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Contaminated land

A wide variety of industrial, commercial and farming activities can result in chemical contamination of soil, air and water. Some sites within our region have high concentrations of hazardous substances and are considered contaminated sites. Waikato Regional Council is working with site owners, the city and district councils and health authorities to reduce the risks associated with contaminated sites.

What is contaminated land?

A site is considered to be contaminated when hazardous substances are found at significantly higher concentrations than their normal levels, and there is likely to be a risk to human health or the environment.

Potentially contaminated land is land that has been used for an activity that is more likely than other activities to cause contamination (see the Hazardous Activities and Industries List below).

Background levels

It's important to know that many hazardous substances occur naturally in soil, air and water. For example, lead and mercury occur as a result of weathering of rocks or from geothermal areas.

Many chemicals, particularly trace elements, are needed by living organisms in order to live and grow.  However, above a certain level even these chemicals can become toxic, interfering with the complex biochemical reactions of plants and animals.

Other hazardous substances do not occur naturally. Over time, some of these have become widespread in our environment. One example is the organochlorine DDT, which was previously used as a pesticide.

More information about naturally occurring (background) concentrations of major elements and common compounds can be found here.

Hazardous Activities and Industries List

There are a number of activities that can contaminate land. The Ministry for the Environment has put together a Hazardous Activities and Industries List (HAIL) to help identify potentially contaminated sites. This is a list of 52 specific land uses that can potentially cause contamination.

Examples of sites in our region that may be contaminated include:

  • landfills
  • sheep dips
  • timber treatment sites
  • former gasworks
  • scrap yards
  • service stations and motor vehicle workshops
  • former horticultural land
  • bulk fertiliser storage areas
  • mines and mining affected land. 

Contaminated sites can release hazardous substances into the environment through:

  • stormwater run off
  • leaching into ground water
  • loss to air, for example by volatisation or transported as dust.

What we’re doing

Contaminated sites threaten our environment and sometimes human health,  and so they need to be managed carefully. The Waikato Regional Council has a responsibility under the Resource Management Act 1991 to identify and monitor contaminated land.

As part of this function, the council maintains the Land Use Information Register which is a list of more than 8,000 historical and current activities that could cause contamination.  These activities are defined by the Ministry for the Environment’s ‘Hazardous Activities and Industries List’ (also known as HAIL). 

The Waikato Regional Council collects information and maintains this register which is used to inform our own contaminated land investigations and resource consent processes.  We share the register with our district/city council partners to ensure that future development, subdivision, or changes to the use of the land are conducted in a manner that will protect the health of people and the environment.  The register is independent of Land Information Memorandums (LIM) generated by district and city councils, but they may chose to include reference to it if a LIM is requested.

Waikato Regional Council has also worked in conjunction with the Ministry for the Environment to develop and maintain a set of guidelines for identifying and managing contaminated sites. These guidelines are available via the Minitry for the Environment's website:

Find out more about how contaminated land information is managed.

The Land Use Information Register

Waikato Regional Council has compiled a HAIL list of about 8,000 sites within our region that are potentially contaminated (see the HAIL). This list has been compiled from a variety of sources including aerial photography, resource consents, information from district and city councils, dangerous good licences, HSNO test certificate data, land use mapping and historic photographs.

 Information held on the Land Use Information Register is available to anyone who wishes to make an enquiry about a piece of land. 

  • For land within the Hamilton City Council area, contact the Hamilton City Council.
  • For land elsewhere in the region, contact us.

 When making an enquiry, please try to include both the address of the piece of land and the legal description and/or valuation number.  Alternatively, the address and a map showing the extent of the land can also be very helpful.

What happens if my land is a HAIL site?

If your land has been identified as a HAIL site, it does not mean that it is contaminated; only that it has been used for an activity that could have resulted in contamination.  Living on a HAIL site does not necessarily mean your health or that of the environment around it is affected. 

It is unlikely that you would have to undertake any sort of investigation unless you chose to do so.  However, if you chose to undertake any of the following activities, you may be asked to provide further information or soil sampling to ensure there is no increased risk to health or the environment by carrying out that activity.  If you have any questions about changes you may wish to make to your HAIL land, please contact Waikato Regional Council.

  • Undertake earthworks.
  • Extract groundwater.
  • Discharge sediments from the site.
  • Redevelop the land or change its use (refer to your local city/district council).
  • Subdivide (refer to your local city/district council).

How would I go about soil testing?

There are many options if you’d like to investigate the soil quality of land.  If you are simply wishing to undertake your own due diligence, or satisfy your own curiosity; you may wish to collect your own soil samples and submit them to a testing laboratory yourself.

However; if you are undertaking further investigation for a regulatory requirement (e.g. change in land use or subdivision) then the standard of investigation and quality of reporting will be important.  District/city and regional councils usually require contaminated land investigation work to be carried out by a suitably qualified and experience person, and also require soil testing and reports to be prepared in accordance with the Ministry for the Environment’s Contaminated Land Management Guidelines (see here).

For this reason, you may chose to employ a consultant to help you.  You can find some information about choosing a contaminated land consultant here.

Cleaning up contaminated sites

Most often, land is remediated by private landowners or developers who wish to ensure that their land does not pose a risk to human health or the environment.  This is often the case if the landuse is changing to something more sensitive (e.g. from an industrial site to a childcare facility or residential house) and improvements to soil quality are required.  Depending on the type of contamination there are different ways to remediate the land.

The Waikato Regional Council might take a more active role in the remediation of contaminated land if the contamination poses an unacceptable risk to human health or the environment.  . We work together with health authorities, and city and district councils to investigate and assess the degree of risk of both existing and potentially contaminated sites. Where owners can be identified we work with them to manage the risks at their site, for example the remediation of the Hamilton Gasworks and Tui Mine in Te Aroha.

Where owners cannot be identified, or are unable to manage the risks at a contaminated site, we work with local communities and other agencies to seek central government funding for remediation or management. This approach was used to clean up the Rotowaro Carbonisation Plant.

If you have a contaminated site, there may be financial assistance available from the Ministry for the Environment’s Contaminated Site Remediation Fund.  Regional councils can apply to the fund to help investigation and remediate sites that meet the following conditions:

  • The site poses or is likely to pose a high risk to human health.
  • The site is located in environmentally or culturally sensitive areas.
  • The landowners do not have the financial resources to undertake all the work themselves but want to do something about the problem.

Links to further information