What's been happening since the chemicals were unearthed at Marfell Park?
The Taranaki Regional Council has been working with a group of Marfell community representatives, contaminated sites specialist Dr Graeme Proffitt, and others to draw up a plan designed to answer questions about whether there are any risks to local residents and users of Marfell Park.
Marfell Park’s neighbours were also invited to take part in the process by telling the Council about their questions and concerns. A number responded, and the Cuoncil appreciates their input.
The Park is on the site of an old rubbish dump, which was closed in 1976 and covered with soil before the playing fields and other facilities were established. In early May, two drum remnants and small amounts of agrichemical residues were excavated from approximately two metres below the surface while a stormwater drain was being laid by the New Plymouth Distict Council. All of this material was safely disposed of by the District Council.
The plan now is to assess any risk by analyzing soil samples taken from various places and depths in the Park, and at the same time measuring the depth of the soil cover at the sampling locations to get an idea of how well buried the old landfill is.
This plan, drawn up by Dr Proffitt, has been approved by the Marfell representatives, the Taranaki District Health Board, the New Plymouth District Council and the Ministry for the Environment. The Taranaki Regional Council has asked Dr Proffitt to carry out the plan.
Click here to access a PDF version of the plan prepared by Dr Proffitt.
What will happen next?
The plan is about to swing into action. Over the coming week you may see one of Dr Proffitt’s environmental scientists and an assistant in the Park taking soil samples using an auger that looks something like a post-hole borer, operated from a mini-digger. Small amounts of soil or other material will be unearthed but they will either be taken away, or reburied under clean fill. The immediate area will be covered by a sheet during sampling to ensure no material is left behind on the grass.
As a normal safety measure, and to avoid contamination of the samples, the public will be asked to keep clear while the work is carried out.
The testing of the samples will be extremely sensitive. To avoid contaminating the soil samples, people must not smoke within 50 metres of the sampling. Staff will wear white protective overalls while doing the sampling, also to avoid contaminating the samples.
Which parts of the park will samples be taken from?
About 90 soil samples will be taken:
About 48 samples will be taken from random locations spread across the two top fields.
Six to 10 samples will be taken from the area of the BMX track, at low points beside the track and in the grassed areas. The track itself will not be damaged.
Eighteen samples will be taken from the children’s playground – from locations close to the swings, roundabout and other equipment – and from the grassed area nearby and from the area where the agrichemicals were found.
Twelve samples will be taken from areas where we know excavation has taken place, both along the line of the new stormwater pipe trench, and along the line of a stormwater pipe that was installed beside the BMX track some years ago.
Samples will mostly be taken from soil on the surface. However, on the top two fields, the auger will be used to drill down through the soil to the top of the landfill material, where samples will also be taken for analysis. Deeper soil samples will also be taken where the agrichemical wastes were found.
The soil samples will be analysed at an independent laboratory for a range of contaminants, with the emphasis on dioxins. The laboratory is expected to take a number of weeks to work through them all.
Why don’t you also test samples from deep inside the old landfill?
We know that any former rubbish dump will contain hazardous material. The issue is not that this material is buried below Marfell Park. The crucial questions are: How effective is the barrier that contains it, and could it come to the surface?
Dr Proffitt’s programme will address these questions by taking samples from the top of the layer of rubbish and at the same time measuring how deep the capping layer is.
What will happen after all the samples have been analysed?
Dr Proffitt will study the results and assess any risks.
He will then report to the Taranaki Regional Council on the level of risk to people using or living near Marfell Park. The report will make things clearer for everyone on the Park’s safety.
The community will be able to have confidence in the testing and sampling programme which all interested people and agencies have agreed to. The report may then be taken into account by the community in looking at the use and management of the Park in future.
How can you say the park is safe now?
Since 1994, the Taranaki Regional Council has regularly inspected and monitored leachate discharges from former landfills in this region, including Marfell. No environmental risk has been detected.
The material that was found in May was very hazardous. But it was dug up from approximately two metres below the ground and until it was unearthed, it presented no risk.
The material was taken away on the day it was found, and safely disposed of at the Regional Landfill in Colson Road. Later on more material was removed as a precaution. The area where the drum remnants were found has been covered with clean fill brought in from outside of the area.
Dr Proffitt believes that if there are any risks arising from the site’s former role as a landfill, they are not so high that people need to avoid using the playground. It would be sensible, however, not to dig through the Park’s surface, as it is an old landfill.
What exactly was found in May?
The Taranaki Regional Council took samples of the drum residue and surrounding soil that was dug up on 7 May. The testing showed that the actual drum residue that was dug up included hazardous chemicals called tetrachlorobenzene and trichlorophenol. These chemical residues contained a contaminant called dioxin, at levels high enough to be of major interest
In samples from the surrounding soil a couple of metres away, dioxin levels were thousands to tens of thousands times lower – still higher than you would expect to find naturally (dioxin at very low levels is found in soil everywhere in NZ), but much lower than in the residue. This indicates that the dioxin was centred in the drum residue and had not spread much through the soil.
Small concentrations of some other organic pesticide compounds, including an organophosphate insecticide called dichlofenthion, were also detected. But the levels were too small to be of concern. Anyone can buy organophosphate insecticides at a garden centre to treat soil insects. If you used them on your lawn and garden at recommended rates, the soil and plant concentrations would be similar to the highest concentrations of organophosphates detected in the soil two metres below the surface at Marfell Park.
Later excavation found the remains of seven more containers, but none smelled of agrichemicals. They and the surrounding soil were taken to the Colson Road landfill, just to be on the safe side.
Later tests of stormwater and leachate indicated no environmental risk.
Click here to access PDFs of the laboratory analysis reports.
How can there be no risk at the Park if dioxins and other hazardous chemicals were found there?
Risk occurs when people come into contact with hazardous or toxic materials. But the chemicals found here are stable in that they bind strongly to soil and do not dissolve in water – this is particularly true of dioxins.
If contaminated material is below the surface and covered by sufficient clean soil, the only way it can get to the top is if someone digs it out – which is exactly what happened in the stormwater excavation in May, and which is why it was sensible for the District Council to quickly remove the wastes and surrounding soil that had been uncovered.
If dioxins are in the soil on the surface (and there’s no reason to expect that dioxins are currently on the surface at Marfell Park), then the risk occurs when people, especially children, swallow small amounts of soil.
Children are particularly vulnerable because they are lighter, and they eat more dirt than adults (yes, we all eat dirt unwittingly, by contact between our mouths and dirty hands).
Unless concentrations are extremely high, the risk from soil contaminants results from prolonged exposure over months and years. The scale of the risk depends on how often the exposure takes place, and for how long, as well as how poisonous the contaminant is. This means that the acceptable level of concentration for a contaminant differs, depending on the location and the type of activities people carry out there.
Occasional or limited exposure to even relatively high concentrations of contaminants generally brings no particular risk – for example, a person walking across a park.
It’s different if they’re in your back yard, where you would have exposure every day, have direct contact through bare soil and perhaps be eating vegetables that are grown in it.
What about all the mounds of dirt that were there after the stuff was discovered in May?
The dirt that was around the agrichemical residues was taken away the day it was found, and more was taken away during the second investigation a few weeks later.
The mounds of soil that were left there were clean fill that was brought in from outside, to cover the areas excavated during investigations.
There are still some mounds of clean fill at the Park and they may eventually be used to reinstate the area.
Why can’t you just dig out all the material in the old landfill and take it somewhere else?
That would present more of an environmental and health risk than leaving it where it is. Several hundred thousand cubic metres of waste material is in the old landfill area – digging it up would be a huge job. It would bring contaminants to the surface, with the risk of them being spread in dust during loading and transportation.
Then there is the traffic hazard. Removing the waste would require some 50,000 truck movements through the narrow streets of Marfell over 12 months or so.
Establishing parks on former landfill sites has been common throughout New Zealand as it can be a good use for these areas.
Who can I talk to about health questions?
You can contact the Taranaki District Health Board Medical Officer of Health by phoning 06 753 6139.
Many agencies and Councils seem to be involved. Why?
The Taranaki Regional Council: Responds to pollution incidents and takes enforcement action when necessary. Also issues resource consents setting conditions for discharges from former landfills, and monitors compliance. Investigates sites for potential contamination.
New Plymouth District Council: Owns Marfell Park and is responsible for any environmental effects at the Park and action that may be required to reduce or avoid risks there.
Taranaki District Health Board: Public health responsibilities.
Ministry for the Environment: The Government’s main adviser on contaminated land.
UPDATED 9 JULY 2009
| Marfell Park Sampling Plan July 2009 | 255kb |
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| Investigation of alleged agrichemical waste disposal sites in New Plymouth (2001) | |
| Executive summary | 91kb |
| Information on Marfell Park | 23kb |
| Full Report | 371kb |
| Appendix I: Record of Interviews | 111kb |
| Appendix II: Map | 539kb |
| Appendix III: Sampling Protocols | 3.5mb |
| Appendix IV: GPR Report | 4.1mb |
| Appendix V: Record of Sampling Action | 205kb |
| Appendix VI: Record of Marine Sampling | 2.1mb |
| Appendix VII: Record of Detailed Site Inspections | 393kb |
| Appendix VIII: Record of Site Excavations | 82kb |
| Appendix IX (part 1): Analytical Results | 3.6mb |
| Appendix IX (part 2): Analytical Results | 3.8mb |
| Appendix IX (part 3): Analytical Results | 1.7mb |