Workshop on Disproportionate Costs, 10./11.4.2008 Copenhagen

Navigation-related issues of affordability and extended deadlines.

Consideration of residual life and construction mobilisation costs

Jan Brooke

Chair, WFD Navigation Task Group

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Scope of presentation • Introduction to issues and relevance to Water

Directors’ request

• Overview of pressures, impacts and measures

• Case study examples:

• Bank protection

• Vessel design

• Fish passes

• Key conclusions

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Introduction

• Main methodological issues tackled

• Residual asset life as a consideration in setting an extended deadline

• Construction mobilisation costs as a consideration in setting an extended deadline

• Relevance to Water Directors’ request• Reasons for setting an extended deadline• Affordability considerations

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Overview of the case study

• Pressures and impacts• Physical modifications potentially affecting

aquatic flora, benthic invertebrate fauna and/or fish fauna; also hydromorphological supporting elements (eg. structure of intertidal zone)

• Possible measures • Environmentally-friendly river bank protection

• Low-wash vessel design

• Fish passes around navigation structures

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Bank protection (1)

• Banks of some river navigations historically protected against erosion by steel sheet piling

• Where vertical wall not required (eg. for mooring vessels) best improvement in ecological status or potential obtained by removing piling and replace- ment with environmentally friendly bank protection

• Steel sheet piling typically designed and costed to last 50 years

• ‘Green engineering solutions’ typically have much shorter design life (say 10-15 years)

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Steel sheet piling

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Willow spiling

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Coir rolls

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Established environmentally friendly bank

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Bank protection (2)

• Steel sheet piling installation costs €1,000 to €6,000 per linear metre (€1 million to €6 million/km)

• Removal costs typically 50% of installation costs• Options to improve appearance of existing piling

from €50 per linear metre upwards, but questionable improvement in ecological function

• Options which improve ecological functionality of riparian zone cost from €200 to €2000 per linear metre plus cost of removal of piling (average, say, €2.5 million per km including removal of piling)

• Projected asset life is also important

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Bank protection (3)

• May thus be disproportionately costly to remove and replace steel sheet piling which still has, say, 10 years residual life

• However when that asset reaches the end of its useful life, something needs to be done anyway

• At this point in time, the option that was previously disproportionately costly may become no longer disproportionately costly and affordable (ie. budget is now available)

• So, extending the deadline allows an ecologically better solution

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Vessel design (1)

• Certain types of vessel can generate excessive wash leading to bank erosion and habitat loss

• Speed limits not always practical as reduced speed affects vessel manoeuvrability and/or functionality

• Modified hull design can help to reduce wash but

• Often difficult to exert control over visiting craft: right of innocent passage (UNCLOS) and

• Retro-fitting to an existing vessel prohibitively expensive (eg. retrofit ‘eco-hull’ to existing canal vessel costs between €10,000 and €35,000)

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Vessel design (2)

• Broads Authority (UK) grant-aided development of mould for new hull to minimise additional costs to vessel owners/operators when replacing redundant craft (ie. make low wash hull affordable)

• Port of London Authority patrol craft must respond quickly to incidents, etc. thus need to reduce wash at normal and emergency speeds. New Ecocat patrol launches operate with almost no wash at 6-8 knots and with only 20% of wash wave energy when compared to old-style vessels. Also 65% reduction in fuel consumption and emissions.

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EcoCat patrol vessel

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Vessel design (3)

• Where it is possible to influence vessel design, consideration of the residual life of the existing asset is important

• When the vessel reaches the end of its useful life, an option that was previously disproportionately costly, potentially becomes no longer disproportionately costly and affordable (ie. budget is now available)

• So, extending the deadline enables ecological improvements to be achieved

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Newly constructed fish pass

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Fish passes (1)

• British Waterways owns/operates 140 river weirs which are required to maintain navigable depth

• Most do not have fish passes• Mobilisation/set up/demobilisation costs often

represent a disproportionately high proportion of construction costs

• British Waterways has a limited budget, thus installing large numbers of fish passes by 2015 would detrimentally affect its other services

• However, if works are carried out whilst construction plant is on site for other reasons …..

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Fish passes (2)

• Large river weir fish pass €450,000 including mobilisation, site costs, installation and removal of cofferdam

• Additional cost to install same size fish pass as part of an ongoing project €90,000

• Small river weir fish pass €180,000 including mobilisation, site costs, installation and removal of cofferdam

• Additional cost to install same size fish pass as part of an ongoing project €30,000

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Fish passes (3)

• Mobilisation, site costs, coffer dam installation and removal, and demobilisation can represent up to 80% of costs of fish pass installation, potentially making the measure disproportionately costly

• Extending the deadline to allow fish pass to be installed at time of other planned activities on site enables ecological improvements to be achieved more cost-effectively as well as affordably

• With extended deadlines, British Waterways could have five or six fish passes ‘for the price of one’!

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Key conclusions (1)

• Environmentally preferred hydromorphological measures are not always practicable, however…..

• Where they are practicable, and physical assets and/or construction works are involved, residual life and project mobilisation/site management costs are important considerations

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Key conclusions (2)

• Costs can be high, therefore significant benefits are required to justify expenditure

• Extending deadlines can help to facilitate delivery of win-win solutions - ecological improvements which would otherwise be disproportionately costly or not affordable

• This principle is likely to apply more widely especially to hydromorphological measures

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Thank you for your attention

Contact for further details on the Navigation Case Study

jan@janbrooke.co.uk