In the process of applying for a land use consent involving earthworks, or for a subdivision consent, Auckland Council may have told you that your site is ‘potentially contaminated’. They will have indicated that you will need a contamination specialist to assess your property. What is this all about? This post aims to give a brief explanation of how to assess and deal with potentially contaminated sites.
WHAT MAKES A SITE CONTAMINATED?
On its ‘Hazards and Special Features’ register Auckland Council has a land information ‘tag’ on any piece of land that:
- is former horticultural land (e.g. it was formerly an orchard or market garden area).
- where uncertified fill is known to have been used.
- has had known or suspected contamination from other factors, for example oil spills or industrial processes. (The ‘HAIL’ activity list has all the possible contaminating activities – you can click on this link to check if any of these may be applicable to your site)
For residential land owners the most common of these sources of contamination is former horticultural sites. This is because as the city has spread, areas that were once horticultural land have become part of the urban area of Auckland.
Contamination on horticultural sites is usually from the prolonged use of herbicides and pesticides, the residues of these chemicals build up in the soil to level that is considered a hazard to human health. In the 1950 and 1960s in particular, many herbicides and pesticides were used that do not break down over time (for example, the pesticide DDT).
WHAT TO DO IF YOU HAVE BEEN ASKED TO GET A CONTAMINATED SITE ASSESSMENT REPORT
The rules for how to test for and deal with these contaminants is laid out in the NES (National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health ) and Contaminated Land Management Guidelines created by the Ministry for the Environment. These documents set out the standards for the testing, remediation and monitoring of contaminated land.
To get a contaminated land report you will need to engage a contaminated land specialist. This specialist will do a preliminary site history and then detailed assessment of the site. This will include taking soil samples on your land to be sent to a laboratory for testing. The specialist will then produce a Contaminated Site Assessment Report indicating:
- whether contaminants have been found (if any) and at what levels
- whether your property is safe for residential development or whether remediation is needed
- how remediation should be done
- if the site is unable to be remediated –a proposed monitoring programme will be prepared
Many specialists are also able to organise soil remediation for you and then do the follow up validation testing to make sure the contaminants have been removed. Remediation generally means soil removal and disposal at a certified landfill. It is then replace with uncontaminated topsoil. The validation information prepared by the specialist will be part of Auckland Council’s requirements for issuing the resource consent.
FINDING A CONTAMINATED LAND SPECIALIST
As the cost of this process can be quite high to keep costs to a minimum it is recommended you engage a contaminated site specialist (usually a qualified environmental scientist or chemical engineer) from an established company – getting the job done well from the start will streamline the process and help to minimize costs throughout the process.
For more information on these reports you may want to speak to a specialist, you are welcome to ring or email us at Thomas Consultants Ltd. We have been working in this field many years now and have had extensive experience testing for and dealing with a wide range of sites and site contaminants.