Also included was the construction of 4 x pre cast concrete approach ramps at an average of 26m in length each.
The project enabled the farm previously separated by two roads, to be connected as one dairy farm unit.
The site was located on the Hauraki Plains which meant the in-situ ground conditions were poor in nature.
Significant undercutting of the foundations was undertaken under the direction of the geotechnical engineer.
This involved the removal of approx. 1.0m of marine mud and the replacement with AP65 Aggregate imported from a local quarry which was placed and compacted within layers of both geo synthetic cloth and grid.
Temporary de-watering systems were also installed to control the high (tidal) ground waters during construction.
Specialised water proofing subcontractors were also engaged to seal off the underpass to prevent the ingress of the ground waters within the underpass post construction. Pre cast concrete tilt panels were installed to create the approaches to the underpass.
Tilt slab props were erected to hold the pre cast panels in place until both the in-situ vertical stitching of the tilt panels and the construction of the concrete floor of the approaches had been completed and adequately cured.
A significant Council bulk watermain and strormwater drain were also re-diverted as part of the enabling works as the location of these clashed with the box culvert construction works.
Upon completion of the project the carriageway was fully reinstated to Council specifications.
Client: John Van Goch
Consultant: Taiki Engineering Consultants
Duration: 24 Feb 2019 to 3 Jun 2019
Role: Main Contractor