Published - 27 Aug 2024

This article describes the origins of the Definition of Waste: Development Industry Code of Practice (DoW CoP) leading up to its launch in 2008 and looks ahead to its future development. There is a common misconception that industry or CL:AIRE invented the scheme, and that soil reuse did not happen much before that. However, the scheme had an evolution before the CL: AIRE DoW CoP as we know it today was published.

Back in the 1990s there was strong planning policy to enable brownfield site development and encourage the construction industry to look favourably at these sites for development, particularly for housing. At this time, planning policy required 60% of new housing to be built on brownfield sites. That was an important driver for the development of land contamination assessment, remediation treatment, quality assurance processes and sustainable growth models.

However, by the early 2000s, this drive through planning was hindered by dual regulation. The management of material required compliance with both land quality and waste licencing. Various mechanisms were looked at to make the brownfield development process more efficient and avoid the real and perceived blight issues linked to waste licencing, as it was at this time. Blight affected the ability to raise funding and negatively impacted mortgage deals. Developers asked Government for an alternative approach.

A better system to enable reuse had been worked on during the development of the Channel Tunnel rail link, in the early 1990s where an agreement on excavated material arising was created by the then Waste Regulation Authorities involved, Kent County Council and London Waste Regulation Authority.

This enabled the reuse of clean, naturally occurring materials along the line. It also allowed the reuse of material outside this definition, but which was nonetheless suitable for use (both chemically and geotechnically), by considering reuse site settings e.g. by deriving a site-specific specification based on the proposed end-use.

This local agreement was the backbone to an understanding that was further developed when the Environment Agency created the first document and position statement called the “Definition of waste on greenfield and brownfield sites” published in 2006 in response to a Government request at cabinet office level This document outlined the opportunity to reuse various material, by adopting the approach of land contamination management using site-specific risk assessment. This extended the scope of the Waste Framework Directive exclusion for the reuse of clean naturally occurring materials on the site of origin, to include suitable made-ground materials e.g. those impacted by contamination.

The next step was to enable some material to be treated to “make it suitable for use” and thus enable a more sustainable approach compared to the old dig and dump solution for contaminated soils.

The development and introduction of mobile treatment licences further developed this theme. However, as more developers looked to take up this option the burden of administration on the regulators began to be an issue.

In response an industry steering group, working closely with regulators in England and Wales, including input from Defra, and the predecessors to the Department for Levelling Up, Housing and Communities (DLUHC) and Homes England, developed the approach we now know as the CL:AIRE DoW CoP. This process was coordinated and managed by CL:AIRE towards the end of the 2000s. Defra, the Environment Agency, and several industry organisations, funded CL:AIRE, to develop and publish Version 1 of the DoW CoP.

Version 1 was launched in 2008 and included the Site of Origin and Cluster scenarios. The DoW CoP worked well and adoption increased year on year enabling brownfield site developments to achieve the Waste Framework Directive aim of reducing construction waste going to landfill.At the heart of the scheme, is the role of the Qualified Person, a trained, independent professional, who reviews and declares project conformance with the DoW CoP requirements and ensures reporting aligns with good practice, which should now follow the Environment Agency Land Contamination Risk Management approach. From the point of its launch CL:AIRE developed and began running the QP training course and maintenance of the Register of QPs. Declarations under Version 1 were submitted directly to the Environment Agency’s permitting support team.

Despite this success, it was soon apparent that a lot of surplus clean soil was still being sent to landfill and some developer groups began asking for an extension of the on-site clean, naturally occurring materials option for reuse of this material on third party sites.

Frequently such material transfers were already happening, but not in a quality assured manner compliant with the protective requirements of the Waste Framework Directive. In response the CL:AIRE steering group developed Version 2 of DoW CoP. This enabled direct transfers of clean, naturally occurring materials between sites, once again by adopting the site-specific risk assessment approach to ensure the material was suitable for use at the receiver site.

Alongside the development of Version 2, published in 2011, and in response to the significant increase in use, came the need to better fund the administration and management of DoW CoP; including the QP register, training, the handling of received Declarations and the development of standards of use.

A Declaration fee scheme was introduced to enable CL:AIRE to properly fund oversight, training, administration and further development of the scheme.

Ambiguity in some of the earlier wording, and further aspirations to meet the Waste Framework Directive reduction in soil materials going to landfill, has pushed for additional options in a proposed Version 3 (under development).

In summary - Where did DoW CoP come from?

• The Channel Tunnel Rail Link – a pilot design – Waste Regulation Authorities in the Southeast,
• National planning policy 60% of new housing on brownfield sites,
• Environment Agency document and Regulator Position Statement: Definition of Waste on Greenfield and Brownfield sites,
• Joint industry and regulator development through CL:AIRE to create the DoW CoP as we recognise it today;
  • DoW CoP version 1 Site of Origin & Cluster,
  • DoW CoP version 2 Inclusion of Direct Transfer scenario,
  • DoW CoP version 3 – under development

The 2023 Defra Environmental Improvement Plan has called for additional measures to confirm soil as a resource, not a waste. It encourages the uptake of soil depots or hubs. Additional changes may be needed in Version 3 or further development of the scheme to create the conditions for such sites but only where high-quality operations and material output can be ensured. This has become a point of high priority for CL:AIRE, the industry, Defra, and the regulators.

The creation of Soil hubs / Earthbanks / soil repositories, for long-term storage will create the possibilities for increased sustainable soil reuse and open the system to greater to innovation and efficiency.

It will be important for soil resources to be safeguarded for a more sustainable future across all sectors. This will help with addressing the issues of climate change, food security, natural flood management, water resource safeguarding and biodiversity net gain. The further development of the DoW CoP system with full industry support will help achieve this, underpinned by a recognised quality mechanism for material reuse. Ultimately this will continue to reduce the disposal of valuable soil resources.