FOAM discharged into a river near sewage treatment works has prompted an investigation. 

The “unusual’ discharge in River Chess was first noticed by River Chess Association volunteers on Saturday February 4 beyond Chesham Sewage Treatment Works outfall.

It has prompted an investigation by Thames Water, who claimed the sewage treatment process was “working as it’s designed to”.

Chair of the River Chess Association Paul Jennings feared the chemical in the river was a result of fly-tipping by an unlicenced trader.

Bucks Free Press: Foam at Dodds Mill in CheniesFoam at Dodds Mill in Chenies (Image: River Chess Association)

Thames Water said in a statement on February 7: “Current evidence suggests the foam has been caused by a substance that has entered our sewage network upstream of the treatment works, and which the treatment process isn’t designed to remove.

“We carried out investigations over the weekend but weren’t able to trace the source. Our specialist team are talking to local businesses to try to identify the substance and find out how it has entered the sewer network. They’ve ruled out a number of potential sources but not yet found the cause.

Bucks Free Press: The situation at Bois Mill over the weekend The situation at Bois Mill over the weekend (Image: River Chess Association)

“Work is ongoing to analyse the samples we’ve taken over the weekend, but the processes involved mean we don’t expect results until the end of this week.”

Now the Chesham and Amersham MP Sarah Green has called for the Environment Agency to “mitigate the impact of this pollution incident”.

“I also urge you to ensure that the incident is fully investigated by the Environment Agency to ensure its cause is identified and the appropriate steps taken by Thames Water to ensure it does not happen again,” she told the area director of Environment Agency Samantha Lumb.

Bucks Free Press: Dodds Mill in Chenies further downstream from the sewage treatment worksDodds Mill in Chenies further downstream from the sewage treatment works (Image: River Chess Association)

Although sewage discharge by Thames Water into River Chess was “sadly quite normal,” dumping of chemicals was “unusual”, Mr Jennings said.

An Environment Agency spokesperson said: “Our officers visited the River Chess on Saturday and again today (Monday February 6) to assess the potential environmental impacts of the foam and to also investigate its cause.

 “While our investigation is ongoing, we can’t comment any further.

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 “We thank the members of the public who alerted us to this incident and encourage anyone who witnesses pollution or any other environmental incident to call our free 24-hour hotline on 0800 80 70 60.”

River Chess Association said on its social media site it was “interesting to know that Sewage Treatment Works can’t cope with all chemicals”.

“What is the protocol when things like this happens, it looks like the river and the environment is the default and they take the hit,” they said.