Case study:Blackbrook Slow the Flow, St Helens

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Location: 53° 28' 3.93" N, 2° 42' 3.44" W

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Project overview

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Status	In progress
Project web site	http://www.therrc.co.uk/sites/default/files/projects/17_blackbrook.pdf
Themes	Flood risk management, Habitat and biodiversity, Hydromorphology, Water quality
Country	England
Main contact forename	Mike
Main contact surname	Norbury
Main contact user ID
Contact organisation	University of Liverpool
Contact organisation web site	http://www.liverpool.ac.uk/
Partner organisations	St Helens Council, Natural England, Waterco Consultants, Groundwork, Environment Agency
Parent multi-site project
This is a parent project encompassing the following projects	No

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Project summary

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Blackbrook in St Helens, Merseyside, experiences repeat flooding from a combination of main river and surface water sources. There are 18 properties at flood risk, 3 of which are businesses; a major truck A-road is also at risk. The current flood risk is high. Blackbrook has a 5% chance of flooding in any given year and sits in a low-lying bowl at the confluence of 5 rapid response catchments whose upstream area is 21km2. The property level protection put in place has had limited success, partly due to a failure in its operation at the time of the last flood (26 December 2016). Flooding also occurred on 28–29 October 2000 and 24–26 September 2012. Capital solutions to reduce the flood risk are prohibitively expensive, as culvert enlarging would be required to reduce the flow constriction. Such considerable capital interventions do not qualify for full funding under HM Treasury rules on cost–benefitratios. Significant additional funding would therefore be required.

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Catchment and subcatchment Select a catchment/subcatchment Site Edit site Name Blackbrook WFD water body codes WFD (national) typology WFD water body name Pre-project morphology Reference morphology Desired post project morphology Heavily modified water body No National/international site designation Local/regional site designations Protected species present No Invasive species present No Species of interest Dominant hydrology Dominant substrate River corridor land use Average bankfull channel width category Average bankfull channel width (m) Average bankfull channel depth category Average bankfull channel depth (m) Mean discharge category Mean annual discharge (m3/s) Average channel gradient category Average channel gradient Average unit stream power (W/m2) Project background Edit project background Reach length directly affected (m) Project started 2012 Works started Works completed Project completed Total cost category Total cost (k€) £1200"£" is not declared as a valid unit of measurement for this property. Benefit to cost ratio Funding sources Natural England, Environment Agency, Local levy council tax funding, National Environmental Research Council (NERC), Waterco, Arup Cost for project phases Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname Investigation and design Stakeholder engagement and communication Works and works supervision Post-project management and maintenance Monitoring Reasons for river restoration Edit reasons for restoration Mitigation of a pressure Flood risk management Hydromorphology Biology Physico-chemical Other reasons for the project Measures Edit Measures Structural measures Bank/bed modifications Floodplain / River corridor Planform / Channel pattern leaky woody dams Other Non-structural measures Management interventions Social measures (incl. engagement) Other Monitoring Hydromorphological quality elements Edit Hydromorphological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Biological quality elements Edit biological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Physico-chemical quality elements Edit Physico-chemical quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Any other monitoring, e.g. social, economic Edit Other responses Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Monitoring documents Upload monitoring documents Additional documents and videos Upload additional documents Additional links and references Edit links and references Link Description Supplementary Information Edit Supplementary Information