Tarraqua ES Case Study
Contractor: Land & Water Services Ltd, Guildford, Surrey.
Land & Water Services had to provide a sustainable solution for a difficult and unique dredging challenge at Falmouth Marina in Cornwall.
A bespoke curtain was designed & manufactured 94m long by 8.4m deep, ballasted to enclose the purpose built Land & Water pontoon and thus prevent contamination leaking into the River Fowey during the dredging operation. The curtain weighing approx 2 tonnes was installed by a 15 men team, including 4 divers, in one day.
The marina site falls within the Fal-Helford area, a SSSI, however the site formerly occupied the Empire & Kings wharves, each more than 200m long, which were constructed in the 1930s. The wharves have now been removed and as they have not 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 marina environment- needs to be removed from site.
The silt being unsuitable for disposal at sea, due to the local oyster & mussel beds, is being transported in sealed lorries to the redundant China Clay workings at St Austell where, after being mixed with green waste and sewage, it will be used to landscape the former industrial site without the contamination proving to be an on-going issue.
See video of the silt curtains in use to enable dredging in the marina.