Helping clean-up after the Ōhau village fire
As the clean-up begins after the catastrophic fire at Ōhau Village, it’s important that it is done in a way that minimises environmental effects.
Regional leader compliance delivery James Tricker said, “The fire had caused considerable pain and distress to the village residents, and our sympathies go out to them.”
“As the clean-up progresses, we want to ensure there are minimal environmental effects, while also ensuring it is done in a way that minimises cost to the residents involved.”
Preventing soil contamination
Tricker said ash and debris from house fires can potentially contaminate soils due to items such as treated timber, cars, electronics, plastics, carpets, and household cleaners that can all be present within houses when fires occur.
“It’s important that ash and debris is removed from a property following a fire, and that the remaining soil is confirmed to be safe for residential use.”
We’ve made recommendations to Waitaki District Council about the best ways to deal with waste and soil removal and disposal, in an environmentally friendly and cost-effective way as possible.
The clean-up will require independent specialist advice to manage potential effects and ensure the remediated site is validated as clean.
“Our role is to control any discharges during the clean-up to ensure minimal environmental impact, and we also provide advice to the local territorial authority as needed on how best manage potentially contaminated sites. Meanwhile, the Waitaki District Council is responsible for rules and regulations in terms of rebuilding on the site.”
Any matters relating to demolition notices or rates for work undertaken are between the insurers and the residents.
Any resident wanting to access the site or has who has general queries (such as about site validation) need to contact Waitaki District Council.
Managing potentially contaminated sites
Below we’ve outlined some advice about; waste management and disposal, contaminated land, and erosion and sediment control.
Class 1 landfill is a municipal solid waste landfill which is a type of landfill that accepts household waste as well as other wastes. Further information is outlined on the Ministry for the Environment website.
The landfill will provide a completed waste manifest as a record of the waste received and this is considered suitable waste disposal documentation that should be maintained.
The company transporting the waste will also provide documentation. At a minimum, this documentation will include:
- Name of the party receiving the waste i.e. demo company name.
- Date and time waste were picked up or received.
- Origin of waste received i.e. address or addresses.
- Type of waste e.g. fire debris and contaminated soil.
- Volume of waste received per waste type (note: if truck numbers are reported then the volume of the truck holding capacity should be included).
- Waste destination e.g. name of landfill or waste company.
It is important that ash and debris is removed from a property following a fire, and that the remaining soil is confirmed to be safe for residential use.
We have recommended to Waitaki District Council that the best approach to ensure that properties affected by the fire are suitable and safe for ongoing residential use is:
- That a Suitably Qualified and Experienced Practitioner (SQEP) is engaged to assess and conduct validation sampling of the cleared sites.
- The SQEP should liaise with us regarding the investigation approach to ensure that the validation methodology is sufficiently robust.
- The SQEP should provide a validation report(s) following the clearance works that confirms that soil on the sites is suitable for ongoing residential use.
It is up to Waitaki District Council to ensure the land is safe for future use. We have been advised that only HSNO approved fire suppressants and retardants were used to control the fire.
There are a range of simple and cost-effective measures that can be used when clearing a site after a fire disaster:
- Keep clean water away from disturbed soil – use a clean water diversion drain to move clean, upslope water around the disturbance area. See information about managing clean water.
- Protect disturbed soil from erosion by using soil binders – these can reduce the potential for erosion by 95% and are probably the most cost-effective tool of all. See information about soil binders.
- Protecting moderate slopes from erosion by roughening soil surfaces – using an excavator to create horizontal grooves. See information about surface roughing.
- If there is a danger of water running down disturbed slopes and causing erosion, use contour drains to mid-slope direct flows to flat areas or to a settlement pond. See information about managing dirty water.
- Minimise the tracking of soil on vehicle wheels from a disturbed site, by installing a stabilized high traffic area.