Prioritisation of Closed Landfill Sites for Environmental Monitoring
User Manual
November 2008


The Scotland and Northern Ireland Forum for Environmental Research (SNIFFER) seeks the development of an Environmental Monitoring Prioritisation Tool in order to rank the potential risks to human health and the environment from closed landfill sites in both Scotland and Northern Ireland, until surrender of their Waste Management Licences (WML).

The Scottish Environment Protection Agency (SEPA) and the Northern Ireland Environment Agency (NIEA) therefore require a fair, transparent and non-subjective system to prioritise closed landfill sites in terms of risks to human health and the environment. This will enable resources to be focussed on landfill sites where the greatest priority is identified. The need for additional monitoring and/or remedial measures can then be emphasised to the Operator. In addition, the tool and subsequent ranking should assist both regulators and operators to identify low priority landfill sites where licence surrender may be readily achievable.

This user manual is a clear and concise non-technical document that can be used by a range of audiences including regulators and waste management operators to accurately input data into the prioritisation tool. The process flow diagrams and tool methodology, Appendices I and II respectively, should be consulted in conjunction with this document.

1.1    Environmental Monitoring Prioritisation Tool

The purpose of the prioritisation tool is a first step in highlighting potential risks from Closed Landfill Sites (hereafter referred to as Sites) and identifying possible areas for further investigation

The initial task in the development of the environmental monitoring prioritisation tool was a scoping exercise to assess the type and quality of information available for sites in Scotland and Northern Ireland. The desk based exercise reviewed the type of information typically required for Site Closure Plans, Gas Risk Assessments, Groundwater RiskAssessments and Pollution Hazards Assessments. The selection process enabled a range of sites to be chosen that allowed for differences in:
Once the initial data was collected this enabled the prioritisation tool to be drafted using the information from categories above to feed into a source-pathway-receptor layout. The tool follows the structure as shown in the flow diagrams detailed within Appendix I. As shown in Appendix I, the prioritisation tool clearly follows the established criteria of source, pathway and receptor. The prioritisation tool also incorporates a priority weighting system, which is used to rank the landfill sites in order of priority, with particular attention given to leachate and landfill gas migration issues.

1.2    Scoring and Ranking

The process flow diagrams contained within Appendix I illustrate the scoring that is applied to each question or strand of a question. In general the higher the score applied, the higher the priority and the lower the score, the lower the priority. When the user answers questions within the tool, the scores are collated and a priority level is applied i.e. Priority 1, 2 or 3.

The priority spider diagrams shown in Appendix III illustrate how the priority levels associated with gas, groundwater, surface water and global warming is derived from the individual questions. Once the data has been input to the prioritisation tool, the priority level associated with gas, groundwater, surface water and global warming will be produced. Table 1 illustrates the maximum priority score that can be achieved for each parameter in the prioritisation tool.

Table 1 – Maximum priority score
Parameter  Maximum priority
Gas priority  315
Groundwater priority 355
Surface water priority 355
Global warming priority 165
The priority levels from the closed landfill sites are identified as Priority 1, Priority 2, Priority 3 or Negligible. The priority score range for each of these options is split into quarterly intervals (e.g. Gas Priority: negligible scores between 27 (lowest possible score available) to 99, low scores between 100 to 171, medium scores between 172 to 243 and high scores between 244 and 315 (highest possible score available).

Note that where information is absent for key parameters, e.g. waste type, then this in itself will create the priority level of the site.

1.3 Limitations
This prioritisation tool is only for use on closed landfill sites with existing Waste Management Licences.

In Scotland the following issues were the most frequently encountered during the collection of landfill data:
In Northern Ireland the following issue was the most frequently encountered during the collection of landfill data:
It is also considered that it may be difficult for the user to identify an appropriate answer in the prioritisation tool for the following questions:
Given the above, there may be a significant number of sites that obtain a high score due to the large number of unknowns that may be present and the default option within the tool of applying the maximum score where issues are not known or are uncertain.

1.4 Assumptions

The prioritisation tool assumes that the user has sufficient information available to them to be able to answer all questions in the tool. If this is not the case then the user will be required to make assumptions to answer some questions. When assumptions are made these should be noted in the comment box at the bottom of each page.

Copies of this report are available from the Foundation, in electronic format on CDRom at 20.00+VAT or hard copy at 15.00, less 20% to FWR members.

N.B. The report is available for download from the SNIFFER Website