Proforma D for Oxford

Tasks to be completed Elaboration/Rationale Oxford example
Review all likely interventions to reduce flood risk at the site and their likely effective functional lives It is wise NOT to rush to identify the “best” solution to the local flood problem that you are studying, rather identify several options at different standards and types (structural and non-structural; major or minor). The Oxford “long list”:·         Upstream storage

o    In the river Thames catchment

o    In the Cherwell catchment

o    In both catchments

·         Property level flood protection in the city

·         Bypass channels

o    Large

o    Medium

o    Small

·         Ring embankments (at Botley Road; Grandpont)

·         Raising roads to make them flood-free

·         Local defences

·         Culverts under the railway line

·         Doing nothing

·         Doing as little as possible (“Do minimum”)

·         All possible combinations of the above (as portfolios of measures)

 

Decide on a shortlist of, say, 6 interventions at different costs and hence standards of protection  Upstream storage would not reduce risk very much. Ring embankments are rendered unviable by rising groundwater during floods. Large channel is too expensive. Small channel not effective, etc. etc. The Oxford “short list”:1.     Do nothing

2.     Do minimum

3.     Do minimum (“extend”) [This needs clarification]

4.     Defences (at Gandpont, etc.)

5.     Channel and medium sized culverts under the railway

6.     Channel, medium culverts and defences (as a “portfolio”)

Estimate the likely whole life costs of each of the above interventions (i.e. capital costs and maintenance costs) This can be a difficult but necessary task. Ask the advice of:·  Flood risk management authorities

·  Local Authorities

·  Friendly consulting engineers

·  Engineering academics

·  Quantity surveyors

ONLY APPROXIMATE FIGURES ARE NEEDED AT THIS STAGE, even (intelligent) guesses are better than nothing.

The whole life estimated costs of the Oxford Scheme options (£m): 

Option Cost ID
1.     Do nothing 0.0 1
2.     Do minimum 17.4 2a
3.     Do minimum (“extend”) 21.4 2b
4.     Defences (at Gandpont, etc.) 25.1 3
5.     Channel and medium sized culverts 113.3 4
6.       Channel, medium culverts and defences 17.0 5

 

July 2016 figures (from CH2MHill).

 

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