OceanaGold Waihi North Project Vibration Performance Assessment Page 17 of 41 Project Number: HP2006-2 Heilig & Partners Save Date: 21/06/2022 5:55:00 PM ABN 56 082 976 714 File Name: WAI-985-000-REP-LC-0018_Rev 0 9. MODELLING VIBRATION The prediction of vibration levels from blasting activities has been well studied in Waihi and covered in detail as part of the previous consent applications. It is known that several factors exhibit an influence over the measured vibration level and these have been identified and generally well understood for the Waihi area. The knowledge base for the Waihi area is far better than many other sites because of the long history of mining in the area, the intense monitoring program and the frequent analyses of the measured results. The vibration level from blasting is most affected by: The distance between the monitoring location and the blast area. The scale of blasting, and in particular the explosive weight per blasthole. The delaying sequence between successively initiating blastholes. The rock mass. In addition to these parameters, and in particular for the Waihi area, it is also known that the following other aspects of blast design influence vibration level to a varying degree: The degree of water saturation in the areas around the monitoring location with highly saturated zones leading to elevated levels of vibration. The presence of large open discontinuities, such as old workings, which can prevent the uniform geometric spreading of the vibration pulse leading to elevated values in some direction and reduced values in others. Variable ground conditions which can lead to isolated and localised zones of elevated or depressed vibration. The number of blastholes fired in quick succession with some locations experiencing a gradual build up in vibration with increasing number of blastholes. The influence of these parameters leads to varying levels of vibration, even though the blast design parameters and the separation distance between the blast and monitor are unchanged. The overall variability in vibration level is however consistent with that observed at other sites and therefore reasonably well predicted by those same equations that have been used for the different Waihi areas over the previous 30 years. The form of these equations is consistent with the recommendations given in the Australian Standard AS2187.2 for assessing and predicting blasting effects. Since 2003, the vibration monitoring system for each of the Waihi projects has been automated and allows for the reporting and analysis of vibration results. The same system that has been used to demonstrate compliance can also be interrogated to determine area specific vibration relationships. Assessment of the blasting data from Martha, Favona, Trio and Correnso has been considered in the selection of data for subsequent analyses. All vibration data at Waihi have been analysed using techniques consistent with the recommendations provided in the Australian Standard AS2187.2. The form of the equation typically used to predict the level of vibration for a given explosive quantity and distance is used and has the following form: α = w PPV K d where PPV is the peak particle velocity measured in mm/s, d is the distance from the blast measured in metres,
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