MASW & VS30 Testing for Seismic Site Classification in Richmond Hill

Yes. The City of Richmond Hill enforces the Ontario Building Code, which references NBCC 2015 for seismic provisions. MASW is an accepted method for determining the average shear wave velocity in the upper 30 meters (VS30), provided the survey is conducted and stamped by a Professional Engineer licensed in Ontario. The stamped report must include the dispersion curve, the inverted 1D VS profile, and the assigned site class per NBCC Table 4.1.8.4.A. We have submitted MASW reports for mid-rise and high-rise projects along the Yonge Street corridor and they have been accepted without revision.

For a standard residential or mid-rise lot, field acquisition for one MASW line takes 60 to 90 minutes, and two lines are usually completed within two hours. The site needs a relatively flat and accessible strip 46 to 92 meters long, which can be on pavement, compacted gravel, or short grass. Data processing, inversion, and the stamped report are delivered in 3 to 5 business days. Larger multi-line microzonation surveys may require a half-day on site.

A single-line MASW survey with a stamped VS30 site class letter typically ranges from CA$2,040 to CA$3,990, depending on the number of lines, array length, site access conditions, and whether supplementary refraction or geophysical methods are needed. A two-line survey on a standard commercial lot falls in the middle of that range. We provide a fixed-price proposal after reviewing the site address and the scope of the proposed development.

Most of Richmond Hill sits on glacial till and sand deposits of the Oak Ridges Moraine, which produce VS30 values between 300 and 600 m/s, corresponding to Site Class C per NBCC 2015. However, pockets of softer silt and clay east of Leslie Street and in low-lying areas near the Rouge River watershed can drop VS30 below 300 m/s, resulting in a Class D classification. A Class D site amplifies seismic ground motion more than Class C, and the structural design must account for the higher spectral acceleration. The only reliable way to confirm the class is with a direct VS30 measurement.