Managing contaminated sites

The Hazardous Activities and Industries List (HAIL) lists specific land uses that can potentially cause contamination of sites. Waikato Regional Council  is maintains a Land Use Information Register, compiled ofproperties in the Waikato region where HAIL activities have historically or are currently being carried out. 

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

Site categories

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.

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) and/or 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.

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.

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.

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.

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.

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.