Hazard Assessment & Waste Classification

The determination of hazardous properties of soils is not simply an assessment of total contaminant concentrations or a review of a site risk assessment. To carry out a full hazard assessment it would be necessary to undertake a source characterisation, including:-

• Site History - to determine the potential contaminants that may be present in the site soil
• Strata and volumes - Intrusive investigation to determine the physical nature and extent, both lateral and vertical of materials below the site
• Chemical quality - Targeted laboratory analysis to chemically assess the various materials encountered
• Hazardous Waste classification

The final hazardous waste classification is based upon specific substances exceeding specific thresholds. This requires the determination of the likely form (compound) of a contaminant within the soil, which will be in part determined by the physico-chemical nature of the soil, i.e. aerobic or anaerobic, clay based, high in organic matter etc.

The form of the contaminant will then determine the hazard(s) and in turn the associated risk(s). For each risk there is a threshold limit, above which the contaminant would be considered hazardous.

As a result of the Landfill (England and Wales) Regulations 2002, which came into force on 15 June 2002, sites receiving waste are now classified as: hazardous, non-hazardous or inert. The outcome of the source characterisation will allow the identification of appropriate disposal/recovery options to be selected for the waste. This may include:-

• Pre-treatment followed by disposal to a hazardous permitted facility
• Disposal to an inert or non-hazardous permitted facility
• Re-use, Recycling or Recovery at an appropriately permitted facility

Dependent upon the route identified for managing the waste soils it is possible that additional characterisation may be required in the form of leaching tests to determine the mobility of the contaminants and to confirm conformance with the new Waste Acceptance Criteria (WAC) limits for the designated site.

At TGEN our consultants have a wealth of experience in dealing with contaminated sites, assessing soils for potential hazardous properties and classifying soils for recovery or disposal. Our expertise in this area allows us to manage all aspects of a hazard assessment, from the investigation through to the identification of suitable disposal routes in-house.