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Managing contaminated sites

Contaminated sites pose a threat to both our health and the environment and need to be managed. To assess how much of a threat they pose we need to identify the number of sites in the Region. Waikato Regional Council is working with the city and district councils within our Region to compile a list of properties with contaminated sites.

Photograph of risk assessment at a contaminated site.
On this page:
Identifying contaminated sites, Assessing risk, Minimising risk, What you can do

The management of contaminated sites involves four steps:

  1. Identification of contaminated sites.
  2. Assessment of risk to human health or the environment.
  3. Remediation of high risk historic sites.
  4. Minimising the contamination caused by currently operating sites.

Identifying contaminated sites

The Hazardous Activities and Industries List (HAIL) lists 52 specific land uses that can potentially cause contamination of sites. Waikato Regional Council  is working with city and district councils to compile a register of properties within our region where activities on the HAIL have historically or are currently being carried out. This register is known as the Land Use Information Register.

Site categories

Properties listed on the Land Use Information Register are assigned a category depending on how much is known about the site.

Unverified - sites where activities listed in the HAIL may have taken place, or are taking place, but this has not yet been independently verified. These sites will be verified before testing for contamination takes place.

Verified - sites where activities listed in the HAIL have taken place, or are taking place. It is likely that contamination may be present and samples may be taken for further testing.

Confirmed contaminated - sites where contamination is present and has been confirmed by chemical analysis.

Remediated - sites that have been cleaned up.

Currently there are 107 sites in our region listed as Confirmed Contaminated. However, the actual number of contaminated sites is likely to be much higher than this as more sites get tested.

Information for property buyers

Over time information on the Land Use Information Register will be recorded in Land Information Memoranda (LIMs) and Project Information Memoranda (PIMs). An added bonus of this system will be the protection for property buyers who may be unaware that a site is potentially contaminated. If a site has been identified as falling into Category V, this will become apparent when a title search has been conducted by a buyer’s lawyer.

A series of four brochures (available below) have been developed on the topics of what you need to know when:

Information includes why contamination is a problem, how to find out if land is contaminated, who is responsible for a contaminated site, regional and unitary council role in contaminated land as well as advice for prospective buyers, sellers, lawyers and valuers.

Contact us to request copies of the brochures to be sent to you.

Assessing risk

Contaminated sites can pose risks to both the environment and human health. It is important that we assess the amount of risk posed by a site.

The Ministry for the Environment has developed a rapid risk screening system  for ranking contaminated sites as being of high, medium or low risk. Using the source-pathway-receptor model, categories are determined by the following factors:

  1. Source - presence of a significant source of contamination.
  2. Pathways - through which contamination moves from the source to the receptors.
  3. Receptors - the plants, animals and/or people which may be adversely affected by the contamination.

Contaminants can move from the source to the receptor via food, air and water (such as contaminated surface water or ground water).

For people the main ways (pathways) contaminants can enter our bodies are by:

  • ingestion (eating or drinking)
  • inhalation (breathing in)
  • direct contact (for example, absorption through the skin).

Sites that are assessed as being high risk will be of the highest priority for remediation work.

Minimising risk

Risks associated with contaminated sites can be minimised by breaking the source-pathway-receptor chain. This can be done by:

  • Removing the source of contamination (remediation).
  • Removing the pathways that allow contaminants to reach receptors (management).
  • Removing the receptors (management).

The first approach implies a complete cleanup of a contaminated site (remediation), while the second and third approaches are possible management options. In the case of soil intended for home gardens, remediation is the preferred option.

Find out about the clean-ups at the Hamilton Gasworks and Rotowaro Carbonisation Plant.

What you can do

We can minimise the effects of hazardous substances in our environment by:

  • Only using hazardous substances when absolutely necessary.
  • Applying safe practice when using and storing hazardous substances.
  • Transporting hazardous substances safely.
  • Disposing of hazardous substances correctly.