Sunday, 28 November 2010


This week's topic is sewage. Where does it come from? Where does it go? I think we all know the answer to the first question.

At Paxton Pits the journey might start at the new Environmental Education Centre. Waste is sent along a new pipe to join ours from the Visitors' Centre and then it is pumped all the way along the High Street to a point near the pub where it turns left along the main pipe. It eventually joins a bigger pumping station near the allotments.

The journey then continues beneath the allotments and under the Meadow Trail for 150 metres along the East side of the Hayling Pit, across the Little Meadow and so to the river. But the story doesn't end there. The pipe crosses the river to the treatment plant on the other side.

The section of sewer on the Reserve is very old and seems to spring a leak most years, especially after heavy rain. Anglian Water have bitten the bullet and decided to replace the whole section, probably this month.

This means that the affected path will be closed, possibly for a few weeks. Diversion signs will be in place as soon as the work starts.

But we have not finished with our sewage yet! What happens at the treatment plant and after that?

At the plant, the waste is simply sorted into solids and liquids. The solids get shipped out for landfill or incineration and the liquids are purified and sent back to the river. Then it gets really interesting.

Downstream of us, at Offord, there is an Anglian Water pumping station that takes some water out of the river and pumps it up to Grafham Water. Then it is filtered, treated, sent back to our taps, and guess what? We drink it!

You might have fond memories of sewage treatment plants. Old fashioned treatment plants used to be great places for birds, and for tomatoes. When I was an RSPB warden in Scotland, I managed to get a trip on the "Gardyloo". (The name comes from the French "Garde de l'eau" which is what you would shout just as, or just after, you threw the contents of your po out of the bedroom window into the communal drain, or your neighbours, below.) The boat made a circuit out of Leith into the Firth of Forth, passing by fabulous birding sites such as the Bass Rock and the Isle of May. You could get great views of gannets, puffins and seals while you left a brown trail across the blue waters!
Fact: Did you know that the catacombs in "The Italian Job" movie were actually filmed in the sewers beneath Coventry?