Case Studies

We’re proud of every project we undertake and the solutions they provide for our clients. We hope our case study section will provide some insight into the successful projects and partnerships that make Longwood Engineering a leader in our field.

Preston Tunnel Lancashire, UK

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Client: United Utilities
Project: Preston Tunnel, Lancashire, UK
Project partners: KIER Construction Ltd, J Murphy & Sons, Interserve Project Services, Integrated Alliance, KMI Joint Ventures, United Utilities

Located on the River Ribble’s north bank, the city of Preston is served by a combined sewer system installed in the 1870s. As the population grew, numerous reliefs were added to the small-bore pipes in order to drain excess flows into Ribble tributaries and Savick Brook. Inevitably, the city’s growing population and industry placed rising demands on this archaic system.
In 2005 the Environment Agency (EA) issued consents requiring a maximum of three spills per summer (Bathing Water Directive) and 10 spills per annum (Shellfish Waters Directive). All storm spills to the River Ribble were to be screened to 6mm in two dimensions.
Faced with seven unsatisfactory intermittent discharges (UIDs) from the existing sewer network, United Utilities needed to resolve these threats and provide the appropriate storage to satisfy the EA’s directives.

Longwood Engineering, United Utilities and its project partners worked closely together throughout the process. Longwood was commissioned to design, manufacture and install four huge Escalators capable of diverting Preston’s excess stormwater into a new 3.5km underground tunnel.
Produced at Longwood’s Yorkshire plant, the 12m long, 9 tonne Escalators are the largest ever manufactured. They comprise four Escalator screens and four off-conveyors (two horizontal and two inclined) which feed into two off-screenings compactor skips. The screw conveyors’ normal operating capacity is 5.5m3/hour.
The complex project also saw Longwood Engineering transporting the giant Escalators in sections and re-assembling them on-site. Longwood installed the Escalators at 60° angles with channel depths of 9000mm, a screen width of 2200mm and a flow capacity of 9000 ltrs/sec.

KMI Joint Ventures commented: “The installation and commissioning went very well. Post-installation snags were dealt with effectively, leading to a timely completion for both the screen installation and project as a whole. The screens have been in use for 14 months on intermittent storm duty without issue, which is a bonus for all concerned.”

Thames Water Beckton, UK

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Client: Thames Water’s Sewage Treatment Works
Project: Installation of the UK’s largest Escalator Screens for UK’s largest sewage treatment works
Project partners: Laing O’Rourke

Located in the London Borough of Newham, treating daily sewage from 3.4 million Londoners, Thames Water’s sewage treatment works at Beckton is the largest sewage treatment works in the UK. As part of a major programme of extension and upgrade of these works, undertaken by primary contractor, Laing O’Rourke, Longwood Engineering was awarded the contract to install a total of 8 new Escalator Screens. The contract was awarded in October 2007 and completed in March 2009.

Weighing 12 tonnes each and measuring 2.85m wide by 5.8m deep, these were the largest Escalator Screens ever manufactured by Longwood Engineering at the time of installation. In order to meet increased volumes of waste, the screens are designed to each handle a flow of 4,500 litres per second and are installed at a 45 degree incline for maximum screening area. Each screen was also fitted with dual speed motors, to enable waste to be removed at a faster rate in times of storm. Six of the screens were located inside and had to be manufactured in modular form to ensure they would go into the building, while the other two were located outdoors, with the additional capability of being pivoted out of the floor to act as an emergency bypass.

Longwood Engineering originally installed Storm Screens at Beckton in 2006 and also 12 Escalator Screens to Thames Water’s sewage treatment works at Mogden in 1999. Altogether, Longwood Engineering have now installed over 1100 Escalators worldwide.

Says Mike Ellis, Project Manager, Laing O’Rourke:

“We chose to work with Longwood Engineering due to their renowned expertise in providing bespoke screening and screening handling solutions along with their proven track record, having previously supplied screens for Thames Water. The new screens are continuing to meet expectations and are operating well. Both Laing O’Rourke and Thames Water are very happy with Longwood Engineering’s management of this part of the project.”



Thames Water

Project Omega Northern Ireland, UK

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Client: Northern Ireland Water and Glen Water
Project: The supply and successful installation of fine screening and screenings handling capability for Project Omega in Northern Ireland.
Project partners: Laing O’Rourke

Project Omega is a Public Private Partnership project between Northern Ireland Water and Glen Water (a joint venture company incorporating Veolia Water and Laing O’Rourke) for capital works and the operation of seven wastewater treatment facilities, across 6 sites in Northern Ireland. The majority of the project involved improvements to existing facilities with the exception of the North Down/Ards Peninsula in County Down, where a brand new treatment works and associated feeder pumping stations were needed to provide treatment for sewage from Bangor, Donaghadee and Millisle.

The £1 million contract for the screens and screenings handling element of the project was awarded in two parts by Laing O’Rourke to Longwood Engineering. Phase 1, awarded in June 06, formed part of the advance works, prior to the finalisation of the PPP contract, which required the completion of the brand new treatment works in North Down/ Ards by January 08. Longwood Engineering’s brief was to manage the supply and installation of 2 new Escalator screens.

Phase 2 was awarded in June 07 and for this part of the project Longwood Engineering was responsible for both the screens and screenings handling across the remaining sites – Seagoe, Bullays Hill, Ballyrickard, Ballynacor and Armagh. The work involved a combination of retro-fit and new channels. A total of twelve, 6mm (2D)Escalator screens and ten Combi-Wash units, along with Local Control Panels, were successfully installed across the five sites, meeting all required criteria and deadlines.

Project Omega