Approved methods for sampling and analysing air emissions

Always use the approved sampling and analysis methods unless your licence condition specifically requires or allows for the use of alternatives. EPA approval is required for use of an alternative method. Licensees must seek written approval from the EPA prior to use. Further guidance is provided in Section 4.5.2 of the Approved methods for the sampling and analysis of air pollutants (AMSAAP) (PDF 1153KB)

If your licence requires ambient air monitoring specified by a coded AM method (for example. ‘AM-X’), you must still comply with the requirement to undertake monitoring in accordance with that method.  AM-coded ambient air monitoring methods have been removed from the Approved methods for the sampling and analysis of air pollutants and are now in the Table of AM-coded methods for ambient air monitoring (PDF 137KB).

We've prepared a principles-based Ambient air monitoring guidance note (PDF 689KB) to assist in selecting appropriate monitoring methods where a method is not specifically listed in the licence.

AMSAAP nominates methods for sampling and analysing hydrogen sulfide in stack emissions. The methods vary in certain ways, including sensitivity of detection. USEPA Method 11 is a cost-effective method for sampling and analysing hydrogen sulfide in stack emissions, but may not be sensitive enough to demonstrate regulatory compliance. However, there is scope to improve the sensitivity.

The nominal sampling time of at least 10 minutes can be legitimately increased to allow capture of hydrogen sulfide from an increased gas stream volume. This reduces the low limit of detection. However, care is needed to ensure that the capture solutions are not saturated during the increased sampling time.

This modification is considered to be within the scope of the method and does not need approval by the EPA.

Approved method USEPA Method 7E requires a sample to be continuously extracted from the gaseous stream and a fraction of this conveyed to an instrumental analyser which determines the concentrations of nitric oxide (NO) and oxides of nitrogen (NO_x). The method nominates use of a chemiluminescence analyser. However, as noted under TM-11 of AMSAAP, the EPA recognises the use of any appropriate instrumental analyser for this purpose, provided the performance specifications of USEPA Method 7E are met to ensure reliable data.

Following from this, the concentration of NO₂ can be calculated as the difference between measured NO and NO_x. This data can be reported directly or, if required, converted into an equivalent NO₂ concentration. Details of these calculations are given in Appendix I of AMSAAP.

Odour is expressed as a concentration, and is represented as a number of 'odour units' (OU). One OU is defined as the minimum concentration of the substance that causes a positive physiological response in a reference panel of individuals.

Cycling times and data recording requirements 

• For opacity – minimum of 1 cycle of sampling and analysis for each successive 10-second period and 1 cycle of data recording for each successive 6-minute period.
• For all CEM systems except opacity – minimum of 1 cycle of operation (sampling, analysis and data recording) for each successive 15-minute period. 

Averaging period requirements 

Except as otherwise specified in the relevant environment protection, the averaging periods to be used are

• for opacity, all data must be reduced to 6-minute averages calculated from 36 or more data points equally spaced over each 6-minute period
• for all CEM systems except opacity, all data must be reduced to 1-hour averages calculated from 4 or more data points equally spaced over each 1-hour period

Monitor downtime 

As a guide, the minimum data capture for opacity monitoring should be 95%, and for all other CEM systems, 90%. This allows a reasonable period of monitor downtime in the following situations

• monitor breakdown
• scheduled monitor maintenance
• daily zero and span checks
• performance specification testing

This Guidance provides a detailed overview of the factors to consider when evaluating and installing Particulate Matter – Continuous Emissions Monitoring Systems (PM-CEMS). 

This Guidance was originally developed for large combustion plant operating in NSW. However, the EPA considers it relevant to a wide range of industry sectors and recommends it be used by anyone required to undertake continuous particle monitoring for statutory purposes in NSW. 

• Feasibility of Continuous Particle Monitoring at NSW Coal Fired Power Stations: Guidance Document (PDF 1.2MB)

Calculating emissions from combined sources

A licensed pulp and paper mill is operating

• a lime kiln fired on timber waste
• a kraft recovery boiler fired on solid fuel (boiler 1)
• a gas-fired power boiler (boiler 2)

all of which discharge through a single main stack. Each emission unit belongs to Group 6 under the Regulation.

What is the oxides of nitrogen standard of concentration and reference oxygen concentration for the main stack if all three emission units are operating?

The applicable standards of concentration for emission of oxides of nitrogen (NO_x) for each individual emission unit are specified in Schedule 2,  Division 2 of the Protection of the Environment Operations (Clean Air) Regulation, under 'Paper, paper pulp or pulp products industries'. The oxygen reference level that applies to each emission unit is specified in Schedule 3, Part 3, Division 1 of the Regulation. The volumetric flow rate of each emission unit is also known. This information is summarised below:

The alternative standard of concentration for a combined source (Cr) is calculated as follows:

(1)

C₁q₁ + C₂q₂ + ........ + C_N q_N
C_r =  _________________________
             q₁ + q₂ + ........ + q_N

where

C_N  = the standard of concentration applicable to the Nth emission unit
 q_N  =  the volumetric flow rate of the Nth emission unit

Using Equation 1, the oxides of nitrogen alternative standard of concentration for the main stack is

C_r =    300 x 35 + 300 x 50 + 400 x 5 
            35 + 50 + 5

=   27500 
     90

= 305.5

= 306 mg/Nm³ rounded to the nearest integer

The reference oxygen concentration for a combined source (O_r ) is calculated as follows

(2)

O₁q₁ + O₂q₂ + ........ + O_N q_N
O_r =  _________________________
             q₁ + q₂ + ........ + q_N

where

O_N  =  the reference oxygen concentration applicable to the Nth emission unit
 q_N  =  the volumetric flow rate of the Nth emission unit

 Using Equation 2, the reference oxygen concentration for the main stack is

C_r =    7 x 35 + 3 x 50 + 7 x 5 
                   35 + 50 + 5 

=   430 
     90

= 4.77%

= 5% rounded to the nearest integer

305.5 mg/Nm³ @ 4.77% O₂ = 305.5 x    (21 - 5)    = 301 mg/Nm³ @ 5% O₂                   
   (21 - 4.77)

The oxides of nitrogen standard of concentration for the main stack, when all three emission units are operating, is 301 mg/Nm³ @ 5% O₂

What are the oxides of nitrogen standard of concentration and reference oxygen concentration for the main stack if boiler 1 is shut down?

Using Equation 1, the oxides of nitrogen alternative standard of concentration for the main stack is calculated assuming C_N  and  q_N  for boiler 1 is zero        

C_r =   300 x 50 + 400 x 5

50 + 5

=   17000

55

= 309.1

= 309 mg/Nm₃ rounded to the nearest integer

Using Equation 2, the reference oxygen concentration for the main stack is

C_r =   3 x 50 + 7 x 5

50 + 5

= 3.36%

= 3% rounded to the nearest integer

309.1 mg/Nm³ @ 3.36% O₂ = 309.1 x    (21 - 5)    = 315 mg/Nm³ @ 5% O₂                   

(21 - 3.36)

The oxides of nitrogen standard of concentration for the main stack when boiler 1 is shut down is 315 mg/Nm³ @ 3% O₂