Case Study

Moonpool Silt Curtain

Premier Falmouth Marina
Land and Water Services
Cornwall
May 2011
Moonpool curtain - design, fabrication and installation assistance Land and Water Services – Falmouth Marina.

Silt Curtains UK designed and fabricated the bespoke 94m long by 8.4m deep ballasted curtain in their Isle of Wight factory unit and transported it to site for finishing. The curtain enclosed a purpose built L&W pontoon to create a ‘moonpool’.

Silt Curtains UK designed and fabricated the bespoke 94m long by 8.4m deep ballasted curtain to enclose the purpose built L&W pontoon and thus prevent contamination leaking into the River Fowey during the dredging operation. The curtain, weighing in excess of 1.5 tonne was installed by a team of 15 men including 4 divers largely in one day, despite the tide variations which hampered the process somewhat.

The Marina site falls within the Fal-Helford area, a SSSI, however the site formerly occupied the Empire and Kings wharves and had not been dredged since 1938 almost 10,000m3 of highly contaminated material containing heavy metals toxins such as TBT – which experts claim is the most toxic substance ever deliberately introduced into the marine environment – needed to be removed from site.

Installation successfully completed.

Land and Water Services removing over 32,000 tonnes of contaminated sediment from the harbour area. The silt being unsuitable for disposal at sea, due to the local oyster and mussel beds, was transported in sealed lorries to the redundant China Clay workings at St Austell where, after being mixed with green waste and sewage, was used to landscape the former industrial site without the contamination proving to be an on-going issue.