Reviving the debate around intervention

While Norton’s option for raising the bridge was accepted, his suggestion for a controlled release of the lahar with explosives was met with opposition from DOC. Norton said, “DOC by that point had got to the point where they were ‘winning’ and there was nothing they were going to do that would interrupt the natural process”. Norton had come upon the idea of a controlled release after talking with the Damwatch consultants who were on the Ministerial advisory panel and also the Australian

consultants, who were brought in to estimate the size of a lahar. However, Norton said, DOC were determined that the lahar would occur without any form of intervention:

DOC actually got more consultants to do a report on that proposal [the Meritec report]. [The consultants] completely misunderstood the mechanism I was asking to be investigated. They did a report that talked about the logistics of

can’t blast a channel reliably in the dam. I don’t need your report to tell me that, but you haven’t done the things I asked you to do.” DOC briefed them and DOC was happy with the report. So that option was not properly evaluated or put before the politicians.

Norton believed that DOC’s denial of the feasibility of other options – for example, a controlled release – actually sustained the debate around the options as the engineers and scientists involved knew they could be implemented. Instead, Norton said, DOC got “tied up in knots with all the other reasons that were relatively spurious – lacking in real credibility”:

Technically, you could have dug a channel in that dam without any fatality at all and without any risk to life. It might have cost a lot of money, but it could be done if it were a practicable solution. And DOC tried to argue that it couldn’t be done.

However, Norton introduced another argument that strengthened DOC’s position:

Cutting a hole in the dam was not practicable because the process had been occurring for five million years and there was no way that man was going to stop those lahars occurring. We might stop the first one. If we dug a hole through the centre of six metre dam and move 10% of the material to let the water out the next eruption would go on top of the six metre dam, which means we end up with a 10 or 12 metre dam. One day the lahar will burst. And the more you try to stop it, the bigger it will get. I think that was the only rationale DOC needed not to dig a channel through the dam. And they tied themselves in knots with all the other reasons, which really were a load of rubbish. The risk to the bulldozer driver – goodness gracious - that happens every day of the year. I suppose what’s interesting here is that the discussion about the risk and the communication around it became quite distorted.

Norton’s view was that the problem could have been dealt with more easily:

With some care in explaining the risk issues, DOC could have diminished that media issue probably in 12 months. In the end, there was no issue. In the end, the media were not arguing with anybody. And in the end, all the arrangements were in place – there were no arguments about what needed to be done. The issue became, “okay, we’ve resolved this and everyone is happy”.

However, Norton was quick to add, “I have a lot of respect for DOC. But this was one issue on which I differed with them”. He also observed:

It was interesting that most of this was done from Turangi with Harry and his boss, Paul Green. They were quite autonomous and we got on really well with them. We had pretty upfront discussions on the issues.

Sheppard said, that the Taig report forced DOC to re-examine the risk relating to the lahar:

The thing that really grabbed attention, he had a statement, I can’t remember the wording, you can find it in the report, that led people who were not statisticians to say that one in six people, one in ten, whatever it was, were likely to die as a result of this. That was a level that to anyone if that was truly the case, would have meant that if that’s the case, then we’re not managing this risk properly. So we really had to look at that.

In particular, Sheppard suggested the Taig Report provided a checklist of practical things to reduce the risk:

The focus went on to “well, how do we identify the component risks” and Tony Taig had done that very accurately for us. For instance, we hadn’t been able to raise the State Highway 49 barriers and things like that, and he was working on the basis: if things like that don’t work, then you’ve got these risks. It was something to focus our attention and say we’ve got to tick off these things.

The result, Sheppard said, was increased confidence in the lahar’s management: “Gradually, we got enough of a feeling of confidence that we could do this and reduce to a negligible level the risk to public safety.” However, in hindsight, Sheppard wished that DOC and Civil Defence had worked together sooner.