Case study:Ironbridge Farm

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Location: 51° 55' 41.94" N, 0° 31' 6.19" E

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Project overview

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Status	In progress
Project web site	http://www.essexrivershub.co.uk
Themes	Habitat and biodiversity, Water quality
Country	England
Main contact forename	Kieren
Main contact surname	Alexander
Main contact user ID	User:KierenAlexander
Contact organisation	Essex Wildlife Trust
Contact organisation web site	http://www.essexwt.org.uk
Partner organisations
Parent multi-site project
This is a parent project encompassing the following projects	No

The wet woodland at Ironbridge which will be enhanced

Project summary

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The river restoration at Ironbridge Farm builds on the work undertaken at Little Waltham meadows on the River Chelmer and the nearby Local Nature reserve at Bocking Blackwater.

As with all of these works the aim of the project is to improve the water-body under the Water Framework Directive. Currently the River Pant is failing under Water Framework Directive for a number of reasons including diffuse pollution, fish passage, point source and physical modification. It should be noted that this area does suffer from low flows during the summer months, especially if the Abberton scheme which transfers water from the Ouse to Abberton is closed.

There are some local issues with the river in this area, that are largely typical of those found elsewhere in Essex. Namely the disconnection of the river from the surrounding floodplain, this has led to a reduction in quality and type of Riparian habitat, in this case specifically wet woodland which is drying out and fen meadows which are decreasing in number and quality. Interestingly and of some note, the site at Ironbridge Farm and the surrounds are a Local Wildlife Site (LoWS) this means they have been recognised as an outstanding site in the context of Essex. Largely the site is notified for its mosaic of habitat but a key element of this is the presence of wet woodland and Fen meadow. So, besides contributing to raising the WFD status of the site, it is also contributing to the rehabilitation of the LoWS in the shape of an enhanced wet woodland and and enhanced Fen meadow.

In order to achieve this, a plan has been designed which will increase the seasonal inundation and flooding of the woodland and fen meadow. This will have the multi benefits of reconnecting the floodplain, reducing flooding and improving water quality.

A simple pipe will be installed which has been set to a level which will not only protect low flows but achieve the desired ecological effects. The level of the pipe was calculated by taking measurements on days of known flows and supported by Mannings equation.

It is hoped that the pipe level (nominally 44.30OD) will allow the site to flood 4 or 5 times during the winter months, an existing land drain will also be diverted to feed into the woodland.

In addition to the installation of a pipe there will also be some limited earthworks to help the water move around the site in an effective manner and also to provide further enhancement of the local wildlife site. There will be around 15 to 20cm's taken off the existing field surface to delineate a channel and hold water. The spoil created by this will then be used to create a small bund which will stop any uncontrolled water spreading across the floodplain.

A number of considerations had to be considered before undertaking this work, most notably in this case the presence of trees on the site. This resulted in a number of tree assessments being undertaken in order to manage and mitigate any impact on the tree's including HERAS fencing, root protection tracks and a number of arrangements put in place to protect these trees.

Work should be undertaken in August 2015, all the necessary consents are in place and a contractor has been appointed to undertake the works.

Monitoring surveys and results

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A key component of this project is to rehabilitate and enhance the LoWs including Fen Meadow and Wet woodland. Therefore any monitoring will focus on any improvement is this habitat. There will also be fixed point photography, before, after and as the site develops.

Lessons learnt

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There are some significant limitations to Manning's equation, especially in waters that are heavily impounded as most Essex rivers are. This means that any attempts to use this equation to work out the flow and height of the water is limited, this adds a degree of complication to any water height and flow calculations. If this is the case, then water heights from specific days or contact with the local EA hydrologist is recommended to allow real time calculations to be taken at times of known flow.

Image gallery

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Catchment and subcatchment Select a catchment/subcatchment Edit the catchment and subcatchment details (affects all case studies in this subcatchment) Catchment River basin district Anglian River basin Combined Essex Subcatchment River name Blackwater Pant Area category 10 - 100 km² Area (km2) Maximum altitude category Less than 100 m Maximum altitude (m) 6868 m <br />0.068 km <br />6,800 cm <br /> Dominant geology Calcareous Ecoregion Great Britain Dominant land cover Arable and Horticulture Waterbody ID GB105037033860 Other case studies in this subcatchment: Bocking Blackwater River Restoration Site Edit site Name Ironbridge Farm WFD water body codes WFD (national) typology WFD water body name Pre-project morphology Reference morphology Desired post project morphology Heavily modified water body Yes National/international site designation Local/regional site designations Protected species present No Invasive species present Yes 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) 250250 m <br />0.25 km <br />25,000 cm <br /> Project started 2012/04/01 Works started 2016/08/07 Works completed Project completed Total cost category Total cost (k€) Benefit to cost ratio Funding sources Cost for project phases Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname Investigation and design Essex Wildlife Trust Kieren Alexander Stakeholder engagement and communication Essex Wildlife Trust Kieren Alexander Works and works supervision Essex Wildlife Trust Kieren Alexander Post-project management and maintenance Essex Wildlife Trust Kieren Alexander Monitoring Essex Wildlife Trust Kieren Alexander Reasons for river restoration Edit reasons for restoration Mitigation of a pressure Hydromorphology Structure & condition of riparian/lake shore zones, Channel pattern/planform Biology Invertebrates, Macrophytes, Fish Physico-chemical Specific non-synthetic pollutants Other reasons for the project Habitat creation, Landscape enhancement Measures Edit Measures Structural measures Bank/bed modifications Habitat restoration Floodplain / River corridor Creation of backwaters, BAP habitat creation, Creation of wetlands, Creation of backwater and ponds Planform / Channel pattern Introduction of backwaters, Reconnect and restore aquatic habitats Other Non-structural measures Management interventions Ensuring biodiversity, Woodland management, Promoting riparian vegetation 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 http://www.essexrivershub.org.uk For more information on this and other projects in Combined Essex catchment Supplementary Information Edit Supplementary Information