A number of highly innovative construction processes have been introduced by Penrith-based contractor Kelly & Shepherd during its work on Stage 2.7 of the McCarthy's Terrace cut, fill and compaction project at Penrith Lakes.
Despite being a relatively straightforward earthmoving project, this project features a number of innovations designed to improve quality, earthworks accuracy, on-site safety, operator fatigue and project management.
Industry-leading innovations on this project include:
The project is being carried out by Kelly & Shepherd on behalf of client the Penrith Lakes Development Corporation, with the aim of bringing a previously filled area up to a suitable standard of compaction for proposed future developments.
It covers an area of 44 ha, requiring cut, fill and compaction of 800,000 cu m of material.
Tolerances on the project are -100 mm, +0 mm on cut and +100 mm, -0 mm on finish.
Kelly & Shepherd's use of GPS-based machine control to automate scraper operation ensures far more accurate cut and fill during final trim work (within last 100 mm), reducing options for operator error and minimising stress and strain on operators.
This is believed to be a world first, and posed some real design challenges for Laserquip in implementing Kelly & Shepherd's request.
Another innovation on this project is the introduction of the "Optimum Moisture Plough", a modified agricultural offset plough towed by a Challenger tractor, fitted with a 7000 litre water tank and a high-pressure water spray system. A filler tank above the main tank allows the plough to be filled "on the run" from a water cart cannon.
The plough travels over cut or filled material, "injecting" water up to 300 mm below the surface, to ensure evenly mixed, optimum moisture levels throughout the soil layer to be compacted.
This machine helps ensure that two of the three key factors in compaction (moisture, mixture and layer thickness) are achieved, ensuring optimum compaction.
In addition, the plough minimises water wastage - a common occurrence when using a water cart, with up to 30% of water being lost due to fine spray blow off and evaporation before it has the opportunity to penetrate the surface.
A further advantage is reduced machine downtime during hot or windy conditions, when other equipment (scrapers, dozers, rollers, trucks, etc) are held up waiting for optimum moisture levels to be achieved between placing each layer.
A further new development on this project is the use of a prototype GPS-based machine positioning system, which will ultimately be fitted to all earthmoving equipment on site.
Developed and implemented by Kelly & Shepherd - and made available to the client and consultant - this provides a realtime view of where all equipment is at any time, and where it has been.
Capable of being viewed remotely in an office, it is designed not only as a site and machine management tool, but also as a quality management tool, identifying to the contractor and compaction consultant any areas which may have been "missed" by a roller or other equipment, and therefore requiring additional checking.
Background information: The PLDC is a joint venture between Boral, Readymix and Hansen, which operates the Penrith Lakes scheme, a 2000 hectare site in Sydney's western suburbs supplying about 65% of Sydney's sand, aggregate and other quarry products, with a throughput of around 5 million tonnes of material a year.
Kelly & Shepherd's contracts with PLDC include:
Work on this project is being carried out using a team of six scrapers, two dozers, a grader, plus compactors, rollers and the water plough.
All levels and grades are controlled by a Topcon System 5 GPS+ system, providing both automated and indicate control of the dozers and scrapers. There are no pegs or stringlines on site.
All volumes and finished works are checked by PLDC's surveyor Matt Eddy, using Topcon's GPS+ rover systems.