Regina sits on a glacial lakebed, and the thick lacustrine clays underfoot don't just settle—they amplify ground motion in ways that catch engineers off guard. We've seen it on Wascana Creek projects and out near the bypass: two sites a kilometre apart, same soil map unit, but Class D and Class E response because of a thin soft layer at twelve metres. That's why a basic borehole log won't cut it. The MASW method gives you a continuous shear wave velocity profile down to thirty metres, measured from surface, so you can nail the VS30 value and the NBCC site class without guessing. In a city where the frost line hits two metres and the clay can be fifteen metres thick, the difference between Class C and Class D carries real structural cost. We run the survey, process the dispersion curve, and deliver a report you can submit the same week. For deeper investigations, we combine MASW with seismic refraction to map the bedrock interface across a site.
Regina's lacustrine clays can hide a Class E site beneath a stiff crust—MASW catches the soft layer that a drill rig might miss.
Methodology and scope
On the Wascana floodplain, we often find a stiff crust over soft clay that masks the real VS30 if you only look at the top few metres. MASW sees through it. The method uses an active source—a sledgehammer or weight drop—and a linear array of geophones to capture surface waves. We invert the fundamental-mode dispersion curve to produce a 1D shear wave velocity profile, then calculate VS30 per NBCC 2020. Key points we control on every Regina job: geophone spacing matched to target depth, multiple shot points to verify lateral consistency, and dispersion picks reviewed by a senior geophysicist—not auto-picked by software and shipped blind.
Our reporting includes the velocity profile, VS30 calculation, NBCC site class, and the raw dispersion image so your geotechnical engineer can cross-check the interpretation. Turnaround is typically three business days for a single array. For subdivision-scale work, we run multi-line surveys and deliver a VS30 contour map. The equipment is calibrated to ISO 17025 through our partner lab, and all processing follows ASTM D7400 and D5777 guidelines for surface wave and seismic refraction methods respectively.
Common questions
What does a MASW survey cost in Regina?
For a single-array VS30 site classification in Regina, expect CA$2,250 to CA$3,200 depending on site access and line length. Multi-line surveys for larger sites typically run CA$3,800 to CA$4,660. All prices include data processing, VS30 calculation, and the signed report. We quote firm before mobilizing—no surprise travel charges within city limits.
How long does the field work take?
A single MASW array takes about ninety minutes on site, including setup and multiple shot points. We can complete two arrays in a morning, and you'll have the report within three business days. The surface-only method means no drilling, no excavation, and no disturbance to the site.
Do I still need a borehole if I run MASW?
MASW gives you shear wave velocity and site class, but it doesn't replace a borehole for bearing capacity, moisture content, or Atterberg limits. In Regina's clay, we recommend at least one borehole paired with MASW—the borehole logs calibrate the velocity interpretation, and the MASW fills in the dynamic properties that N-values alone can't predict reliably.
Which NBCC site class applies to my Regina property?
Regina varies. The stiff clay till east of the city often falls into Class C (360–760 m/s). The Wascana Creek corridor and areas with thick lacustrine clay can hit Class D (180–360 m/s), and we've measured Class E (<180 m/s) in a few pockets with soft, high-plasticity clay below ten metres. The only way to know is a direct VS30 measurement—soil maps and surficial geology won't give you the answer for structural design.
