Peatland Restoration Project

15 November

Burwell bund almost complete

Burwell Fen

The formation of the perimeter bund is on the back straight and nearing completion. We have also installed a solar pump, which will allow us to put water on to the fen during the summer months. Work will start soon on the installation of the water transfer pipe and new crossing point.

Spinney Bank

The final length of liner has been installed this week. After much consideration, the historic engine house will be retained as it was possible to install the liner behind the brickwork (see photograph).

Tubney Fen

The southern bund has been installed and an old redundant water control removed to help retain water on the Fen.

Verrall’s Fen

Work starts next week on the installation of the new crossing points to enable safe access for our management activities. There will be some disruption in the main car park and outside visitor centre but these remain open during works - thank you for your understanding.

24 October

6,000 years of history exposed

Burwell Fen

Around one third of the perimeter bund is now complete. It will be compacted and covered with site-won sandy soils found during the trench works to promote vegetation growth and prevent the clay cracking. The borrow pit is now being partially infilled with site won peat and sands to reduce depth and create irregular profile. Some deeper deposits of peat (2 metres) have been found during the works.

Spinney Bank

Cambridge Archaeological Unit (CAU) have been documenting the foundations of a historic windpump (pictured), which was used to drain surrounding land. There have been a few finds including an intact ginger beer bottle made in nearby Burwell and remainsof an ancient bog oak, which is being dated using a dendrochronology sample taken. There is a clear seam of woody material, which indicates the inundation of sea water likely in the bronze age c. 2,600 years BC. The earthworks have exposed nearly 6,000 years of history!

The waterproof liner is being installed and anchored in with clay to form a watertight seal to keep water on the Fen.

Tubney Fen

Next week sees the start of works to create similar bunds being constructed on Burwell but these will intersect the historic palaeochannel (ancient, extinct river) to raise water levels on the Fen. CAU will be undertaking further investigations.

17 October

Work continues at pace

Burwell

Works continue at pace. Contractors have installed around 250 metres of the perimeter bund, formed from site-won clay. A trench is initially cut and any field drains broken. The top layer of peat is temporarily set aside and the underlying clay mixed with site won clay to form impermeable barrier. The peat excavated will be returned to the borrow pit and then saturated with water. There has been one archaeological find; a worked flint.

Spinney Bank (Verrall’s Fen)

Contractors have been stripping the bank surface material and forming two trenches, which the new impermeable liner will be laid over and anchored in (by clay) alongside the existing liner. This will form a watertight seal preventing water being lost from the Fen. A layer about 2 metres below ground contains a large quantity of bog oaks (partially decomposed trees). Cambridge University Archaeological Unit have taken samples of these to determine species and age.

The scrub clearance work on Verrall's Fen is now complete. Scrub had developed over the years without intervention, quickly swamping rare fenland habitat with trees. This area will now be managed through extensive grazing and further mechanical cutting on rotation to promote a diverse habitat structure.

Tubney Fen

Works on Tubney have been brought forward and are due to start next week. Further updates to follow.

10 October

Bunding begins

Contractors have broken ground at Burwell after initial archaeological investigations of the borrow pit (where we source clay to form the bunds) found insignificant activity. There was some evidence of ploughing marks and field drainage within the clay layer, probably from the ‘Dig for Britain’ push in the 1940s. Work has now started on forming the perimeter bund. This is constructed by creating a trench and backfilling with site-won clay to form a waterproof seal. The excavated peat will then be laid back into the borrow pit after the clay is excavated and saturated, forming a wetland feature.

7 October

Work starts

Earthworks commence on Burwell Fen, with the footpath closure coming into place. Work also starts on Verrall's Fen along Spinney Bank, there will be a partial path diversion over the next six months here, too. This is to ensure a safe working area for construction and re-establishment of vegetation.

4 October

Preparation

Tree contractors are working on Verrall’s Fen, contained within Wicken SSSI, to reduce the dominance of scrub which can, without intervention, overcome rare fenland sedge habitat and increase carbon dioxide emissions. Trees on peat draw up water through transpiration, which can - depending on weather conditions - lead to a decrease in water levels and increased peat decomposition into carbon dioxide. The aim is to achieve a balance between valuable scrub habitats and peat that supports rare fen communities.  A combination of grazing and rotational cutting with a specialist Fen Harvester, will help restore this balance. This replicates centuries of historic management of the Fen.

Archaeological investigations are being undertaken by Cambridge Archaeological Unit across the areas the sites set for restoration.  Restoration has been informed through peat coring to understand condition and depths; hydrological monitoring through dipwells (which measure water level fluctuations) and historical records of relic river channels and anthropogenic use.  Initial investigations will focus on the potential opportunity for intact peat structures which represent layers through time.  Further investigations will then focus on the level of prehistoric activity prior to freshwater and marine inundation.