A two-metre valve (penstock) in a major sewer serving Heathrow Airport jammed shut on Saturday afternoon at Cranford Bridge on the A4 Bath Road while engineers carried out routine maintenance.
Initial attempts to re-open the valve were unsuccessful but, using custom-made hydraulic lifting equipment overnight, our engineers were able to force open the jammed shutter this morning (Mon).
While we are able to take a lot of backed-up sewage away in tanker lorries for treatment and enlarge a contingency pipe to bypass the problematic shutter, the volume of sewage was such that we were not able to tanker all of it.
Faced with the unpalatable choice of letting the remaining sewage back up into the airport or spill to the River Crane, we were forced to opt for the latter, resulting in sewage entering the river and damaging wildlife, which we deeply regret.
We are working with all those affected by this problem and with the Environment Agency, who are aware of our plan to tackle this problem as soon as possible.
Once normal flows resume, probably later this morning, some stronger than normal effluent will arrive at Mogden and this may cause elevated odour levels for a few hours, for which we wish to apologise in advance.
From Thames Water - External Affairs - Oct 31, 2011 12:20 Heathrow sewer penstock, River Crane
And the result - major fish-kill on the River Crane.
David Harvey of the Thames Anglers Conservancy checked Crane Park around the Hospital Bridge Roundabout area on Monday morning. He reported a revolting sickly stink; Water birds trying to get up in to the trees to roost rather than being on the water; Foul black residue and considerable numbers of dead fish, small and large, on the banks where the water level has receded. What should be clear healthy water is grey and stinking of effluent.
People should not paddle in the water and wash thoroughly after contact. We advise Dog walkers to keep their pets away from the water.
– from Ed Randall