Chemical legacy of sheep dips in North Canterbury
A land use research project has found the most common potential source of soil contamination in North Canterbury is old sheep dips.
The research involved reviewing historical aerial imagery to identify areas where hazardous activities and industries (HAIL) have taken place. This means it is possible hazardous substances were used, disposed of, or stored on that land.
Regional councils throughout New Zealand are responsible for keeping records for these sites, and land use research for Christchurch, Selwyn, Waimakariri and Timaru areas has been completed in previous years.
New information for Hurunui and Kaikōura
The latest research, which focussed on the Hurunui and Kaikōura districts, found about 800 sites that had not been previously recorded. Of these, around 500 are old sheep dips or spray race operations, around 200 are horticultural sites where sprays may have been used, and around 60 are infilled pits.
“People have a right to know what their land has been used for in the past. It’s our job to keep records and let the landowner know,” said Graham Aveyard, Environment Canterbury’s science team leader for contaminated land.
“In many cases, the soil will be fine. Just because someone’s land has been an orchard, for instance, does not necessarily mean hazardous substances were used or buried there, just that they could have been.
“Most people will not need to do anything. It’s only in some future circumstances, like when undertaking major earthworks or subdividing, that property owners may need to take action.”
Sharing the research results
Many of the urban sites in these districts had already been identified. The new information mostly relates to rural-based activities best-seen from the air, such as sheep dips, farm rubbish pits and horticultural land uses.
Environment Canterbury will this month write to landowners to let them know about sites found on their property. People can discuss their property’s history and information held on the region’s Listed Land Use Register, and add relevant information.
Is the land contaminated?
This research project is about land use, not identifying contaminated sites. HAIL activities can contaminate land because of the use, storage or disposal of hazardous substances. This can include former market gardens and orchards, landfills and rubbish pits, sheep dips, timber treatment sites, gasworks, fuel suppliers and service stations. The only way to know if soil is contaminated is to test it.
You can find out more about potentially contaminated land on Environment Canterbury’s website. There are factsheets about different HAIL activities, including sheep dips, horticultural sites and landfills.
Wheeler and Son Sheep dip 1887, courtesy of Canterbury Museum
What do landowners need to do?
Probably nothing. There is no requirement to do anything unless a landowner is:
- Doing major earthworks
- Subdividing
- Changing the use of the land
If carrying out these activities, landowners should contact the Kaikōura District Council or Hurunui District Council to check if consents are required.
Landowners should let tenants or prospective buyers know about a property’s land use history.
Are there health risks?
The risk of exposure to contaminants in soil is likely to be low if people follow Canterbury District Health Board’s common sense precautions. There is more information on the Community & Public Health website.