Good progress is being made on an ~Environment Agency~ local authority scheme to improve flood defences in the west Cornwall resort town of St Ives.
There were fears that the start of the £10M project to improve defences in St Ives might have been hampered by the number of utility pipes, and challenges posed by the need to remove large quantities of ‘blue elvan’, a local hard rock.
The rock, which engineers on the project said was stronger than concrete, was used in the construction of a 900m concrete culvert that takes the River Stennack under the town to the sea.
Much of the rock needed to be broken up by hand, as part of the work to upgrade the drainage system, and then winched out of the culvert through a maze of pipes by ~Cornwall County Council~'s direct labour organisation, Cormac.
The culvert system has overflowed 10 times in the past 20 years, mainly due to debris becoming caught in it, which has put 87 residential properties, 19 businesses and three public buildings at significant risk from flooding.
As with many culverts, when the flow of water is high, the structure struggles to cope, resulting in water overflowing on to the road surface.
Because of the length of the culvert and the fact it runs under the town centre, there was no other option for the Environment Agency – leading on the scheme – than to reline the tunnels and install improved flood-prevention measures.
The improvements, to be carried out by contractor Mowlem to a design by Halcrow, will see five new trash screens installed to catch debris and stop the culvert blocking, and the raising of flood walls along the open channel by 60cm. Mowlem was due to arrive on site this week, after Cormac finished the highway element.
St Ives has suffered four major floods in the last 12 years – the most recent taking place in 2002, when 40 homes and businesses were flooded up to 1.4m deep.
Fiona Geddes, project manager from the Environment Agency said: ‘We will continue to carefully timetable our work to minimise traffic disruption, particularly in the summer. ‘Everyone has been very co-operative and understanding, and we hope they will continue to bear with us while these important flood defences are completed.’
The work is expected to be finished by 2008.