Noise, vibration and airblast are significant environmental aspects to be managed by KCGM. Historically, residential areas have been located near KCGM and the operations preceding it. Just prior to the formation of KCGM, six underground mines on the Golden Mile operated “around the clock”. With the change of mining method from underground to open pit operations, the noise environment altered.
In November 1992, Ministerial Conditions set noise-level standards for the KCGM Fimiston Open Pit operation including general noise levels and airblast standards. In 1993, following extensive study and discussion, KCGM established noise, vibration and airblast monitoring and management programmes (NVMMP) for the operation.
Noise Monitoring and Management
KCGM carried out extensive noise assessment and modelling work to determine the best means of reducing nuisance noise from the Fimiston Operations. The results of the modelling work indicated that an earthen bund between the Fimiston Open Pit and Kalgoorlie-Boulder would significantly reduce nuisance noise. The first stage of the environmental noise bund was constructed using waste rock in 1993 with other minor modifications undertaken between 1999 and 2001.
KCGM revised its NVMMP in June 2004, as part of the approval process for the Southern Landform Extension Project, which included a major southern extension of the noise bund. In 2006, an application for a realignment of the noise bund was approved for the Golden Pike Cutback with construction commencing in June 2007.
Construction of the realignment, which extends for two and a half kilometres, was completed in January 2011. Rehabilitation earthworks on the realignment, which commenced in July 2011, were completed during May 2012 with seeding completed by September 2012. The Environmental Noise Bund now extends for a total distance of six kilometres along the western edge of the Fimiston Open Pit.
The NVMMP was revised and approved in 2009 again in 2010, with the current version of the NVMMP (October 2010) submitted to the OEPA and the DER on 19 October 2010. The NVMMP was subsequently approved by the OEPA on 6 December 2010. In 2013 a number of minor changes were made and approved by the DER on 21 June 2013.
KCGM conducts environmental noise, blast vibration and airblast monitoring to measure performance in terms of compliance with the approved standards, and the effectiveness of its management strategies. The noise and blast monitoring results obtained during this five year review period have been evaluated as a key indicator of performance.
KCGM undertakes both compliance and continuous environmental noise monitoring programmes and has been advertising noise monitoring results in the Kalgoorlie Miner newspaper each quarter since 1993.
The compliance noise monitoring is conducted at five reference locations, Boulder Primary School (BPS), Baron Street Williamstown (BSW), Kalgoorlie Technical School (KTS), York Street Boulder (YSB) and Outram Street Boulder (Figure 4). Continuous noise monitoring is conducted at KTS and at BPS.
Download the KCGM Noise Information Sheet for more information on ways KCGM is reducing noise from operations.
Real-Time Noise Monitoring
KCGM has installed a real-time noise monitor near Holmes Street, Kalgoorlie, to measure continuous sound levels at this location. From these measurements a report is generated, which is designed to provide the residents of Kalgoorlie-Boulder with an indication of sound levels within the community.
The report is updated every 15 minutes and is available for public viewing.
Download Real-Time Noise Monitoring Report
Vibration Monitoring and Management
KCGM has developed and implemented an airblast and vibration control strategy to minimise the impacts from its mining activities. The strategy ensures compliance with relevant standards and is based on recommendations of specialist consultants and past experience. The key components of the strategy include:
- Restricting blasting times to daylight hours (between 07:00 and 18:00 hours). On most occasions blasting occurs at a publicised time each day (generally 13:00 or 17:00 hours). Whenever possible, explosives placed for surface blasts are fired when weather conditions are such that the impact of airblast and dust emissions on residential areas of Kalgoorlie-Boulder are minimised.
- Avoiding blasting on Sundays where possible. Sunday blasts are not included in the fortnightly production schedules and any Sunday blasts fired are reported in the OEPA Noise and Blast Monitoring Quarterly Reports.
- Internal procedures and training for blasting to ensure that the quality of the blast design and set up is within the set guidelines.
- Implementing a quality assurance (QA) system of continuous measurement and review of drilling, charging and firing practices to ensure the best possible outcomes from a blast. KCGM has completed several QA studies measuring every aspect of drilling and charging. The studies have revealed that the more intense the QA, the more accurate is the drill and blast process.
- Selection of competent personnel and subsequent supervision to overcome the ‘human factor’ in the implementation of procedures and encouragement of a professional culture within the respective drilling and blasting crews. Any blasts which exceed the KCGM internal limits is fully investigated and notification is provided to the people responsible for preparing the blast.
KCGM has also been proactive in research and development in less invasive blasting techniques while still achieving the mining outcomes required. Initiatives include:
- The ‘near field’ vibration study to further understanding of how the rock behaves when subject to the pressure waves of a blast and ‘fine tune’ blasting methods to minimise blasting vibration.
- Continued research into the use of electronic detonators, driven in part from the perceived environmental benefits (reduced vibration) of extremely accurate timing that is ‘customised’ for particular ground conditions.
- Studies of ‘domain blasting’ where the rock strength is predicted by examining the penetration rate of drills or studying the geology of the area. The aim of the exercise is to have a formal prediction process that prevents weaker rock areas being overcharged, which can lead to elevated airblast levels.
- Use of a high speed camera capable of showing blasts in one two-thousandth of a second frames to provide a better understanding of what processes are leading to unfavourable events within blasts.
KCGM monitors ground vibration due to blasting at six reference locations between the Fimiston Open Pit and Kalgoorlie-Boulder and at eight locations around Mt Charlotte Underground Mine. Vibration caused by a blast is recorded when ground vibration exceeds the set trigger level of 0.2 mm/sec, and is referred to as a blast “trigger event”.
The approved vibration levels due to blasting are set out in Condition 9-5 of Ministerial Statement 782 for the Fimiston Operations. Vibration is measured as peak particle velocity (ppv), in units of mm/sec. aproved vibration limits for KCGM are:
- No blast greater than 10mm/sec
- 9 in any 10 consecutive blasts less than 5mm/sec
- 90% of blasts per year less than 5mm/sec
Download KCGM Blasting Information Sheet