Treated sewage could boost flow of Chelmer

Essex & Suffolk Water has asked the Environment Agency (EA) for a consent to discharge 40,000m3/d of tertiary treated sewage into the River Chelmer, a tributary of the River Blackwater.

At present, this wastewater is subjected to secondary treatment at Anglian Water’s sewage treatment plant in Chelmsford and then pumped out into the Blackwater estuary, via a 70-year old pipeline.

Essex & Suffolk is now proposing to replace this route with a link to a new tertiary STP, including phosphorus and nitrogen removal and UV disinfection technology. If the application is approved, Essex & Suffolk hopes to maintain summer flows in the Chelmer at acceptable levels and abstract more water downstream for drinking water treatment.

According to John Daniels, the EA’s regional water quality consent manager: “Population growth in the area has meant that demand has now outstripped supply.” Two public meetings have now been held by the EA to discuss Essex & Suffolk’s plans.

Objectors have so far included marine business associations in Maldon who are concerned that the Blackwater estuary could silt up as a result of the altered pattern of freshwater flow, and anglers on the Chelmer, who fear the effects of oestrogens (which will not be removed) on fish.

Mr Daniels said the effects of the input on wildlife would be closely monitored. As with many increasingly urbanised rivers, treated effluent contributes to a large proportion of the flow. With this latest scheme, Mr Daniels said: “You could be looking at a flow contribution in summer of up to 50%.”

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