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Cost estimation for channel management –summary of evidenceReport – SC080039/R3

We are the Environment Agency. We protect and improve theenvironment and make it a better place for people and wildlife.We operate at the place where environmental change has itsgreatest impact on people’s lives. We reduce the risks to people andproperties from flooding; make sure there is enough water for peopleand wildlife; protect and improve air, land and water quality andapply the environmental standards within which industry canoperate.Acting to reduce climate change and helping people and wildlifeadapt to its consequences are at the heart of all that we do.We cannot do this alone. We work closely with a wide range ofpartners including government, business, local authorities, otheragencies, civil society groups and the communities we serve.This report is the result of research commissioned by theEnvironment Agency’s Evidence Directorate and funded by the jointFlood and Coastal Erosion Risk Management Research andDevelopment Programme.Published by:Environment Agency, Horizon House, Deanery Road,Bristol, BS1 5AHAuthor(s):Paul Jones, JBA ConsultingKevin Keating, JBA ConsultingAngus Pettit, JBA Consultingwww.environment-agency.gov.uk Environment Agency – March 2015All rights reserved. This document may be reproducedwith prior permission of the Environment Agency.The views and statements expressed in this report arethose of the author alone. The views or statementsexpressed in this publication do not necessarilyrepresent the views of the Environment Agency and theEnvironment Agency cannot accept any responsibility forsuch views or statements.Email: tion Status:Publicly availableKeywords:Whole life costing, cost estimation, channelmanagementResearch Contractor:JBA ConsultingSouth Barn, Broughton Hall, SkiptonNorth Yorkshire BD23 3AE01756 799919Environment Agency’s Project Manager:Adam Baylis, Evidence DirectorateFurther copies of this report are available from ourpublications orator(s):John Chattertonor our National Customer Contact Centre:T: 03708 506506Project Number:SC080039/R3Email: enquiries@environment-agency.gov.ukiiCost estimation for channel management – summary of evidence

Evidence at theEnvironment AgencyEvidence underpins the work of the Environment Agency. It provides an up-to-dateunderstanding of the world about us, helps us to develop tools and techniques tomonitor and manage our environment as efficiently and effectively as possible. It alsohelps us to understand how the environment is changing and to identify what the futurepressures may be.The work of the Environment Agency’s Evidence Directorate is a key ingredient in thepartnership between research, guidance and operations that enables the EnvironmentAgency to protect and restore our environment.This report was produced by the Scientific and Evidence Services team withinEvidence. The team focuses on four main areas of activity: Setting the agenda, by providing the evidence for decisions; Maintaining scientific credibility, by ensuring that our programmes andprojects are fit for purpose and executed according to international standards; Carrying out research, either by contracting it out to research organisationsand consultancies or by doing it ourselves; Delivering information, advice, tools and techniques, by makingappropriate products available.Miranda KavanaghDirector of EvidenceCost estimation for channel management – summary of evidenceiii

Executive summaryThis summary of evidence provides indicative costs and guidance on a number ofchannel management and maintenance aspects for natural and engineeredchannels/banks.Channel managementKey costcomponentsOperation and maintenance costs can make up a large proportionof total revenue spend for organisations with responsibility tomaintain channels. The most important cost components aretherefore operational (inspection) and maintenance costs (desilting, bank repairs, obstruction removal and so on).Management of environmental features within channels can be asignificant issue, resulting in additional costs.Capital costs of new channels may be significant – the availability ofunit costs for new channels is limited and will be highly variable.Key assettypes Natural channels and banks Engineered channels and banksData reviewedin specificguidanceKey reports and data sources include: Environment Agency Unit Cost Database (capital costs) Environment Agency Maintenance Standards (maintenancecosts) limited information on unit costs for narrow new channels in theEnvironment Agency Unit Cost Database Estimating Guide IDB unit costs provided by the Shire Group of IDBs indicative costs and case studies associated with dredging SEPA indicative costs associated with hard and soft bankprotection measuresOther relevantdataLocal or proxy records such as data from Environment AgencySAMPs and local authority informationRelative costimportanceEnabling costsNot applicable unless new channels areconstructed.Capital costsNot applicable unless new channel areconstructed.Maintenance costsVariable operation and maintenance costsare critical for channels relative to other costelements.Other costconsiderationsVariable costs. May need to considerdredging, bankrestoration/reinforcement/repair costs.ivCost estimation for channel management – summary of evidence

CostInitial concept/estimationnational appraisalmethodologyStrategic, regional, orconceptual designPreliminaryfeasibility/designApproximate O&M range of rates availableApproximate O&M range of rates availableCosts built up using guidance to allowappraisers to define type and frequency ofworks.Design lifeinformationNot applicable unless hard engineering works are used to create achannel, in which case the design life of the materials/structures isrelevant.Quality ofdataApproximate unit rates for the maintenance aspects are availablealong with a number of historical data and reference projects.Available data for unit costs are provided, although cost curveinformation is not available. Unit rates and examples from a number ofsources are available.AdditionalguidanceChecklist of factors likely to influence maintenance costs and keyfactors to consider for detailed costs estimationList of R&D and general design guidanceCost estimation for channel management – summary of evidencev

AcknowledgementsThe authors wish to thank the Project Board (Ian Meadowcroft, Linsay Hensman andAdam Baylis) and the Environment Agency, local authority and Internal Drainage Boardrepresentatives and operational staff who were consulted.viCost estimation for channel management – summary of evidence

Contents1Flood mitigation measure – channel management11.1Data requirements11.2Channel and bank operation and maintenance11.3Channel dredging81.4Capital costs associated with new channels111.5Bank protection measures141.6Hard bank decommissioning costs191.71.8Other cost estimation requirementsCost estimation methodology19201.9Case studies211.10Checklist231.111.12R&D and general design guidanceReferences2425Table 1.1Table 1.2Table 1.3Table 1.4Table 1.5Table 1.6Table 1.7Table 1.8Table 1.9Table 1.10Table 1.11Table 1.12Table 1.13Table 1.14Table 1.15Table 1.16Table 1.17Table 1.17Open channel maintenance unit costs ( /km/year)Engineered channel maintenance unit costs ( /km/year)Weighting and scoring approach to work out appropriate cost within rangeAverage maintenance costs per kmIDB watercourse maintenance cost per km by methodSuggested annual maintenance activities and frequenciesSuggested intermittent maintenance activities and frequenciesIndicative costs for channel dredgingKey factors affecting channel management costsUnit costs for new channel constructionEstimated channel excavation costsTypical work items for new channelsKey factors affecting new channel capital costsIndicative hard bank reinforcement costsIndicative soft bank reinforcement costsSoft bank reinforcement supply and installation costsIndicative costs for bioengineering design elementsIndicative hard bank decommissioning costs3345577910111213141517181819Figure 1.1Figure 1.2Figure 1.3Figure 1.4Figure 1.5Average annual costs per km by length of watercourse maintainedFlow diagram for channel whole life costsBioengineering on the Gwendraeth FawrBioengineering on the River PinnBioengineering on the River Ebbw520212223Cost estimation for channel management – summary of evidencevii

1Flood mitigation measure –channel managementChannel management and maintenance works are performed on rural channels withnatural banks and engineered channels by a range of organisations and for a range offlood risk and environmental aspects providing multiple benefits. The purpose ofchannel management and maintenance works is to: retain flow capacity and conveyance sustain riparian rights to the ordinary use of water flowing past their land manage water levels to sustain land functions retain and protect flora and fauna dependent or resident within thewatercourseFurther general guidance on design and maintenance aspects are provided in theEnvironment Agency’s Fluvial Design Guide. Additional links to research and morespecific guidance are provided at the end of this evidence summary.1.1Data requirementsA number of standard cost parameters are required for channel management. Theseinclude the following aspects: capital costs of new channels (if applicable) operational costs (inspection) maintenance costs (de-silting, bank repairs, obstruction removal and so on)Capital expenditure may be required where new channels are constructed such as partof a river realignment scheme, an existing channel is re-graded, bank slope stability isan issue or river restoration measures are necessary. While river restoration measuresare covered elsewhere in the guidance, the capital costs associated with theconstruction of new channels are provided in this evidence summary.There is also a link between riverbank protection and the use of bioengineeringsolutions that can provide alternative sustainable solutions for riverbank protection,bankside stabilisation and marginal vegetation habitats. The costs associated withthese sorts of measures are provided in this evidence summary for completeness.1.2Channel and bank operation and maintenanceChannel maintenance costs as a percentage of total expenditure represented anaverage of 35% for all Internal Drainage Boards (IDBs) in the 2009-2010 financialyear. 1 Some 46% of the estimated frequent maintenance activities identified for allEnvironment Agency System Asset Management Plans (SAMPs) for the 2010-20111Based on IDB1 returns for 2009-2010.