Organochlorines Programme Briefing

For several years we have known that a range of local sites have been contaminated by organochlorines.

We know that pentachlorophenol and dioxin contamination of soil and wastes is an issue at some sawmill sites. For example the Waipa sawmill site, Rotorua, and the old Forest Service sawmill at Hanmer, were two sawmills where pentachlorophenol was used in the past in relatively large quantities.

We know that the old Fruitgrowers Chemical Company site in Mapua, near Nelson, is contaminated with DDT and lindane.

We know that the dieldrin dump sites are an issue in Southland.

Identifying and assessing sites contaminated by organochlorines is still evolving. A case in point was the finding recently of PCB contamination of the Pacific Steel Ltd site, Glenbrook, on the Manakau Harbour.

I want to make two general comments about site contamination from chemicals such as organochlorines. First, the extent of site contamination needs to be accurately charted and the on-site and off-site risks to people and the environment properly evaluated.

Second, the risks that are identified need to be managed according to an agreed plan involving the liable party, or parties, and regulatory authorities.

Until now it has been judged impossible or unfeasible to actually clean-up sites contaminated by organochlorines, apart from physically removing material from the site and putting it somewhere else. This is all about to change.

The organochlorine contaminants - PCP, dioxin, OC pesticides - have been regarded (and are still regarded) as extremely difficult to destroy in a safe and effective way.

In other countries where clean up of these contaminants has occurred, high temperature incineration (HTI) has been widely used.

This is an overly expensive way to do the job and HTI is not seriously considered as a viable option in New Zealand.

Over recent years, advances in technology research and development internationally have seen practical alternatives to HTI investigated.

Emerging technologies are now offering a firm promise of safe, effective and cheaper ways to treat organochlorine contaminants.

Three years ago, the Government and local timber industry corporates undertook a review of the available technologies.

As a result of this study, the most promising of the emerging organochlorine treatment technologies were identified.

In an effort to address the specific problem of PCP and dioxin contamination at major sawmills, the New Zealand parties have continued to work with ADI Limited of Australia, a technology developer.

A collaborative effort has evolved in which ESR Ltd took a key role in providing specialist analytical and organic chemistry skills.

A problem solving approach to the work was adopted.

Trials on the New Zealand materials have been carried out in the laboratory, both in Australia and on the Gracefield campus at a pilot scale.

Today we are presenting the findings of this work.

On behalf of the collaborating parties, we are delighted to announce that these trials have proved successful.

We have on our hands an exciting breakthrough in the form of a treatment technology which provides a real chance of achieving the first full-scale clean up of an OC contaminated site in this country.

The process is known as thermal desorption. Its use to treat organochlorines represents a 'world first' and is an excellent illustration of what might be called 'ANZAC technology'.

The 'hardware' or machinery involved is not new, but the application of it to destroy organochlorines is.

Mechanically, it is a relatively simple process which involves indirectly heating the contaminated material - such as soil- in an enclosed chamber with lime and cracking apart the toxic molecules.

All gaseous emissions from the process are washed and filtered and any particulate material caused by the movement of gases is captured and recycled back through the process.

All that remains of the organic contaminants at the end is calcium salt, carbon and water.

The treated soil is sterile and safe to return to the site.

Compost can even be added to it to restore its viability as a plant growing medium.

I now want to give you a quick rundown of the sequence of trials that have been undertaken with this new technology.

The first phase of the study was commissioned in April 1995 by the collaborating sponsors - Fletcher Challenge Forests, Carter Holt Harvey Timber Group, Forestry Corporation of New Zealand and the Ministry for the Environment.

By the end of that year, the effectiveness of the ADI thermal desorption process was confirmed at a laboratory scale.

This verification suggested operating conditions and additives necessary to remediate soils contaminated with PCP and dioxins.

As a result of those initial encouraging results, trials were recommended to demonstrate the technology and to develop further confidence in the process at a pilot scale.

The second study phase consisted of a series of four trials involving combinations of PCPs, dioxins, and organochlorine pesticides in soils, sawdust/sand mixtures, and dust.

An important technical aspect of this phase was to achieve residual concentrations in the soil better than or consistent with clean up criteria adopted for residential land use in New Zealand.

The trials concluded that:

A range of soils contaminated with various levels of PCP, dioxins and organochlorine based pesticides can be effectively treated with this technology.

The required environmental objectives of less than 50 parts per billion PCP and one part per billion dioxin in treated soils can be safely achieved.

Sawdust contaminated with PCP and dioxins when mixed with sand, can also be effectively treated.

The levels of the organochlorine pesticides DDT and lindane can be reduced to below one part per billion after treatment.

A single stage treatment technique based on recycling dusts from the process vapour streams back through the desorber could be implemented in a full scale plant.
Only two years ago, what I am outlining today had not been contemplated anywhere in the world.

While both delighted and optimistic, we remain cautious, however, about tackling an expensive and difficult task of this magnitude.

But we are confident that we are now in a position to begin serious planning for the clean up of sites contaminated with these long-lasting toxic chemicals.

As a result of these trials and previous technology development efforts, ADI Limited tells us that it has the technology to clean up dioxin and other organochlorine contaminated materials to residential standards.

ADI says that the process is cost effective, environmentally acceptable and ready to be scaled up to full operation.

To achieve the best economies of scale, clean up probably needs to be carried out in a coordinated way.

Clean up of contaminated sites at Mapua, at the old Hanmer sawmill site, at the Southland dieldrin dumpsites, and at a number of privately owned sawmills, carries a price tag of many millions of dollars.

The decision over which technology - or combination of technologies to use - is crucial and needs the most careful evaluation.

The clean up of organochlorines is increasingly identified as a global environmental challenge. Additional technologies are emerging.

For example, ADI has also acquired rights to a BCD (Base Catalysed Decomposition) process that has been successfully used in treating PCBs in transformer oils.

But for now the focus is on the thermal desorption technology.

The Ministry is talking to Tasman District Council and to the major timber companies with the suggestion that the available information on the ADI technology - and any other realistic contenders - be reviewed in a rigorous manner.

With the Ministry having a large involvement in the funding of the Mapua clean up, the Government is a potential purchaser of clean up services. For a task as important as this, we want to review prospective technologies as to their cost, reliability, effectiveness, and operating safety. Any environmental effects that are identified need to be acceptable to the community, and any discharges and land use requirements will need Resource Management Act consents.

Costs for the planning process as well as the actual clean up will need to be identified and evaluated. This will all take a little time.

A range of issues need to be considered here, not the least being the sourcing of extra funds beyond that presently budgeted.

It is clear that for a clean up to proceed at Mapua, the parties will need to find extra funds, and some portion would need to be obtained from part of the Government's overall budget expenditure. Such funding would need to compete with other priority areas.

I have asked the Ministry to prioritise this initiative and to report back on progress within three months.

In the meantime, I want to congratulate ADI Limited and ESR scientists at the Gracefield campus where this work was done.

It's heartening for me as Minister for CRIs, as well as the Environment, to see a NZ Crown Research Institute being so closely involved in the development of such leading edge and significant technology.