UK water tunnels awarded - TunnelTalk
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UK water industry awards boost confidence Jan 2010
Shani Wallis, TunnelTalk
Award of two major sewer tunnel contracts in the UK have lifted the prospects for the UK industry at the start of 2010. The Morgan Est/Vinci/Bachy Soletanche JV is awarded the Lee Tunnel contract as a £400 million ($US652 million) start for London's mega Thames Tideway sewer project while in Preston, the River Ribble CSO interceptor sewer for United Utilities is confirmed to the Kier/Murphy/Interserve JV for a tender price of £114 million ($US186 million). The ripple effect of the awards to suppliers, subcontractors and tunnel workers is a good New Year factor.
After months of indecision, Thames Water has confirmed award of its largest single construction contract ever to the MVB - Morgan Est/Vinci/Bachy Soletanche JV. The £400 million design-build Lee Tunnel contract is the start of Thames Water's mega £2 billion (US$3.25 billion) Thames Tideway project designed to reduce by half the 32 million tonne of combined stormwater sewage per year that overflows into the London reaches of the Thames and its regional tributaries. The total £600 million Lee Tunnel investment comprises a 7km long x 7m i.d. tunnel to provide substantially upgraded storage/conveyance capacity from the Abbey Mills pumping station to the Beckton treatment works for processing. The new tunnel will close down a single combined stormwater overflow facility at Abbey Mills that releases more than 16 million tonne of sewage/year into the River Lee, a principal Thames tributary downstream of central London (Fig 1).
Pic 2

Fig 1. Tideway aligment with the Lee Tunnel to the north east

The far longer and more complex 32km Thames Tunnel section of the project is expected to go into its public consultation phase in mid-2010. Thames Water is currently reviewing final design options with both the preferred route, for taking the tunnel all the way under the Thames to the Beckton works, and a cost-saving alternative, of connecting into a larger capacity Lee Tunnel project for the final downstream end currently, under review.
Morgan Est confirmed that orders for the Lee Tunnel contract, including purchase of a near 8m o.d. EPBM machine and supply of 7km of 350mm thick precast concrete segmental lining, are yet to be announced. Construction on site however is to start in April towards a completion in 2014. The sewer tunnel runs at up to 75m beneath the east London suburbs and requires the sinking of four large diameter shafts; three of up to 25m i.d. - two at Beckton and another at Abbey Mills - and a fourth 80m deep by up to 38m diameter at Beckton to house a massive pumping station to lift flow from the proposed 32km long Thames Tunnel into the treatment works.
MVB wins the Lee Tunnel contract against strong competition from joint finalist the Hochtief/Murphy JV and earlier shortlisted competition from the Laing O'Rourke/Impregilo JV and from FCC of Spain. Reference design of a project that basically repeats the historic achievement of engineer Joseph Bazalgette who designed London's existing trunk sewer system to the Beckton and Woolwich treatment works in the 1850s, is by Faber Maunsell, now AECOM. Programme manager is the CH2M-Halcrow partnership. Bazalgette's still operating sewer system is now is significantly under capacity to handle the population growth of the London area, the concreting over of green spaces and the more torrential downpours of recent years, causing the system's CSOs to operate on a more frequent and more damaging basis. The new Tideway project will intercept at least 34 of these overflows bring operation of the system by Thames Water into compliance with strict EU Urban Waste Water Treatment Directives.
Ribble River protection in Preston
Meanwhile on the northeast coast of the UK, water authority United Utilities has awarded a contract to the KMI - Kier/Murphy/Interserve JV to build a 3.5km long x 2.85m i.d. storm water storage sewer tunnel.
Pic 2

Fig 2. Alignment of the new CSO
interceptor through Preston

The £114 million project, with a retention capacity of up to 40 million litres, will prevent CSO overflows into the River Ribble and direct surcharges instead to the Preston treatment works. The tunnel will run up to 30m deep in the Preston and Penwortham areas and will bring significant environmental improvements to the Fylde coast bathing waters and designated shellfish beds located within the Ribble Estuary.
The 3.5km long tunnel alignment runs directly under the Preston city centre and includes construction of eight access/drop shafts as well as two passes under the Ribble River and additional microtunnel connections and drop shafts (Fig 2). A 30m diameter x 34m shaft at Penwortham will house a deep pumping station to lift flows to the waste treatment works at Clifton Marsh.
United Utilities has promised to work with the local government councils to keep disruption in the city to a minimum. Construction work is planned to start this spring for an overall completion by 2012 with work within the city targeted for completion before the end of year holidays 2011.
References
Super sewer to revitalize River Thames - TunnelTalk , March 2009
Thames Water Facts and Figures
United Utilities Capital Programmes

           

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