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Contaminated land management

It is important that contaminated land is managed to avoid harm to people and the environment. Hazardous substances in soil (contaminants) can have significant adverse effects on human health, and on the quality of soil and water resources. At hazardous concentrations, contaminants can limit the use of land, cause corrosion that threatens building structures, and reduce land value.


This web page provides information on contaminated land management in New Zealand including:

New Zealand’s legacy of contaminated land

The past use of chemicals (hazardous substances) in industry, agriculture and horticulture has left a legacy of soil contamination in New Zealand. This contamination has been mainly caused by past practices in which chemicals were used, stored and disposed of in a way that is not safe by today’s standards.

Contaminated sites are commonly associated with past activities such as:

  • The manufacture and use of pesticides – these activities have resulted in contamination at locations where pesticides were manufactured as well as the wider contamination associated with the use of the chemicals (eg, agrichemical sprays).
  • Production of gas and coal products – includes old gasworks sites located in most towns and cities.
  • Production, storage and use of petroleum products – contamination has occurred from leaking fuel storage facilities at tank farms and service stations.
  • Historic mining – usually associated with metals leaching from old tailings dams and mine shafts.
  • Timber treatment – pentachlorophenol (PCP) was one of a number of chemical formulations used routinely at most sawmills and timber treatment plants from the 1950s until 1988, when its use ceased.
  • Sheep dipping – from use of DDT, dieldrin, arsenic and other chemicals to treat parasites on sheep.  Old sheep dips can be located on farms with a history of sheep farming , as well as on public land used at the time as stockyards and railway sidings.

When contaminants in soil are a problem

Contaminants are a problem when the hazardous substances are at a concentration and a place where they have, or are reasonably likely to have, an adverse effect on human health and the environment. Contaminants are a greater problem in environments where food is grown or in close proximity to buildings, people, water bodies and important habitats.


Contamination is not always limited to a specific site. Hazardous substances may seep through the soil into groundwater, or be carried to nearby land and waterways in rainwater and attached to dust. Hazardous gases can also pollute our air. The different pathways by which humans can be exposed to contaminants in soil are shown in the diagram below.

Pathways by which contaminants in soil can affect human health

Pathways by which contaminants in soil can affect human health

Read a description of this figure

This diagram shows the main pathways by which contaminants in soil can affect human health. The diagram depicts a rural residential setting with a house and home garden connected to roof water and groundwater supplies. Cows are fenced behind the house and chickens are scratching and pecking in the garden. Adjacent to the house is a stream containing trout and eels. The house, garden, cows and chickens are shown located on contaminated soil. Arrows show the pathways by which contaminants in soil can expose the human receptors directly or indirectly through food, air, soil and water. The human receptors in this diagram are a father and son in the garden, a mother and child wading in the stream, and an angler on the stream bank. The arrows describe the pathways as follows:

  1. Primary pathways
    • Inhalation of dust
    • Soil contact (eating and skin absorption)
  2. Secondary pathways
    • Crop uptake and eating of contaminated crops
    • Uptake by livestock and eating contaminated livestock
    • Surface water contact
  3. Contaminant leaching/runoff pathways
    • Contaminant leaching to groundwater, uptake of contaminated groundwater by water supply bore, and drinking of contaminated water
    • Surface runoff from rainfall, uptake by aquatic animals, and eating of aquatic animals and surface water contact
    • Contaminant leaching to stream, uptake by aquatic animals, and eating of aquatic animals and surface water contact
  4. Vapour intrusion into the house from contaminated soil.

Agencies responsible for managing contaminated land

The Ministry for the Environment provides leadership on land contamination across central and local government. Regional councils and territorial authorities have functions under the RMA, Sections 30 and 31 respectively, for the day-to-day management of contaminated land.


Further information about the roles and legislative responsibilities of all involved agencies is described in the Ministry for the Environment discussion document, Working Towards a Comprehensive Policy Framework for Managing Contaminated Land in New Zealand.

Tools and guidance for managing contaminated land

To help local government fulfil their RMA functions the Ministry for the Environment has developed a framework for managing land contamination that includes a mix of laws and regulations, guidelines and funding arrangements.


For more information see:

Contaminated land remediation projects

The Ministry for the Environment is taking a lead on addressing historical issues relating to land contamination. This includes helping investigate contaminated sites and remediate high-risk areas.


Examples of high-risk contaminated sites are:

You can receive email updates about Tui mine by subscribing to the Tui mine newsletter. Or check out the Environment Waikato website.

How to find out if your land is contaminated

If you are concerned that your land may be contaminated check out our How to find out if your land is contaminated web page.

Further information

For enquiries about the Ministry’s work on contaminated land please email standards@mfe.govt.nz.

 

Last updated: 21 December 2011