July 2006 - Castonguay Blasting   

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ProSonics was retained by Castonguay Blasting to investigate noise complaints regarding the noise coming from rock drilling operations for rock blasting for the widening of highway 69 south of Sudbury, Ontario, Canada.

Castonguay was operating a number of rock drills as the blasting contractor for the work, while another contractor was operating other heavy equipment in the same area moving blasted rock and preparing the road sub-grade.

The government ministry responsible for the work had requested of Castonguay to operate different kinds of drilling equipment that they believed would be quieter and would result in fewer complaints about the noise of the construction. ProSonics was asked by Castonguay to come to the work site to do field measurements of the drilling equipment in actual operations to identify how noisy each type of drill was, as well as the combined effect of the drills working together. An additional request was to determine if the blast warning signal being used was sufficiently loud so as to meet ministry requirements.

The work was performed safely on-site with the co-operation of the drill operators to allow for individual noise measurements as well as combined operation measurements. Working on an active heavy-construction site is very dangerous. ProSonics staff have been working in heavy-industrial environments for fifteen years, and were able to work in this environment safely and effectively with minimal disruption to the fast-paced activities on the work site.

Spot-measurements were taken of SPL at 1m, 3m, and 6m from the operating rock drills with a calibrated hand-held meter, and long-distance measurements were made at 50m and 100m using a calibrated measurement microphone and SIA SmaartLive analysis software. With SmaartLive we were able to do instantaneous SPL measurements as well as to perform Leq measurements over various time periods to determine the equivalent SPL from the equipment - necessary because the noise generated from the rock drills varied in SPL as the 4" drill bit moved deeper into the rock. The rock drills were driving 4" diameter holes, approximately 20' into solid granite in about 3 minutes each requiring fast work to make the measurements consistent.

The warning whistle was measured at 900m utilizing the same set-up.(Note the regulations state performance at 1000m, but due to field conditions and heavy equipment operations we could only safely get 900m from the whistle with the measurement equipment). The 900m measurement was factored to produce a predicted SPL at 1000m.

The results of the testing determined that the ministry recommended drilling equipment was actually the noisiest on the site, and that the SPL at the property lines was within ministry guidelines. The warning whistle also met ministry guidelines for audibility.