Case study:Blackbrook Slow the Flow, St Helens

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Location: 53° 28' 4", -2° 42' 3"
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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
Project picture

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



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)
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Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
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Average channel gradient
Average unit stream power (W/m2)


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

Mitigation of a pressure Flood risk management
Hydromorphology
Biology
Physico-chemical
Other reasons for the project


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

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

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Physico-chemical quality elements

Element When monitored Type of monitoring Control site used Result
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Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative


Monitoring documents



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Additional links and references

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Supplementary Information

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