Ground vibration and airblast limits for mines and quarries

Environmental guidelines

1. Purpose

This document describes the policy of the Department of Energy, Environment and Climate Action (the department) with respect to the limits on blasting impacts at residential premises and other sensitive sites*.

The ground vibration* and airblast* limits recommended by the Guidelines have been set to minimise annoyance to people because of blasting on mine and quarry sites. They are therefore considerably lower than the levels that could give rise to damage to competent structures. More stringent limits may be required, however, in cases where the objective is protection of fragile structures such as historic buildings.

The Guidelines are based on the Australian and New Zealand Environment Council’s Technical Basis for Guidelines to Minimise Annoyance Due to Blasting Overpressure and Ground Vibration, September 1990 (ANZEC Guidelines 1990).

The Guidelines apply to mine and quarry sites.

Words marked with an asterisk (*) are defined in the Appendix to the Guidelines.

2. Introduction

Blasting is necessary for the recovery of ore or stone in most underground mines, and many open cut mines and quarries. Uncontrolled blasting at mines and quarries could adversely impact upon neighbouring premises, consequently, proper control of blasting practices is necessary to ensure both the safety of employees and the protection of the community.

Blasting at mines and quarries causes ground vibration and airblast (vibrations through the air and noise) at levels which can cause objects in nearby residences to rattle, however, structural damage is most unlikely to occur. In addition, the noise levels experienced from blasting are unlikely to cause any hearing damage to any persons residing nearby.

Annoyance and discomfort from blasting can occur when noise startles individuals or when airblast and or ground vibration causes vibration of windows or other items. The degree of annoyance is influenced by the level of airblast and ground vibration as well as factors such as the time of day, the frequency of occurrence and the sensitivity of individuals.

Mine and quarry operators can usually accurately and reliably predict airblast and ground vibration levels at residences to ensure compliance with permissible levels, however, sometimes unforeseen factors (e.g., geology and weather) can result in elevated levels.

3. Implementation of limits

Separate limits apply depending upon whether the site was in operation prior to 1 July 2001. In some cases, the limits recommended by the Guidelines may not be consistent with the current mine approval document (the Mining Licence) or the quarry approval ( the Work Authority). In such cases the applicable limits are those set down in the Mining Licence or the Work Authority.

Ground vibration and airblast levels are generally measured at the nearest sensitive site.

3.1 Pre 1 July 2001 sites

The limits for mines and quarries in operation prior to 1 July 2001 are as follows:

• Ground vibration at sensitive sites must not exceed 10mm/s (ppv*), and
• Airblast at sensitive sites must not exceed 120dB (Lin Peak*).

3.2 On or post Post 1 July 2001 sites

The limits for mines and quarries that commenced operation on or after 1 July 2001 are as follows:

• Ground vibration at sensitive sites must not exceed 5 mm/s (ppv) for 95 per cent and 10mm/s (ppv) for 100 per cent of all blasts.
• Airblast at sensitive sites must not exceed 115dB (Lin Peak) for 95 per cent and 120dB (Lin Peak) for 100 per cent of all blasts.

Note: The ANZEC Guidelines 1990 state that experience has shown that for almost all sites a ppv of less than 1mm/sec is generally achieved. It is recognised that it is not practicable to achieve a ppv of this level at all sites and hence a recommended maximum level of 5mm/sec has been selected. However, it is recommended that a level of 2mm/sec (ppv) be considered as the long-term regulatory goal for the control of ground vibration.

3.3 Evening & night operations

3.3.1 Open cuts and surface mines

Blasting at open cut or surface mines and quarries should only occur during the hours of 9.00am to 5.00pm Monday to Saturday (the “day period”). Blasting outside these hours may sometimes be justified for unforeseen circumstances with permission from the department and WorkSafe along with appropriate community consultation. Surface blasting in hours of darkness is not normally approved.

3.3.2 Underground mines

Blasting times at underground mines are often limited to shift changes or other times when personnel can be safely removed from the blast area. Blasting outside the day period is therefore often necessary. Where the department approves night-time blasting in underground mines it is considered appropriate to apply more stringent limits to ground vibration during the hours usually devoted to sleep. In these circumstances, the ground vibration level at sensitive sites is usually set at 3 mm/s between the hours 10:00pm and 7:00am.

4. Approach to changed conditions

A significant factor in determining the impact of blasting at mines and quarries on residences and other sensitive sites is the separation distance between the blast site and the sensitive sites. This distance can be reduced by expansion of the operation or by the development of sensitive land uses closer to the operation. Different policies apply to these two situations.

4.1 Operator initiated change

It is not proposed that this guideline will apply retrospectively to mine or extractive sites where a Mining Licence or a Work Authority has been issued. However, where an operator proposes changes to an existing operation, and this requires:

• changing the area to which a Work Authority applies; or
• a significant change to the area to which a mining Work Plan applies, the airblast and ground vibration criteria will be reviewed.

Where the proposed change does not result in operations occurring closer to the nearest sensitive site (i.e., operations extend in other directions, and not towards the sensitive site), the existing limits should continue to apply. This will mean that the maximum airblast and ground vibration levels received at the sensitive sites will be unchanged.

Where a change to a Work Authority or Work Plan results in operations moving closer to sensitive sites, the department may set new limits at a level typical of the levels occurring at sensitive sites prior to the change. However, the new limits will not be lower than those set out in section 3.2.

4.2 Surrounding land use change

In cases where the separation distance is reduced as new sensitive sites are developed closer to an existing mine or quarry, the existing vibration and airblast criteria will be applied to the new properties.

This means that the encroachment of legally approved housing or other sensitive sites will impose restrictions on operating mines and quarries. Mining and quarrying operators should therefore ensure that they are aware of proposed new development.

5. Measurement & monitoring

Blast vibration and airblast monitoring should be carried out at all sites where blasting occurs and where there are residences and other sensitive sites that may be affected. The extent of monitoring and locations will be considered prior to approval of the Work Plan for the operation. It is recommended that applicants for a Work Plan consult with the departments “Guideline for a mine or quarry that requires blasting”. (Currently in draft form)

5.1 Monitoring

Monitoring should generally be in two parts, the initial monitoring and ongoing monitoring.

5.1.1 Initial monitoring

Initial monitoring should be conducted where it is possible that one or more sensitive sites may be exposed to airblast and or ground vibration to ensure that the blasting program is able to comply with the prescribed criteria. This will enable changes to be made to the blasting methods if it is found that the levels do not comply with the criteria.

Initial monitoring should be done over enough blasts to show consistent results, usually a minimum of five. These tests should be done at the most affected sensitive sites in two or more directions (unless there are sensitive sites only in one direction)

Initial monitoring should be undertaken directly at or adjacent to sensitive sites or where this is not practical it may be at defined locations. Where monitoring cannot be done at sensitive sites initial monitoring may be done at sites such as at site boundaries, depending upon the requirements of the Work Authority or Mining Licence and the specifications of the approved Environmental Monitoring Plan.

5.1.2 Ongoing monitoring

On-going monitoring should generally be conducted at sensitive sites around each mine and quarry to confirm that the airblast and ground vibration levels do not exceed the criteria specified. The monitoring program will generally be included in the approved Environmental Monitoring Plan. Blasts should be randomly selected or monitored on a fixed schedule (e.g., five consecutive blasts).

Where initial monitoring shows that all blasts are below 2 mm/s and below 115 dB (Lin Peak) ongoing monitoring may not be required. However, any change in the methods of blasting or other factors such as the direction of a rock face, or proximity to sensitive sites, should be monitored as for an initial monitoring program.

5.2 Monitoring data

Records of initial monitoring data should be reported to the department within four weeks of being completed.

Any exceedances must be reported to the department forthwith.

In the event of community complaints, or suspected non-compliance with blasting limits, the department may request on-going monitoring and submission of data by the proponent.

Blast monitoring results should be stored and maintained in a systematic manner. Data should be available for perusal by the department when and if necessary. Data may be stored in electronic or hard copy form. However, operators should ensure themselves that whatever storage medium is used is secure and that data is retained for at least 5 years.

5.3 Measurement

Measurements should be conducted by suitably trained personnel using appropriate equipment. Equipment used for blast monitoring should meet or exceed the relevant Australian Standards or equivalent overseas standards for field equipment.

Equipment should be calibrated on a regular basis in accordance with the manufacturer’s recommendations or other appropriate standards.

Measurement procedures should be in accordance with the equipment manufacturers’ recommendations. In particular, the use of the ground vibration transducer should be consistent with achieving optimum coupling with the ground.

Appendix: Definitions

1. Sensitive site: Includes any land within 10 metres of a residence, hospital, school, or other premises in which people could reasonably expected to be free from undue annoyance and nuisance caused by blasting.
2. Airblast: Is the maximum noise level in dB Lin Peak due to a blast measured anywhere on a sensitive site which is located at least 3.5 metres from any building or other acoustically reflective surface (other than the ground).
3. Ground vibration: Is the level of vibration (peak particle velocity) measured in mm/s in the ground anywhere on a sensitive site. The measurement point should be at least the longest dimension of the foundations of a building or structure away from the building or structure if possible. If this is not possible, the site should be chosen to be as far from the building or structure as is practical.
4. PPV - Peak Particle Velocity: the instantaneous sum of the velocity vectors (measured in millimetres per second) of the ground movement caused by the passage of vibration from blasting.
5. Lin Peak - Linear Peak: the maximum level of air pressure fluctuation measured in decibels without frequency weighting. (NB frequency weightings are often applied to sound measurements to ensure the measured parameter is indicative of the level experienced by the human auditory system. Weighting is not applied to airblast measurements as much of the sound from an airblast is at inaudible frequencies and would therefore be excluded).

Page last updated: 15 Oct 2024