Sewage Update 2 – And they think it’s all over

Just when you think it’s all done and a line drawn under it:

You see a message from Redrow stating that there was no blockage.

Excuse me! But I shall vigorously contend my point here.

From the drainage diagram supplied during conveyancing:


The manhole that overflowed is identified as FW70 on the diagram. The key numbers are CL which is the Manhole Cover Level at 51.63m and IL, the Invert Level is 48.51m where the outflow from this manhole is. That is a difference of 3.1m which must have filled with liquid for it to overflow. I’m no particular drainage or building expert, but I would strongly suspect this would indicate the drain was blocked beyond this point.

Notes, the IL BD number indicate this is a backdrop manhole with an inflow higher up the chamber at 50.10m.

Also interesting that the cover level where it was overflowing is higher than the Finished Floor Level of some of the plots, so think they might have had serious problems if they had tried to use their toilets or drains.

The other supporting statement for a blockage would be that after the initial flow was stopped at around 1:40pm . Our security camera appears to show a tanker from RMS Waste arrived at around 3:15pm. It was onsite for about an hour and a half with a team pumping out the manhole and rodding down the hole.

The manhole looks to be about 600mm x 600mm, so volume wise 0.6 x 0.6 x 3.1 = 1.1 cubic metres = over 1 metric tonne of liquid, which didn’t drain in 3 hours, flow rate = zero. It doesn’t take a civil engineer to work out that equals BLOCKED!

We’ve accepted all along that drains do get blocked and are probably at a higher risk on an active construction site. In fairness, the initial problem was dealt with swiftly and cleared in relatively short order of a few hours. But to have your version of the incident dismissed is more than just a bit irritating.

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