MANAGING DUST

Managing dust on your site so that dust emissions are minimised, impacts on neighbours are managed and health of workers maintained can be a costly and time consuming issue. DR LYN DENISON, Principal Scientist – Air Quality, EPA Victoria provides a summary on the EPA dust requirements as presented at the recent CMPA Dust Workshop.

THE State Environment Protection Policy (Air Quality Management) (SEPP (AQM)) establishes the framework for managing emissions to the air environment in Victoria. When the SEPP (AQM) was revised in 2001 it was agreed that a Protocol for Environmental Management (Mining and Extractive Industries) (PEM) would be developed to provide further guidance on the SEPP (AQM) requirements to these industries.

A working group consisting of representatives from EPA Victoria, Department of Primary Industries, Department of Human Services, Minerals Council of Australia and CCAA developed the PEM with consultation with key stakeholders. The PEM is an incorporated document to SEPP (AQM) and has the same statutory power.

The PEM sets out the requirements for an assessment of air quality impacts from mining and extractive industries. It is triggered when an activity requires an EPA Works Approval, an EES or when a change to a DPI work plan would lead to a significant increase in air emissions. The PEM identifies the level of assessment that is required and establishes the pollutants and associated assessment criteria that need to be considered. It also establishes the monitoring requirements for compliance (where required) and for reactive management of the site.

The PEM provides a risk based approach to the assessment with operations potentially posing the greatest risk to communities, eg. large operations in urban areas, requiring the most stringent assessments. For operations where extraction is less than 50,000 tonnes per year no air quality modelling is required but best practice site management must be undertaken. Table 1 sets out the risk based requirements for assessment.

The SEPP (AQM) requires control of all emissions to the air environment in Victoria to be controlled by the application of best practice. For Class 3 indicators, such as respirable crystalline silica, emissions must be controlled to the maximum extent achievable (MEA). In determining what constitutes best practice and MEA consideration must be given to the wastes hierarchy:

• Avoidance
• Reuse
• Recycling
• Recovery of energy
• Treatment
• Containment
• Disposal

Best practice refers to international best practice for the industry sector. It is determined for industries of similar size, location and operations. MEA goes beyond best practice to take into consideration what site-specific action can be taken.

This may include, for example:

• Ceasing operation for several hours under certain meteorological conditions
• Increased water sprays or use of chemical dust suppressants
• Use of blast mats

In determining best practice for an operation the following should be taken into account:

• Most recent documented definition for the industry sector from national and international sources
• Most recent documented definition for the industry sector in Victoria (if any)
• Performance standards or benchmarks for the industry in terms of management of emissions, wastes, energy and resources and their impacts
• Any constraints that may apply to each situation (eg., availability, affordability or practicability)
• Comparison of different approaches currently used in the industry

The indicators to be assessed are as follows:

• PM10
• PM2.5
• Respirable crystalline silica
• Asbestos
• Arsenic
• Hydrogen Cyanide
• Heavy metals (eg, lead antimony)
• PAHs
• Radioactive isotopes

Not all pollutants will be relevant for all sites. PM10 and PM2.5 will need to be assessed for all sites. Respirable crystalline silica (RCS) will need to be assessed unless the geological assessment of the site indicates that RCS will not be present. This will be dependent on rock type.

Where air quality modelling is required, the PEM establishes the procedures to be followed. Background data for Level 1 and 2 assessments is required. In many instances EPA will have appropriate background data for use in these assessments.

However, there may be some instances where background data will need to be collected prior to the assessment being undertaken. It is important to contact EPA early in the planning stages of a development to get advice on the availability of background data for your site.

The PEM requires monitoring for two purposes:

• Compliance with assessment criteria and
• Reactive management of the site once operational.

Confirmation monitoring to assess whether the site complies with the assessment criteria is conducted for limited time period (eg 12 months).

For Level 1 sites real time continuous PM10 and PM2.5 monitoring, nuisance dust monitoring at sensitive receptors and crystalline silica and metal monitoring (conducted using low-volume samplers for a period of 1 week per month) is required.

For Level 2 sites 1 in 6 day 24-hour PM10 and PM2.5 monitoring, nuisance dust monitoring at sensitive receptors and limited crystalline silica and metal monitoring (conducted using low-volume samplers for a period of 1 week per month) must be undertaken.

For Level 3 sites monitoring for nuisance dust is required at sensitive receptors.

Data collected through nuisance dust monitoring is to be assessed using DPI criteria of 4 g/m2/month on a monthly basis (not an annual average) – no more than 2 g/m2/month above background.

Monitoring for reactive management purposes is required for Level 1 and 2 facilities as part of the site environmental management plan. It is a real-time tool to react to short term particle peaks which may impact on the overall daily concentration. It enables site operators to manage dust issues as they arise. EPA can assist with short term trigger levels and advise on appropriate instrumentation.

Instruments are typically sited at the sensitive receptors that are predicted to be worst affected or boundary closest to those locations. Instrumentation not the same as that required for compliance monitoring. Th ere is a range of equipment available that is relatively inexpensive and portable that would be suitable for reactive management purposes.

The results of this type of monitoring can also assist in identifying whether dust is originating from the site or from off -site. This information is valuable in communicating with local communities when dust complaints are received.

The PEM (publication 1191) is available from the EPA Victoria website
www.epa.vic.gov.au/publications

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