Construction Vibration Mitigation and Monitoring Plan

The Work

King Township will be proceeding to reconstruct a 720 m segment of Kettleby Road between Kettleby Bridge on the west and the eastern limit of the community. The work will be completed by Graham Bros. Construction Limited. As part of the project, the Township is requiring that the contractor be responsible to retain a vibration engineer to monitor vibration during construction.

To help ensure that the contractor implements a proper vibration mitigation plan including vibration monitoring, King Township has retained HGC Engineering, a leading consulting engineering firm specializing in noise, vibration, and acoustics, to develop recommendations for the contractor to follow. See below for background information concerning construction vibration, an overview of typical criteria, and a summary of the monitoring plan.

Construction Vibration and Criteria

During road construction, vibrations can sometimes be felt by nearby residents. These vibrations, while typically minor, can raise concerns of potential effects on building structures. The sources of vibration during the project are most likely to be during the excavation of the current road surface and during the compaction of the granular roadbed.

Internationally recognized construction vibration guidelines have been in place for decades, most notably in European jurisdictions, where criteria have been developed to avoid cosmetic damage like cracking in structures. Locally, one of the most detailed documents that contains specific vibration criteria is the City of Toronto By-Law number 514, which has been informally adopted by many surrounding regions. Under this by-law, where a construction project will involve activity with a potential for vibration impact at off-site structures, a preliminary vibration assessment must be undertaken identifying a vibration Zone of Influence (ZOI), and a vibration monitoring plan must be developed. The by-law also requires supplementary preconstruction condition surveys of surrounding structures that are in the ZOI.

For vibration affecting structures, the use of peak particle velocity in units of millimeters per second (mm/s) is most common, with the vibration frequency described in units of cycles-per-second or Hertz (Hz).

The specific vibration criteria applicable at neighbouring structures, stated as the Prohibited Construction Vibrations in the by-law are shown in the table below.

City of Toronto By-Law “Prohibited Construction Vibrations”

Two additional points are worth mentioning. First, it is common for more stringent criteria to be applicable at sensitive or heritage-listed buildings. Second, cautionary vibration limits are recommended for use in monitoring, which include a factor of safety, beyond which greater care should be taken in proceeding with construction activities to help ensure that the prohibited vibration levels are not exceeded.

Vibration Monitoring

1. The potential vibration Zone of Influence (ZOI) for excavation and compaction activities on the Kettleby Road Reconstruction project is predicted to extend up to 12 meters from the perimeter of the road reconstruction. As such, several properties along the perimeter of the project are at least partially located in the vibration ZOI.
2. Three automated vibration monitors are to be installed, one at the closest building to the roadworks in each of three representative sections along the project corridor.
3. Automated vibration monitors will be fixed in place to the concrete foundation or slab, inside or on the exterior of the buildings at a point closest to the road construction.
4. The monitors will be equipped with wireless modems and configured to automatically notify site personnel and the municipality in the event of vibration exceeding 80% of the limits presented above (60% for heritage-listed buildings).
5. Vibratory compaction is to be minimized in areas adjacent to buildings, where practical, and should the cautionary vibration criteria be exceeded, lower energy settings, thinner lifts, and lighter equipment should be implemented as necessary.
6. Pre-construction condition surveys of buildings and structures located within the ZOI are also required and these are being arranged by the contractor.

IMPORTANT DATES:

Thursday August 29^th at 11:59 PM – Deadline to submit any questions or comments on the vibration monitoring background and process. Questions can be directed to Colin Parks – Project Manager (contact information below)

September 3^rd to September 13^th – Tentative window where the contractor will conduct pre-condition home surveys. Residents will be given a minimum of 48-72 hours notice to make an appointment with the consultants. These notices will be hand delivered to each property. The Township strongly encourages residents to partake in these surveys. If residents do not allow access to the home, it will be documented as such with the understanding that potential damage claims will likely be denied.

Colin Parks

Project Manager – Public Works

Township of King

2585 King Rd, King City, ON L7B 1A1

905-833-5321 x6568

cparks@king.ca

Brian Howe, M.Eng., MBA, LLM, P.Eng.

Principal Acoustical Engineer

HGC Engineering

2000 Argentina Rd, Plaza One, Suite 203

Mississauga, ON L5N 1P7

905-826-4044

bhowe@hgcengineering.com