Project Sea Dragon
Core Breeding Centre and Broodstock Maturation Centre, Bynoe Harbour
Draft Environmental Impact Statement
PART B ‐ ENVIRONMENTAL ASSESSMENT 13‐256
13 AIR QUALITY AND NOISE
13.1 TERMS OF REFERENCE ADDRESSED IN CHAPTER
This chapter provides a description of potential air and noise impact from incineration and power facilities
associated with the Project as required under Section 4.1 and 4.3.3 of the ToR.
Two options for disposal of prawn mortalities are being considered by Seafarms i.e. disposal by incineration or
transport and disposal offsite to landfill. In the event incineration is selected as the preferred option, the
assessment air quality emissions from the incinerator applies to the proposed action.
Potential air and noise emissions from the power facility on site has been assessed to address Section 4.1 of the
ToR.
Table 13‐1 summarises the requirements of the ToR and references where they have been addressed in this
EIS.
TABLE 13‐1 TERMS OF REFERENCE
Terms of Reference Sections
4 Risk Assessment
4.1 The EIS should be undertaken with specific emphasis on the
identification, analysis and mitigation of potential impacts through a
whole‐of‐project risk assessment.
Chapter 6 and 13
4.3.3 Mitigation and monitoring
If incineration is proposed, the EIS should refer to the NT EPA
Guideline Disposal of Waste by Incineration at
https://ntepa.nt.gov.au/waste‐pollution/guidelines/guidelines, for
information that should be considered.
Chapter 13
Appendix 19
13.2 OVERVIEW
Based on the risk assessment undertaken in Chapter 6, incineration and power station facilities have been
identified as potentially impacting sensitive receptors within close proximity to the facilities. This chapter
provides a summary of the assessment criteria, assessment method and predicted impacts at the nearest
sensitive receiver when the Project is at full scale operation, and outlines management measures.
The nearest sensitive receptor to the incineration and power generation facilities is the accommodation facility
located approximately 60 m to the southwest. The power station and accommodation locations are shown in
Figure 1‐4 and Figure 13‐1. The incinerator will be located in close proximity to the power facility fuel storage,
currently within the common facilities area, and be housed in a shed.
Project Sea Dragon
Core Breeding Centre and Broodstock Maturation Centre, Bynoe Harbour
Draft Environmental Impact Statement
PART B ‐ ENVIRONMENTAL ASSESSMENT 13‐257
FIGURE 13‐1 LOCATION OF PROPOSED POWER FACILITY AND ACCOMMODATION FACILITY
The National Environment Protection Council (NEPC) set uniform standards for Australian ambient air in
February 2016. These are known as the National Environment Protection (Ambient Air Quality) Measure (Air
NEPM), which sets non‐binding standards and ten‐year goals. In the absence of specific Northern Territory
regulated standards, appropriate criteria have been adopted from other jurisdictions and the most stringent
NEPM goals and standards have been used as a benchmark. It should be noted that the NEPM is for ambient
monitoring and not for the regulation of specific point sources.
There is no specific guidance in the Northern Territory for the assessment and management of air quality
impacts however guidelines exist for disposal of waste by incineration (Guideline for disposal of waste by
incineration, NT EPA 2013).
A conservative screening level assessment has been undertaken to determine the potential air quality impacts
to sensitive receptors within the area as a result of incineration and power generation facilities proposed
during operation of the project. Occupational air quality impacts on workers at these facilities has not been
assessed.
13.2.1 Air emissions from power facility
The proposed power facility at the site will generate 6 MW of power A worst case scenario was assessed
including nine CAT32 diesel generators, packaged in containers. One of the generators would remain in
standby, and the assessment assumes that eight would be operating at any one time. The exact generator
model and layout is subject to detailed design and commercial arrangements.
Project Sea Dragon
Core Breeding Centre and Broodstock Maturation Centre, Bynoe Harbour
Draft Environmental Impact Statement
PART B ‐ ENVIRONMENTAL ASSESSMENT 13‐258
Emissions from the diesel generators have been obtained from the product specification and are summarised
in Table 13‐2. The most significant air pollutant generated by this facility, based on the ratio of its emission rate
to impact assessment criterion, will be nitrogen dioxide (NO2) released as oxides of nitrogen (NOx) from onsite
diesel generation units. NOx from combustion consists largely of nitric oxide (NO) and partly NO2, and after
emission from the stack NO is transformed to NO2 through oxidation with atmospheric ozone. This process is
accelerated in warmer temperatures and sunlight.
In accordance with the US EPA Guideline of Air Quality Models (2005), the US EPA emission database specifies
a 5.7 % exhaust exit ratio of NO2 to NOx for Caterpillar reciprocating diesel generators. For a screening
assessment, a conservative ratio of 10% has been assumed – this allows for some oxidation to occur in the
near‐field immediately after release from an exhaust.
Even though the immediate exhaust exit NO2 to NOx ratio is likely to be below 10%, the high heat and
ultraviolet light levels can lead to rapid oxidation in a tropical climate and a ratio of 30% is a conservative
assumption. A scenario has also been assessed assuming a ratio of 30%.
TABLE 13‐2 DIESEL GENERATION NOX EMISSIONS
Pollutant Emissions
(g/hp‐hr)*
Emissions g/s
(1 generator)
Emissions from 8 generators
(g/s)
NOx 5.8 1.73 13.84
NO2 – 10% conversion 0.173 1.384
NO2 – 30% conversion 0.519 4.152
*grams per horsepower‐hour
As the air quality criteria is the 100th percentile, worst case conditions would generally occur in every direction
from the power facility for at least one hour per year. A review of wind rose data from Dum In Mirrie (BoM site
014277) shows that winds are predominantly from the west (wet season), and east (dry season) with very little
wind from the south during the year.
A screening level air quality assessment was undertaken using AUSPLUME assuming worst‐case meteorological
conditions. Each generator is assumed to have a 7 m high, 0.2 m diameter stack, with an exit velocity of
21.9 m/s. The exit velocity is based on exhaust flow rates given in the CATC32 specification. Eight out of the
nine generators are assumed to be operating concurrently.
13.2.2 Air emissions from incineration
The proposed incinerator is a small dual chamber system. Waste is burnt in the primary chamber and hot gases
and emissions are burnt in the secondary chamber. The incinerator will be located in close proximity to the
power facility fuel storage and be housed in a shed.
An incinerator with a burn rate of 50 kg/hr is proposed in order to dispose of prawn carcasses/mortalities. At
full scale operation of the BMC and CBC the potential incineration task is approximately 200 kg of prawn
carcasses each week. Given the capacity of the proposed unit, this equates to the incineration of 50 kg of
prawn mortalities for one hour four times per week. However initially, the task is much less. The incinerator is
proposed to be located adjacent the power facility, approximately 90 m away from the accommodation facility.
Project Sea Dragon
Core Breeding Centre and Broodstock Maturation Centre, Bynoe Harbour
Draft Environmental Impact Statement
PART B ‐ ENVIRONMENTAL ASSESSMENT 13‐259
The NT Guideline for Disposal of Waste by Incineration (2013) sets out emission limits for incinerators as well
as other requirements listed below:
Two chambers
A minimum temperature of 850 ºC in the primary chamber
Air supply to achieve efficient combustion of all wastes
A minimum retention time of two seconds
No impingement of exhaust gases onto building or sensitive sites.
The guideline also recommends a radial buffer distance of 500 m between the incinerator and any sensitive
land uses such as the accommodation facilities. The incinerator may achieve the air quality goals under normal
operation, however should equipment fail, accidents occur or following other causes, then a buffer is a means
to let these residual emissions dissipate without adversely impacting on sensitive land uses or amenity. The
guideline does not consider the volume of waste being incinerated, nor the frequency of operation.
Waste is burnt in the primary chamber and hot gases and emissions are burnt in the secondary chamber. The
incinerator will be located in close proximity to the power facility fuel storage and be housed in a shed.
The proposed incinerator with a two second retention, secondary chamber meets requirements of the NT EPA
guideline listed above, however the proposed buffer distance of 500 m has not been achieved (refer to Figure
13‐2).
13.2.3 Noise from power facility
Noise levels for each generator (CAT32, 800 eKW) were modelled assuming a sound pressure level of 85 dB(A)
at one metre, as required in the design specification. The generators are enclosed within containers and the
noise level is assumed to be outside of the container.
NT EPA offers guidance for noise levels from construction sites (Noise guidelines for development sites in the
Northern Territory (NT EPA 2014) however has no guidelines for operational noise impacts. Intrusive noise
impacts are often assessed as acceptable where the industrial noise source does not exceed the background
noise level by more than 5 dB(A). An example of this is the NSW Industrial Noise Policy 2000 which classifies
intrusive noise as being ‘noise that intrudes above the background level by more than 5 decibels’.
13.3 POTENTIAL IMPACTS
13.3.1 Air emissions from power facility
The worst case predicted hourly NO2 levels at a distance of 60 m from the power facility is an hourly average
peak of 123 µg/m³, which is 50% of the impact assessment criterion. The distance of 60 m represents the
approximate distance of the accommodation facility in the proposed concept layout (Figure 1‐4).
Assuming the conservative 30% conversion of NOX to NO2, an additional model scenario was run. The predicted
peak hourly NO2 at the accommodation facility is 370 µg/m³, which exceeds the criterion. A buffer of 300 m
from the power facility is needed in order to reduce the maximum predicted impact to the criteria level of 246
µg/m³.
The screening air quality assessment shows that operation of the power facility has the potential to exceed the
maximum hourly average NO2 level at the accommodation facility.
Project Sea Dragon
Core Breeding Centre and Broodstock Maturation Centre, Bynoe Harbour
Draft Environmental Impact Statement
PART B ‐ ENVIRONMENTAL ASSESSMENT 13‐260
13.3.2 Air emissions from incineration
The UK government considers that “The use of an onsite incinerator with afterburner can be considered to
represent BAT for animal remains disposal” (BAT = Best Available Technology) (DEFRA, 2002, p.viii). Further,
the UK consider "shells from shellfish with soft tissue" as Category 2 ABP (Animal by Product) and allow for
small onsite incineration (with similar operational controls to that of the NT EPA Guideline) and this is classed
as low risk.
Relevant allowable emission limits from incinerators in the Northern Territory are presented below in Table
13‐3. Arsenic and mercury are included as they are possible in an industry related to marine organisms. Also
note that the United Kingdom Department for Environment, Food & Rural Affairs (DEFRA) (2002) found that
dioxin and furans can be generated by small carcass incinerators with afterburners – poultry farms, general
farms and hunt kennels generating levels above recognised best practice standards (a pig farm incinerator
operating on diesel was right on the 0.1 ng/m³ limit).
TABLE 13‐3 SUMMARY OF RELEVANT ALLOWABLE INCINERATOR EXHAUST EMISSIONS
Substance Emission limit Source
Particles (as TSP) 50 mg/m³ NTEPA Waste Incinerator Guidelines adopting the
Biohazard Waste Industry (BWI) of Australia and
New Zealand Industry Code of Practice for the
Management of Clinical and Related Wastes
NOx (as NO2) 350 mg/ m³
SO2 150 mg/m³
HCl 100 mg/m³
Arsenic 0.5 mg/m³
Mercury 0.05 mg/m³
Dioxins / furans 0.1 ng/m³
The proposed incinerator is a small facility and will operate for a limited number of hours during the day, a few
days a week. With such a low mass throughput, a risk assessment approach has identified very low residual
impact upon the environment. Residual risk associated with potential impact can be managed through the
adoption of standard operating procedures that require the facility to be operated when favourable winds limit
exposure to accommodation facilities. Choosing to operate the facilities when accommodation is vacant may
also be possible.
13.3.3 Noise emissions from power facility
Existing background noise levels at the site would be very low, as there are no existing industrial noise sources.
As the power facility will operate during both the day and night time, it is expected that background noise
levels would be below 30 dB(A). In areas where the background noise level may drop below 30 dB(A), a level of
30 dB(A) is adopted. The criteria for this site would therefore be the background plus 5 dB(A), which is 35
dB(A). The day time noise level and criteria would potentially be higher than the night time however as the
power facility operates with a relatively constant noise level the night time would be the most stringent criteria
that needs to be assessed against.
A preliminary noise model has been prepared to gain an understanding of predicted noise levels at the
accommodation village and also how far the power facility should be from the accommodation to minimise
potential noise impacts. The following assumptions in Table 13‐4 were made in the preliminary noise model.
Project Sea Dragon
Core Breeding Centre and Broodstock Maturation Centre, Bynoe Harbour
Draft Environmental Impact Statement
PART B ‐ ENVIRONMENTAL ASSESSMENT 13‐261
TABLE 13‐4 NOISE MODEL ASSUMPTIONS
Input/assumption Data used in the model
Prediction algorithm ISO 9613‐2 ‘Acoustics – Attenuation of sound during propagation
outdoors’
Modelling software Cadna A 4.6
Ground absorption coefficient 1 for soft ground
Generator height 4 m
Number of generators operating 8 (worst case scenario)
Sound pressure level at 1 m 85 dB(A)
Meteorological conditions Atmospheric propagation conditions were modelled with noise
enhancing wind conditions for noise propagation (downwind
conditions) or equivalently a well‐developed moderate ground
based temperature inversions
Preliminary model results show that the predicted noise level at the accommodation facility would be 56 dBA,
which exceeds the adopted noise criteria by more than 20 dBA.
Refer to Figure 13‐2 for an indication of predicted noise contours generated from eight operating generators.
13.4 MITIGATION AND MONITORING
Preliminary air and noise assessments of the proposed power facility and incinerator have been undertaken to
determine potential impacts on the nearest sensitive receiver. The nearest sensitive receivers to the power
facility are personnel at the accommodation facility approximately 60 m away.
The outcomes of the assessment recommended that the accommodation facility be moved to a location that is
approximately 520 m from the power facility in order to achieve both noise and air quality outcomes.
Therefore, as part of detailed design, the location of the power facility will be moved approximately 520 m
south along the access road. In the event incinerator is the preferred method for disposing of prawn
mortalities, the incinerator will also be moved 520 m south along the proposed access road. In the event the
incinerator is not the preferred method for disposing of prawn mortalities, and noise attenuation to achieve
noise criteria was applied to the power facility, the separation distance of 520 m would still be required to
achieve air quality outcomes related to the power facility.
Project Sea Dragon
Core Breeding Centre and Broodstock Maturation Centre, Bynoe Harbour
Draft Environmental Impact Statement
PART B ‐ ENVIRONMENTAL ASSESSMENT 13‐262
FIGURE 13‐2 AIR AND NOISE MODELLING RESULTS
Project Sea Dragon
Core Breeding Centre and Broodstock Maturation Centre, Bynoe Harbour
Draft Environmental Impact Statement
PART B ‐ ENVIRONMENTAL ASSESSMENT 13‐263
13.4.1 Air emissions from power facility
The screening air quality assessment shows that operation of the power facility has the potential to exceed the
maximum hourly average NO2 level at the accommodation facility. The noise assessment for the diesel
generator in dictates a 520 m separation distance would reduce ambient noise at the accommodation facilities
to meet the proposed threshold. A further screening modelling run was performed with this distance. In this
instance, the 1‐hour assessment criterion of 246 µg/m³ can be achieved with an NO2 to NOx ratio of 43%. This
ratio is well within the expected worst‐case scenario due to the tropical conditions.
Even with an oxidation rate producing a 43% NO2 to NOx ratio, the 1‐hr NO2 criterion will not be exceeded at
the accommodation facility 520 m away.
By increasing the separation distance between the power facility and accommodation facility to 520 m, the
potential impact on air quality from power facility air emissions would be a residual risk of Very Low.
13.4.2 Air emissions from incinerator
The following mitigation and design requirements are recommended:
Exhaust should be three metres higher than the top of any building within 100 m of the incinerator
Exhaust efflux velocity should be 10 m/s or more during all operational hours of waste incineration
Once operational, a stack test be undertaken to confirm emission limits comply with requirements of the
NT EPA Guideline for Disposal of Waste by Incineration
Conduct a risk assessment accounting for the small number of hours operating and calculate a mass
balance to assess the potential amount of arsenic and mercury that may be found in prawn carcasses in
prawn carcasses that may be present in exhaust emissions.
By increasing the separation distance between the incinerator and accommodation facility to 520 m, the
potential impact on amenity from incineration air emissions would be a residual risk of Low.
13.4.3 Noise emissions from power facility
Results show that a distance of approximately 520 m would be needed for the sound level emitted from all
eight generators operating at one time to be 35 dB(A) at the accommodation facility. For comparative purposes
the approximate distance to achieve a noise level of 40 dBA would be 320 m and 45 dBA would be 200 m from
the power facility.
Therefore, by increasing the separation distance between the power facility and accommodation facility to
520 m, the potential impact on amenity from power facility noise emissions would be a residual risk of Low.