Habitat creation. Langford Quarry
Hafren Water undertook a hydrological and hydrogeological assessment of the proposed restoration of the site to reedbeds and lakes designed to attract wetland bird species.
The design was developed in close collaboration with the RSPB to ensure that habitat was particularly suitable for Bitterns (a Biodiversity Action Plan (BAP) priority species). A system of weirs was proposed that would control water level and discharge for each of the reedbed areas and a water balance model was created to assess the influence of rainfall, evapotranspiration, groundwater and stage levels in the River Trent.
Using this model the feasibility of the quarry restoration was assessed and optimisation of water management and the weir levels undertaken.
By the time the site is fully restored in 2025 it is envisaged that 63 hectares of reedbed will have been created. When complete, not only will Langford Lowfields be capable of supporting breeding bitterns but it will also act as a route for species migrating across the country.
Prees Heath, Shropshire. Design of a new wetland.
The design of a new wetland area, informed by the local habitat, was proposed by Hafren Water utilising available resources at the site of an old airfield and SSSI. The design included the following measures:
- An open watercourse to replace a culverted section of the existing field drainage system
- Maximisation of wetted perimeter using foot drains
- Creation of several small waterbodies fed by either surface water or groundwater
- Excavation and landforming to intercept the watertable and create a seepage fen
- Increase of the extent of existing reedbeds in a poorly-drained area, with additional water level control
- Proposal for water level control structures and outlet weir to increase water levels and water retention on-site and allow seasonal flooding for willow control
Aerial photograph
Groundwater hydrograph
Lindow Moss, Cheshire. Re-wetting of moss
Hafren Water was appointed to inform the design and undertake an impact assessment for the restoration of a peat works. The proposals primarily included the re-wetting of a large area of peat bog.
A comprehensive groundwater assessment was undertaken as part of this study to determine groundwater levels within the area and the influence of dewatering by the existing peat works. This included detailed monitoring of surface and groundwaters and determination of peat and underlying sand permeabilities. Work was undertaken in close consultation with consultant ecologists, Natural England and the Environment Agency to determine the feasibility of controlling water levels to enable peat generation to be re-established.
It was found that careful water management would be required to achieve the proposed restoration of the site for ecological benefit as the principal water-supported features being fen and bog, would require different hydrological conditions. The former are groundwater-supported and would be created in the low-lying sections of the site, whereas the bog would be created in those sections of worked peat at higher elevations where direct contribution from groundwater would be precluded.
Naturally restored former peat workings
Current peat workings
MIRO-funded project: water-based quarry restoration
A 3-year research project was undertaken on “Water Based Quarry Restoration” under funding from the Minerals Industry Research Organisation. Numerous water-based restoration options were examined incorporating fens and mire, reed beds, wet grassland and the potential for floating wetlands. Habitat creation was also studied alongside other potential end uses for sub-watertable quarry workings including amenity and renewable energy options.
A summary of the aims and the final output of the work is given on the project website www.quarry-restoration.com
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