The objective of the options appraisal at the OBC stage is to identify a single option that has the potential to provide an affordable and deliverable solution for the Authority's MWMS objectives.
At the outset of the appraisal process it should be clear to all those taking part what the process involves and what the objective is. This is often best achieved by documenting the steps in the process and having briefing sessions for all those involved. Given the diversity of criteria to be evaluated it is likely that people with very different backgrounds and levels of experience will be involved. It is therefore important to make sure good briefing is given at the outset.
Such briefings may include a summary of the sort of output that will be generated. Table 1 shows, in summary form, a typical output from an evaluation process.
It identifies the:
• Options considered;
• Top level criteria12 assessed;
• Weights attached to each criterion;
• Unweighted scores awarded for each option for each criterion;
• Clear and transparent calculation of the overall weighted score;
• Full Economic Cost (FEC)13 of each option;
• The relative weight attached to FEC and the scored criteria; and
• The overall ranking reflecting both the weighed score and the FEC.
The scoring system illustrated is a simple mark out of five. The options available for scoring are discussed further in Section 7.
Table 1: A Typical Output from the Options Appraisal Process
| Options | ||||||||
| A | B | C | D | E | ||||
|
Max | Unweighted Scores | |||||||
| Criteria | ||||||||
| Landfill diversion | 5 | 3 | 4 | 2 | 4 | 3 | ||
| Value Recovery | 5 | 2 | 4 | 3 | 5 | 1 | ||
| Emissions | 5 | 2 | 3 | 3 | 3 | 3 | ||
| Flexibility | 5 | 3 | 4 | 2 | 4 | 3 | ||
| Commercial risk | 5 | 5 | 5 | 3 | 2 | 1 | ||
| Deliverability | 5 | 1 | 3 | 4 | 5 | 4 | ||
| Unweighted Scores | 30 | 16 | 23 | 17 | 23 | 15 | ||
|
Weighted Scores | ||||||||
| Criteria | Weighting14 | Max | ||||||
| Landfill diversion | 0.10 | 0.50 | 0.30 | 0.40 | 0.20 | 0.40 | 0.30 | |
| Value Recovery | 0.30 | 1.50 | 0.60 | 1.20 | 0.90 | 1.50 | 0.30 | |
| Emissions | 0.15 | 0.75 | 0.30 | 0.45 | 0.45 | 0.45 | 0.45 | |
| Flexibility | 0.10 | 0.50 | 0.30 | 0.40 | 0.20 | 0.40 | 0.30 | |
| Commercial risk | 0.15 | 0.75 | 0.75 | 0.75 | 0.45 | 0.30 | 0.15 | |
| Deliverability | 0.20 | 1.00 | 0.20 | 0.60 | 0.80 | 1.00 | 0.80 | |
| Weighted Scores | 1.00 | 5.00 | 2.45 | 3.80 | 3.00 | 4.05 | 2.30 | |
|
Weighting15 | ||||||||
| Score (%) | 0.60 | 49% | 76% | 60% | 81% | 46% | ||
| Full Economic Cost | 0.40 | £140m
| £100m
| £150m
| £110m
| £150m
| ||
| Ranking
| 1.00 |
=3rd |
= 1st |
=3rd |
= 1st |
5th | ||
Whilst it is clear, in this example that options B and D are unambiguously better than options A, C and E (because they have a higher score and a lower cost) it is not clear from the table above which of option B or D should be ranked first. Whilst B is a lower cost solution, option D offers a better score. This illustrates the typical outcome from such processes and demonstrates the potential need to apply judgement to reach a final decision. The issues associated with drawing conclusions from an options appraisal are discussed further in Section 9.
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12 The Authority, with appropriate input from its advisers, will have to determine as necessary any second or third level evaluation factors that will be scored and fed into the score for each top level criteria.
13 See Section 6.3 for further information on calculating the FEC.
14 The weightings shown in the table are provided purely for illustration. They do not represent a recommended approach by WIDP and should not be used as such. Each Authority should decide how much weight it attaches to each scored criteria and how it weights cost against the scored criteria.
15 The weightings shown in the table are provided purely for illustration. They do not represent a recommended approach by WIDP and should not be used as such. Each Authority should decide how much weight it attaches to each scored criteria and how it weights cost against the scored criteria.