Case Study: Steel Sheet Pile Cut Off Wall at Redmires Reservoir

Steel Sheet Pile Cut Off Wall at Redmires Reservoir

Contract No:C1295
Client:Mott McDonald Bentley
Location:Redmires Upper Reservoir
Summary:Supply & Installation of 16.0m – 20.0m long Arcelor Mittal PU32 sheet piles to provide a remedial steel sheet pile cut off wall to puddle clay core.

Sheet Piling (UK) Ltd have recently completed installation of steel sheet piles at Redmires Reservoir creating a steel sheet pile cut off wall.

Redmires Reservoirs are a group of three reservoirs in Fulwood Sheffield. The three reservoirs are named Upper, Middle and Lower and date from 1836 when they were built to provide clean drinking water to Sheffield following the devastating Cholera epidemic of 1832.

Yorkshire Water and their AMP6 Framework Contract (Mott McDonald Bentley) had identified seepage of groundwater through the impermeable embankment Clay core using a Willowstick geophysical survey of 2015.

The Willowstick survey identified five preferential seepage areas to the Upper and Middle Reservoirs.

At this stage Yorkshire Water only intend to carry out the remedial works to seepage through the Puddle Clay core to the Upper Reservoir with the Middle Reservoir works planned to be undertaken at a later date.

Redmires Upper Reservoir is retained by an earthfill embankment with a Puddle Clay core. The embankment is approximately 15m high and has a crest width of 3m. The total embankment length is 686m.

The ground conditions underlying the earthfill embankment, were up to 7m of stiff Glacial Till underlying bedrock consisting of the Millstone Grit Group.

In total, 668No Arcelor Mittal PU32 Steel Sheet Piles ranging in length from 16.0m to 20.0m were installed through the reservoir Puddle Clay core and into the underlying Glacial Till.

The sheet piles were installed using a Giken F201 Silent Vibrationless Pile Press complete with EU300 Tracked Power Pack.

Steel Sheet Pile Cut Off Wall

Due to loading restrictions on the reservoir embankment crest, the piling equipment and sheet piles were handled using a 350Te Crawler Crane located on a Working Platform constructed in the bottom of the drained Upper Reservoir.

During the driving process, the steel sheet piles were intended to be assisted using water jetting techniques delivered by sacrificial lane tubes. However, during pile installation on site, no water jetting was required thus eliminating the potential for damaging the Puddle Clay core which is a significant risk on such projects.

The sheet piles were successfully installed between July and October 2018 to the satisfaction of all parties involved on the project.