As stated above the criteria relevant to the options appraisal process at the OBC stage may differ from those used at the MWMS stage in that, at the OBC stage, the focus is likely to be much more on deliverability issues. However it is for each Authority to determine its own criteria.
The evaluation criteria may include:
• The extent of diversion of MSW from landfill;
• The degree of value recovery either through additional recycling delivered by the technology or through energy recovery (heat and power);
• Emissions or overall environmental impact;
• The flexibility of the system in responding to variances in the tonnage and composition of the waste;
• Commercial risk;
• Deliverability, including issues in relation to securing planning for the facility and funding for the project as a whole; and
• FEC.
Each of these broad headings is capable of further analysis into sub-issues. Wherever possible this analysis should focus on issues where there are objective measures of the relevant outputs and avoid criteria that require subjective assessment. It can be helpful to have second or even third level evaluation criteria to structure the analysis that is required within each heading. Establishing a hierarchy in this way is the recommended approach as it allows the results to be presented in a number of different levels of detail. This can be helpful given that the results are likely to be presented to a number of different audiences. However, the methodology should also be kept as simple as possible and additional levels of sub-criteria should only be used where they add value.
The issues associated with defining the evaluation criteria are discussed further below.