Lee Satisfied With Ruapehu Lahar Risk Management
18 December 2001 Media Statement
Lee Satisfied With Ruapehu Lahar Risk Response Management
Conservation Minister Sandra Lee has completed a review of the management decisions taken to date to minimise the risks to safety associated with the impending Ruapehu Crater Lake lahar.
The Minister has announced today she is satisfied that the installation of a state of the art alarm and warning system, and the construction of a stopbank alongside the Whangaehu River are sufficient to address risks to public safety from an expected lahar.
Ms Lee said that in addition to the installation of an alarm and warning systems and the construction of a stopbank, the Department of Conservation was working closely with the Police and the Ministry of Civil Defence and Emergency Management to develop an appropriate emergency response plan.
As well, the Ministry is helping organisations with assets in the predicted lahar path to review their individual civil defence response plans.
As part of the review, Ms Lee had considered proposals to undertake engineering work at the Ruapehu Crater Lake to reduce the impact of a lahar. The Minister has decided against undertaking this action.
She said engineering works had been suggested by some local authorities but were opposed by environmental and recreational groups, the Tongariro/Taupo Conservation Board, the New Zealand Conservation Authority and by local iwi.
“The Government has also agreed to favourably consider any application for recovery assistance for the reinstatement of any damaged infrastructure made by the Ruapehu District Council in the event of the worst case, or near worst case, lahar event," Ms Lee said
“On balance I
am satisfied, that the potential risk to staff working on
the creation of a partial trench at the Crater rim is
greater and cannot be mitigated or managed while the risk to
the public using the park or at risk infrastructure without
engineering at the Crater rim can.
"Intervention will create some significant risks for the workers at the crater rim. These risks are at least as high as any residual risks downstream.
"These factors, taken together with public concerns about the impact on national park values that would occur by bulldozing into the summit of the mountain, have convinced me that the recommended measures are the most appropriate response to the lahar threat. Accordingly I have decided against the proposal to undertake engineering work at the crater rim”, Ms Lee said.
Ms Lee said lahars were a well-known hazard on Ruapehu. The combination of a large volume of water poised high above the surrounding terrain on top of an active volcano constitutes a potentially hazardous situation should the volcano erupt or crater rim fail.
Over 60 lahars have been recorded in the Whangaehu valley since the 1860s, the latest occurring during the 1996 eruption. Lahars can be triggered by a number of causes with the most common cause being eruptions.
Ms Lee said the issue was complex and that her decision against asking the Department of Conservation to undertake engineering work at the crater rim followed a lengthy period of consultation with technical experts, the community and other stakeholders.
“The significant amount of information gathered has been subject to independent peer review and I have also had input from other Government Ministers with portfolios that would be affected by a lahar.
“This information and advice, and my subsequent decision, is based on the worst case scenario of a sudden collapse of the crater rim when the lake has filled to the top of the dam. The lake is predicted to fill between late 2002 and 2005.”
“In addition, an engineering intervention at the Crater Lake would be inconsistent with the provisions of the National Parks Act, the Tongariro National Park Management Plan and the World Heritage Convention.
"This area is of outstanding international significance for its natural values. Given the high natural values of the crater and the intense interest in the area," she said, "intervention would have been highly controversial and there would have been considerable uncertainty as to whether the required consents could have been obtained."