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5 Actions for Waste Disposal Sources

There are important reasons for making waste disposal the first priority in a dioxin action plan.(See footnote 16)

  • Over half the dioxin currently discharged to air comes from the combustion of waste materials.
  • Even one large municipal waste incinerator could increase total dioxin discharges significantly.
  • Because dioxin concentrations in combustion gases are relatively high, control technologies will be relatively cost-effective.
  • The focus for action in other developed countries has been on dioxin discharged from waste incineration.

The actions recommended in this chapter on waste disposal sources are consistent with and complementary to the Government's proposed Waste Minimisation and Management Strategy.(See footnote 17) As a minimum, the proposed actions should encourage waste minimisation including increased recycling initiatives.

5.1 Landfill fires

Uncontrolled burning of rubbish in landfills is estimated to be the largest source of dioxin discharges to air in New Zealand (39%). Combustion gases from such fires contain more dioxin when the rubbish contains chlorinated materials such as PVC. However, the very poor combustion conditions are also an important factor in the high dioxin discharges.

While landfill fires do reduce the volume of municipal waste, the environmental damage from the discharge of products of incomplete combustion, including dioxin, far outweighs any environmental value of waste reduction. If municipal waste is to be burned, it should be done in a controlled manner using a purpose-built waste incinerator with state-of-the-art emission control systems. The only practical means of reducing discharges from landfill fires is by minimising their occurrence. If this very large source of dioxin discharges to air is not eliminated, the case for controlling any other source is weak.

In 1997 the Ministry for the Environment released guidelines on the hazards of burning at landfills, which explicitly stated, "deliberate burning should not occur". These guidelines, together with regional and industry initiatives, appear to have had some positive effect, with an approximate 50% reduction in the occurrence of landfill fires over the last five years. Nonetheless, data from the New Zealand Fire Service for 2000/01 show that there were still around 130 fires at public and private landfills, not including fires at waste transfer stations. Since action to date has been only partially effective, there is a strong case for banning the discharges to air from the burning of wastes at landfills by way of an NES. This will send a clear and unequivocal message that these discharges are unacceptable.

When landfill fires do occur, it would be important for landfill operators to report these incidences along with information on the severity of the fire, including an estimate of the volume of waste burned. This will enable more accurate discharge estimates to be made for this source in future dioxin inventories.(See footnote 18)

A ban would have additional environmental benefits; it would prevent loss of amenity values to a local community arising from a landfill fire, and would reduce the discharge to air of other toxic contaminants. Most regional council air plans already list waste burning at landfills as a prohibited activity. A ban on air discharges is therefore consistent with these regional initiatives. A ban is also consistent with the Government's current Landfill Management Programme, which seeks to improve landfill standards including management practises.

Regional councils could also require that landfill management plans include mechanisms for the early detection of fires, and procedures for prompt, effective action to extinguish fires that do occur.

Actions
  • Ban discharges to air from the burning of waste within landfill sites, waste transfer stations, and waste recovery sites, through a National Environmental Standard.
  • Educate waste management operators on the environmental impacts of waste burning, and the need for information when landfill fires do occur.
What do we mean by waste when considering action for waste disposal?

Defining waste is problematic. It could be defined generally with specified exclusions, or defined specifically with a detailed list of waste materials. However, the range of possible materials is exceedingly wide and it would be difficult to ensure that all wastes are included in any specific definition. A more general definition is therefore preferred.

For the purposes of dioxin action on waste disposal sources, waste is defined as:
"Any material, whether it is a solid or liquid, that is discarded or discharged for final disposal by its holder".

Disposal means: "Incineration, co-incineration, burning or any other thermal treatment process, with or without recovery of the heat generated".

Dioxin discharges from waste detailed on the New Zealand Waste List are covered by the proposed actions in this plan. Waste includes but is not limited to:

  1. refuse, garbage or municipal waste
  2. hospital, medical, clinical, pathological or veterinary waste
  3. quarantine waste
  4. sludge or solids derived from liquid-borne municipal, industrial or trade waste
  5. agricultural chemicals or agricultural chemical waste
  6. wood preservatives or biocides
  7. wood waste including plywood, particle board or wood waste and timber that may contain halogenated organic compounds, including pentachlorophenol (PCP), or metals as a result of treatment with wood-preservatives or coatings, or wood waste originating from construction and demolition waste.
  8. plastic, rubber, resins or adhesives
  9. paints, inks, dyes, pigments, liquors, varnishes or other surface coatings
  10. halogenated solvents or solvent residues
  11. waste liquids, including used oil or other waste petroleum products, with a calorific value of 30 megajoules per kilogram (MJ/kg) or less, or containing 10 milligrams per kilogram (mg/kg) or more of polychlorinated aromatic compounds, PCP or polychlorinated biphenyls (PCBs), or 1000 mg/kg or more of chlorine
  12. unidentified chemicals or laboratory residues
  13. waste from contaminated sites or buildings
  14. motor vehicles or vehicle parts, or any other combination of metals and combustible material.

Some materials often considered 'wastes' might be more appropriately termed 'fuels' because they are primarily used to generate energy or material products, and burn with similar discharge characteristics to fuels like coal, oil or gas. To ensure such fuels are not captured under the definition of waste, it is important to specifically exclude these types of materials. Other exclusions may also be appropriate, such as bodies destined for cremation. Discharges from activities or materials that should not be captured by the proposed dioxin action on waste disposal are:

  1. cremation of human beings or pets
  2. burning of vegetable wastes from agriculture, forestry or food processing
  3. burning of virgin wood or virgin wood waste
  4. burning of waste liquids with a calorific value greater than 30 MJ/kg, containing less than 10 mg/kg of polychlorinated aromatic compounds, PCP or PCBs, and less than 1000 mg/kg of chlorine
  5. burning of black liquor or fibrous vegetable waste from virgin pulp and paper production
  6. incineration plants used for research, development or testing in order to improve the incineration process and which treat less than 50 tonnes of waste each year.

5.2 Domestic waste burning

The second largest source of dioxin from waste combustion is the burning of domestic waste in backyard fires and '44-gallon drum incinerators'. About 11% of all dioxin discharged to air comes from this source.

It is thought that some waste is also burned on indoor fires and in wood burners, although no information is available on the prevalence of this practise or how much waste is burned.

Combustion gases from uncontrolled burning of mixed household waste contain about the same concentration of dioxin as waste burned in landfill fires. Burning garden waste (i.e. vegetation, such as shrub and tree prunings) will discharge much less dioxin than burning household waste.

Although the estimate of dioxin produced from the backyard burning of domestic waste is highly uncertain, gathering more data and more analysis would add little value. Like landfill fires, this is a major source of dioxin due to an undesirable practice, and dioxin discharge to air from the practice should be prohibited, at least for certain types of wastes.(See footnote 19)

Generally, backyard burning of most domestic waste occurs in an unselective manner, with little or no segregation of the waste streams. Therefore, the most effective way to reduce dioxin discharges from this source would be to ban the discharge from all items that make up domestic waste. There is an argument to extend a ban to include vegetation in urban areas. This approach recognises the availability of alternatives, such as composting and recycling, and would make enforcement much simpler and more effective.

However, it does not recognise that some waste items will discharge much less dioxins when burned than other wastes, or that segregation of some wastes such as vegetation and paper are common and effective. Most regional council air plans regulate the open burning of certain wastes (See footnote 20) as either a permitted activity (subject to conditions) or discretionary activity, and for other specified wastes (See footnote 21) as a prohibited activity. A similar approach should be adopted here. In summary, a ban on discharges from domestic waste burning should not apply to vegetation, untreated wood (i.e. virgin wood), paper or cardboard.

The amount of household waste burned in backyard fires is only about 1% of the total amount of domestic waste landfilled in New Zealand. Consequently, any ban on discharges from this activity would have a very small effect on the quantity of waste taken to waste disposal facilities, or on the amount of waste that is illegally dumped.

Bans on outdoor fires of all kinds are common in summer because of the fire risk. Because of other adverse air quality effects, outdoor fires are also banned during winter in Christchurch.

Community education will contribute to an increased awareness of the environmental damage of waste burning, both on outdoor and indoor fires, and raise the level of compliance. It will also assist with self-monitoring and enforcement, especially within residential neighbourhoods. A mechanism for reporting plumes of offensive smoke is already in place as part of existing pollution response services operated by regional councils.

A short (two to three year) transition period is suggested to facilitate a change in behaviour not to burn waste. Thereafter, the extent to which councils should become proactive in identifying breaches of the NES would need to be chosen after assessment of costs. The cost of enforcement would probably be quite small in urban areas, but comparatively more expensive in rural areas. Notwithstanding, it may be expected that regional councils would progressively enforce the standard, including prosecutions where necessary, when they become aware of occurrences of domestic waste burning.

The proposed action would be complementary to the nuisance provisions of the Health Act, enforced by territorial authorities. But, it will be necessary to avoid the duplication of functions. Territorial authorities are empowered by the Health Act to monitor and control activities causing a nuisance or likely to be injurious to health, and on this premise, the proposed action on dioxin could equally be regulated under the provisions of this Act.

The problems with addressing waste in rural New Zealand

Rural New Zealand creates a significant portion of New Zealand's waste stream, much of which is thought to be inadequately managed due to a lack of environmentally sound disposal choices. Farms and other rural properties are often without kerbside collection schemes, and may be located far away from landfills.

As well as general household wastes, the agricultural sector generates an estimated one million 20 litre plastic agrichemical containers, thousands of kilometres of plastic baling wrap, together with a variety of other wastes. Some of this waste is known to be disposed of in farm 'waste pit' fires, which is effectively uncontrolled burning.

More recently, small-scale incinerators have been developed for disposing of tripled rinsed high density polyethylene agrichemical containers. These incinerators are simply a 44-gallon drum modified for improved airflow. They are unlikely to meet the discharge limit of a national environmental standard (NES) as outlined in Section 5.3 (especially if mixed wastes or chlorinated materials are burned, or if combustion conditions are poor) nor will they meet the operating requirements of this standard. Because of a lack of waste segregation, ready access to an incinerator whether on a farm or any rural property will only encourage the disposal of waste for which the incinerator was not intended.

Waste disposal burning in flare pits or 44-gallon drums is likely to be as environmentally damaging as domestic backyard burning, if not more so given the volume and types of waste burned. Ironically, dioxin discharges in rural areas can be the most dangerous because of the greater potential for dioxin to be deposited onto farmland and to enter the food chain.

With an increasing likelihood that New Zealand agricultural produce will need to meet export produce requirements for dioxin, the need to demonstrate good environmental practice will become increasingly important. There is little justification from an environmental perspective why waste burning in rural areas should be treated any differently to backyard burning in urban centres. Accordingly, action by way of an NES that bans dioxin discharges to air from waste burning on outdoor fires must also include waste burning in rural New Zealand. This standard should therefore apply to discharges from small-scale 44-gallon drum incinerators.

Current alternatives to the burning of waste in rural New Zealand are landfilling, recycling and waste minimisation. For some waste streams, such as agrichemical containers, the establishment of a collection and recycling scheme is an option that should be explored. Schemes for farm plastic wastes already operate overseas. The used oil collection and recovery programme already established in New Zealand suggest that similar approaches for other wastes are possible. These types of initiatives will need careful evaluation during the transition period suggested for the NES.

There will be a comparatively high cost of enforcement of an NES in rural areas, because dioxin discharges from waste burning on outdoor fires are highly dispersed. In addition, there will be higher disposal costs where wastes have to be transported long distances for landfilling, recycling or for other means of waste management. The burning of polyethylene agrichemical containers is a permitted activity in some regional council air plans. Costs will be incurred by councils required to review and revise air plans to reflect the NES.

Actions
  • Ban discharges to air from the burning of waste (excluding vegetation, untreated wood, paper and cardboard) on outdoor fires in urban and rural areas, including agricultural waste burning, through a National Environmental Standard.
  • Develop educational material on the health and environmental effects of waste burning in outdoor fires.

5.3 Municipal waste incineration

Municipal waste incinerators are designed to burn refuse that would otherwise be deposited in landfills. As yet there are no municipal waste incinerators in New Zealand, although some have been proposed. State-of-the-art municipal waste incinerators that are operated well could decrease the incidence of landfill fires, and could therefore result in an overall reduction in dioxin discharges. However, a single large incinerator, if badly designed and operated, could discharge as much dioxin to air as has been estimated for all sources in the New Zealand inventory.(See footnote 22)

Overseas, the reduction of dioxin discharges from municipal waste incinerators has been achieved through regulation. Because any municipal waste incineration plant in New Zealand would be new, it is appropriate to follow best international practice, and as such overseas discharge limits for such plants are especially relevant. The European Commission (EC) has set an upper limit on the concentration of dioxin in exhaust gases of 0.1 ng TEQ/Sm3, and the United States limit is equivalent to approximately 0.2 ng TEQ/Sm3.

Measuring dioxin in exhaust gases

The use of toxic equivalents (TEQ) is an internationally adopted procedure for assessing the combined toxicity of a mix of different dioxins. A limit of 0.1 ng TEQ/Sm3 means that each cubic metre of exhaust gas (standardised to reference conditions) must contain no more than 0.1 nanograms of dioxin adjusted for toxicity. A nanogram is a billionth of a gram.

Because it is important that New Zealand protects and strengthens its clean green image, and because our markets in Europe are increasingly environmentally sensitive, New Zealand should adopt the more stringent EC limit. Dioxin discharges from a waste incinerator of 0.1 ng TEQ/Sm3 would not be expected to result in adverse effects on human health or the environment.

A limit of 0.1 ng TEQ/Sm3 would be effective since dioxin discharges would be only about 1% or less of those from an uncontrolled plant. In practice, many modern municipal waste incineration plants achieve average dioxin discharges of less than 0.05 ng TEQ/Sm3, with some operating as low as 0.002 ng TEQ/Sm3.

Assessing efficiency or cost-effectiveness is more complex. The cost-effectiveness of different levels of dioxin control can be estimated in the form of cost-effectiveness ratios. The control technologies required for an upper limit of 0.1 ng TEQ/Sm3 would prevent dioxin discharges at a cost of about $400 for each milligram of dioxin not discharged. Cost-effectiveness analysis has shown that this is a dioxin reduction 'bargain'. The control technologies required for an upper limit of 0.1 ng TEQ/Sm3 are estimated to account for a significant proportion (30 to 50%) of the capital cost of a municipal waste incinerator.

Since dioxin control technologies are standard in new municipal waste incinerators, an upper limit on dioxin discharges would be expected as a condition of a resource consent for such an incinerator. The establishment of an NES that sets an upper discharge limit can be seen as a proactive approach to the possible introduction into New Zealand of this technology at some future date. An NES that covered municipal waste incinerators would save developers and consenting authorities time and resources, and represents cost savings.

Appendix 3 contains a proposed NES restricting dioxin discharges to air from the incineration of waste. As well as setting an upper discharge limit, the NES includes requirements for incinerator operation, monitoring and reporting. The banning of dioxin discharges to air from uncontrolled waste burning in landfills, and from the burning of waste in outdoor fires is included in this NES.

Co-incineration - the burning of waste to generate heat as well as to dispose of the waste - is a special case of municipal waste incineration. New Zealand does not have any large co-incinerators, and any applications for such facilities should be covered by the proposed NES. Anecdotal evidence suggests that co-incineration occurs to some extent on an ad hoc basis in small to medium sized boilers, including those found at educational and healthcare institutions and possibly some trade and industrial premises. Such boilers are unlikely to be able to be equipped to meet the operational and monitoring requirements proposed in the NES, and furthermore, would be unlikely to meet the discharge limit if burning waste in any significant quantity. In any case, for co-incineration to continue in this way, the discharge from such boilers would need to comply with the discharge limit of 0.1 ng TEQ/Sm3, as well as the monitoring requirements of the NES.

It is also known that the burning of waste at trade and industrial premises occurs in units that are not even designed for fuel combustion purposes. This practice is most commonly found in the smaller towns around New Zealand, and includes waste burned in 44-gallon drums tucked away at the rear of a building or property, and even in open fires. It is reasonable to assume that discharges from waste burned in this way will not comply with any aspect of the NES, and effectively this type of activity will have to cease.

Action
  • Make a National Environmental Standard setting an upper limit of 0.1 ng TEQ/Sm3 on dioxin discharges to air from the burning of waste in specified circumstances, including municipal solid waste.
  • Prepare information material on the National Environmental Standard, including material to assist in identifying co-incinerators.

5.4 Medical waste incineration

The incineration of clinical, pathological, quarantine and veterinary wastes (See footnote 23) is responsible for about 6% of dioxin discharges to air in New Zealand.

Overseas, the reduction of dioxin discharges from medical waste incinerators has been achieved through regulation by setting maximum discharge limits. The EC upper limit for medical waste incinerators is the same as for municipal waste incinerators - 0.1 ng TEQ/Sm3.

Dioxin discharges from large and medium-sized medical waste incinerators in New Zealand are already, or soon will be, at low levels. The largest medical waste incinerator in the country has been fitted with control technologies that enable it to comply with the European discharge limit of 0.1 ng TEQ/Sm3. The next largest has been replaced by an autoclave system.(See footnote 24) Of the two medical waste incinerators of medium size, one is soon to be replaced by an autoclave system, while the other must comply with a limit of 0.1 ng TEQ/Sm3 by 2004 as a condition of its resource consent.

Accordingly, there has already been a decrease in dioxin discharges from medical waste incineration compared with the estimates made in the New Zealand inventory. The priority now is small medical waste incinerators. There are about 19 small medical waste incinerators still being used in New Zealand. Although these incinerators collectively handle about 20% of the waste burned by each of the medium incinerators above, some probably discharge as much dioxin. They have no control equipment, and achieving and maintaining good combustion conditions is difficult because of their size. Many are old and in poor condition.

An estimate of the cost to the owner of a small medical waste incinerator of complying with a limit of 0.1 ng TEQ/Sm3 can be made by assuming that the incinerator is replaced by an autoclave system. The capital cost of an autoclave system large enough to replace a small medical waste incinerator is about $400,000 - less than or about the same as a new incinerator. If an existing incinerator is due for replacement, then the cost of installing an autoclave system instead is zero. If an existing incinerator is not due for replacement, then its premature replacement by an autoclave system involves early expenditure of $400,000, (See footnote 25) which incurs a financial penalty. Operating costs for autoclave systems are likely to be, at most, similar to those for incinerators.

The effectiveness of the autoclave option in virtually eliminating dioxin discharges to air from this source is assured, and it is much more cost-effective than control technologies on small waste incinerators. This supports the adoption of relatively stringent discharge limits for this source of dioxin discharges to air. It is proposed that the NES for municipal waste incinerators be applied to medical waste incinerators as well.

Immediately replacing all small medical waste incinerators with autoclave systems would cost about $8 million. This estimate is based on two assumptions. The first is that all the replaced incinerators are new and immediately junked; clearly, this is not so. The second assumption is that in all cases a nearby boiler is available to provide steam. This may not always be so, in which case the economics would probably lead to transporting the waste to an autoclave system or to a complying 'regional' incinerator. Such decisions have already been made by operators of incinerators that have closed down in the last decade.

A more reasonable estimate of total costs can be made by assuming that the average remaining lifetime of small medical waste incinerators is five years. This gives a total cost of about $3 million.

The actual costs to individual owners of these incinerators would depend on how regional councils decide to implement the proposed NES in reviewing existing resource consents. At one extreme, a regional council might require a phase-in period of a year; at the other extreme, it might not require compliance until incinerators reach the end of their useful lives. In the latter case, the cost to owners would be close to zero.

Action
  • Include dioxin discharges from the burning of medical waste in the National Environmental Standard presented in Section 5.3, with a discharge limit of 0.1 ng TEQ/Sm3.

5.5 Other waste sources

Other waste sources - hazardous waste and sewage sludge incineration - are currently relatively small sources of dioxin discharges to air. Thus, even substantial reductions in dioxin discharges from these sources would have only a marginal effect on total dioxin discharges.

Hazardous waste incineration

There is only one hazardous waste incinerator in New Zealand. The volume of hazardous waste incinerated is minimal, and discharges from the unit are accordingly low. The plant is extensively monitored to ensure compliance with its resource consent, although the discharge limit of 5 ng TEQ/m3 specified in this consent is relatively high and out dated compared to current international best practise.

Action
  • Include dioxin discharges from the burning of hazardous waste in the National Environmental Standard presented in Section 5.3, with a discharge limit of 0.1 ng TEQ/Sm3.

Sewage sludge incineration

Dioxin discharges from New Zealand's only operational sewage sludge incinerator are estimated to be low. Although this incinerator has never been monitored for dioxin, it operates with a large biofilter that should effectively trap any dioxin present in the discharges.

Resource consents have been given for the construction and operation of a sewage sludge vitrification plant - in effect, a high-temperature incinerator - in the lower North Island. The consent condition for this facility specifies a dioxin discharge limit of 0.1 ng TEQ/Sm3.

Action
  • Include dioxin discharges from the burning of sewage sludge in the National Environmental Standard presented in Section 5.3, with a discharge limit of 0.1 ng TEQ/Sm3.

Footnotes:
16 For the purpose of action on dioxin as proposed in Sections 5 and 6, and Appendix 3, dioxin includes the dioxin-like PCBs.

17 Action to manage and minimise waste is an important element of the Government's programme for environmental issues (cf. the December 1999 Speech from the Throne).

18 An obligation of the Stockholm Convention is the development and maintenance of a dioxin source inventory and release estimates. Re-evaluation of landfill fires should form part of any future New Zealand dioxin inventory.

19 Cost effectiveness analysis indicates that a ban on waste burning would be economically efficient, costing around $1000 for each milligram of dioxin not discharged.

20 Such as vegetation, untreated wood, paper and cardboard.

21 Such as plastics (including PVC), tyres, treated timber and used oil.

22 This is hypothetical, and many would argue highly improbable; it is unlikely such an incinerator would ever be given resource consents to operate. However, section 3(f) of the RMA does allow for consideration of 'any potential effect of low probability which has a high potential impact'.

23 Referred to in this action plan generically as 'medical waste'.

24 Dioxin discharges from autoclaves are negligible, and are primarily associated with the burning of coal to generate steam required for sterilisation.

25 This cost does not include a boiler. Small autoclaves would generally be based on hospital sites where steam is likely to be available.

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