The Herald last week reported that Oxfordshire County Council had expressed new concerns about Thames Water’s plans to build a reservoir the size of Heathrow between East Hanney, Marcham and Drayton.
Their concerns relate to the size and need for the reservoir. The reservoir would be built above ground and contained by walls between 15 and 25 metres high. That’s about the height of an 8 storey block of flats and higher than anything else in the Vale.
The reservoir embankments would enclose about 4 square miles and be over 10miles long and be the largest thing visible from the Ridgeway.
Thames Water’s draft Water Resources Management Plan for 2019-2024 is open for public consultation again. Comments should be submitted before 28th November, details can be found on the Group Against Reservoir Development (GARD) website: http://www.gard-oxon.org.uk/
The Thames Water plan still fails to give sufficient justification for the reservoir as a 'storage and distribution hub' for the South-east.
GARD believe that the demand for water in the South East can be met without this reservoir as long as Thames Water meets its obligations to repair leaks in their pipes, and implements, in the medium term, a plan to transfer water from the Severn to the Thames (a scheme first suggested in the 1970s).
The proposed large surface area to depth ratio of the new reservoir will lead to excessive evaporation. In meteorological terms the reservoir would amount to a large puddle. Why take millions of gallons of water from the River Thames, then to spread it across a large area of Oxfordshire so that it can evaporate?
There is also the problem with flooding around the reservoir.
We have two types of clay subsoil (which are relatively impermeable) and greensand which is very permeable. Part of the reservoir will be built over greensand so is taking away over one square mile of the land that soaks up flood water which may increase the flood risk in the rest of the Vale.
Equally important, if water from the reservoir could leak into the greensand below it, it could create a river leading straight to Steventon, Drayton and Abingdon and on into the Thames.
Thames Water have not yet done any detailed designs to show what the risk of these flooding and leakage risks are, and how they could mitigate it, yet expect to start building in 2025.
Please submit your comments to the Secretary of State now.