- 22nd March 2017
- Posted by: Joanne Woodhouse
- Category: Projects
Last week we installed an Archimedes screw pump at our Thorne Moors project. The pump, provided by Aquatic Control Engineering (ACE), signals the approaching conclusion of a major phase in the Thorne Moors scheme.
An area of Lowland Raised Peat bog, Thorne Moors lies to the North East of Doncaster and has been designated as a National Nature Reserve (NNR), Site of Special Scientific Interest (SSSI), Special Areas of Conservation (SAC), and Special Protection Areas (SPA).
The site has been subject to the extraction of peat on an industrial scale since around 1900 up until 2004. The hydrology of the site has been extensively modified through the cutting of drains, used to lower the water table in the area, enabling the extraction of peat, with much of the mire surface being destroyed.
Following on from the development of the Thorne, Crowle, and Goole Moors Water Level Management Plan (WLMP), the project aimed to implement the recommendations of the original WLMP study, which aimed to ultimately create favourable conditions for the colonisation, and growth, of peat forming vegetation. Achieving the desired conditions, and balancing the water levels across the site required:
- The design and construction of a new pumping station
- The installation of numerous water level control structures
- Over 32km of peat bunding and plastic sheet piling
- Approximately 350ha of scrub clearance.
As the area is home to a number of protected species, most notably the nesting Nightjar, Adder, and nationally and internationally rare insect species, the works have been carried out over the past 5/6 years in the winter months to minimise any disturbance.
The water levels across the site have been managed through the installation of peat bunding which mostly follows the topographic contours, allowing water to build up behind and minimising runoff. Main drains across the site have been blocked, or have the levels controlled through the use of tilting weirs.
Ultimately, the water level is controlled using an Enclosed Archimedes Screw Pump (the first of its kind in the UK), operating at a range of outputs up to 300l/s, to maintain the water level in the approach drains, and ultimately over the site.
The pump station incorporates a telemetry system which allows remote monitoring and operation of the screw pump, minimising the need for the client to frequently visit the site.
There is evidence that the works carried out are succeeding in their aims, with water levels across the site increasing behind the peat bunding, along with the slow colonisation of peat forming vegetation and the decline of birch trees.