Environmental issues

Air

FAQ: Approved methods for the modelling and assessment of air pollutants in NSW

  • Introduction
  • Frequently asked questions
    • What is the 'nearest sensitive receptor'?
    • How do I determine the appropriate odour assessment criteria?
    • How should Table 3.4 of the Draft Policy: Assessment and management of odour from stationary sources in NSW : Technical notes be interpreted?
    • What is the process for developing industry-specific odour criteria?
  • Case studies and examples


Introduction

The Approved Methods for the Modelling and Assessment of Air Pollutants in NSW (AMMAAP) lists the statutory methods that are to be used to model and assess emissions of air pollutants from stationary sources in NSW.

The AMMAAP is referred to in Part 5: 'Air impurities from emitted activities and plant' in the Protection of the Environment Operations (Clean Air) Regulation 2010 and includes procedures for developing site-specific emission limits for hydrogen sulfide as specified in clause 42 of the Regulation. The procedures in AMMAAP are also used to determine appropriate alternative standards under several provisions of the Regulation, such as clauses 36 and 42.

AMMAAP may also be referred to in conditions attached to statutory instruments, such as licences or notices issued under the Protection of the Environment Operations Act 1997, and DECCW Director General requirements under Part 4 of the Environmental Planning and Assessment Act 1979.

Download the document

Approved Methods for the Modelling and Assessment of Air Pollutants in NSW (AMMAAP):
Available as PDF - ammodelling05361.pdf, 403 kb; requires Acrobat Reader 

The procedures outlined in AMMAAP are largely self-contained and the following questions supplement the information already provided in the document.

Frequently asked questions

What is the 'nearest sensitive receptor'?

The purpose of an air quality impact assessment is to demonstrate acceptable impacts at all nearby sensitive receptors. Where AMMAAP refers to criteria being applied at the nearest sensitive receptor, the criteria should be applied to the most impacted sensitive receptor.

How do I determine the appropriate odour assessment criteria?

It is not possible to provide detailed guidance that will cover all situations. In many cases, some professional judgement will need to be applied. Where there is doubt about how to select the appropriate odour criteria, consult OEH's Air Technical Advisory Services Unit.

The following items must be considered when selecting the appropriate odour assessment criteria:

  1. A 'receptor' may be an individual dwelling, a group of receptors or a population.
     
  2. Receptors that are part of a proposal, that is are owned by the proponent, or where a permanent, immutable agreement exists, are not counted as receptors in establishing criteria or assessing impact.
     
  3. Areas zoned for human habitation must be considered receptors. Areas where future human habitation is likely must be considered in the assessment to inform future land-use planning decisions.
     
  4. The criterion that applies at a specific receptor depends on the nature of the receptor, its surrounding environment, the population density (people per square kilometre) and the size of the population.
     
  5. Normally, each isolated rural receptor will have a criterion of 7 OU, while urban areas and/or schools and hospitals will have a criterion of 2 OU.
     
  6. In some cases different criteria can apply to different receptors: for example, where the only receptors are a medium-sized town and a single isolated rural receiver on the opposite side of the source. In this case 7 OU would apply at the isolated receptor and 2 OU at the town.
     
  7. Isolated rural receptors are typically characterised as areas having no more than 1 dwelling in any square kilometre, that is dwellings more than ~1130 metres apart (note that a circular area covering 1 square kilometre  is 1130 m in diameter).
     
  8. Urban areas are typically characterised as having a population density of more than 1000 people per square kilometre. Urban areas cannot be dissected by eliminating those parts of a contiguous urban area that would not receive more than 2 OU.
     
  9. Consideration of the lot size may assist in deciding the population density and category of receivers.
     
  10.  Common principles of scientific precision apply. Modelling the impact of complex mixtures of odorous pollutants is not precise, so predicted impacts and criteria must be rounded to whole numbers.

How should Table 3.4 of the Draft Policy: Assessment and management of odour from stationary sources in NSW : Technical notes be interpreted?

Table 3.4 of the draft policy has been mis-drafted as there should not be a range of values for population of affected community. Refer to Equation 3.1 of the Technical Notes instead of the table to determine the applicable criteria.

The tables below may assist in interpreting the relevant equations and criteria found in the draft odour policy and AMMAAP. Note that Table 7.5 of AMMAAP is correct.

Note that the final Technical Framework and Technical Notes for the Assessment and Management of Odour from Stationary Sources in NSW were published in November 2006. These documents replace the draft odour policy published in 2001.

What is the process for developing industry-specific odour criteria?

Section 3.2 of the Technical Notes: Assessment and management of odour from stationary sources in NSW sets out the process for development and approval of alternate odour criteria.

The development of industry-specific odour criteria should also include a percentile compliance level for the criteria. The default percentile compliance is 100% for a level 2 assessment and 99% for a level 3 assessment.

Contact OEH before undertaking development of alternative odour criteria to ensure the proposed work will comply with the policy.

Case studies and examples

AMMAAP contains worked examples for:

  • determining site-specific emission limits
  • dealing with elevated background concentrations. 

Criteria

Values at specific points  

Range of values  

Population density (people/km2)  

Approx. lot size assuming 2.6 people/lot  

Typical dwelling 
separation (m) 
(circular area 
around each)  

Population density (people/km2)

Criteria range (criteria actual*)  

Approx. lot size (m2) (2.6 people/lot)  

m2

acres

2

2,000  

1,300

1/3

40

> 1,000

< 2.5 (2) 

< 2,600

3

500

5,200

1.3

80

> 50, < 1,000  

> 2.5, < 3.5 (3)  

> 2,600, < 10,400  

4

125

20,800

5

160

> 60, < 250

> 3.5, < 4.5 (4)  

> 10,400, < 43,300  

5

30

86,700

20

330

> 17, < 60

> 4.5, < 5.5 (5)  

> 43,300, < 153,000  

6

10

260,000

65

575

> 4, < 17

> 5.5, < 6.5 (6)  

> 153,000,
~ < 650,000

7

Single residence

1 km2

250

1,130

Single residence

> 6.5, < 7.5 (7)  

1 km2

* Use only whole numbers for actual criteria


 

Page last updated: 02 June 2011