Reducing Blast Vibration Amplitudes Close-In to Structures of Sub-Standard Construction Vitor Luconi Rosenhaim, Copelmi Mineração, Ltda Enrique Munaretti, Universidade Federal do Rio Grande do Sul Jair Carlos Koppe, Universidade Federal do Rio Grande do Sul Cathy Aimone-Martin, Aimone-Martin Associates, LLC Abstract Production blasts at one of Copelmi’s coal mine operations will be carried out 100 m (330 ft) from a neighborhood located in the town of Butiá, southern Brazil. Mine management is concerned about the possibility of damages and complaints due to blasting operations at close distances to structures of sub- standard construction. Blasting in the area is characterized by the use of very low powder factor resulting in confined shots in which movement is restricted to a point of almost undershooting the rock. Over the past year, tests were conducted mainly in the overburden area to determine the best approach to be implemented when blasts move closer to the town. Mine management wants vibration levels to be reduced lower than the damage limits proposed by Brazilian regulations to ensure a safety margin and mitigate perception by the community hoping to reduce the number of complaints. Modifications to blast designs included changes in the burden and spacing with the goal of decreasing blast confinement and increasing powder factor, the use of different combinations of delay periods and the introduction of a cast primer replacing emulsion as the initiating charge. Analysis was conducted for every blast design change to evaluate the impacts on vibration levels and blasting operation costs. This paper presents the challenges faced in order to blast close-in to a residential area and test results for various approaches used to mitigate blast vibrations along with the impacts on the operation cost. Initial results show a reduction in close-in ground vibrations with tighter blast patterns. Smaller burden and spacing resulted in a decrease in blast confinement and an increase of powder factor with an increase in cost of explosives, accessories, and labor.