River Thames: Sewage

(asked on 17th July 2014) - View Source

Question to the Department for Environment, Food and Rural Affairs:

To ask Her Majesty’s Government, further to the Written Answer by Lord De Mauley on 14 May (WA 542), what is the actual annual average frequency of discharge of storm sewage of the upgraded Mogden works; whether it meets the requirements of the Urban Waste Water Treatment Directive; if not, what action is to be taken to ensure that it does; and what is the explanation for the number of such discharges between March and December 2013 compared with Thames Water’s statement made before the upgrade that "post upgrade the Mogden works would spill about once every two and a half years."


Answered by
Lord De Mauley Portrait
Lord De Mauley
This question was answered on 30th July 2014

It is not possible to provide the annual average frequency of discharge of storm sewage from the upgraded Mogden sewage treatment works (STW) as the upgrades only came into effect on 31 March 2013. A discharge from Mogden STW storm tanks has occurred on 54 days in the 12 months from 31 March 2013. This compares to an annual average of 95 spill days for the preceding 5 years. The period since 31 March 2013 has been exceptionally wet, causing additional spills. Despite this the storm discharges from Mogden STW have not led to a significant adverse impact on the quality of the river since the upgrades. The Environment Agency will continue to assess the performance of the upgrade to ensure it continues to comply with the Urban Waste Water Treatment Directive. The basis on which Thames Water estimated that Mogden STW will spill about once every two and a half years is not known.

Reticulating Splines