Elgin, one of Scotland’s oldest towns, is situated along the banks of the River Lossie. Due to its proximity to the river, the town has experienced multiple flooding incidents over the last two decades. The £86 million Elgin Flood Alleviation Scheme, the largest civil engineering project to be undertaken in Moray, North Scotland, is designed to prevent further flooding and protect the residents and businesses in the town.
Bachy Soletanche was appointed by Morrison Construction to deliver the foundation package to provide support for a flood defence wall adjacent to the river. The contract was awarded based on technical excellence, programme and capabilities offered.
DESIGN AND PLANNING
The piles were designed in-house with careful consideration given to the installation process and choice of plant and equipment.
The pile locations were situated alongside an existing retaining wall which was sensitive to potential plant loadings. In addition to this the available working area was very limited, therefore the team opted to use a Hutte 203 rig, which provide the perfect combination of size and capability.
Prior to the main piling operations commencing, the team installed a test pile, which was used to confirm the parameters used within the agreed design. The pile was tested to 1.5 times the maximum working load of 270KN.
The foundation solution was split across two locations, one along the existing river wall and the other adjacent to the Mansion House Hotel. At the first location, 43 auger bored piles were installed with a diameter of 300mm, bored to a depth of 12m. The pile bore was cased for the first six metres using a 340mm casing. The team had to overcome challenging ground conditions, which included the need to core significant steel inclusions.
The second location, adjacent to the Mansion House Hotel, saw the installation of 28 piles using the same method. These piles were 300mm in diameter and bored to a depth of 12m. The project was completed on time and handed over to the client to progress with the scheme.