Medicine Hat's development along the steep banks of the South Saskatchewan River has always demanded a precise understanding of subsurface behavior. The downtown core sits atop the Paskapoo Formation, composed of interbedded sandstones and mudstones that react unpredictably to stress relief during excavation. When the city expanded its water treatment infrastructure near the river valley in the early 2000s, engineers documented lateral movements exceeding 12 mm in temporary shoring walls, a direct result of the formation's swelling claystone layers. Today, our team applies that same rigorous observation methodology to every excavation deeper than 4.5 meters, ensuring the stability of adjacent structures and public roadways. We integrate real-time data from inclinometers, piezometers, and optical survey targets to build a complete picture of ground response. For projects near the clay-rich soils of the Flats industrial district, we often pair monitoring with stone columns as a ground improvement technique before major cuts begin. In the higher benchlands, where the overburden consists of glacial till and outwash sands, the deep excavations strategy shifts toward staged benching and continuous deformation control. Our protocols align with Section 4.2 of the NBCC and relevant CSA guidelines for temporary works.
A 0.2 mm displacement detected at the casing toe can translate to a 5 mm settlement at the adjacent kerb within 72 hours in Medicine Hat's Paskapoo mudstone.
Our approach and scope
Local considerations
Compare the riverbank sections of Riverside with the commercial district along Kingsway Avenue, and you will see two completely different risk profiles. Riverside sits on steep slopes where the Paskapoo Formation's interbedded mudstones and sandstones create a classic wedge failure hazard; we recorded a 9 mm lateral shift in a Riverside retaining wall during a 2018 excavation for a residential foundation, directly tied to stress relief in the underlying bedrock. Kingsway Avenue, by contrast, is underlain by 15 meters of glacial till with high silt content, where the primary risk is not rock wedge failure but rapid pore pressure equalization triggering bottom heave in open cuts. In that zone, we specify piezometer arrays at three depths to track the dissipation curve. If the allowable deformation threshold is exceeded, the protocol calls for immediate backfilling of the lower bench and re-evaluation of the slope stability model. Ignoring the lag effect in the mudstone — where movements continue for days after the cut is finished — is the single most common oversight we see in this city.
Reference standards
NBCC Part 4 — Structural Design (Excavation and Shoring), CSA A23.3 — Design of Concrete Structures (Anchorage and Shoring), ASTM D6230 — Standard Test Method for Monitoring Ground Movement Using Probe-Type Inclinometers, ASTM D7299 — Standard Practice for Verifying Performance of Vertical Inclinometer Probes, CSA Z797 — Code of Practice for Access Scaffold (Shoring and Access)
Complementary services
Automated Inclinometer and Piezometer Arrays
We install and maintain real-time monitoring networks using in-place inclinometer strings and vibrating wire piezometers. Data is logged continuously and pushed to a web portal configured with SMS and email alerts when pre-set deformation or pore pressure thresholds are exceeded.
Optical Survey and Settlement Monitoring
Using digital levels and total stations, we track 3D displacement on adjacent structures, kerbs, and utility vaults. Each monitoring point is referenced to a stable benchmark outside the zone of influence, with weekly summary reports issued to the project engineer and the city's building department.
Typical parameters
Common questions
How much does geotechnical excavation monitoring cost for a typical project in Medicine Hat?
For a standard monitoring program covering one excavation phase with inclinometers, piezometers, and surface settlement markers, the cost ranges from CA$1,220 to CA$3,740 depending on the number of instruments, the monitoring duration, and the data reporting frequency required by the project specifications.
Which monitoring parameters are essential for excavations in the Paskapoo Formation?
Lateral deformation measured by inclinometers, pore water pressure from piezometers, and surface settlement are the three critical parameters. In the Paskapoo Formation, we pay particular attention to the time lag between excavation and mudstone response, which can be up to 72 hours.
How long does monitoring need to continue after the final excavation depth is reached?
We typically maintain the monitoring system for a minimum of two weeks after reaching the final grade, or until the rate of deformation stabilizes below 0.1 mm/day for five consecutive readings. In clay-rich zones of Medicine Hat, this stabilization period can extend to three or four weeks.
Can you install monitoring equipment before construction starts to establish baseline readings?
Yes, baseline monitoring is a standard part of our protocol. We install inclinometer casings and survey targets at least one week before excavation begins, taking daily readings to establish the natural background movement and temperature-related fluctuations.