Thursday, 31 October 2013

Hilgay: end of construction in sight

Nick Carter, Conservation Officer (Fens)

The pool being created in the SW corner of the site
The construction phase at Hilgay is coming to an end. Recent work by Fen Group has centred on the construction of pools which will remain reed-free and form refuges for fish. The reed-lined edges of these deep water pools will be an important habitat for bitterns and other birds searching for fish and amphibians. Despite the wet weather Fen Group have been able to form these pools using a bulldozer and an excavator, although the deeper they have gone the wetter it has become and the more difficult to work.

The finishing touches are being done to the abstraction system from the River Wissey and it is hoped to start filling the perimeter ditch and lagoon in November. The latter has to be filled in stages, checking the integrity of the bank to ensure there is no seepage or signs of instability. The electric pump, which circulates water back into the lagoon for re-distribution, is almost installed too. We are waiting for the meter to be installed in the next couple of weeks and for the pump to be tested. All of the sluices have been installed so we can build up the water levels on the site over winter which will not only aid spread of the reeds but also suppress the terrestrial plants, such as nettles, that have covered much of the site during development.

Over 45,000 reed plugs have been planted along the ditch sides, in chicken wire cages to reduce grazing pressure from deer and geese, to aid their spread across the site. The recent wet weather has helped them to establish prior to the winter. The reeds that were planted in 2012 by a Children’s Wildlife Watch group have established well and are seeding this year and small pockets of naturally occurring reeds are spreading. The locally-sourced reed rhizomes that were planted in the spring have survived the dry summer and the attentions of grazing brown hares, which are common on the site. These reeds will help prevent wave erosion of the lagoon banks as it is slowly filled over the winter.

Aerial image taken by Hexcam looking south east across the site, with the lagoon in the foreground
At the end of September Hexcam took some aerial shots of the site with their remote-controlled 'Octocopter'. These will form the start of a historical record of the site over time to show how it develops as the reeds spread across the site. The aerial shot clearly shows the extent of development and also highlights, in the foreground, the old ditch and drain network, which show up as straight lines criss-crossing the site.

1 comment:

  1. It is good that the engineers are taking this project as a big challenge for them.

    Sanola Jerry

    Plos Constructions