Soil disposal routes explained: classification, WAC and where muck goes

Step one: is it even waste?

Soil you reuse on the site it came from, in line with the CL:AIRE Definition of Waste Code of Practice, is not waste at all — no transfer notes, no landfill tax, no disposal cost. Cut-and-fill balance is always the cheapest disposal route because it avoids disposal entirely.

Once material leaves the site boundary without a Materials Management Plan behind it, it is waste, and duty of care applies from the moment it is loaded.

Step two: hazardous or non-hazardous (WM3)

Classification under WM3 decides whether the soil is hazardous. It is an assessment, not a single test: sample the material to a sound regime, analyse for the contaminants the site history makes plausible, then compare against hazardous-property thresholds.

Site history drives the analytical suite. Greenfield subsoil needs far less than a former garage forecourt, a gasworks or an infill plot with unknown made ground. Guessing the suite is how projects end up re-sampling.

The output is a classification report you keep in the site file. It states whether the material is hazardous or non-hazardous, and it is what a receiving facility will ask to see.

Step three: WAC testing — what it does and does not tell you

WAC (Waste Acceptance Criteria) testing is a leachate test to BS EN 12457-3. It tells you which class of landfill can legally accept the material: inert, stable non-reactive hazardous, or hazardous.

WAC does not classify the waste. A common and expensive misunderstanding is ordering WAC alone and assuming it proves the soil is non-hazardous — it does not. WM3 classification comes first; WAC then confirms the acceptable destination.

Not every load needs WAC. Clean, well-documented inert arisings often move on classification and a facility's own acceptance procedure. Testing becomes necessary where contamination is plausible or the receiving site insists.

Typical lab turnaround is around five working days, with accelerated options where the programme demands it. Plan sampling before the dig starts, not after the muck is stockpiled.

The disposal routes, cheapest first

Reuse on site under a Materials Management Plan — no disposal cost, no landfill tax.

Recovery or restoration site — inert soils used for engineering or landscaping at a permitted facility.

Soil treatment or washing centre — recovers a usable fraction from contaminated arisings and reduces what ends up in landfill.

Inert landfill — for material that meets inert WAC.

Non-hazardous or hazardous landfill — the last resort, and the route where correct classification matters most because misdescription is an offence.

Paperwork that has to follow the load

A waste transfer note (or consignment note for hazardous waste) for every movement, recording the carrier, the description and code, and the receiving facility.

Evidence the carrier is a registered waste carrier, and that the destination holds a permit to accept that material.

Your WM3 classification and, where used, the WAC results — kept together so an inspection or an audit can be answered from one file.

Atlas Stone Supplies handles sampling, UKAS-accredited analysis, classification and haulage as one job, and back-loads aggregate on the return leg. See our WAC testing hub for the detail, or request a quote with your site postcode and volumes.