Tonnage
10
Material
Hydro Excavation Waste, Road Sweepings & Gully Waste
Output
Clean Sand & Aggregates
The Challenge of Hydrovac Waste in Urbanized New Zealand
Once considered a minor by-product, hydrovac waste is now a significant issue in the push toward a truly circular economy, with high potential as a sustainable alternative to virgin sand and aggregates. Rapid redevelopment and growing urbanization have increased the use of non-destructive digging (NDD), a reliable and precise excavation method in high-density areas. However, this has also led to a large volume of difficult-to-process slurry containing soil, water, and debris.
According to Stats NZ, the country’s total urban area expanded by 14.6 percent between 1996 and 2018. Since then, the population has continued to grow, reaching 5.31 million at the end of 2024, with estimates projecting 7 million by the 2060s. This upward trend in population and urban land will lead to a continued reliance on hydro excavation.
Our business development executive Eoin Butcher notes that with increased urban density comes a high concentration of underground utilities, which require precise excavation for new developments. As the population grows, the adoption of NDD will increase, as will the volume of solid-liquid waste generated. This waste stream is challenging to process and, as a liquid waste, must be disposed of at specialized facilities, leading to high transportation and disposal costs. However, effective dewatering equipment can make the process cost-effective, and we are actively working with companies to achieve this.
InterGroup's Innovative Solution
InterGroup, a leading provider of industrial and infrastructure services, has invested in a new resource recovery facility at its Auckland premises. As one of the first wet processing plants of its kind in New Zealand, it provides an opportunity to reuse materials and reduce the need for landfill disposal.
The facility processes more than just hydro excavation waste. InterGroup has ensured it can also handle road sweepings and drainage waste, achieving the same high-quality recovery results. The plant processes up to 10 tonnes per hour of road sweepings and hydrovac muds, dewatering the waste and recovering a variety of washed and graded aggregates.
The facility has been operational since early 2024 and is recovering around 48,000 tonnes of reusable material annually, achieving a 64% diversion from landfill.
Based at InterGroup’s Auckland depot, the resource recovery facility features a range of innovative technologies including the HYDRO:TIP™ solid/liquid tipping system, an AquaCycle™ thickener water cleaning and treatment system, and an AggMax™ scrubbing and classification system.
A Win-Win for the Environment and Business
The New Zealand Infrastructure Commission has found that construction waste makes up between 40% and 50% of all waste sent to landfill—around 4.4 million tonnes annually from construction and demolition sources.
Sam Clive, general manager for business development at InterGroup, states that investing in this type of solution is not only a smart environmental decision but also a good commercial one. He explains that as demand for hydro excavation grows, the resulting waste must be handled responsibly.
Clive says, “We are recovering valuable construction materials that would have otherwise gone to landfill, and at the same time reducing our own operational costs. This leads to reduced emissions and extends the life of our natural resources by supplementing demand with sustainably sourced recycled products. It’s a total win-win.”
InterGroup, with over 500 staff and a fleet of over 400 specialized plants, is dedicated to providing sustainable solid and liquid waste management through its environmental services.
