Case study:Unit 3a – Hurst Bridge 2013

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Location: 50° 42' 48.30" N, 2° 17' 26.03" W
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Project overview

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Status Complete
Project web site http://www.environment-agency.gov.uk
Themes Fisheries, Habitat and biodiversity, Hydromorphology
Country England
Main contact forename Alastair
Main contact surname Maxwell
Main contact user ID
Contact organisation Environment Agency
Contact organisation web site http://www.environment-agency.gov.uk
Partner organisations
Parent multi-site project

Case_study:River Frome Rehabilitation Plan

This is a parent project
encompassing the following
projects
No
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Project summary

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The main River Frome Unit 3a flows mostly through the Moreton Estate. This reach in particular is downstream of the Hurst road bridge. It was historically part of an old mill system and the reach retains a fixed crest weir at the location of the former mill. Removal of the weir was discounted early on due to costs and possible impacts on the road bridge. Works were concentrated on the reach between the bridge and the weir looking to improve the channel and bank structure and creating a greater range of habitats in particular for fish.

The River Frome Rehabilitation Plan states the main proposals to improve the SSSI condition and WFD objectives of Unit 3a and to incorporate as part of the Hurst Bridge Project are: a) increase / diversify channel bed profile creating deep pools and gullies and b) to introduce large woody debris to provide in channel habitat and vary bed profiles through scour and deposition.

Monitoring surveys and results

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Lessons learnt

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This project did pose some issues during its delivery. The extent of the berm creation and bed reprofiling was limited due to the presence of overhead power lines. A safe working method was implemented by the Ops Delivery team. Initially the excavator to be used had an 8m reach; this was also used on the North Channel job. However this reach was wider and to maximise the benefits of the project a long reach had to be brought to site. This came at additional cost but enabled effective delivery of the project. The long reach machine was also used on a few parts of the North Channel project which were out of reach form the original machine. The tree works described above were also able to be carried out with the larger machine.


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Catchment and subcatchment

Catchment

River basin district South West
River basin Dorset

Subcatchment

River name Frome Dorset (Lower) & Furzebrook Stream
Area category 100 - 1000 km²
Area (km2)
Maximum altitude category 200 - 500 m
Maximum altitude (m) 223223 m <br />0.223 km <br />22,300 cm <br />
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Arable and Horticulture
Waterbody ID GB108044009690



Other case studies in this subcatchment: 2e Lower Woodsford River and Floodplain Enhancement, Bockhampton Enhancement, Hurst Bridge (downstream), Louds Mill (Downstream)m Enhancement, Lower Bockhampton, Lower Woodsford, Martins River Island, Moreton Channel Gravel Reprofiling, North Channel Upper Reach, River Frome Rehabilitation Plan... further results


Site

Name
WFD water body codes GB108044009690
WFD (national) typology
WFD water body name Frome Dorset (Lower) & Furzebrook Stream
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
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Dominant substrate
River corridor land use
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Average unit stream power (W/m2)


Project background

Reach length directly affected (m) 150150 m <br />0.15 km <br />15,000 cm <br />
Project started
Works started
Works completed
Project completed
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Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
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Reasons for river restoration

Mitigation of a pressure
Hydromorphology
Biology
Physico-chemical
Other reasons for the project To meet Natural England’s target for standard conditions


Measures

Structural measures
Bank/bed modifications
Floodplain / River corridor
Planform / Channel pattern
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other


Monitoring

Hydromorphological quality elements

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Monitoring documents



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Supplementary Information

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