WAC Testing vs Waste Classification: Why You Need Both on Construction Projects

On busy construction and infrastructure projects, “waste classification” and “WAC Testing” are often used interchangeably. In reality they answer two different questions – and getting them muddled can lead to expensive surprises when soils reach the landfill gate.

Waste classification, carried out in line with WM3, determines what the waste is. Using a combination of desk study, visual assessment and laboratory data, you assign an EWC code and decide whether the material is hazardous, non‑hazardous or a mirror entry. That classification is a legal requirement before waste leaves site.

WAC Testing tackles a different issue: how that classified waste will behave once it is in a landfill. WAC tests focus on leachability and other parameters that influence whether the waste is suitable for an inert, non‑hazardous or hazardous cell. A soil may correctly be classed as non‑hazardous but still fail the leaching limits for an inert site, meaning it cannot follow the cheaper disposal route you were hoping for.

For developers, this distinction matters because budgets are usually set on the basis of a particular disposal assumption. If you price a scheme on inert disposal but the WAC results push you into non‑hazardous, you can lose tens of thousands of pounds even though your classification was technically correct.

The safest approach is to plan classification and WAC together. Early‑stage characterisation testing can be used to support both, while targeted WAC tests confirm which disposal options are genuinely available. EnviroSolution works with clients to design sampling strategies that deliver both data sets efficiently, rather than duplicating effort late in the programme.

By treating classification and WAC Testing as complementary rather than competing requirements, you gain a defensible Duty of Care trail and far greater cost certainty.