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Mining Minerals and Environment Issues
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Photo: An aerial view provides a clear perspective on bunding designed to limit noise impacts near the Kalgoorlie Consolidated Gold Mines in Western Australia
INTRODUCTION:SOURCES OF NOISE, VIBRATION AND AIRBLAST GENERATION
Resource exploration, extraction, processing and transportation generally involve plant, equipment and techniques which have the potential to produce significant levels of noise, vibration and airblast, and which may impact on the surrounding environment.Even at the exploration stage, significant levels of noise, vibration and airblast can be produced, for example from engines, airblast drilling equipment, shot hole drilling and blasting or vibrating machines for seismic exploration (mostly in the search for oil and gas).
With the exception of hand excavation, all other mining and some exploration methods generate noise and/or ground vibration which may disturb the surrounding community unless properly managed through design, choice of equipment, operational controls, physical barriers or a combination of these approaches. Seismic exploration requires a series of explosive charges to detemine underlying geology. In open-cut and strip mines, draglines and large mobile equipment are used in prestripping, topsoil and overburden removal and extraction. Blasting is often used to remove material which is too hard for ripping. In underground mines, drilling, boring, blasting and excavating are used in the extraction process.
Hard rock quarries and open pit ore mines generally use blasting or mobile equipment to remove material. Mineral sands and gravels are generally extracted by means of draglining or by bucket, cutter suction or trailer suction dredge. In each case, the extracted material is subsequently loaded for transportation to a processing plant where crushing, screening, washing, drying and various other processes are conducted prior to final loading and product dispatch.
Good planning is essential to mitigate noise, vibration and airblast impacts which might otherwise lead to unacceptable effects on the community or the natural environment. Optimising the design and layout of a mine, or the way in which an exploration program is conducted, will avoid or minimise adverse impacts and assist in meeting community expectations. In addition, best practice environmental management to minimise noise, vibration and airblast produces long term benefits to the mining sector by increasing efficiency and improving community acceptance of local mining activities and general community attitudes towards mining. Furthermore it will improve occupational health and safety on site. While onshore exploration activities are relatively benign, noise and vibration from offshore oil exploration activities is technically different and its environmental effects are distinctive. Therefore it is not considered within the scope of this booklet.
WHY NOISE, VIBRATION AND AIRBLAST ARE CONCERNS TO THE COMMUNITY
Noise from mining is a common source of community concern because operational noise emissions frequently occur on a continuous basis. This can interfere unreasonably with day to day activities, particularly concentration, recreation and sleep, and result in an adverse impact on residential amenity.
Vibration and airblast from blasting can lead to community concern primarily due to the fear of structural damage. This fear occurs because people are able to detect vibration at levels which are well below those which result in even superficial damage to buildings and items of heritage value. In Australia this concern may extend beyond man-made structures, to sites of natural or cultural significance such as Aboriginal art and sacred sites and valued landscapes.
Communities can experience noise and vibration impacts from mining operations in many ways. Measures are proposed to limit such impacts in NSW's Hunter Valley, with coal trains affecting residents. These include sound barriers, rubber buffering for rail line supports and additional rail electricification so fewer diesels were needed for haulage.
BEST PRACTICE MANAGEMENT OF NOISE, VIBRATION AND AIRBLAST:Effective management of noise, vibration and airblast involves a three stage approach incorporating:
Noise, Vibration and Airblast Impact Assessment-potential impacts are identified and approaches for mitigation are devised. :Noise, Vibration and Airblast Management Plan-establishes baseline data for existing conditions (of both the acoustic and built environment). It details the methods for monitoring and achieving compliance with the consent conditions and clearly defines the mine's environmental quality objectives: and Monitoring and Audit Program-assures the means by which the management plan and quality objectives will be verified, documented and modified to meet noise, vibration and airblast levels acceptable to all stakeholders.
CASE STUDY : OBERON QUARRY, NEW SOUTH WALES
An "enclosed" pit design, shields quarry operations on four sides for the majority of the life of the quarry. This design enables mobile equipment in less acoustically screened position for short periods when it is necessary to operate equipment within 2 m to 3 m of the top of Racecourse Hill.
The quarry floor is approximately 1140 m AHD with equipment operating the majority of the time either on the quarry floor or on a bench within the quarry at approximately 1150 m AHD. During these times, quarry activities are visually and acoustically shielded from all distant dwellings by a 10 m to 20 m high rock wall.
PROCESSING OPERATIONS
The crushing and processing facilities are on a level area at approximately 1125 m AHD adjacent to a 6 m to 8 m high wall of undisturbed material. Additional acoustic bunding 2 m high and approximately 80 m long, will also significantly attenuate noise from the crushing/processing area.

Photo: A view of the processing plant during construction, showing the bunded area being built and the shielded haul entrance in the background.
Noise emission from the permanent crushing plant will be further attenuated by enclosing the primary and secondary crushers, and by providing additional bunding around the end of the product storage bays. Maintaining all permanent crushing and screening equipment in a serviceable condition also reduces the potential for noise emission.
TRANSPORTATION
To minimise potential impacts associated with transportation noise, a new access road has been sealed and is maintained in a good condition from the edge of the processing area to the public road. Sealing the access road minimises potential noise emissions from trucks clattering over rough roads.

Looking from the bunded area toward the extraction area, where the haul road has been excavated several meters to create a narrow opening. A mobile crushing plant is in the foreground.
DRILLING AND BLASTING CONTROLS
Drilling periods are minimised by using modern and efficient hydraulic drilling equipment. Drilling could occasionally become audible when working in exposed locations so a lightweight, partial enclosure will be used around the drill when drilling in exposed areas. All best practice design noise control measures have been implemented in the construction and operation of the Oberon Quarry and, as a result, negligible noise impact has occurred at the nearby residential locations. (For details, refer to Report N32-R1 'Oberon Quarry-review of Noise and Vibration Impacts', Richard Heggie Associates 30 April 1995. [phone 2 9427 8100.]

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