Waste Classification or WAC testing?

At Roberts Environmental we are asked on many occasions to classify waste soils arising from development activities, solely using Waste Acceptance Criteria (WAC) testing, which is incorrect and illegal as it fails to comply the Duty of Care Regulations.

This incorrect process has been followed for many years and has become a fairly common approach on development projects. However, this opens both the waste producer and their advisors to future legal action as well as potentially increasing waste disposal costs by excluding the Non-Hazardous landfill from the disposal options.

As such, in order to protect our clients, ensure compliance with UK legislation and give greater flexibility when determining waste disposal requirements, Roberts Environmental has provided an explanation as to the roles of both Waste Classification and WAC testing below.

Two Stage Process

Stage 1 – Waste Classification

Under ‘The Environmental Protection (Duty of Care) Regulations’, the waste producer must classify waste;

  • Before it is collected, disposed of or recovered
  • To identify the controls that apply to the movement of the waste
  • To complete waste documents and records
  • To identify suitably authorised waste management options
  • To prevent harm to people and the environment

To do this, guidance presented in WM3 ‘Waste Classification – Guidance on the classification and assessment of waste: Technical Guidance’ should be followed.

This first stage can be described as Waste Classification, and determines if the waste holds any hazardous property, which among others can include;

  • Explosive
  • Flammable
  • Corrosive
  • Carcinogenic
  • Ecotoxic

To do this, laboratory analysis must be undertaken on a representative number of samples, with the suite of analysis chosen to identify those contaminants which are most likely to have impacted the site based on its historic and current usage. Quite often this suite is extensive, covering a range of contaminants including heavy metals, inorganics and organics.

The concentrations of contaminants recorded are then assessed to determine if they represent a Hazard, with some contaminants being considered on their own and others considered together. This can be a complicated process, requiring special software.

Ultimately, this assessment will determine if a particular waste is Non-Hazardous or Hazardous, thereby informing waste storage, transportation and disposal requirements and allowing for appropriate measures to be adopted to protect the health and safety of anyone who may be exposed to the waste.

Once Stage 1 is complete, the waste producer can then decide how they wish to dispose of the waste. Possible waste disposal options may include Landfilling, Incineration, Composting, Anaerobic Digestion or Pyrolysis etc. However, despite a push for sustainable development, on most development sites, landfill disposal remains the chosen and preferred option for waste.

Stage 2 – Waste Acceptance Criteria Testing (WAC)

There are four main landfill categories, these being;

  • Inert
  • Non-Hazardous
  • Stable Non-Reactive Hazardous
  • Hazardous

Waste classified as Hazardous in Stage 1 can only be deposited to either the Stable Non-Reactive Hazardous or Hazardous landfill. With the Inert and Non-Hazardous landfills accepting only Non-Hazardous waste.

Prior to depositing waste to a landfill, an acceptability assessment often needs to be undertaken. This involves carrying out WAC testing, which entails the collection of representative samples of the waste and laboratory analysis.

The suite of testing is typically far less extensive, missing many of the contaminants considered in Stage 1.

This assessment, rather than determining if the waste holds a hazardous property as in Stage 1, is used to determine if particular waste arising can be deposited to landfill without compromising the stability and ability of a landfill to process leachate and gas generated by deposited waste as it ages.

Therefore, WAC has no role in determining if a Waste is Non-Hazardous or Hazardous.

Once the laboratory analysis has been completed, the results can be compared against threshold levels for three Landfill types, these being:

  • Inert Landfill
  • Stable Non-Reactive Hazardous Landfill
  • Hazardous Landfill.

There are no WAC threshold values for a Non-Hazardous landfill, as material classified as Non-Hazardous in Stage 1, can be disposed of directly to a Non-Hazardous Landfill without WAC testing, thereby avoiding WAC testing costs.

Should the waste producer wish to deposit the waste to an Inert Landfill, WAC testing would be required. In the event Non-Hazardous waste (classified in stage 1) fails to meet the requirements of the Inert Landfill, the waste can be deposited to a Non-Hazardous Landfill without further WAC testing.

However, due to the lack of WAC thresholds for Non-Hazardous landfill, should Stage 1 not be completed, in addition to failing to comply with Duty of Care regulations, the next landfill disposal option would be a Hazardous Landfill, which could have significant cost implications to a development.

In addition, as the scope of testing is much less extensive in Stage 2, there is a risk, by relying only on WAC results, that Hazardous Waste is being deposited into a Non-Hazardous Landfill, creating a potential future liability and putting the health and safety of people who may come into contact with the waste at risk.


By solely relying only on WAC testing when disposing waste arisings, the waste producer is failing to comply with their legal duties, opening themselves and their advisers up to future regulatory action and potentially limiting their landfill disposal options, potentially adding unnecessary costs on a development project.

Therefore, any Waste Assessment must first involve an assessment in line with WM3 (Stage 1 above), and where Inert, Stable Non-Reactive or Hazardous Landfilling is required, WAC testing (Stage 2) to ensure the most appropriate landfill category is chosen.

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For further information on how we can assist you with Geo-Environmental Assessments please do not hesitate to contact us on 0191 230 4521 or email: Enquiries@robertsenvironmental.co.uk.

1 Croft Stairs
Newcastle Upon Tyne

55 Whitfield Street

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