Ground movement could mean a second sinkhole in Waihi

by Michael Mosher on December 4, 2017

Post image for Ground movement could mean a second sinkhole in Waihi

Some ground movement in Waihi may indicate a second sinkhole in the area.

The first sinkhole, 20 metres wide, was discovered in the Coromandel mining town in August.

Hauraki District Council discovered the hole on a piece of council reserve land adjacent to the Martha open pit mine.

The earlier sinkhole has now been backfilled, but Oceana Gold geotechnical experts have said that there is a possibility recent ground movement could indicate the development of a second sinkhole.

The affected area is above an unfilled stope in the historic Royal workings within the High Hazard zone.

Original records indicate that the historic stope was partially backfilled, but the upper 20 metres remained unfilled.

The lower part of the pit rim walkway has been cordoned off as a precaution.

The upper part of the walkway will still be accessible as there are no concerns about ground stability in that area.

“The council would work closely with Oceana Gold to monitor and assess the situation and decide on any remedial action,” said Langley Cavers, Hauraki District Council chief executive.

He said although unfortunate, some ground movement in the area known to be above historic workings was predicted in a GNS subsidence report.

“The affected site was classified as a hazard zone in 2002, and was closed to vehicles and residential housing accordingly.”



Full Article…Here

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