Blast monitoring at Diavik Diamond Mines Inc. to protect fish habitat

Diavik Diamond Mines Inc. is conducting open pit and underground mining of kimberlites within close proximity of a large freshwater lake that supports populations of fishes and other aquatic organisms. As the principal method of excavation is through blasting; the resulting blast wave is expected to expose incubating fish eggs to peak particle velocities (PPVs) greater than guidelines suggested by the Department of Fisheries and Oceans (DFO). Blasts were monitored using specialised 4-component underwater sensors which measured the particle velocities and overpressures simultaneously. PPVs were related to mortality in fish eggs both in the lake and in a laboratory setting where blasting events were simulated. Standard blast monitoring techniques were used to analyse data and create scaled distance relations in order to predict the attenuation of PPVs. Results show that attenuation was greater than initially expected. Further analysis showed no changes in blasting effects as the pit deepened.