Hazardous Soil: Classification, Testing and Disposal Guide
Hazardous soil is excavated or surplus soil that has been classified as hazardous waste because it contains hazardous substances or has one or more hazardous properties at a level that meets the relevant classification criteria.
It is commonly encountered on construction, demolition, remediation and infrastructure projects where ground has been affected by previous industrial, commercial or other potentially contaminative activities.
Hazardous soil cannot simply be treated as ordinary excavated material. Before it is removed from site, it needs to be properly assessed and classified, and it must be handled, transported and disposed of through appropriate permitted routes.
If you have excavated soil that may be contaminated, the first step is to establish what is in the soil, how much is present and how the material should legally be classified.
What is hazardous soil?
Hazardous soil is soil that meets the regulatory criteria for classification as hazardous waste.
The fact that soil contains a contaminant does not automatically mean it is hazardous. The classification depends on the substances present, their concentrations and properties, and the relevant hazardous waste criteria.
Common contaminants found in potentially hazardous excavated soil include:
- Heavy metals
- Hydrocarbons
- Petroleum hydrocarbons
- Polycyclic aromatic hydrocarbons (PAHs)
- Solvents
- Pesticides
- Creosote
- Coal tar-related contamination
- Certain asbestos-containing materials
- Other substances associated with historic industrial or commercial land use
The potential source of contamination can provide an indication of what may be present, but laboratory analysis is normally needed to properly characterise the waste.
For example, soil excavated from a former petrol station may require investigation for petroleum hydrocarbons, while ground from a former industrial site could contain a wider range of metals, PAHs, solvents or other contaminants.
What makes soil hazardous?
There is an important distinction between contaminated soil and hazardous soil.
Contaminated soil may contain substances of concern but still be classified as non-hazardous if the concentrations and properties do not result in the waste meeting hazardous classification criteria.
Hazardous soil, on the other hand, meets the applicable criteria for hazardous waste.
This is why the phrase “contaminated soil” should not automatically be used interchangeably with “hazardous soil”.
The classification should be based on the characteristics of the actual waste rather than simply its history or appearance. Soil can look perfectly normal and still require hazardous waste classification. Conversely, soil containing detectable contamination may not necessarily be hazardous.
Hazardous soil EWC code
For excavated soil and stones arising from construction and excavation activities, the relevant List of Waste (LoW) category is generally found under 17 05 – soil, stones and dredging spoil.
The key entries include:
| EWC / LoW code | Description |
| 17 05 03* | Soil and stones containing hazardous substances |
| 17 05 04 | Soil and stones other than those mentioned in 17 05 03 |
The asterisk is important because it identifies a hazardous waste entry.
The Environment Agency’s waste classification guidance identifies 17 05 03* as a hazardous entry and 17 05 04 as its non-hazardous counterpart.
However, the correct waste code should be established as part of the waste classification process. It should not be selected simply because soil comes from a contaminated site.
Other waste codes can apply depending on the source and composition of the material. For example, waste from soil remediation can fall within the 19 13 category.
How is hazardous soil classified?
Before hazardous soil is sent for disposal or recovery, the waste needs to be properly classified. The process will depend on the circumstances of the project, but typically involves:
Establish the source of the soil
Understanding where the soil came from is an important first step.
Information from a site investigation, desk study, previous land use, remediation report and excavation records can help identify potential contaminants.
Identify potential contaminants
The investigation should establish which substances may be present.
Depending on the site, this could include:
- Metals
- PAHs
- TPH
- BTEX
- VOCs
- SVOCs
- Hydrocarbons
- Pesticides
- Asbestos
- Other site-specific contaminants
Sample and analyse the soil
Representative samples may need to be collected and sent to an appropriately competent laboratory for analysis. The testing required will depend on the site history and the suspected contamination. There is no single testing suite that is appropriate for every excavation.
Assess the laboratory results
The analytical results can then be assessed against the relevant waste classification criteria.
This is where an important distinction is made between soil that is:
- Inert
- Non-hazardous
- Hazardous
A waste producer must assess and describe their waste before sending it for recovery or disposal. GOV.UK specifically identifies 17 05 03* soil and stones containing hazardous substances as an example of a waste stream that may require classification.
Confirm the disposal or recovery route
Once the waste has been classified, the receiving facility needs to confirm that it is permitted to accept that particular waste. A classification alone does not mean that every landfill or treatment facility can accept the material.
Hazardous soil vs non-hazardous soil
One of the most common mistakes on construction projects is assuming that all contaminated soil is hazardous. It isn’t. The difference comes down to the classification of the waste.
Inert soil
Inert waste does not undergo significant physical, chemical or biological transformation and must meet the relevant requirements for inert waste. For landfill disposal, inert waste must meet applicable Waste Acceptance Criteria (WAC), including relevant leaching limits.
Examples may include suitable uncontaminated excavated soil and stone that has been appropriately assessed.
Non-hazardous soil
Non-hazardous soil may contain contaminants but does not meet the criteria for classification as hazardous waste. It may still require testing, documentation and an appropriate permitted disposal or recovery route.
Hazardous soil
Hazardous soil meets the relevant hazardous waste criteria. It requires greater controls around its management, including ensuring that the receiving facility is permitted to accept the waste. The Environment Agency recognises separate landfill classes for inert, non-hazardous and hazardous waste, with acceptance requirements applying to each.
Does contaminated soil always have to go to hazardous landfill?
No.
This is an important point for anyone planning a remediation or excavation project.
The presence of contamination does not automatically mean that soil must be sent to a hazardous landfill.
First, the waste needs to be correctly classified. Once its classification and characteristics are understood, the available options may include:
- Reuse on the same site where permitted
- Treatment
- Soil washing or other treatment technologies
- Recovery
- Transfer to a suitable permitted facility
- Disposal at an appropriately permitted landfill
The most suitable route will depend on the contamination, waste classification, physical properties, project requirements and the facilities available. The Environment Agency also recognises routes for waste recovery, but contaminated or non-inert material may require sampling, analysis and potentially further assessment before it can be accepted for recovery.
Hazardous soil disposal
Hazardous soil disposal needs to be planned before excavation wherever possible.
This is because the cost and availability of disposal routes can vary significantly depending on the waste classification and contamination profile.
A typical hazardous soil disposal process may look like this:
Site investigation → Soil sampling → Laboratory analysis → Waste classification → Facility approval → Collection → Transport → Treatment/recovery or disposal
The receiving facility will normally need sufficient information about the waste before accepting it. This can include the waste classification, description, analytical results and other information needed to demonstrate that the waste is suitable for the proposed facility.
Environment Agency guidance requires landfill operators to check the classification of waste and its compliance with the relevant waste acceptance criteria before accepting it.
What testing is required for hazardous soil?
The testing required depends on the site. There is no sensible “one size fits all” analytical package because the likely contaminants depend on the site’s history and the material being excavated.
For example:
| Potential source | Contaminants that may be investigated |
| Former petrol station | TPH, BTEX and other petroleum hydrocarbons |
| Industrial site | Metals, PAHs, hydrocarbons and site-specific contaminants |
| Former gasworks | PAHs, hydrocarbons, cyanide and other contaminants |
| Agricultural land | Pesticides, herbicides and metals |
| Railway land | Hydrocarbons, metals, PAHs and other site-specific contaminants |
| Made ground | Variable; depends on historical fill and previous land use |
Testing should be designed around the site investigation and intended waste route.
The laboratory report is only one part of the process. The analytical results need to be interpreted as part of the overall waste classification.
What is WAC testing?
Waste Acceptance Criteria, commonly referred to as WAC, are criteria used to determine whether certain waste is acceptable at a particular class of landfill. WAC should not be confused with waste classification.
Waste classification:
Is the waste hazardous, non-hazardous or inert?
WAC testing:
Does the waste meet the acceptance criteria for the proposed landfill route?
These are related but different assessments. The Environment Agency states that landfill operators must only accept waste that meets the relevant waste acceptance criteria for the class of landfill concerned. For inert landfill, for example, the material needs to meet applicable leaching limits and other requirements.aping, recycled materials are just as effective and kinder to the budget and the environment.
How much does hazardous soil disposal cost?
There is no single price for hazardous soil disposal.
The cost can vary considerably depending on:
- Waste classification
- Contaminant concentrations
- Type of contaminant
- Quantity of soil
- Soil composition
- Laboratory testing requirements
- Treatment requirements
- Disposal facility
- Transport distance
- Loading arrangements
- Project location
- Whether the material can be recovered or treated instead of disposed of
For this reason, hazardous soil disposal should be priced against the actual analytical information wherever possible. A cheaper-looking disposal option may not be suitable if the facility cannot legally accept the waste or if additional treatment or testing is required.
Can hazardous soil be recycled or recovered?
Potentially, yes.
Disposal should not necessarily be the first option considered. Depending on its classification, composition and intended use, excavated soil may be suitable for treatment or recovery.
However, contaminated material cannot simply be moved to another site and described as “fill”. The proposed recovery route must be appropriate and compliant with the relevant environmental permitting requirements.
The Environment Agency’s current guidance on deposit for recovery states that waste must be characterised against the waste classification guidance and that non-inert or potentially contaminated waste may require sampling and analysis. Where recovery is possible, it can reduce the amount of material requiring landfill disposal and may provide a more sustainable solution for a construction project.
Transporting hazardous soil
Once soil has been classified as hazardous waste, the collection and transport arrangements need to reflect its classification. The waste producer remains responsible for ensuring that the waste is properly described and transferred through an appropriate waste management route.
The carrier and receiving facility must be suitable for the waste being transported and accepted. The paperwork and information accompanying the waste should accurately describe what is being moved, where it has come from and its classification. Importantly, the waste should not be classified differently simply to obtain a cheaper disposal route.
Why hazardous soil should be assessed before excavation
Testing and classification before large-scale excavation can prevent significant problems later.
If contaminated soil is excavated before its disposal route has been confirmed, the project can potentially be left with:
- Large stockpiles occupying valuable site space
- Delays to excavation works
- Unexpected disposal costs
- Additional testing requirements
- Limited availability at suitable facilities
- Problems with accepting facilities
- Programme delays
Where contamination is suspected, early assessment gives the project team a much clearer picture of what will be excavated and how it can be managed. This is particularly important on large developments where thousands of tonnes of soil may need to leave site.
Hazardous soil disposal: what information do you need?
If you are looking to arrange hazardous soil disposal, having the following information available can make the process considerably easier:
- Site location
- Estimated quantity in tonnes
- Where the soil has come from
- Site investigation information
- Laboratory analysis
- Waste classification
- Proposed EWC/LoW code
- Contaminants identified
- Whether the material is soil, made ground or mixed material
- Excavation programme
- Preferred collection dates
- Whether the soil is stockpiled or being excavated directly
If you don’t have all of this information, it doesn’t necessarily mean the material cannot be assessed. However, additional investigation or testing may be required before a disposal route can be confirmed.
Frequently asked questions about hazardous soil
What is the EWC code for hazardous soil?
For construction and excavation waste, 17 05 03* covers soil and stones containing hazardous substances. The corresponding non-hazardous entry is 17 05 04. The correct code should be confirmed as part of the waste classification process.
Is contaminated soil hazardous waste?
Not necessarily. Contaminated soil may be classified as non-hazardous depending on the contaminants present, their concentrations and the applicable hazardous waste criteria.
Can soil containing hydrocarbons be hazardous?
It can be, but the presence of hydrocarbons alone does not automatically determine the classification. The type and concentration of the substances and their relevant hazardous properties need to be assessed.
Can soil containing asbestos be hazardous?
Potentially. Asbestos-containing material requires particular care and the correct classification and disposal route depend on the nature and characteristics of the waste. It should not be assumed that the presence of a small amount of asbestos automatically determines the same classification in every circumstance.
Does hazardous soil need to go to landfill?
Not necessarily. Depending on its characteristics and the available permitted routes, hazardous or contaminated soil may potentially be treated or recovered rather than simply disposed of.
Do I need to test soil before disposal?
Where the classification or acceptance route cannot be established from existing information, testing may be required. The appropriate testing depends on the site history, suspected contaminants and proposed waste route.
What is the difference between soil classification and WAC testing?
Waste classification determines the status and characteristics of the waste, while WAC testing is used to establish whether material meets the acceptance requirements for a particular landfill class.
Can hazardous soil be reused on another site?
Not simply because it is excavated soil. Any proposed reuse or recovery route needs to comply with the relevant environmental requirements and be appropriate for the material. Potentially contaminated or non-inert waste may require sampling, analysis and further assessment.
Need to dispose of hazardous soil?
If you have excavated soil that may be contaminated, getting the classification and disposal route right before moving the material can save time, avoid unnecessary costs and prevent delays to your project.
We can help assess your requirements and arrange an appropriate route for hazardous and contaminated soil from construction, demolition, remediation and development projects.
Provide details of the site, estimated tonnage and any available laboratory results or waste classification information, and we can advise on the next steps.
Contact our team to discuss your hazardous soil disposal requirements.
