The first of 3400 stone columns, which would reach from the project site to Waihi Beach if they were laid out end to end, are being installed on the Baypark to Bayfair Link project. The columns will improve the ground conditions throughout the site so it can eventually take the weight of the two flyovers.
Installing stone columns involves putting vertical columns of stone (gravel) into the ground and using vibration to move the sand to make way for the stone. This will be done using a 80 tonne crawler crane with a 3.2 tonne ‘vibroflot’ attached - the vibrating element that carries out the compaction and delivers the stone.
NZ Transport Agency Project Manager John McCarthy says the installation of the columns is a significant milestone for the project.
“The stone columns will cover more than 2 rugby fields and use enough gravel to fill eight Olympic-size swimming pools.
“They push against the surrounding ground, increasing its density and enabling the ground to support the weight of the on and off ramps that will be built on top. It will also protect the ground from the risks of liquefaction during an earthquake.
“Each stone column is relatively small (up to 16.5m deep and 1.1m in diameter) and installation takes 20 to 40 minutes each to complete,” Mr McCarthy says.
The stone column work has started on SH2 Maunganui Road near the Te Maunga roundabout. A second stone column rig will arrive in a few weeks. Construction of the 3,400 stone columns is expected to take approximately 10 months.
Mr McCarthy says that while nearby residents can expect some vibration during the stone column works, every effort will be made to minimise the impact of noise and vibration during the project.
The Baypark to Bayfair Link is designed to reduce congestion and improve safety by separating local and state highway traffic and providing walking and cycling connections. The key features include the construction of two flyovers and improvements to the SH29A and Truman Lane roundabout, and the SH2 Maunganui-Girven roads roundabout.
View a video of the stone column work(external link) (a shorter version will also be posted on our Facebook page).
Facts on the stone column work for this project;
Stone columns are well suited for sandy soils and help limit the consequences of future liquefaction during an earthquake.
People can expect to see some changes at the Bayfair roundabout this week, with traffic switching to new lanes from Wednesday 24 October 2018.
The traffic switch will allow for earthworks to begin and utility services to be relocated on Maunganui Road between Girven Road and Exeter Street, in preparation for construction of the Papamoa-bound on and off ramps.
City-bound traffic will use the new lanes from Wednesday morning, and from Friday morning, 26 October, traffic travelling towards Papamoa and Baypark will move onto the old city-bound lanes.
Also, from Friday, access onto Maunganui Road from Exeter Street will be temporarily closed, and there will be no right turn option from Bayfair carpark onto Girven Road near the roundabout.
The Transport Agency thanks people for their patience while this work is carried out, and reminds drivers to stick to the temporary speed limits throughout the construction site.