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Good Practice Guide for Assessing Discharges to Air from Industry

Acknowledgements

Foreword by the Ministry

1 Introduction

2 Legislative Context

3 Assessing Discharges to Air: General Considerations

4 The Assessment Process

5 Air Quality Criteria

6 Tier 1 Preliminary Assessment

7 Tier 2 Screening Assessment

8 Tier 3 Full Assessment

Appendix 1: Assessment Checklist

Appendix 2: NO to NO₂ Conversion

References

4 The Assessment Process

4.1 Key steps in the assessment process

An assessment of discharges to air from industry will typically involve the following steps.

1. Gather information and make a qualitative preliminary assessment of air quality impacts.
2. Liaise with the consenting authority.
3. Predict the industry contribution to ground-level concentrations.
4. Characterise the existing environment.
5. Assess the cumulative air quality impacts.

In practice the process may be simpler - or more complex. For example, an assessment of effects for a permitted activity would generally only require a preliminary assessment.

Each of these steps should be undertaken to a level of detail that is appropriate to the nature and scale of the proposal. This guide suggests a three-tiered approach to assessment, as discussed below. A brief description of each component of the process is provided in this section, with more detail given in the following sections of the guide.

Make a preliminary assessment

The first step in any assessment of air quality impacts is to compile information and make a qualitative assessment of the likely impacts. For some proposals this preliminary assessment may be all that is needed. However, in most cases the purpose of this stage is to identify key issues early in the process. The preliminary assessment is referred to as a Tier 1 assessment in this guide.

Liaise with the consenting authority

Early liaison between the consent applicant and the consenting authority is essential to confirm the consenting requirements. (The importance of liaison for air quality assessments is discussed in section 3.) Liaison is not a one-off process. The applicant and the consenting authority should keep talking until they confirm an agreed approach for each stage of the assessment process.

Predict industry contribution to the ground-level concentration of pollutants

Atmospheric dispersion modelling is often used to predict the likely contribution of the proposal to ground-level pollutant concentrations. Detailed guidance is provided in the Good Practice Guide for Atmospheric Dispersion Modelling (Ministry for the Environment, 2004a).

Characterise the existing environment

The potential impacts of the proposal on air quality must be considered in light of the existing air quality, the sensitivity of the receiving environment, and the local topography and meteorology.

Assess the cumulative impacts of the proposed discharges

Industrial emissions can cause a range of environmental effects, including human health effects and effects on ecosystems. These effects can generally be assessed by comparing the predicted ground-level concentration of pollutants (including existing background concentrations) with appropriate assessment criteria. Air quality assessment criteria are discussed in section 5.

4.2 The level of assessment required

Section 88 of the RMA requires an assessment of environmental effects to be provided “in such detail as corresponds with the scale and significance of the effects that the activity may have on the environment”. This section provides guidance on the level of assessment that is appropriate for industrial assessments. Figure 4.1 illustrates the overall assessment process recommended in this guide. The three-tiered approach is intended to ensure the level of assessment undertaken reflects the likely level of effect from a proposal.

The three tiers are:

• Tier 1 – a preliminary assessment to identify whether there are likely to be significant air quality effects

• Tier 2 – a largely qualitative assessment with screening-level modelling only

• Tier 3 – a largely quantitative assessment with increased complexity in modelling and reliance on site-specific data.

4.2.1 Tier 1 assessment

The Tier 1 preliminary assessment is a qualitative assessment to determine whether there are likely to be adverse effects. In some cases a preliminary Tier 1 assessment may be all that is needed. For larger projects the preliminary assessment provides an opportunity to identify key issues early in the process.

It is likely that a Tier 1 assessment will be all that is required for a controlled activity in an appropriately zoned area with no highly sensitive receptors located nearby. The appropriate level of assessment for this type of project is essentially a notification to the consenting authority of the key features of the operation, such as its location, scale, design, environmental controls and contact details. Discharges to air from these activities are likely to be minimal and easily controlled by process design and standard operating practices. Adequate dispersion of air emissions should be achievable via appropriately designed discharge points. The potential for offsite human health, environmental or amenity effects would be low.

4.2.2 Tier 2 assessment

This level of assessment focuses on - but is not exclusively - a qualitative approach to assessing the potential effects of the development on air quality. It considers the design and operation of the development and the nature of the local environment, and relies on a screening modelling assessment of the potential effects of any air discharges. This level of assessment may require some compliance testing for existing facilities.

A Tier 2 screening dispersion modelling study provides conservative estimates of likely air quality impacts. This means the assessment can provide confidence that a project will not result in a significant air quality impact, despite the relative inaccuracy of the predictions.

If this screening assessment indicates there is a potential for adverse impacts or non-compliance with air quality criteria, then the modelling and assessment approach may need to move up to the Tier 3 assessment level, with the modelling further refined to increase the accuracy of the estimates, enabling some of the conservativeness of the assessment to be removed.

4.2.3 Tier 3 assessment

This level of assessment involves a more comprehensive quantitative assessment of the potential effects on air quality of the operation. It will often include the use of emission testing, atmospheric dispersion modelling with local meteorological data (actual or derived), and/or ambient monitoring techniques.

Monitoring or estimating air emissions from process parameters will probably be required to provide data for a quantitative assessment of potential off-site human health, environmental or amenity effects.

More detailed atmospheric dispersion modelling studies are likely to be required to provide estimates of downwind pollutant concentrations, provided the emissions can be reliably characterised and simulated in such a study. For existing sites, or those where there is poor data availability, data from an ambient monitoring programme may be required to verify the results of the modelling.

4.2.4 Deciding which tier

The concept of splitting the assessment methodology into three tiers is somewhat arbitrary, and may not be entirely consistent with the preferences and processes used by all councils. The aim is to provide some guidance – particularly to people new to the field – on the different levels of work and detail needed. For instance, looking crudely at the resources required:

• Tier 1 probably requires just several hours of work, using existing documentation and information (these might be smaller businesses and will almost certainly all be controlled activities).

• Tier 2 probably requires several days of work, including the generation of some new results, and probably a report (these might be medium to larger business, and will probably be either controlled or discretionary activities).

• Tier 3 probably requires several weeks (or months) of work, needing advanced modelling, possibly new monitoring, the use of a number of experts, and probably several reports, with peer review. These types of activities are those most likely to be appealed to the Environment Court. They typically have significant potential discharges and are almost always discretionary activities.

Thus the delineation between Tiers 1 and 2 is fairly straightforward (controlled vs discretionary or other), while that between Tiers 2 and 3 is more subjective. Different councils may have different requirements. The primary advice is to contact the consents manager at the relevant council at an early stage to discuss the application process.

4.3 Factors affecting the level of assessment

The factors affecting the level of assessment include the:

• scale of the development

• adoption of pollution prevention measures

• complaints/compliance record

• nature of the pollutants released to air

• airshed designation under the Standards

• existing air quality (particularly if background levels are elevated)

• physical geography of the receiving environment

• land use of the receiving environment

• type of consent required.

The Tier 1 preliminary assessment process includes a qualitative assessment of these factors. In some cases it will be obvious from the preliminary assessment and discussions with the consenting authority that a Tier 3 assessment will be required. However, a Tier 2 screening assessment may still be undertaken to identify the pollutants or sources of most concern before undertaking a Tier 3 assessment.

In reality, it is likely that the methodologies described in the Tier 2 and Tier 3 procedures would be combined for any significant assessment. For example, a scarcity of information on existing air quality may result in the need for air quality monitoring, whereas the required dispersion modelling technique may be very straightforward due to simple topography.

It is important to remember that every assessment is different and that the level of assessment required should be confirmed with the relevant consenting authority. To help this liaison process with the consenting authority, a simple checklist is provided in Appendix 1. It is recommended that this checklist be completed before a pre-application meeting, as mentioned in section 3.

One of the advantages of early consultation with the council is the opportunity to get advice on the level of quantitative assessment that is likely to be required, based on their experience with similar proposals. In this way, the assessment process can be targeted at the appropriate level rather than wasting time by following an iterative approach of increasing detail and complexity.

Figure 4.2 provides an example of the application of the tiers of assessment to three developments.

4.3.1 National environmental standards for air quality

At the time of publication, 69 areas throughout New Zealand have been gazetted as 'airsheds' under the provisions of the Standards. Of these, around 30 are likely to exceed the national ambient air quality standard for PM₁₀ and are therefore subject to controls on the granting of resource consents. It is likely that any industrial development within these airsheds that shows any significant increase in PM₁₀ emissions will require a Tier 3 assessment.

The additional requirements imposed by the Standards (as well as those already in council plans) cover many other pollutants as well as PM₁₀. For instance, some regions have an issue with NO₂ (mainly in Auckland due to its high level of traffic emissions), and some with SO₂ (mainly due to industries using coal). Regions with these issues will invariably have additional specific requirements on industrial dischargers if they have an impact on high ambient concentrations of these pollutants.

4.3.2 Assessments for an existing activity

Where an application is for the continued discharge from an existing consented activity, and no changes to the emissions have occurred (or are likely to occur) since the previous application was processed, it may be appropriate to provide significantly less information with the application.

Similarly, a minor change to a large-scale industry may only require a low level of assessment. This is because for changes to existing industry, far more relevant performance data are typically available than would be the case for a greenfield development, such as:

• emissions and ambient monitoring data

• complaints records

• the use of management systems and their effectiveness in process operation and control.

An assessment of changes to an existing facility will typically be required to consider both the existing and new emissions. The existing performance data will be valuable in any assessment of the level to which evidence of improvements to existing processes might be sought. For a new development process, information is based on similar developments, and greater attention will be required to generate and demonstrate reliable process data.

4.4 Reporting

It is a good idea to develop a standard reporting methodology and format. Although specific projects will have specific requirements, any report should contain the following features.

1. Executive summary: a one-page statement of the key features and results. This may be the only part of the report that some users read, so it should be succinct and clear.
2. Scope: who has commissioned the project, and why, including the intended outcomes.
3. Introduction: the background to the issues and the relevance of any previous work.
4. Methodology: a description of the process used, any models employed, assumptions made, and any statistics or analysis used.
5. Site description: the area being assessed, including maps with all relevant features (and photos if available). Show any facilities where there are likely to be sensitive members of the public (eg, young, old, sick), such as hospitals and schools, in relation to the proposal.
6. Description of proposal: a description of the project and any changes to existing activities. This section should include adequate information to characterise the discharges and the receiving environment, as detailed in later sections of this guide.
7. Description of receiving environment: a description of the receiving environment as detailed in later sections of this guide.
8. Existing consenting requirements: include details of any existing consent requirement and the level of compliance with these requirements.
9. Data used: the sources and validity of all input data, including emissions and process data, meteorology, existing concentrations and all assumptions made.
10. Assessment of effects: the outcomes of the study, and all options assessed, as much as possible in summary tabular and graphic form. The emphasis should be on key results that can inform decision-making. Detailed results should be given in an appendix.
11. Discussion: any implications, uncertainties and reliance on assumptions. Include discussion of possible mitigation options and associated emissions reduction.
12. Conclusion: a summary of the scope, method, results and implications.
13. References: all material used should be referenced explicitly, and should include web-based links where appropriate.
14. Appendices: any detailed calculations or results that are used. This should include model control files.

The size and nature of each of these sections will depend on the project, but it is anticipated that for any Tier 3 assessment each section will be included and the report will run to 30 to 60 pages. Specific requirements for Tier 1, 2 and 3 assessments are discussed in sections 6, 7 and 8, of this guide.

Any assessment of effects for a resource consent application should address all matters outlined in the Fourth Schedule of the RMA, as well as any requirements of the council.

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