Redetermination of maximum permissible quantities of sulphur dioxide under the Environmental Protection (Kwinana) (Atmospheric Wastes) Policy 1999

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Redetermination of maximum permissible quantities of sulphur dioxide under the Environmental Protection (Kwinana) (Atmospheric Wastes) Policy 1999

July 2009

2009211

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Recommended reference

The recommended reference for this report is: Department of Environment and

Conservation, W.A., July 2009, Redetermination of maximum permissible quantities

of sulphur dioxide under the Environmental Protection (Kwinana) (Atmospheric Wastes) Policy 1999.

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1. Introduction

This report describes the process and results of a redetermination of maximum permissible quantities of sulphur dioxide under the Environmental Protection (Kwinana) (Atmospheric Wastes) Policy 1999 (hereafter called the Kwinana EPP or EPP). The redetermination, which includes all industries covered by the current determination, has been prompted primarily by the benefits of redefining maximum permissible quantities on a statistical basis, as permitted under the EPP.

This report does not repeat in detail previously published information about the Kwinana EPP or the previous determination and redeterminations of maximum permissible quantities (i.e. emissions limits) but provides references and, where appropriate, summary information.

Publications referenced herein (other than scientific papers from international journals) may be downloaded from the following website:

http://www.dec.wa.gov.au/pollution-prevention/air-quality-publications/technical-reports.html The Environmental Protection Authority (EPA) Bulletin 644 can be downloaded from the EPA website at:

http://www.epa.wa.gov.au/docs/708_B644.pdf

The computer modelling results and portions of the text and figures in this report have been provided by the Kwinana Industries Council (prepared by ENVIRON Australia Pty Ltd).

These have been assessed and verified by DEC. The cooperation of the Kwinana Industries Council and assistance of ENVIRON is gratefully acknowledged.

Throughout this report the abbreviations “Kwinana EPP” and “EPP” refer to the

Environmental Protection (Kwinana) (Atmospheric Wastes) Policy 1999 and, where relevant, the Environmental Protection (Kwinana) (Atmospheric Wastes) Regulations 1992

(Regulations)

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2. The Kwinana EPP 1992 to 2009

2.1 Overview of the EPP

The Kwinana EPP was first approved in 1992 and reviewed without change in 1999. The 1999 EPP review process is described in EPA (1999). While the regulations associated with the Kwinana EPP prescribe sulphur dioxide and total suspended particulates as atmospheric wastes for the purposes of the EPP, the primary focus of emissions management under the EPP has been on sulphur dioxide. Only sulphur dioxide is considered in this report.

At the time of writing, the EPA has initiated the process for reviewing the Kwinana EPP under s 36 of the Environmental Protection Act 1986.

The Kwinana EPP defines three areas (Areas A, B and C), where:

• Area A is the area of land on which heavy industry is located;

• Area B is a buffer area surrounding industry;

• Area C is beyond Areas A and B, predominantly rural and residential.

Figure 1 in Appendix A shows these areas and the location of monitoring stations.

The Kwinana EPP sets ambient standard and limits for the three EPP areas, with these increasing in stringency from Area A to Area C. Standards and Limits for sulphur dioxide were set for 1-hour, 24-hour and annual averaging periods with the most important of these being 1-hour averages with respect to controlling air quality in Kwinana. Table 1 sets out the Standards and Limits.

Table 1: Kwinana EPP Standards and Limits for Sulphur Dioxide

Concentration (µg/m³) Averaging

Period Area A Area B Area C

Standard 700 500 350 1-hour

Limit 1,400 1,000 700

Standard 200 150 125 24-hour

Limit 365 200 200

Standard 60 50 50 Annual

Limit 80 60 60

Notes

1. µg/m³ means the concentration in micrograms per cubic metre of dry air at 0 degrees Celsius and one atmosphere pressure (101.325 kilopascals).

The Kwinana EPP provides for the CEO (of DEC) to determine the maximum permissible quantities (emission limits) of sulphur dioxide from significant sources in the EPP Area so that, in his opinion, the EPP Standards and Limits will be complied with. The EPP also provides for a redetermination of emission limits as and when required (e.g. to accommodate new industries or variations to existing industry emissions).

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EPA Bulletin 644 (1992) provides a detailed description of the background to the EPP development, the underlying management strategy (which is current) and the computer model employed for calculating maximum permissible quantities. This bulletin also fulfils the reporting requirements of the EPP in relation to the determination procedure and the

maximum permissible quantities as determined in 1992.

2.2 Ambient sulphur dioxide monitoring

Under the provisions of the EPP, ambient concentrations of sulphur dioxide have been monitored by six monitoring stations in the Kwinana Region since 1993. Three of these have been operated at fixed locations by DEC and three have been operated by industry through the Kwinana Industries Council (KIC). Two of these industry operated stations were located at fixed locations, with the third station moving between successive locations. Details of the monitoring sites are as follows:

• Wattleup (DEC owned and operated);

• Hope Valley (DEC owned and operated);

• Rockingham (also called North Rockingham) (DEC owned and operated);

• Miguel Road (KIC owned and operated);

• Abercrombie Road (KIC owned and operated); and

• One KIC monitoring station operated at the following locations in sequence:- Hillman Primary School, Rhodes Park in Calista, Henderson Road, Fanstone Avenue and Fancote Avenue.

The industry monitoring program described above has been approved by DEC at each stage.

Figure 2 in Appendix A presents the maximum and 99.9^th percentile (i.e. 9^th highest) 1-hour average concentrations of sulphur dioxide recorded at each of the monitoring stations since 1993 through to the end of 2008.

These data show that over the 16 years, there have been no exceedances of the EPP limits at any of the monitoring stations. The maximum recorded 1-hour average concentrations of sulphur dioxide exceeded the relevant EPP standard:

• three times at Hope Valley (1993, 1994 and 2007); and

• once at Wattleup (1993), Miguel Road (1994) and Rockingham (1994).

The 1993 and 1994 exceedances of the EPP standards were associated with unexpected process upsets. The exceedance of the EPP standard at Hope Valley during 2007 was the first exceedance of the standard recorded since 1994 and no specific cause for this has been identified.

The monitoring data show that the ambient concentrations of sulphur dioxide are generally well below the EPP standard although the maximum recorded concentrations have tended to increase at the Hope Valley and Abercrombie monitoring sites during 2006, 2007 and 2008.

The Hope Valley monitoring site was decommissioned in 2008 due to its location no longer being available to DEC. Hope Valley is no longer a residential area.

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2.3 Computer model evaluation

As envisaged in Bulletin 644, the accumulated data on emissions, ambient concentrations and meteorology has allowed progressive evaluation and improvement of the computer model used for determination of maximum permissible quantities.

At the time that the maximum permissible quantities were defined in 1992, limitations in the scientific basis of the model (know as DISPMOD) were recognized and documented in Bulletin 644 and by Rayner (1992).

A major field experiment was conducted at Kwinana in early 1995 to better understand the process of plume mixing within sea breezes (specifically the process known as “shoreline fumigation”, see Figure 3). The experiment and subsequent theoretical work was led by the CSIRO (Sawford et al., 1996). Results of this work were incorporated as improvements to DISPMOD. These and other improvements described by Rayner and Blockley (2000) form the basis for an improved version of the model named (for the purposes of this report) DISPMOD97.

DISPMOD97 was run for the 1995, 1996 and 1997 calendar years using the actual emission characteristics provided by industry as part of their licence conditions. The modelled versus measured 1-hour average concentration statistics for two years are presented in Figure 4.

Each annual plot for each monitoring station (identified on the horizontal axis) shows the measured and modelled 9^th highest 1-hour average concentration and the average of the top ten 1-hour average concentrations. Apart from a tendency to over-predict at Henderson Road, the model results are very good (more detail is given by Rayner and Blockley (2000)).

A revised version of the model called DISPMOD05 was subsequently created from DISPMOD97 to address the following issues:

• The convective dispersion formulation used by AUSPLUME was incorporated into DISPMOD05 to more correctly model plumes released within the coastal boundary layer and offshore flow mixed layer. The plume lofting scheme from the US model AERMOD was also added to DISPMOD05.

• Testing of the lateral dispersion relationship in DISPMOD97 showed that it performed poorly under light wind conditions. The relevant formula proposed by Draxler (1976) as used in earlier version of DISPMOD was reinstated in the model as a preferred option.

• Alternative schemes to compute plume trapping under, or penetration through, temperature inversions were added to DISPMOD05 and used in associated

meteorological pre-processing. The original method is believed to over-predict plume trapping and associated predicted concentrations.

DISPMOD05 was run for 1995 and 1996 using the actual emission characteristics provided by industry as part of their licence conditions (as for DISPMOD97). The modelled versus measured 1-hour average concentration statistics for these years are presented in Figure 5.

The key outcomes of the modelling using DISPMOD05 are:

• Increased over-prediction at the North Rockingham station (for 1995 at least).

• Improved predictions for the Miguel Rd station (due to a correction of the treatment of the mechanical internal boundary layer).

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• Minor over-prediction at the Wattleup station with other sites remaining relatively unchanged. There is good reason to believe higher concentrations within 1-2 km northeast of the stacks are due to the convective down-mixing of plumes, as now simulated by all reputable models.

DISPMOD05 also results in very high concentrations immediately west of BP Refinery which are likely to be primarily due to the convective down-mixing and Draxler’s lateral dispersion formula. The existence of these high concentrations so close to the sources is questionable and, in any event, irrelevant to a redetermination under the EPP as they do not occur on neighbouring properties.

In summary, apart from the North Rockingham site there is not a strong argument that one version of DISPMOD (i.e. DISPMOD97 or DISPMOD05) matches the monitoring results better than the other. Both give very good results by the standards commonly accepted for such tests. Both versions were therefore run for the current redetermination.

2.3 Forms of maximum permissible quantities

The EPP allows maximum permissible quantities to be expressed as constant values, as formulae describing variations, or on a statistical (probabilistic) basis. (The latter option means to define the allowable probability of emissions reaching various levels including, for some industries, high emissions associated with plant upset conditions that occur for a small fraction of the year.) For the first determination in 1992, most maximum permissible

quantities were specified as constant values which set upper limits on emissions (with the Verve [SECWA at the time], CSBP and BP maximum permissible quantities expressed as formulae). At that time the emissions data necessary to define emissions limits on a probabilistic basis were not available (had not yet been collected). Computer modelling, using the constant emission values, showed the air capacity (relative to the EPP Area C standard) to be almost fully allocated at key locations. (As described in the previous section we are confident in the model’s capability).

In reality, most industrial emissions are considerably less than these constant upper limits most of the time. This fact is clearly reflected in the monitoring results of Figure 2 which show the 99.9 percentile measurements to be well below EPP standards at all sites.

The option of expressing maximum permissible quantities on a statistical (probabilistic) basis has advantages for industries (it much better accommodates their operational requirements) while at the same time allowing more realistic management of the total ambient loading of sulphur dioxide and more reliable assessment of the acceptability of additional emissions in the EPP area.

Since 1992 there have been two redeterminations of the maximum permissible quantities, with probabilistic values being applied in both cases:

In 1994 the maximum permissible quantities of BP and Alcoa were redetermined to provide for low probability / high emissions associated with failure of sulphur recover units at BP.

In 2000 the maximum permissible quantities for Tiwest were redetermined to provide for the emissions profile for Stage 1 of the expansion approved by the Minister for Environment in 1997.

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DEC has developed software to handle probabilistic emissions (summarised by Rayner and Blockley, 2000). In essence the software post-processes the results of a DISPMOD run completed with constant emissions, scaling the DISPMOD results for each non-negligible combination of probabilistic emissions across a full year, computing exceedance frequencies of a range of concentrations for that combination of emissions (as if they occurred for the full year), multiplying these exceedance frequencies by the probability of the emissions

combination, and summing these probability-weighted exceedance frequencies across all non-negligible combinations of emissions to give a final result. The same outcome can be achieved via a Monte Carlo simulation (this has been verified).

The two versions of DISPMOD and the software for processing probabilistic emissions were provided to the KIC.

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3. Redetermination principles and procedure

All Kwinana industries covered under the current EPP determination have indicated either collectively through the KIC or via other interactions with DEC or EPA that they wish to have their maximum permissible quantities redetermined on a probabilistic basis.

3.1 Principles

In the course of discussions, DEC has advised the KIC and its individual members of the following principles which must be followed in addition to those which are obvious from the EPP itself:

1. All maximum permissible quantities are to be determined in accordance with the principle of waste minimisation (as specified in the Environmental Protection Act 1986) which states that all reasonable and practicable measures should be taken to minimise the generation of waste and its discharge to the environment.

2. All maximum permissible quantities must be in accordance with any relevant

approvals and associated conditions under Part IV of the Environmental Protect Act 1986.

3. Maximum permissible quantities that are in accordance with principles 1 and 2 and represent the reasonable needs of an industry, with allowance for variability as appropriate to that industry, will be considered by DEC to be a secure allocation (not to be reduced to make room for new sources).

4. The capacity of the airshed to accommodate additional emissions beyond secure allocations (as per principle 3) will be reserved by DEC for future uses, as per the EPP clause 7(2).

5. Any emissions which DEC permits in excess of a secure allocation will have a specified end date and will not be a secure allocation.

6. Ambient sulphur dioxide monitoring can reduce only to the extent that licensed emissions limits reduce, thereby reducing the likelihood of exceedance of the EPP Standards and Limits.

3.2 Procedure for redetermining maximum permissible quantities of sulphur dioxide

Clause 14 of the EPP requires DEC to make details of the procedure for determining or redetermining maximum permissible quantities of atmospheric waste (EPP Clause 7(1)) available for public inspection. The following summary of the procedure relating to sulphur dioxide is provided to fulfil this requirement. It is based on the procedure in EPA Bulletin 644 (1992) with changes in bold type. The change to point (4) reflects the fact that there is now a large amount of emissions monitoring data and other information available which can be used to assess industry emissions requirements.

(1) For the purpose of this procedure, define maximum permissible quantity to mean the mass of sulphur dioxide emitted per unit time, expressed in units of grams per second, kilograms per second or dimensionally equivalent units.

(2) Accept the computer model DISPMOD (both versions DISPMOD97 and DISPMOD05) together with the data files, or samples thereof, in Appendix B as being the best

available means of calculating ground level concentrations of sulphur dioxide in the

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Policy Area, noting that multiple calculations may be performed as necessary to exclude from the concentration within any industrial premises the concentration contribution from that premise's own discharges, in accordance with Clause 6 of the EPP.

(3) Provide the model and data files to representatives of Kwinana industry so that they, with the assistance of expert consultants, might propose maximum permissible quantities of sulphur dioxide for each industrial source which enable the ambient air quality standards and limits to be achieved and complied with.

(4) Use the model and data files to verify that the industry proposal is correct and

acceptable and, if so, determine the maximum permissible quantities of sulphur dioxide to be those proposed by industry, subject to point (6).

(5) In the event that the industry proposal is unsuitable, for whatever reason, interact with Kwinana industries to define acceptable emissions and proceed to determine the maximum permissible quantities, subject to point (6).

(6) If maximum permissible quantities are to be expressed on a statistical basis, DEC may (after modelling) convert detailed source emissions information to industry site totals of maximum permissible quantities (possibly with associated upper limits on specified sources), if industries agree to provide evidence on an annual basis, to DEC’s satisfaction, that the distribution of emissions is substantially as modelled or that any changes are inconsequential with respect to increasing ambient concentrations of sulphur dioxide.

(7) Under the provisions of the EPP, continue the programme of monitoring the discharge of sulphur dioxide from all relevant industrial sources and of monitoring the ambient concentrations of sulphur dioxide at selected sites in the Policy Area and use this data to assess the adequacy of the model, the associated data and, therefore, the

determination of (4) or (5).

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4. Emissions and modelling results

4.1 Industry emissions proposals and decisions

Industries, through the KIC, were asked to identify and quantify between one (i.e. fixed emissions) and ten emissions cases that were expected to occur at their facilities and the associated probability that each emissions case would occur. An “emissions case” is a defined combination of emissions from the various sulphur dioxide sources within a plant.

For some industries, the details of probabilistic emission limits had been previously determined via Part IV approvals or direct interaction with DEC.

The emissions defined by industries were reviewed by DEC for conformity with the principles in Section 3.1.

For each industry emission case, the emission characteristics for each individual source (i.e.

volume, temperature, and mass emission rates) were also defined. The combined details of industry emissions are given in Table 2, for use in modelling. The source called BP

THEORETIC refers to a collection of low emission rate sources.

Table 2: Proposed Industry Emission Cases for Sulphur Dioxide

Case No. Probability (%) Source SO2

Emission Rate (kg/s)

Volumetric Flowrate

(m³/s)

Density (kg/m³)

BP Refinery

BP VDU 2 0.0049 7.5 0.7

BP WEST 10 0 10 0.6

BP WEST 20 0.01 20 0.6

BP WEST 70 0 70 0.6

BP WEST 200 0 200 0.6

BP WEST 300 0 300 0.6

BP CRACKER 0.215 90 0.59

BP SRU 1 0.0304 4.8 0.39

BP SRU 2 0.0371 5.1 0.39

Case 1 Normal 200-300 g/s

56.929%

BP THEORETIC 0.0026 16.8 0.7

BP VDU 2 0.0033 7.5 0.7

BP WEST 10 0.005 10 0.6

BP WEST 20 0 20 0.6

BP WEST 70 0 70 0.6

BP WEST 200 0 200 0.6

BP WEST 300 0 300 0.6

BP CRACKER 0.14 90 0.59

BP SRU 1 0.0225 4.8 0.39

BP SRU 2 0.0275 5.1 0.39

Case 2 Normal 150-200g/s

20.000%

BP THEORETIC 0.0018 16.8 0.7

BP VDU 2 0.013 7.5 0.7

BP WEST 10 0 10 0.6

BP WEST 20 0 20 0.6

BP WEST 70 0 70 0.6

BP WEST 200 0.28 200 0.6

BP WEST 300 0 300 0.6

BP CRACKER 0 90 0.59

BP SRU 1 0 4.8 0.39

BP SRU 2 0 5.1 0.39

Case 3 RCU and SRU

Shutdown Hydrofiners to flare

10.959%

BP THEORETIC 0.007 16.8 0.7

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(m³/s)

BP VDU 2 0.0033 7.5 0.7

BP WEST 10 0.005 10 0.6

BP WEST 20 0 20 0.6

BP WEST 70 0 70 0.6

BP WEST 200 0 200 0.6

BP WEST 300 0 300 0.6

BP CRACKER 0.1 90 0.59

BP SRU 1 0.018 4.8 0.39

BP SRU 2 0.022 5.1 0.39

Case 4 Normal

<150 g/s

10.000%

BP THEORETIC 0.0018 16.8 0.7

BP VDU 2 0.0033 7.5 0.7

BP WEST 10 0 10 0.6

BP WEST 20 0.01 20 0.6

BP WEST 70 0 70 0.6

BP WEST 200 0 200 0.6

BP WEST 300 0 300 0.6

BP CRACKER 0.25 90 0.59

BP SRU 1 0.03825 4.8 0.39

BP SRU 2 0.04675 5.1 0.39

Case 5 Normal High RCU S

feed

0.936%

BP THEORETIC 0.0018 16.8 0.7

BP VDU 2 0.0033 7.5 0.7

BP WEST 10 0 10 0.6

BP WEST 20 0 20 0.6

BP WEST 70 0.18 70 0.6

BP WEST 200 0 200 0.6

BP WEST 300 0 300 0.6

BP SRU 1 0.02925 4.8 0.39

BP SRU 2 0.03575 5.1 0.39

Case 6 Minor Flaring Events

@ Low S RCU Feed

0.342%

BP THEORETIC 0.0018 16.8 0.7

BP VDU 2 0.0033 7.5 0.7

BP WEST 10 0 10 0.6

BP WEST 20 0 20 0.6

BP WEST 70 0.13 70 0.6

BP WEST 200 0 200 0.6

BP WEST 300 0 300 0.6

BP SRU 1 0.02925 4.8 0.39

BP SRU 2 0.03575 5.1 0.39

Case 7 Minor Flaring Events

@ High S RCU Feed

0.285%

BP THEORETIC 0.0018 16.8 0.7

BP VDU 2 0.0033 7.5 0.7

BP WEST 10 0 10 0.6

BP WEST 20 0 20 0.6

BP WEST 70 0 70 0.6

BP WEST 200 0 200 0.6

BP WEST 300 0.86 300 0.6

BP SRU 1 0.01575 4.8 0.39

BP SRU 2 0.01925 5.1 0.39

Case 8 SRU Trip, Wet Gas Compressor Upset and Other major Flaring Events @ Low

Sulphur RCU feed

0.263%

BP THEORETIC 0.0018 16.8 0.7

BP VDU 2 0.0033 7.5 0.7

BP WEST 10 0 10 0.6

BP WEST 20 0 20 0.6

BP WEST 70 0 70 0.6

Case 9 SRU Trip, Wet Gas Compressor Upset and Other major Flaring Events @

0.228%

BP WEST 200 0 200 0.6

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(m³/s)

BP WEST 300 0.73 300 0.6

BP SRU 1 0.02925 4.8 0.39

BP SRU 2 0.03575 5.1 0.39

High Sulphur RCU feed

BP THEORETIC 0.0018 16.8 0.7

BP VDU 2 0.0248 7.5 0.7

BP WEST 10 0.005 10 0.6

BP WEST 20 0 20 0.6

BP WEST 70 0 70 0.6

BP WEST 200 0 200 0.6

BP WEST 300 0 300 0.6

BP CRACKER 0.16 90 0.59

BP SRU 1 0.0315 4.8 0.39

BP SRU 2 0.0385 5.1 0.39

Case 10 Furnace

Upset 0.057%

BP THEORETIC 0.1403 16.8 0.7

Tiwest

Case 1 80.00% 0.005 5.9 0.347

Case 2 18.00% 0.085 28.5 0.347

Case 3 2.00%

TIWEST BYPASS

0.155 49.1 0.347

International Power

HRSG1A 0.01 173.7 0.827

Case 1 99.00%

HRSG1B 0.01 173.7 0.827

HRSG1A 0.025 173.7 0.827

Case 2 1.00%

HRSG1B 0.025 173.7 0.827

Nickel West - KNR

KNR SF 123 0.002 6.9 0.5

KNR H2S PLANT 0 1.4 0.28

Case 1

Normal Operations 98.50%

KNR H2S SCRUB 0 0.3 0.28

KNR SF 123 0.002 6.9 0.5

KNR H2S FLARE 0 1.4 0.28

Case 2 H2S Vent Gas Scrubber Flare upset

1.20%

KNR H2S SCRUB 0.0095 0.3 0.28

KNR SF 123 0.002 6.9 0.5

KNR H2S FLARE 0.007 1.4 0.28

Case 3 New H2S Plant Flare

Upset

0.30%

KNR H2S SCRUB 0 0.3 0.28

Alcoa

ALC POWERHSE 1 0.00055 55.1 0.735 ALC POWERHSE 2 0.00055 56.8 0.767 ALC POWERHSE 3 0.00055 65.8 0.735 ALC POWERHSE 4 0.00055 66.2 0.731 ALC CALCINER 1 0.00067 58.1 0.614 ALC CALCINER 2 0.00067 66.8 0.614 Case 1

Normal 50.00%

ALC CALCINER 3 0.00067 73.9 0.614 ALC POWERHSE 1 0.00055 55.1 0.735 ALC POWERHSE 2 0.00055 56.8 0.767 ALC POWERHSE 3 0.00055 65.8 0.735 ALC POWERHSE 4 0.00055 66.2 0.731 ALC CALCINER 1 0.00167 58.1 0.614 ALC CALCINER 2 0.00167 66.8 0.614 Case 2

Oil Test 40.00%

ALC CALCINER 3 0.00167 73.9 0.614 ALC POWERHSE 1 0.00055 55.1 0.735 ALC POWERHSE 2 0.00055 56.8 0.767 ALC POWERHSE 3 0.00055 65.8 0.735 ALC POWERHSE 4 0.00055 66.2 0.731 ALC CALCINER 1 0.00467 58.1 0.614 Case 3

Gas Outage

10.00%

ALC CALCINER 2 0.00467 66.8 0.614

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(m³/s)

ALC CALCINER 3 0.00467 73.9 0.614 Cockburn Cement

CC KILN 1&2 0.00675 29.6 0.64

CC KILN 3 0.00987 77.8 0.74

CC KILN 4 0.00987 93.5 0.73

CC KILN 5 0.00339 116 0.71

Case 1

30g/s 50.00%

CC KILN 6 0.00012 113.7 0.91 CC KILN 1&2 0.018 29.6 0.64

CC KILN 3 0.02632 77.8 0.74

CC KILN 4 0.02632 93.5 0.73

CC KILN 5 0.00904 116 0.71

Case 2

80 g/s 40.00%

CC KILN 6 0.00032 113.7 0.91 CC KILN 1&2 0.068 29.6 0.64

CC KILN 3 0.02632 77.8 0.74

CC KILN 4 0.02632 93.5 0.73

CC KILN 5 0.00904 116 0.71

Case 3

130g/s 9.00%

CC KILN 6 0.00032 113.7 0.91 CC KILN 1&2 0.118 29.6 0.64

CC KILN 3 0.02632 77.8 0.74

CC KILN 4 0.02632 93.5 0.73

CC KILN 5 0.00904 116 0.71

Case 4

180g/s 1.00%

CC KILN 6 0.00032 113.7 0.91 Verve

SEC STAGE A 0.34 356 0.823

SEC STAGE B 0 354 0.805

Case 1 100.00%

SEC STAGE C 0.35 374 0.84

HIsmelt

Case 1 100.00% HISMELT 0.035 130 1.07

Notes

1. Emission volume and density provided at stack conditions.

Within Table 2 the “BP WEST 10” to “BP WEST 300” emission sources represent the Western Flare at the BP Refinery operating under different flow conditions. For the purpose of processing emissions cases it is convenient to treat the different flow conditions as multiple co-located sources (flares), each of which only emits within the case related to its flow condition. The Tiwest Bypass stack was also modelled as three co-located sources due to the differences in its emission volume.

HIsmelt’s emissions are constrained to comply with its Public Environmental Review (PER) (HIsmelt, 2002) and associated approvals under Part IV of the Environmental Protect Act 1986. A probabilistic distribution of sulphur dioxide emissions is defined by the data in

Appendix C of the HIsmelt PER, with emissions well below the peak 35 g/s most of the time.

HIsmelt has indicated that it is likely to require an allocation for emissions greater than 35 g/s to accommodate outages of its scrubbing equipment. HIsmelt will need to seek advice from the EPA in relation to this change to its proposal. The current determination reflects

HIsmelt’s 2002 approval, however a constant emission rate of 35 g/s has been used in the modelling to informally reserve “space” for HIsmelt’s scrubber outage requirements.

DEC advised Cockburn Cement in 2001 about its decision regarding acceptable sulphur dioxide emissions from its Munster operations based on an analysis of emission monitoring

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data provided to DEC under licence conditions. This advice was for site-wide total emissions as follows:

• 30 g/s for 50% of the time;

• 80 g/s for 40% of the time;

• 130 g/s for 9% of the time; and

• 180 g/s for 1% of the time.

In order to complete the modelling, it was assumed that the distribution of the emissions between the Cockburn Cement stacks for the 30 g/s and 80 g/s cases were as per the ratios used in the 1992 determination with a small amount allocated to Kiln 6. For the remaining two cases, the emissions above the 80 g/s were assumed to be emitted from the Kiln 1 and 2 stack which had the lowest emission volume and was therefore assumed to most likely result in the highest predicted ground level concentrations. The modelling is likely to be conservative (i.e. results in a conservatively high estimate of the maximum ground level concentrations).

4.2 Modelling of industry emissions - setup

As per the redetermination procedure, both versions of DISPMOD (i.e. DISPMOD97 and DISPMOD05) have been used in modelling to determine the acceptability of industry emissions for the purpose of the current redetermination. The models have been run for three individual years of meteorological data being 1980 (the data used in the 1992

determination), 1995 and 1996 (the data used in the verification studies discussed in Section 2.3).

The air dispersion modelling was completed using three model domains as summarised in Table 3.

Domain Name Full Eastern Northern

Bottom Left Coordinate (mE AMG) 375000 385700 386350 Bottom Left Coordinate (mN AMG) 6424000 6433050 6442600

Number of x coordinates 21 18 18

Number of x coordinates 26 18 18

Grid Interval (m) 1000 100 100

The full model domain is the same as that used in the 1992 determination and covers the area shown on Figure 6 with a grid interval of 1,000 m. The northern and eastern model domains were used to better define the potential impacts in areas where elevated concentrations (1-hour average for northern and 24-hour average for eastern) were predicted to occur on the full grid. The northern and eastern model domains used a grid interval of 100 m and are also shown on Figure 6.

All model input files are held by the DEC Air Quality Management Branch and are available for inspection.

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4.3 Modelling of industry emissions - results

Table 4 presents the summary of the modelling results for the three model domains and the predicted ground level concentrations are also presented as Figures 7 to 52 (Appendix A).

o Full Model Domain

The results presented in Table 4 and Figures 7 to 28 show that there are no predicted exceedances of the EPP limits across the model domain for either model (i.e. DISPMOD97 or DISMPOD05) or modelled year. DISPMOD05 predicted a very localised area of

exceedance of the 1-hour standard (based on the predicted 9^th highest concentrations being above the standards) in the immediate vicinity of the BP Refinery. Based on the information presented in Section 2.3, it is thought that these high concentrations are associated with the modelled convective down-mixing and Draxler’s lateral plume dispersion formulation and may represent an over-prediction of the actual ground level concentrations in this area. In any event the apparent exceedances are predicted to occur on BP’s property due to BP’s emissions – this is not covered under the EPP (see the EPP clause 6(2)).

DISPMOD05 also predicted exceedances of the EPP 24-hour standard in Area A over an area in the vicinity of the BP Refinery for the 2006 model year (see Figure 24). The second highest 24-hour average concentration of sulphur dioxide predicted for each grid point across the model domain is presented as Figure 25 and shows that the maximum second highest predicted 24-hour average concentration (193 µg/m³) was below the EPP 24-hour standard for Area A. Again, the apparent exceedance on BP property is not covered by the EPP.

o Eastern and Northern Model Domains

No exceedances of the EPP limits were predicted across the eastern and northern modelling domains. While there were a number of predicted exceedances of the 1-hour standard in some of the modelled years, there were no more than four exceedances of the Area C 1- hour standard predicted in any single year. The 99.9^th percentile 1-hour average and maximum 24-hour average concentrations were all predicted to be well below the EPP standard for each of the EPP areas.

DISPMOD05 tended to predict higher ground level concentrations than DISPMOD97 over the northern model domain and it is expected that this is due to the convective down-mixing, Draxler’s lateral plume dispersion formulation and the proximity of the Cockburn Cement emission sources.

Over the eastern modelling domain DISPMOD97 and DISPMOD05 tended to predict similar ground level concentrations.

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Table 4a: Air Dispersion Modelling Results – Full Modelling Domain

DISPMOD 1997 DISPMOD 2005 EPP Guidelines % of guidelines DM 1997 % of guidelines DM 2005 Full Domain EPP

Area 1980 1995 1996 1980 1995 1996 Standard Limit 1980 1995 1996 1980 1995 1996

A 682 717 700 965 1016 1084 na 1400 49% 51% 50% 69% 73% 77%

B 422 412 416 454 481 450 na 1000 42% 41% 42% 45% 48% 45%

1hr max. (µg/m³)

C 305 316 323 375 357 339 na 700 44% 45% 46% 54% 51% 48%

A 515 605 591 730 872 869 700 na 74% 86% 84% 104% 125% 124%

B 319 298 338 335 322 362 500 na 64% 60% 68% 67% 64% 72%

1hr 99.9th percentile (µg/m³)

C 233 223 257 235 233 258 350 na 67% 64% 73% 67% 67% 74%

A 33 80 63 132 166 127

B 3 2 7 5 4 12 No. hours 1hr max.

>350 µg/m³

C 0 1 0 1 1 1

A 10 27 23 34 96 72

B 0 0 0 0 1 0

No. hours 1hr max.

>500 µg/m³

C 0 0 0 0 0 0

A 0.7 1.6 1.0 11 39 32

B 0 0 0 0 0 0

No. hours 1hr max.

>700 µg/m³

C 0 0 0 0 0 0

A 106 117 121 143 186 208 200 365 29% 32% 33% 39% 51% 57%

B 84 94 91 98 93 126 150 200 42% 47% 45% 49% 47% 63%

24hr max. (µg/m³)

C 72 97 67 70 87 68 125 200 36% 49% 34% 35% 44% 34%

A 0 0 0 3 6 5

B 0 0 0 0 0 1

No. days 24hr max.

>125 µg/m³

C 0 0 0 0 0 0

A 24 22 23 31 26 29 60 80 41% 36% 38% 52% 43% 48%

B 14 12 15 14 13 16 50 60 28% 25% 30% 29% 25% 32%

Annual average (µg/m³)

C 11 11 12 10 10 11 50 60 23% 21% 25% 21% 20% 22%

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19 Table 4b: Air Dispersion Modelling Results – Eastern Modelling Domain

DISPMOD 1997 DISPMOD 2005 EPP Guidelines % of guidelines DM 1997 % of guidelines DM 2005 Eastern Domain EPP

A 305 311 342 331 353 354 na 1400 22% 22% 24% 24% 25% 25%

B 431 391 405 470 431 433 na 1000 43% 39% 41% 47% 43% 43%

1hr max. (µg/m³)

C 356 358 329 397 405 379 na 700 51% 51% 47% 57% 58% 54%

A 202 228 210 220 241 228 700 na 29% 33% 30% 31% 34% 33%

B 261 292 261 281 311 281 500 na 52% 58% 52% 56% 62% 56%

C 200 251 208 218 266 227 350 na 57% 72% 59% 62% 76% 65%

A 0 1 1 1 1 1 B 3 3 4 4 6 4 No. hours 1hr max.

>350 µg/m³

C 1 2 0 1 3 1 A 0 0 0 0 0 0 B 0 0 0 1 1 0 No. hours 1hr max.

>500 µg/m³

>700 µg/m³

C 0 0 0 0 0 0 A 62 52 70 63 53 70 200 365 31% 26% 35% 31% 26% 19%

B 88 72 64 89 74 67 150 200 59% 48% 43% 60% 49% 45%

24hr max. (µg/m³)

C 54 68 50 56 70 51 125 200 43% 55% 40% 44% 56% 41%

A 0 0 0 0 0 0 B 0 0 0 0 0 0 No. days 24hr max.

>125 µg/m³

C 0 0 0 0 0 0 A 6 5 5 6 5 5 60 80 9% 9% 9% 9% 9% 9%

B 8 7 8 8 7 8 50 60 17% 14% 16% 17% 14% 16%

C 5 5 4 5 5 4 50 60 9% 9% 9% 10% 9% 9%

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Table 4c: Air Dispersion Modelling Results – Northern Modelling Domain

DISPMOD 1997 DISPMOD 2005 EPP Guidelines % of guidelines DM 1997 % of guidelines DM 2005 Northern Domain EPP

A 381 320 381 480 434 506 na 1400 27% 23% 27% 34% 31% 36%

B 329 308 356 371 367 409 na 1000 33% 31% 36% 37% 37% 41%

1hr max. (µg/m³)

C 350 305 363 396 359 416 na 700 50% 44% 52% 57% 51% 59%

A 292 250 300 350 313 369 700 na 42% 36% 43% 50% 45% 53%

B 269 248 287 292 272 317 500 na 54% 50% 57% 58% 54% 63%

C 277 246 288 298 263 315 350 na 79% 70% 82% 85% 75% 90%

A 2 1 2 9 5 12 B 1 0 1 2 1 4 No. hours 1hr max.

>350 µg/m³

>500 µg/m³

>700 µg/m³

C 0 0 0 0 0 0 A 80 103 66 90 94 80 200 365 40% 52% 33% 45% 47% 22%

B 75 105 69 82 95 72 150 200 50% 70% 46% 55% 63% 48%

24hr max. (µg/m³)

C 74 105 65 78 95 68 125 200 59% 84% 52% 62% 76% 54%

A 0 0 0 0 0 0 B 0 0 0 0 0 0 No. days 24hr max.

>125 µg/m³

C 0 0 0 0 0 0 A 14 12 14 15 13 16 60 80 23% 20% 24% 25% 22% 26%

B 13 12 14 15 13 15 50 60 27% 25% 28% 29% 26% 30%

C 13 12 13 12 12 13 50 60 25% 24% 27% 25% 24% 26%

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5. Redetermination of maximum permissible quantities

This section provides details of the redetermination of maximum permissible quantities of sulphur dioxide following the procedure of Section 3.2 and in light of the successful modelling of emissions described in Section 4.

Table 5 lists the maximum permissible quantities of sulphur dioxide for each industry with significant emissions of sulphur dioxide in the Policy Area of the Kwinana EPP. The

maximum permissible quantities are expressed as site totals as per the revised procedure.

maximum permissible quantities have been obtained from the detailed information in Table 2 (exceptions and variations described below) but have been re-expressed in a form more appropriate for licence conditions and more useful for progressive tracking of compliance.

If the percentage of time is 0%, this means the associated maximum permissible quantity is never to be exceeded

Some of the 10 cases modelled for BP had exactly the same total emission rates as other cases. Such cases have been combined yielding six cases in Table 5.

The formula for Verve is as per the 1992 determination (the emissions for Verve in Table 2 were in accordance with this formula).

The maximum permissible quantities assigned to HIsmelt were derived by DEC from Figure 4-4 of Appendix C in the PER (HIsmelt, 2002). A small comfort margin was applied to the emissions profile except for the upper limit of 35 g/s. HIsmelt has the opportunity to seek approval from the EPA for a change to its project as approved in 2002 in order to accommodate infrequent plant upset conditions with an emission rate greater than 35 g/s.

If this is approved, HIsmelt’s maximum permissible quantities will be redetermined accordingly.

Separate from the redetermination of maximum permissible quantities in the form of site totals, it may be the case for some industries that DEC applies conditions of licence specifying limits and/or targets on the sulphur dioxide emissions from particular sources within industrial premises, as is currently done. Any such limits and/or targets will not be inconsistent with the maximum permissible quantities expressed as site totals.

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Table 5. maximum permissible quantities of sulphur dioxide for each industry in the Kwinana EPP Policy Area

Column A Column B

Maximum Permissible Quantities (g/s)

% of time in any 12 consecutive calendar months for which total site emissions

may exceed the emission rate in Column A BP Refinery

150.1 90.00%

200.1 70.00%

300 2.11%

350.1 0.83%

400.1 0.49%

1000.1 0.00%

Tiwest

5 20.00%

85 2.00%

155 0.00%

International Power

20 1.00%

50 0.00%

Nickelwest - KNR

2 1.50%

9 1.20%

11.5 0.00%

Alcoa

4.21 50.00%

7.21 10.00%

16.21 0.00%

Cockburn Cement

30 50.00%

80 10.00%

130 1.00%

180 0.00%

Verve

Formula for Stages A and C:

QA+QC/2.2=530; 0.00%

QC not greater than 530, where QA and QC are quantities from Stages A and C respectively.

HiSmelt

13 65.00%

21 5.00%

35 0.00%

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6. Monitoring

Monitoring and reporting of sulphur dioxide emissions is required as an ongoing condition of licence on all industries covered under this redetermination.

There are no changes currently envisaged to monitoring and reporting of ambient

concentrations of sulphur dioxide. As described in 2.2 and marked on Figure 1, monitoring is currently occurring at:

• Wattleup (DEC owned and operated);

• Rockingham (DEC owned and operated);

• Miguel Road (KIC owned and operated);

• Abercrombie Road (KIC owned and operated); and

• Fancote Avenue (KIC owned and operated).

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7. References

Draxler, R.R, 1976. “Determination of Atmospheric Diffusion Parameters”

Atmospheric Environment, 10, 99-105

EPA, 1992. “Development of an Environmental Protection Policy for Air Quality at Kwinana”. Environmental Protection Authority, Bulletin 644, August 1992 EPA 1999, Revised Draft Environmental Protection (Kwinana) (Atmospheric

Wastes) Policy 1999. Report to the Minister for the Environment.

Environmental Protection Authority, Perth, Western Australia, June 1999 HIsmelt. 2002, Commercial HIsmelt Plant Kwinana Western Australia :

Public Environmental Review. HIsmelt (Operations) Pty Ltd, April 2002.

Rayner K. 1992, ‘Development of an Environmental Protection Policy for air quality at Kwinana’, Proceedings of the 11th International Clean Air and

Environment Conference, Brisbane, 1992, Clean Air Society of Australia &

New Zealand, Eastwood, NSW, Australia

Rayner, K. and Blockley, A. 2000. “Improvements in the coastal dispersion model DISPMOD”. Proceedings of the 15

^thConference of the Clean Air Society of Aust. and New Zealand, Sydney, November, 2000. Clean Air Society of

Australia & New Zealand, Eastwood, NSW, Australia

Sawford B. L., Young S. A., Noonan J. A., Luhar A. K., Hacker J. M., Carras J. N.,

Williams D. J. and Rayner K. N. 1996 ‘The 1995 Kwinana Fumigation Study

- I. Program overview, experimental design and some results.’ Proceedings

of the 13th International Clean Air and Environment Conference, Adelaide, 1996, Clean Air Society of Australia & New Zealand, Eastwood, NSW,

Australia.

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Appendix A Figures

Figure 1. Kwinana EPP Area A and B Boundaries and Monitoring Station Sites

Note: The areas shown on this map are approximate only. The official map is the DEP Map 990902 held by the DEC.

Area A to B Boundary Area B to C Boundary

Date: 15 April 09 Drawn: BB

Project: EPP SO2 Redetermination Client: Kwinana Industries Council

Miguel Road

Wattleup

Hope Valley

Abercrombie Road Henderson Road

North Rockingham

Hillman Primary School

Rhodes Park Fanstone Av Fancote Av

Area A

Area B

Area C

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Figure 2. Ambient Sulphur Dioxide Monitoring Results for the Kwinana Region

Source: DEC (Pers. comm. Arthur Grieco, DEC, 2 April 2009)

Abecrombie Road (Area C)

0 100 200 300 400 500 600 700

93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08

SO2 ug/m

Area C Limit

Area C Standard

Miguel Road (Area C)

0 100 200 300 400 500 600 700

93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08

SO2 ug/m

Area C Limit

Area C Standard

Rockingham (Area C)

0 100 200 300 400 500 600 700

93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08

SO2 ug/m

Area C Limit

Area C Standard

Hillman Primary / Rhodes Park / Henderson Rd / Fanstone Ave /

Fancote Ave (Area B)

0 100 200 300 400 500 600 700 800 900 1000

93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08

SO2 ug/m

Area B Limit

Area B Standard

6 months on Fanstone Avenue 10 months on

Rhodes Park

Hillman Primary School

Hope Valley (Area B)

0 100 200 300 400 500 600 700 800 900 1000

93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08

SO2 ug/m

Area B Limit

Area B Standard

Wattleup (Area B)

0 100 200 300 400 500 600 700 800 900 1000

93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08

SO2 ug/m

Area B Limit

Area B Standard

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Figure 3. Illustration of Shoreline Fumigation under a TIBL Source: EPA (1992) Date: 15 April 09Drawn: BBProject: EPP SO2 Redetermination Client: KwinanaIndustries Council Date: 15 April 09Drawn: BBProject: EPP SO2 Redetermination

Client: KwinanaIndustries Council

Redetermination of maximum permissible quantities of sulphur dioxide under the Environmental Protection (Kwinana) (Atmospheric Wastes) Policy 1999