21 Sep, 2023
Simtec Materials Testing Laboratory

Soil Waste Classification

Soil waste classification is the process of characterising and categorising soil that is intended to be discarded by disposal to landfill. The process applies to ‘excess’ soils regardless of whether the soils is deemed to be contaminated.

The characterisation is based on the history and activities related to the material, the assigned appropriate European Waste Code (EWC), and because soils are a 'mirror' entry in the EWC, i.e. they can be classified as hazardous wastes or non-hazardous wastes, the measured concentrations of contaminants.

Part of the waste producer's legal "duty of care" is to ensure that waste soils are precisely and appropriately defined before being categorised for disposal at an establishment with the appropriate licence. The Environment Agency and/or HMRC may pursue legal action as a result of improper characterisation, classification, or disposal.  

What Are The Different Soil Waste Classifications?

Waste soils are classified into two main categories, Hazardous and Non-hazardous.

“Guidance on the classification and assessment of Waste, (1st Editionv1.2) September 2021  (EA/SEPA/ NRW)

The waste classifications are determined by the chemical properties of the waste and how it behaves in the environment, specifically within a landfill. The categories are defined by the category of landfill that can accept the waste.

‘Inert waste’ is a sub-category of non-hazardous waste. This poses minimal risk and is acceptable into a licensed inert landfill.  

‘Stable Non-reactive hazardous waste’ (SNRHW) is a subcategory of hazardous waste. This has a low potential for leaching and, subject to meeting additional physical criteria, may be deposited in landfill cells with a less onerous standard of containment than other hazardous wastes. That cell may exist within a landfill licensed for non-hazardous wastes.

Soil waste characterisation and classification is based on laboratory measurement of the total amount of chemical contaminants in the material.

Waste Acceptance Criteria (WAC) Tests

Waste Acceptance Criteria (WAC) tests are a supplementary set of tests that determine the acceptability of waste soils into the determined category of landfill based on the waste classification.

The WAC test includes two sections: a direct measurement of specified organic substances and a measurement of leachability of metals, sulfate and selected physio-chemical parameters, i.e. the ability of the waste material to release such substances into water.

The results of WAC testing determine if the waste would be likely to meet the relevant permitting requirements of the determined classification of landfill, where the classification is hazardous or may potentially be inert.

Differences Between Soil Waste Classification and WAC Tests

The most important difference to note is that waste cannot be classified by use of WAC testing.

For hazardous wastes, WAC testing provides additional information that supports whether specific additional pre-treatment of waste is required to meet the landfill permit requirements. For potentially inert non-hazardous waste, WAC testing determines whether the lower waste classification applies.

The combination of waste soil classification and relevant WAC testing is used to determine the appropriate way to manage and dispose of excess soil intended for disposal to landfill.

Soil Waste Classification & WAC Testing by Simtec Materials Testing

In conclusion, waste soil classification and WAC tests are two important concepts in the field of waste management.

While both are related to the management of waste, they are different in terms of their purpose and methodology. Understanding the differences between waste soil classification and WAC tests is essential for effective waste management and for protecting human health and the environment.

To find out more about our waste soil classification and WAC testing services, please get in touch.