Some ground movement has been detected near a sinkhole that was discovered in Waihi earlier this year on Council reserve between the Waihi Rugby Club and the Martha open pit.
The earlier sinkhole has been backfilled but Oceana Gold geotechnical experts have advised there is a possibility the 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.
Cordon a precaution
Public safety is council’s first priority and the immediate area, including 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 for ground stability in that area.
Hauraki District Council Chief Executive Langley Cavers said the Council would work closely with Oceana Gold to monitor and assess the situation and decide on any remedial action.
He said although unfortunate, some ground movement in the area, known to be above historic workings, was predicted in a GNS subsidence report and is to be expected.
“The affected site was classified as a hazard zone in 2002, and was closed to vehicles and residential housing accordingly.”
Aerial showing cordoned off area [PDF, 690 KB]