MEDIA RELEASE
19 October 2005

Investigation into subsidence in Albert Park

Auckland City has commissioned a geotechnical investigation into subsidence in the Albert Park area, following recent cases of soil collapse at the reserve.

There were two instances of subsidence at the inner city park during September, in which small depressions opened up in different locations.

Council staff acted quickly to fill in these sunken areas with loose material as a temporary safety measure.

In both cases, the subsidence appears to have been caused by the slow settling of soil used many years ago to fill ventilation shafts below the surface of the park. The shafts form part of a complex system that fed air to tunnels beneath Albert Park.

The tunnel system was built in 1942 for protection during threatened air raids in World War II. After the war, the tunnels were filled with unfired bricks and sealed. The ventilation structures above the surface were demolished and buried, and the ventilation shafts reaching the surface were filled.

Auckland City's parks manager, Jacqui Dyer, says further investigation is needed to assess the state of all of the blocked-off ventilation shafts in the park.

She says this is a precautionary measure to ensure there is no further risk of subsidence.

"In both cases the subsidence appears to have occurred directly above these old ventilation shafts. There are a number of these shafts throughout the park and we need to get them checked to ensure that there is no further soil collapse in the park.

"Auckland City has commissioned a specialist engineering report to investigate the matter and to advise on any remediation that may be needed."

Ms Dyer says in the meantime, a temporary vehicle weight restriction has been introduced in Albert Park as a precautionary measure.

Auckland City's heritage manager, George Farrant, says much of Albert Park, including the tunnel system below the reserve, is a significant heritage site.

"The existing heritage values of the park and the tunnel system will need to be protected during the investigation and throughout any remedial works that may be needed.

"Minor subsidence has occurred in the past above the ventilation shafts and the time has come to sort out the issue once and for all," he says.

Mr Farrant says the heritage division has a reasonably detailed set of drawings for the tunnels, which will help with the investigation into subsidence.

The council has also contacted event organisers planning events in Albert Park to inform them that an investigation into subsidence is underway. The impact on events over the summer will be assessed once the geotechnical investigations are completed.

The initial investigation is expected to be completed in the next week. Once that report has been received the full impact on the park, users and events will be known along with the costs of any remedial works required.

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