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BCI AWARDS 2016 – OGI AWARDED HIGHLY COMMENDED IN THE CATEGORY TEMPORARY WORKS FOR CIVIL ENGINEERING

 

OGI Awarded Highly Commended in the category of Temporary Works for Civil Engineering for the groundwater control works at Seaforth Passage Widening

OGI GROUNDWATER SPECIALISTS AWARDED HIGHLY COMMENDED BY THE BRITISH CONSTRUCTION INDUSTRY AWARDS 2016 IN THE CATEGORY OF TEMPORARY WORKS FOR CIVIL ENGINEERING as designers of

TEMPORARY GROUNDWATER CONTROL FOR SEAFORTH PASSAGE WIDENING, PORT OF LIVERPOOL

The winners were announced on 12 October 2016 at a glamorous ceremony at the Grosvenor House Hotel, London, where over 1,300 of the industry’s elite joined together for a night of entertainment, celebration and networking.

 

The British Construction Industry Awards were launched in 1987 by Thomas Telford Ltd, the publishing arm of the Institution of Civil Engineers, and New Civil Engineer magazine.

 

The object of the BCI Awards is to recognise excellence in the design, construction and delivery of buildings and civil engineering works. Overall excellence is at the heart of the rigorous judging process employed in the BCI Awards which each year assembles a judging panel of leading clients, designers, contractors and industry commentators to choose the winning projects.

 

Judging is not simply a matter of selecting projects which demonstrate the highest engineering or architectural merit. Decisions are made after consideration of the entire construction process from initial conception to final commissioning and use of the completed infrastructure in a timely and economic fashion, satisfying all the parties involved from the client to the community at large. Careful assessment of best practice, safety, sustainability and other key issues all come under the judges’ scrutiny.

 

The full list of finalists and more information can be found at: https://bcia.nce.co.uk/2016-finalists

 

TEMPORARY GROUNDWATER CONTROL FOR SEAFORTH PASSAGE WIDENING, PORT OF LIVERPOOL

Peel Ports required the widening of the Seaforth Passage to increase efficiency for the transit of vessels within the Royal Seaforth Dock at the Port of Liverpool.

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FARRANS Construction Ltd was appointed the £11m contract to carry out the work to widen the passage from 40m to 60m.

 

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As part of the widening works, a 3.00m diameter siphon, connecting the Liverpool storm drainage system with an existing outfall, was to be extended underneath the passage.

 

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Designed by Royal Haskoning, the structural solution selected to extend the siphon compromised the construction of a combi-wall cofferdam attached to the existing diaphragm wall.

 

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Initial piezometric head was at an average of +6.46mCD, but with a significant tidal response.  The structural design specified the piezometric head to be reduced during temporary conditions to -9.00mCD in the lower aquifer, and to +3.00mCD in the upper aquifer.

 

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OGI Groundwater Specialists Ltd was appointed as designer for the required temporary groundwater control system.

 

OGI identified three key design criteria to be satisfied in order to ensure the safety and therefore success of the project:

 

  1. To provide an alternative to the traditional approach of a large number of active dewatering wells.
  2. To prevent heave resulting from excess pore water pressure in the sandstone below excavation formation
  3. To mitigate against the risk of structural collapse caused by a sudden rise in groundwater pressure as a consequence of power or pump failure.

 

OGI conducted substantial investigation and finite element analysis from which a design specification was produced that comprised the following combination of active and passive dewatering and pressure relief wells:

 

 

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Five deep wells installed with borehole pumps outside the combi-wall

 

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Three vertical active/passive pressure relieve wells inside the combi-wall.

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Approximately fifty inclined passive pressure relief wells installed through the combi-wall into the surrounding sand layers.

 

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The successful temporary groundwater control system designed for the Seaforth Passage Widening project was only made possible by the team approach which included full collaboration between the Groundwater Control Designers (OGI Groundwater Specialists), the Main Works Contractor (Farrans Construction) and the Structural and Geotechnical Designer (Royal Haskoning).

 

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