The Paper describes the design and construction of a concrete-lined tunnel,together with the necessary pumping plant, which will be used to transfer water from the River Thames to the Lee Valley storage reservoirs of the Metropolitan Water Board. This tunnel is believed to be the longest in Europe and the longest tunnel in soft strata in the world. This tunnel main has been made necessary because insufficient water is available from the River Lee to meet the needs of East London.
The main was designed as a gravity main. Electrically driven boreholetype pumps located in a shaft at the Lee Valley end of the main deliver the water into the reservoirs.
Whilst the shafts were lined with bolted reinforced concrete and cast iron segmental rings of conventional design. the tunnel was lined with unreinforced tapered concrete blocks which were expanded against the ground under the pressure of the rams of the shield used in driving the tunnel, thus avoiding the use of grout or bolts.
Other features dealt with in the Paper include a new form of rotary shield which sustained a rate of driving of 360 ft per week for long periods, lining the tunnel with cement mortar by mechanical means, the design and construction of a siphon intake, and a Venturi meter in tunnel.
