Mine shaft repair specialists will resume work on site today to assess ground stability and site safety at the Ipswich property where the sinkhole appeared on Tuesday.
The sinkhole, which has grown to about eight metres in diameter and could be up to 100m deep, opened up in Ray and Lynn McKay’s backyard.
University of Queensland’s occupational health and safety in mining Professor David Cliff told ABC News the site was unstable.
“The concern is that this hole could get much bigger if the water in that hole has destabilised the strata underneath the surface,” he said.
Minister for State Development and Minister for Natural Resources and Mines Dr Anthony Lynham visited the site yesterday with local Member for Ipswich Jennifer Howard to be briefed on Department of Natural Resources and Mines and Ipswich City Council activities on site and meet the property owners.
“An earthmoving contractor is on standby and hopefully in-ground assessments can begin in the morning once the hole is dry,” he said.
“Our abandoned mine specialists are very experienced at dealing with mine subsidence and normally earthmoving equipment is used to remove debris from the hole before it is backfilled.
“I’m also advised the owners should be able to return home on Thursday.”
Specialists from the Queensland Government Abandoned Mines Unit have been on site since Tuesday after the sinkhole appeared in the backyard of private property at 4 Coal Street, Basin Pocket.
Dr Lynham said pumping was completed yesterday following approval from the Department of Environment and Heritage Protection for water to be placed into an adjacent waterway.
“I’m advised the sinkhole is relatively stable today (Wednesday) compared to when it first appeared and will further stabilise now the water has been removed,” he said.
Dr Lynham said it was too early to determine what caused the sinkhole to appear.
“It is known that an historic coal exploration hole was dug in the early 1900s near where the sinkhole appeared.”