The article on sewage reuse (NCE last week) reminded me of a proposal I put to Thames Water's management, when, as principal design engineer, water supply, I was involved in design of the Thames Water Ring Main.
My proposal was to divert a proportion of Beckton sewage works discharge and to transfer this in a tunnel back to the Thames Valley storage reservoir complex to the west of London.
The Beckton water would be diluted and undergo additional treatment due to its storage time in the reservoirs.
Running costs would primarily be focused on pumping, but only the head difference between Beckton and the Thames Valley reservoirs. The flow through the tunnel would be driven by gravity, the same as in the Ring Main.
Capital cost would be high, but in the light of proposals to install desalination plants it would be worthwhile undertaking a cost comparison No doubt my submission is somewhere in Thames Water's records and could be worth investigating as it was well developed and costed.
John Kerslake (M ret), Abingdon, maggie.kerslake@btinternet. com