Hole Lot of Filling
Whenever you hear someone call a location a “hole”, it is almost certainly pejorative but in the case of Australia’s Kinley project it’s literal.
The core of the massive 163 hectare Kinley project is the site of the former Lilydale Quarry – originally 120m deep, the quarry will have a ground surface area of 23 hectares once filled.
Kinley will be the second largest development precinct in Melbourne, with 3,200 homes planned to house 8,000 people and a new town centre at a total development cost of $2 billion (AUD).
“A project of this size and scale presents tremendous opportunities, but also tremendous challenges”, says Tonkin + Taylor Senior Geotechnical Consultant Roger Olds.
“There have been several similar developments on other quarries that are only one-third of the depth. Lilydale is unique in terms of the depth and consequent stresses that are applied to the soil throughout the pit."
There are stringent settlement criteria on this project to ensure that the quarry, once filled, is stable and settled enough for housing and the associated infrastructure that is planned.
The Lilydale Quarry project is a joint venture between Brencorp, Intrapac and Bayport, and calls upon the collaborative experience and skills of Tonkin + Taylor Australia, Chadwick Geotechnics and Geotechnics from New Zealand.
“Collaboration and communication between all parties is key in ensuring that the Lilydale Quarry project risks and opportunities are understood”, says Roger.
“The relationship with the developers is crucial. Without their commitment to do things in accordance with the advice Tonkin + Taylor and Chadwick Geotechnics has provided, the chances for success would be very slim."
Chadwick Geotechnics is providing an onsite ‘level one’ testing service, including a laboratory and full-time inspection of the filling work.
“In order to meet specific project requirements and provide the engineers with an accurate understanding of the groundwater pressures and settlement in the fill, Chadwick Geotechnics has also provided instrumentation services through collaboration with Geotechnics’ experts from New Zealand”, says Chadwick Geotechnics Managing Director, Tim Chadwick.
“Currently, the groundwater levels in the quarry are being maintained by pumping from a purpose-built sump which will be raised with the fill.
“Over time, however, as the filling is completed, these pumps will be turned off allowing groundwater to stabilise. Groundwater is expected to rise by about 80m. Settlement rates will need to be carefully monitored to provide confidence there will not be any adverse effects on future development activities.
The Lilydale Quarry will be progressively filled over the next five to six years as the Kinley project is developed.