As major building projects continue around Australia, Belfast-based CDEnviro explains how disposal solutions for hydro excavation waste are more crucial than ever.
Non-destructive drilling (NDD) or hydro excavation has become recognised globally as the safest, most effective way of drilling while locating underground assets. This method ensures that underground cables, mains, pipes and other buried utilities are protected during excavation.
Benefits of the method also include enhanced safety for operators and time-savings. Hydro excavation provides the basis for infrastructure and expansion work in urban areas, like Sydney, where major infrastructure including the North West Rail Link and WestConnex is rolling out over the next three years.
The Head of Business Development for Belfast-based CDEnviro, Darren Eastwood, says the advantages of hydro excavation are clear, but it presents a problem for companies in how to treat the waste material from the process.
“The waste material is produced due to high-pressure water applied in the excavation process, and the composition varies dependent on the ground type being excavated,” he explains.
Wastes such as hydro excavation muds, dredged materials and drilling muds can be difficult to dispose of due to their solid-to-liquid semi-state. The solids contain both contaminants and useful materials, such as sand, fine aggregates, organic matter and an elevated level of fine silts and clays.
“Disposal of this slurry is not guaranteed at every clean fill site in Australia. However, if it is accepted, it incurs a large cost due to its nature and weight,” adds Darren.
Yet disposal is not the only solution, as CDEnviro has proved. This material contains useful, reusable materials that can be recycled and resold. This includes sand and aggregates that have many further uses, such as pipe bedding, landscaping, and even to make a high-quality recycled concrete.
“As legislation becomes more stringent and infrastructure development booms, there is an urgent need for urban recycling solutions, instead of rural dumping grounds,” states Darren.
The waste material, therefore, requires a specialist recycling process. The particle size of the slurry is too large and too thick to pump. It is also too wet to convey, and so presents a big challenge for NDD companies. Conventional processing technologies are not effective.
The solution comes from wet processing and the introduction of an innovative technical approach to the problem involving pre-screening, sand recovery, ultra-fines recovery and clay de-watering.
CDEnviro specialises in wet processing solutions, providing bespoke reception centres for receiving this waste. Its technology processes it to recover sand, stone and organics to produce independent revenue streams, and de-watering the final clay content to ensure easy and cheap disposal of this smaller source of waste material. The recovered water can then simply be reused to fill outgoing trucks with industry compliant recycled water.
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