WAC testing and soil: what a carrier should ask before taking it

Soil is the load most likely to turn an ordinary job into a hazardous one, and the customer rarely knows. Two different tests decide what happens to it, and people mix them up all the time. This explains both without the chemistry, shows what a lab report actually tells you, and gives you five questions to ask before your grab lorry turns up on site.

Is soil hazardous waste?

Usually not, but it can be, and you cannot tell by looking. Soil and stones have two codes. 17 05 04 is soil and stones that do not contain hazardous substances. 17 05 03*, with the asterisk, is soil and stones that do. A pair like that is called a mirror entry: which one applies depends on what is in the soil, not where it came from.

The Environment Agency's guidance puts the burden the right way round: to call soil non-hazardous, you must be able to prove it does not contain hazardous substances, and the soil has to be assessed before it is passed to anyone else (gov.uk, construction and demolition waste). Any fragments of asbestos-containing material in the soil make it hazardous waste.

The usual culprits are old fuel tanks and spills, made ground (land built up with old fill, ash or rubble), ash and clinker, and asbestos fragments from old buildings. Japanese knotweed is a different problem with its own rules, and it does not by itself make soil hazardous.

Two different tests for two different questions

This is the part that catches people out. There are two tests, they answer different questions, and passing one tells you nothing about the other.

Classification follows the regulators' joint technical guidance, known as WM3. The current version is the first edition, version 1.2, last updated in 2021. A lab tests samples for the substances likely to be there, and an assessor checks the results against the hazard limits.

WAC stands for waste acceptance criteria. Each class of landfill has limits on what it can accept, mostly about how much leaches out of the waste when water runs through it and how much organic matter is in it. Inert landfill is the strictest: total organic carbon has to be under 3%, among other limits (landfill acceptance criteria). WM3 is blunt about the difference: WAC results must not be used to decide whether waste is hazardous.

The order on a job runs like this:

1. 01Dig, or plan to dig.
2. 02Classify the soil: hazardous or not, and which code.
3. 03If it is going to landfill, WAC test it against the class of landfill you want to use.
4. 04Choose the tip that can accept it, then quote.

One shortcut exists. Uncontaminated soil and stones can go to an inert landfill without WAC testing, but the rules exclude topsoil, peat and soil from contaminated sites. If you are not sure the site is clean, that shortcut is not yours to take.

Who is responsible for testing

The producer has to classify the waste before it is collected (gov.uk). On a building job the producer is normally the main contractor or the groundworker, and they arrange and pay for the lab work. WAC sampling can be done by the producer or by the landfill operator, and in practice the landfill asks for results before it agrees to take the soil.

A carrier is not expected to test anything. But under the duty of care you must check that the description matches what you are loading. If you have reason to think soil is hazardous, you must not take it on a non-hazardous transfer note. "The customer said it was clean" is not a defence when the load is full of ash.

Reading a lab report without a chemistry degree

A full lab report runs to dozens of pages of tables. You only need the summary page, and on it, four lines:

• The classification result. Hazardous or non-hazardous. This decides your paperwork.
• The HP codes, if any. These name the hazard, such as HP7 for causes cancer or HP14 for harmful to the environment. Any HP code means hazardous.
• The code. This goes on the transfer note or consignment note, word for word.
• The WAC result, set out against three sets of limits: inert, stable non-reactive hazardous waste (which can go in a separate cell at some non-hazardous landfills) and hazardous. This decides where the load can go.

In the made-up example, the soil is not hazardous but fails inert WAC, so it goes to a non-hazardous landfill or a site permitted to treat or recover it, not to the inert tip. Put the code on the note, and keep a copy of the report with the job, so you can show why you described the load the way you did.

Five questions to ask before you quote a muck-away

1. 01What was on the site before? A garage, a petrol station, a factory, a farmyard with a diesel tank. Former use is the best single clue.
2. 02Has it been tested, and can I see the report? Ask for the summary page, not a phone call saying it is fine.
3. 03Is there any made ground, ash or demolition material mixed in? Black or grey layers, cinders and broken brick all change the answer.
4. 04Is there anything visible? Fragments of sheet, oily patches, a smell of fuel. If your driver would not want it on their boots, ask.
5. 05Where does the customer expect it to go? If they assume an inert tip and the report says otherwise, have that conversation before the price is agreed, not after the first load is turned away.

If the answers are vague, quote subject to a report, and say so in writing.

Questions people ask

What is WAC testing?

A lab test of how a waste behaves in a landfill, mainly what leaches out of it, used to decide which class of landfill can accept it.

How much does a WAC test cost?

Few labs publish prices, and most quote per job. One consultancy's published 2026 prices were £375 to £550 plus VAT a sample, depending on how fast you want the result, with site visits charged on top. Classification testing is a separate charge, so ask for both in one quote.

Can I use the AI classification tool instead of a test?

No. Our AI waste classification tool helps you pick a likely code from a photo or a description. It cannot see what is inside the soil, so it does not replace a lab test where one is needed.

LoadSnap team

UK waste compliance

Written by the team building LoadSnap, the UK waste compliance platform for carriers and receivers.