Investigating Contaminated Sites in Canterbury

When is a site investigation necessary?

An investigation is generally necessary at sites that accommodate, or historically accommodated, activities listed on the Hazardous Activities and Industries List HAIL   where redevelopment work, change of ownership, spills or leaks occur, or when information becomes available suggesting that contamination may be present. If a site investigation is necessary, it is best to engage an environmental consultant with a proven track record in this area.

What are contamination risk factors?

Sites can release hazardous substances beyond the immediate area of contamination and into the environment through:

• stormwater runoff or soakage through soakpit
• leaching into ground water
• volatilisation (where the hazardous substance turns to vapour, which may build up in certain structures)
• loss to air, for example by evaporation or being transported on fine particles (wind blown dust).

The site itself can also present risks to the environment because:

• contamination in soil can be taken up by plants that are consumed by humans, livestock or other animals
• contaminants in the soil or sediment may present a risk to those in direct contact (through skin absorption, inhalation or ingestion routes of exposure)
• Specific flora and fauna or certain ecosystems may not be able to establish or survive because of the levels of contamination in soil or sediment.

Help from a Consultant - what does the consultant do?

An environmental consultant: 

• Identifies what the potential contaminants are, and areas that they were stored and used, disposed of etc.;
• Identifies the vertical and lateral extent of contaminants and what medium they are present in (e.g. soil, groundwater, surface water); 
• Determines the concentrations of contaminants across the site and, if necessary, beyond;
• Describes the environmental characteristics of the site listing all receptors (e.g. humans, ecosystems) and the exposure pathways (route by which the contamination could reach these receptors);
• Compares the concentrations of all the identified contaminants to appropriate background concentrations and environmental acceptance values; 
• Outlines the limitations of the investigation and assessment;
• Identifies and outlines the need for further work, if necessary (a multi-staged approach is usually the most practical way to investigate a site).

The reporting of investigative work needs to document comparison of analytical results with relevant environmental acceptance values. The Ministry for the Environment has produced guidance on the use of environmental acceptance criteria (Contaminated Land Management Guidelines No. 2 Hierarchy and Application in New Zealand of Environmental Guideline Values ).  Printed copies (including CD ROM of environmental acceptance values) are available free from the Ministry for the Environment.

Nationally recognised best practice requirements for reporting on the investigation, assessment and remediation of contaminated sites in New Zealand generally involves five steps:

• Step 1:  Preliminary site investigation report
• Step 2:  Detailed site investigation report
• Step 3:  Site remedial action plan 
• Step 4:  Site validation report 
• Step 5:  Ongoing monitoring and management plan

Environment Canterbury now requires all contaminated site work to be reported using this framework and the guidance contained within the  Ministry for the Environment's Contaminated Land Management Guidelines No. 1  (Reporting on Contaminated Sites in New Zealand) 

You can contact Environment Canterbury for details about environmental consultants, or look in the Yellow Pages.

How much does it cost to get my land investigated?

The cost of site investigations varies according to a number of different factors and therefore Environment Canterbury recommends you contact an environmental consultant for a quote.