Table 3

Expert panel scoring guide

Hazard in relation to water pathway:
Leaching and run-off of chemicals from the landfill site may cause ground and surface water contamination which would form a hazard for residents via drinking water consumption, other domestic water uses, and use of land in the vicinity of the site (i.e. food growing, recreation). The hazard scoring related to this water pathway reflects the ease with which hazardous materials can escape via the water route, and the potential for nearby population to come into contact with the water (via drinking water, surface water, recreation). Factors such as drinking water supply, land use, soil characteristics, distance to groundwater and surface water, and management practices such as leachate collection, lining of the site, monitoring and contamination of groundwater and surface water, are documented in the Site Description Document.
Water hazard scoring guide:
1	2	3	4	5
Low hazard		Medium hazard		High hazard
– Evidence of no contamination of ground or surface water, or – No water monitoring performed, but low potential hazard based on available information (site engineering, soil type, management of the site, size of the site, etc).		– Evidence for some off-site contamination of ground or surface water, and/or some potential for drinking water contamination, or – No, or limited water monitoring performed, but medium potential for off-site contamination on basis of other available information.	– Evidence of high off-site contamination of ground and/or surface water, and/or potential for drinking water contamination, or – No, or limited water monitoring performed, but high potential hazard relating to the water pathway based on available information.

Hazard in relation to air pathway:
Landfill sites may be a source of airborne toxic chemical contamination by evaporation or via windblown particles. The hazard scoring of the air pathway reflects the ease with which hazardous substances in both vapour and particle form may be emitted into the air. Migration of landfill gas is of importance because it may carry along waste vapours, such volatile organic substances. Factors such as the presence of a gas collection system, evidence of gas migration, and evidence of migration of other substances, are documented in the Site Description Document. Waste management practices such as capping and covering of the site are important in relation to the potential of dust and particles being blown off-site.
Air hazard scoring guide:
1	2	3	4	5
Low hazard		Medium hazard		High hazard
– Evidence of no off-site migration of landfill gas or air pollutants, or – No air monitoring performed, but low potential hazard based on information available (site engineering, quantities of waste, age of site, etc.).		– Evidence for some off-site migration of gas or air pollutants, or – No, or limited air monitoring, but medium potential for off-site contamination on basis of available information.	– Evidence of off-site migration of high levels of landfill gas and/or other air pollutants or, – No, or limited air monitoring performed, but high potential hazard based on other available information.

Overall hazard potential:
The scoring of the overall hazard of the sites reflects the overall potential of a site to cause exposure of nearby residential populations. A large, old, badly managed site with many reported problems would get a high overall score and a well-managed, small site with no reported problems would be assigned a low overall hazard score. Factors such as age of the site, size of the site, quantities of waste present, actions taken to prevent leachate and landfill gas emissions, adequacy of the monitoring at the site, and contamination problems, are documented in the Site Description Document.
Overall hazard scoring guide:
1	2	3	4	5
Low hazard		Medium hazard		High hazard
– Relatively new well-managed site with few reported problems. – Relatively small quantity of waste in place. – Adequate measures to prevent gas and leachate migration in place since start of site. – Adequate monitoring of the site.		– Site of medium size and age. – Some reported problems. – Adequate measure to prevent gas and leachate migration have been taken over time/some measures have been taken but not adequate. – Some monitoring, but not adequate.	– Site with large quantities of waste and/or old, uncontrolled site, and: – No measures taken to prevent off-site migration of landfill gas or leachate. – No routine monitoring. – Many problems reported.