Blasting
Get to know how we perform and control blasting at the Bedford plant quarry and how we comply with regulatory standards.
Please note that blasting is carried out at fixed times, during the week, at 9:15 am, 11:30 am or 3:00 pm (± 15min.). If you have any concerns, please do not hesitate to contact a Graymont representative through our Info-Heritage line.
Why the blasting and the vibrations?
Blasting is carried out at the Graymont quarry to separate the stone from the consolidated mineral deposit and allow its use in the transformation processes.
When the blast occurs, the rock breaks under the force of the explosives placed in the boreholes. The force will disperse mainly towards the easiest path, towards the vacuum created by the explosion, but part of the force is dispersed in the ground, creating the vibrations perceived in the surroundings.
Minimizing the vibrations
In order to minimize the force dispersed in the ground and the perceived vibrations, a variety of measures are taken by Graymont. In particular, the blasts are:
- More frequent, therefore of smaller intensity, which minimizes the energy for each blast;
- Modeled to ensure that the minimum energy (explosives) is used;
- Initiated by electronic detonators programmed in sequences spaced apart by fractions of seconds, from the outside to the inside, which helps minimize the transfer of force to the internal rock, allowing the force to dissipate in the vacuum created by the previous detonation;
Safety and predictability
We take the following steps to ensure blasts at the Graymont site are safe and come as no surprise to the neighborhood.
- Fixed schedule for blasting: weekdays, at 9:15 am, 11:30 am or 3:00 pm (± 15 min.);
- Safety perimeter evacuated around the blasting area;
- Sirens emitted 5 min. and 1 min. before each blast and after the blast is complete.
Compliance with standards and regulations
Vibration standards are established by regulation that ensure the protection of the buildings, the infrastructure and the safety of people.
Graymont therefore continuously monitors ground vibrations at strategic locations where, for example, residences are located closest to its activities.
A naturally occurring earthquake rocked Bedford on May 6, 2020. Graymont seismographs recorded a maximum reading of 5.15 mm / s at that time, at a horizontal distance of 9 km from the epicenter.