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Recycling hydro excavation waste

Sustainable Sand and Stone (SSS) is a business born through the desire to carry out hydro-excavation in a more sustainable way – and the materials it produces are ideal for landscapers looking to source more sustainable sand and aggregate 

Established in 2022, SSS was born in Mangere, Auckland and is New Zealand’s first hydro excavation waste recycling plant. It was designed and built in England, constructed in Auckland and overseen by the pioneers of hydro excavation in New Zealand – Southey’s Group. 

The waste it recycles is turned into five product lines, all of which comply with Auckland Council’s ACS740 specifications (which sets out the material requirements for recycled aggregate), and can be used to meet a variety of landscape construction requirements. 

  • All Purpose Sand, which is suitable to use as bedding for patios and pavers, above-ground pools, and sand pits.  

  • Coarse sand suitable for decorative planting, bedding material, and paths.  

  • Chip used for bedding of tanks, pools, pipes, drainage, decorative planting, and paths (2-7mm). 

  • Drainage chip (7mm to 20mm).  

  • Drainage chip (20mm to 40mm). 

An extra tool in a landscaper’s kit

Company director Rob Southey says the product could be particularly useful for landscapers, who are  tendering for commercial contracts with emissions targets and those whose clients have sustainable materials in mind. 

“For landscape companies tendering for work and looking for a low emission recycled aggregate, SSS’s products will lift their sustainability weighting higher, thereby giving them a leading edge in the tender process," says Rob. 

“Also, for homeowners looking for a green, sustainable product to use on their property, our range of landscape products is a no-brainer and is available at competitive prices.” 

A necessary process

Hydro excavation is a popular, precise method of trenching and exposing underground services in urban areas to avoid the risk of damage from excavators and hand tools, which can cause widespread disruption through gas or power outages to residents.  

However, since hydro excavation was launched in New Zealand in 2010, thousands of tonnes of muddy slurry was being dumped into fill sites around the country every year to be stored, dried and used as fill for gullies on farmland. The dumpsites are generally in rural areas, which means trucking the waste long distances, leading to higher fuel and emission costs. 

Finding a better way

This was an unacceptable price to pay for the benefits of hydro excavation, says Southey’s director Rob Southey. 

“As a management team, myself, Sheryl Lean and Kevin Chapman identified it was time to move toa more sustainable path for disposal of hydro excavation waste.” 

The plant takes hydro excavation slurry, removes the clay and organics, and washes the remaining stone and sand, which is then sized to the millimetre to produce a zero-carbon footprint product.  Not only that – it also reduces the demand on resources from seabed sand mining in areas such as Kaipara Harbour and Pakiri Beach, or from other quarrying activities, which produce significant carbon emissions and cause greater environmental impact. 

“In comparison, our extracted resource is a by-product of highly accurate excavation, of which more than 90% can be reused in meaningful applications at a fraction of the CO2 emissions,” says Rob.  

“We’re pretty proud of what we’ve achieved – and it’s just the beginning!”


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