Noise behind the wall along St. Albert Trail didn’t increase significantly when panels were removed to lower the wall’s height, a report shows.
An Environmental Noise Study prepared by Acoustical Consultants Inc. measured the noise level in three residential yards along the wall before and after some panels were removed.
“What we found was the removal didn’t really change the noise that much,” said Sue Howard, capital projects manager for the City of St. Albert.
Panels were removed to bring the wall’s height down to withstand a one-in-10 year wind load. In some places no panels were removed and in others up to four panels were taken away, Howard said.
Monitoring took place earlier this year in the same three backyards that noise measurements were taken from before the panels came down. One of those locations had no panels removed and showed essentially no change, whereas at the location with a couple of panels gone and the one with four removed, the changes were still minor. The results showed an increase of about half a dBA, the unit used to measure sound levels, over a 24-hour period for the two sections where panels had been removed. The 2013 results had none of the sites rise above 60 dBA. The city’s bylaw sets a maximum of 65 dBA over a 24-hour period.
Howard said the equipment was left in the yards for a full 24 hours. The report said monitoring points were placed about 12-15 metres back from the wall.
Administration will be suggesting to council that rebuilding the wall be part of the 10-year plan.
“We know the entire wall along St. Albert Trail … that the entire wall needs to be rebuilt,” Howard said. They’ll be suggesting money for a study and then a subsequent year for construction. What the future rebuild will look like – including any noise attenuation plans – isn’t known yet, she said.
In the meantime the wall, like other city infrastructure, will be monitored for repair needs.
“We were certainly pleased with the results to see that even though there is a small impact it wasn’t worse. We were a little bit concerned there could be a significant increase … the report supports the impacts were minimal,” Howard said.
