The Mott MacDonald Water Utilities Division, in partnership with
the Tunnels Division, was awarded a five-year AMP4 consultancy
services framework with Thames Water to design the strategic
expansion to Thames Water Ring Main (TWRM). The work will increase
resilience of the potable water transfer and distribution system in
London.
The TWRM comprises approximately 80km of 2.5m internal diameter
tunnel that runs underneath London at between 25m and 65m below
ground level. The TWRM supplies over 1000Ml of potable water across
London each day and currently transfers treated water from the
water treatment works (WTW) at Ashford, Hampton, Kempton and Walton
to a number of local pump-out shafts.
The Thames Water resilience programme will ensure that an adequate
water supply will be maintained across the whole of London in the
event of catastrophic failure of one of the main water treatment
works. It comprises four projects:
4DCF – TWRM extension - Brixton to Honor Oak: this project
includes design and construction of approximately 5km of tunnel
between Brixton and Honor Oak and the construction of a new
pump-out shaft at Honor Oak.
5DCF – Coppermills Transfer Pump Shaft: this project
includes design and construction of a new transfer shaft at
Coppermills WTW which will allow water to be pumped to the TWRM to
meet both the normal flow demand and also an increased resilience
demand in the event of failure of one of the other WTW. The
transfer pump shaft will also be able to pump in the reverse
direction i.e. from the TWRM into Coppermills WTW if the operation
of Coppermills is lost.
6DCF – TWRM extension – New River Head to Stoke Newington:
this project includes design and construction of a 5km tunnel
connection between New River Head and Stoke Newington pump-out
shaft which allows Coppermills and the 5DCF projects to be linked
to the rest of the TWRM.
7DCF – Hampton TWRM Pump-Out Shaft: this project includes
design and construction of a new pump-out shaft at Hampton WTW as
well as modifications to existing pipework enabling the whole
output from Hampton WTW to be directed into the TWRM.
Mott MacDonald consultancy services began at the beginning of 2005.
Feasibility studies and outline design for all of the above
projects have been completed. The main scope of work included
outline design of shafts and tunnels, MEICA systems, surge and
hydraulic analysis, environmental and traffic assessments,
geotechnical and topographical studies as well as settlement
assessments.
All projects are currently in construction or at the tendering
stages. The total TWRM resilience project has a budgeted value of
£120million and a programmed completion date of March 2010.
