Testing took place October through December 2023, with locations along Phase 1 of the Green Line route. Additional drilling will be completed in summer 2024.

Both geotechnical and environmental tests involved drilling boreholes into the ground, collecting samples, then analyzing the material. More than 800 boreholes and test pits have been drilled since 2014, providing critical information about the ground and what we can expect.

The information collected was used to help us remove elements of risk from the project, design the best structures for the soil/rock conditions, and better estimate project costs.

Meet the Calgarians Building the Green Line – Damian Brake

“The purpose of our drilling is to recover core samples from multiple layers below the ground so the engineers can design the foundations for the upcoming transit system.” – Damian Brake, Core Drilling

Due diligence

Geotechnical due diligence involved investigating the ground before we build on or tunnel through it.

  • Understanding the soil and rock materials present.
  • Determining the properties of the ground (e.g., hard or soft, clay or gravel).
  • Testing permeability (how much water can flow through the ground).
  • Confirming the ground water table elevation and how it fluctuates over time.

Environmental due diligence involved collecting soil and ground water samples and analyzing them for contaminants.

  • There are known contaminated sites along the alignment where we anticipate finding diesel, gasoline and degreasing solvents in the soil.
  • Other common contaminants include metals and salt from road de-icing.
  • By identifying contaminants, we can determine how to manage them during construction, and how to properly handle the material.
A core sample
A core sample

Hydro-vac excavation to check underground utility locations
Hydro-vac excavation to check underground utility locations

In Fall 2023, our due diligence program achieved

  • 3,000+ drill hours
  • 88 boreholes
  • 1,000+ soil samples

This data helped us determine the best building techniques and materials for the soil and bedrock conditions.