4 May 2016

Undetonated explosives mean a decade of monitoring

8:13 am on 4 May 2016

Taranaki landowners with undetonated seismic survey explosives on their properties face 10 years of monitoring and restrictions on land use, and the possibility it is recorded on their Land Information Memorandum (LIM) report.

The seismic charges contain up to 2kg of explosives which are set 19m underground.

The seismic charges contain up to 2kg of explosives which are set 19m underground. Photo: RNZ / Robin Martin

Shell Todd Oil Services is surveying the 450 square kilometres of the Kapuni field in South Taranaki and laying 24,000 seismic charges or 48 tonnes of explosives.

The company has so far detonated more than 7100 seismic shots, 14 of which have failed to fire.

At least another 28 live charges are lying dormant in Kapuni farmer Nigel Douds' property.

Mr Douds initially gave the company access permission, but is now refusing to let it detonate the explosives.

He just wanted the charges removed, and said it was possible to bore a hole beside the charges and extract them.

"I know it will cost a lot, but if they're coming to bore a hole in one situation it's not actually a big cost for them because they've got to bore them in the first place. Just bring back a crew to bore another one."

The charges weigh about 2kg and are set on average 14 metres underground.

Mr Douds had been told the best way to be rid of the explosives was to set them off.

Nigel Douds with his son Kohya, 2.

Nigel Douds, pictured with his son at his property, wants the explosives removed from his land. Photo: RNZ / Robin Martin

WorkSafe general manager of operations and support services Brett Murray said it was his preference too, but it was not a regulatory requirement.

"We have been advised by the company that retrieving these, [Mr Douds' explosives] and the misfired charges, from the ground by water jetting them out may be a difficult operation and that they are considering leaving them in the ground."

Mr Murray said this eventuality was not covered in Hazardous Substances regulations but did happen overseas.

"We are aware that these charges biodegrade over time, and we have been informed that the detonators connected to the charges are protected by a digital sequencing code. We believe that these environmental and safety safeguards, and that the approach has been employed in other jurisdictions, mean the risk of leaving them in the ground is low."

Shell Todd Oil Services has not replied to RNZ News queries about its procedures for misfires.

In an email to the Taranaki Regional Council, the company said it expected the explosives to be inert between two and three years, but that it monitored misfire locations for 10 years.

This enabled the company to ensure certain, unspecified, activities were not undertaken at the location and to protect the health and safety of people, along with assessing whether the charge had gone off.

South Taranaki District Council environmental services planning manager Blair Sutherland said he was not sure whether the misfired explosives would be recorded on a property's LIM report.

A LIM report is completed by a local council and provides details on a property, including plumbing, drainage, features of the land, etc.

"It may be something that's coming to us. I don't know but I guess our position at the moment is that it is not a situation we've been faced with and it may be this is an issue that isn't within our realm and somebody else is taking care of it. It may be an issue for WorkSafe or somebody."

However, WorkSafe's Brett Murray said LIMs were firmly the territory of local authorities.

Taranaki EnergyWatch spokesperson Sarah Roberts said the confusion was bad news for property owners.

"They have undetonated explosives on their land that can be likened to land mines and this affects the families that live there long term and yet neither of these councils has informed the landowners of the risks and here we are with 14 properties that are potentially going to have them recorded on their LIMs."

Mr Murray said it was examining Shell Todd's plan for Mr Douds' charges - and undetonated seismic charges in general -- and would advise the company if it believed there were missing elements or changes it felt could be made.

However, he said this was not an approvals process.

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