Swerock runs a quarry in Normstorp, in Linköping municipality. In connection with the company applying for a permit to expand the mining area, the question of possible impulse noise from boulder breaking arose. Boulder is a blasting stone too big to feed into a crusher and therefore needs to be knocked apart. This is normally done with an excavator with a hydraulic hammer, so-called boulder breaking.
According to the Swedish Environmental Protection Agency’s guidelines on the external industrial nose, the requirements must be sharpened by 5 dB if frequent impulse noises occur in residences. However, the Swedish Environmental Protection Agency doesn’t specify a method of determining whether impulse noise occurs in advance, which creates problems since there are no activities taking place in the area in question.
Efterklang has performed impulse noise measurements at several occasions in the mining area, which gave a good indication of the existing operation. And in order to assess the impulse noise, we have developed our own calculation method, which helps us identify specific reduction measurements in advance.
In the licensing process were general noise and impulse noise the most important issue. And with Efterklang’s help, Swerock has been able to show that their business meets the current guideline values and that boulder breaking can be avoided- due to noise reduction measures. In 2019, the Environmental Court of Appeal granted Swerock permission to conduct the applied business.