Site Analysis

Understanding all the features of a site, using and protecting the best, and minimising the impact of the worst.

Chemical contamination and pollution

Chemical contamination of a site may occur from past industrial, horticultural or agricultural activity. Typical examples of contaminated sites are when:

  • pesticides and herbicides were manufactured or stored
  • fertilisers were stored
  • timber was treated
  • sheep were dipped
  • petroleum, gas or coal products were produced, used, stored or sold
  • metals or minerals were mined
  • hazardous waste was dumped or landfilled (legally or illegally)
  • asbestos is or was present
  • land is affected by discharges from other contaminated sites
  • scrapyard or recycling activities were carried out.

For existing buildings check that:

  • the property has not been used for the manufacture of drugs such as methamphetamine
  • there is no asbestos contamination
  • activities within the building were not classified as a bio-hazard
  • the building was not used for activities such as paint manufacture, printing, dry cleaning, battery storage, explosives storage and so on.

Hazardous substances can threaten the health of people, animals or the environment where there is direct contact with contaminated soil, vapours or dust are ingested, or food or water from contaminated places is consumed.

Some contaminants may also cause aggressive ground conditions that can attack concrete foundations, speed-up rust in steel or even dissolve plastic pipework.

How to find out if your land is contaminated

To start off, there are some things you can do yourself:

  • Ask your district, city or regional council if it holds a register of contaminated or potentially contaminated land, and see if your land is mentioned.
  • Look for evidence of contamination such as old storage tanks or sheep dips.
  • Look for evidence of earthworks that may be used to cover previous activities.
  • Talk with previous owners or neighbours who have lived in the area for a long time about earlier uses of the property.
  • Look for evidence that your land is (or was) host to an activity on the Hazardous Activities and Industries List (HAIL).
  • Get a Project Information Memorandum (PIM) or Land Information Memorandum (LIM) report from your city or district council. This should contain any information the council holds about the likely presence of hazardous contaminants.

If evidence suggests that your land may be contaminated, talk with a qualified and experienced contaminated land consultant. A consultant will be able to carry out a more detailed land use survey, and if necessary arrange appropriate soil analysis.

Contaminated land laws and standards

Buildings generally have to comply with the Building Code. Clause F1 Hazardous agents on site requires that “sites shall be assessed to determine the presence and potential threat of any hazardous agents or contaminants” and that “buildings shall be constructed to avoid the likelihood of people within the building being adversely affected by hazardous agents or contaminants on a site”. Hazardous agents includes natural features of the land, such as geothermal activity. These matters should be addressed in the building consent process where applicable.

The Resource Management Act defines contaminated land as “land that has a hazardous substance in it or on it that has significant adverse effects on the environment, or is reasonably likely to have [those effects]”. You will need a resource consent to subdivide or change the use of potentially contaminated land. You may also need a consent to undertake earthworks, advance bores or discharge water from the land.

The National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health came into effect on 1 January 2012. It ensures that contaminated land is identified and assessed before development. The land may need to be remediated or the contaminants contained so the land is safe for use. City and district councils must carry out and enforce its requirements. The standard does not affect existing land uses. Regional and district plans may also contain rules relating to contaminated land.

Guidelines are available for managing different types of contaminated land.

Design

If construction is permitted but some degree of risk remains, such as from fuels, solvents or landfill gases, good building design may be one way of managing risk.  Some guidance on risk management is provided in the acceptable solution for Building Code clause F1. There are standards in the United Kingdom and Australia that deal with concrete in aggressive ground and vapour intrusion.

 

Updated: 15 June 2015