The town of Fermoy in County Cork has a long history of flooding from the River Blackwater which flows through the town.
Major floods have occurred approximately 15 times in the past 30 years and in 2005 the Office of Public Works unveiled plans to construct flood defences.
The first phase - Fermoy North - began in 2009 and was completed in 2011. The second phase, which involves works on the south side of the river, commenced in April 2012 and will be completed in early 2014.
As a supplier to Lagan Construction, Groundforce has been heavily involved in the deep pumping station and pipeline network for the €16m project and has supplied its modular hydraulic shoring system to support deep excavations at two pumping station sites either side of the Fermoy Bridge.
Both pumping stations are situated directly on the riverbank and are being constructed within sheet-piled coffer dams.
At the Ash Quay pumping station, upstream of the bridge, Groundforce supplied 12m long PU22+1 piles to line the coffer dam, bracing the excavation with a combination of Mega Brace frames and HSK150 hydraulic struts. This excavation measured 13.5m long by 9m wide and was 7.5m deep.
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Downstream of the bridge, at the O'Neill Crowley Quay, Groundforce supplied the same components to support a permanent piled wall in a deep well measuring 7m x 4m. This too was 7.5m deep.
The Mega Brace frame is a modular support system comprising hydraulically extendable legs which can be pinned together to fit any size or shape of excavation. After assembly, the frame is secured with chains to keep it in place and the hydraulic rams extended to take up play and support the piled walls.
Intermediate support is provided by the HSK150 struts. These are used to span the excavation, side-to-side or across the corners, and are also hydraulically extendable. The HSK150 unit can support lateral loads of up to 150 tonnes.
As well as the heavy support system, Groundforce also provided a range of ancillary equipment including its purpose-designed Edge Safe and Ladder Safe access and guardrail system to ensure safety. Various light support equipment, including manhole boxes and trench boxes, were also supplied for the pipe-laying activities.
Both deep excavations were subject to heavy lateral loadings and with poor soil conditions two frames were required in each – one at the top of the excavation and one near the bottom.
"The bottom frames were removed once the base slab was cast, allowing a clear opening for the formwork contractors and reducing the number of construction joints in the walls," says Groundforce sales engineer Joseph Lenihan.
"The deep well was very tricky, partly due to the lack of space but also due to its irregular shape – all four sides were different lengths," he explains.
Callum O'Connor, senior engineer for Lagan Construction on the project, comments: "I was very impressed with the Groundforce equipment and the speed at which we could install it.
"We estimate that using the modular support system saved almost two weeks on the programme compared with traditional methods," adds Mr O'Connor.
Joseph Lenihan explains: "Each of our frames took only three days to install whereas a traditional frame of fabricated steelwork takes at least two weeks."
During heavy rainfall, and within two days, this water depth can increase to 4m, and some adjacent roads within the town will be covered with 1.5m depth of water.
