Authors: Rod Lidgard (PDP) & Sarah Newall (HAIL Environmental)
Wasteful soil practices cost New Zealand infrastructure projects and developers billions of dollars in direct costs and time each year. Inefficient use of this finite resource costs New Zealanders billions more in indirect costs such as emissions from cartage and disposal, losses of landfill airspace and valuable soil resources, and increased pressure on roading networks.
The appropriately-named ‘Can You Dig It?’ soil reuse workshop – held immediately prior to the WasteMINZ Conference in May 2024 – kicked off a national movement toward recognising and acknowledging the challenges around soil reuse in Aotearoa New Zealand. Before this time, we would occasionally hear presentations promoting this subject matter at our industry conferences, and perhaps even less frequently we might have been involved in specific projects that included a reuse initiative. But we felt we couldn’t continue to ignore the elephant in the room as land development hit the dizzying peaks of a post-Covid boom in the earthworks season of 2021/22, resulting in significant volumes of soil material being disposed of to landfill.
The introduction of broader waste disposal levies and mandatory disposal volume reporting began to highlight the real magnitude of this problem, as they provided real-time metrics for disposal to landfill. Total waste disposal volumes at the classes of landfill required to report in 2009/2010 was 2.9M tonnes. This rose to a whopping 7.0M tonnes in 2022/23, even with Class 5 (cleanfill) sites still exempt from reporting. Considering MfE’s Solid Waste Analysis Protocol (SWAP) data, which shows over 50% of waste to Class 1 landfills in 2022 was ‘inert’ waste (covering a small variety of waste materials, including soil), as well as anecdotal data from our collected industry experience, we have estimated soil disposal to all classes of landfill (including Class 5) to have been closer to 4.5-7.5M tonnes in 2022/23 – with the accompanying disposal costs both direct and indirect. This is a huge volume soil that can never be reused. From our experience, it is noted that the reason(s) for this disposal are not based on the removal of hazardous contaminated soils alone, but rather a raft of reasons which drove and encouraged disposal to landfill over reuse.
Knowing that the need and desire to do better was strong, the idea and architecture of Can You Dig It? was born. Delegates from public and private industry, geotechnical and contaminated land practitioners, contractors, and Ministry, Regional and Territorial authority representatives attended and shared their unique perspectives on soil reuse in Aotearoa New Zealand. The ultimate goal of the workshop was to produce a white paper summarising the perspectives of this cross-sectional industry group and identify the barriers preventing soil reuse. During the workshop we reviewed foreign and domestic examples of soil reuse and application. Rod Lidgard (Pattle Delamore Partners) and co-authors Sarah Newall (HAIL Environmental), Tim Dee (previously Fulton Hogan, now Jacobs), Chris Hillman (Tonkin+ Taylor), Josh Evans (Waikato Regional Council) and Kevin Tearney (SLR) joined forces to prepare the summary white paper and lead the next steps of raising awareness and engagement on these challenges.
The white paper ‘Reclaiming Resources: Optimising Soil Reuse in Infrastructure and Development’ was prepared and submitted to the Minister for the Environment, Hon. Penny Simmonds on 20 October 2024. The key messages the paper detailed as obstacles to soil reuse included:
- There are currently no national requirements for or guidance around the reuse of soil.
Neither the Resource Management Act nor the Contaminated Land Management Guidelines provide any active promotion or encouragement of soil reuse in any application.
- Existing regulatory hurdles are driving the perception that ‘if it’s not cleanfill, it must be contaminated’ – and in support of this, plan rules and standard consent conditions further limit the flexibility of use of these materials with overly prescriptive requirements that are beyond a fit-for-purpose need.
- The perceived liability and lower value of ‘contaminated’ land by industry stakeholders.
- The relative ease of landfilling in Aotearoa New Zealand.
The white paper was also shared with several other relevant ministers, workshop attendees, WasteMINZ working groups, stakeholders, and it was marketed widely through several channels – including via a webinar held on World Soils Day, 5 December 2024; and Radio New Zealand media interview.
The white paper offers a solution – acknowledging the relevant moving parts of industry that will need to work together – and requests a minister-led application for funding from the waste disposal levy fund to support efforts aimed at reducing soil waste to landfill and reclaiming soil as a resource.
The Minister has acknowledged and recognised soil waste to landfill is an issue which needs to be addressed. The government’s 2024-2026 Waste and Resource Efficiency work programme states that the Ministry will ‘work with industry to identify options to help manage surplus soil generated through construction and infrastructure projects – with the aim of developing cost-effective solutions that recognise the value of soil resource and maximise benefits’.
Recent communications from the Minister for the Environment to WasteMINZ and the key author group have further acknowledged the need to progress this relevant issue with a request to meet and begin the process to address these soil reuse challenges.