Thursday, 23 June 2016

Hogsmill River: Spates and Sewage

Clattern Bridge
View west from Blue Bridge
Today the Hogsmill reached 1.1m at the Grange Road/Watersplash Close gauging station. This is the highest level since 2000. There is a good website to view this data relayed from gauging stations here https://flood-warning-information.service
 
An amount of this water is from road  or pluvial run-off; but unfortunately a component-apparent from the smell- is sewage.

Assorted gross litter hanging from trees
Rag at the Hogsmill Sewage works 
Every part of the already hard-pressed sewage infrastructure is overtopped: leaching and  leaking; pouring and pooping - a soup of raw sewage. The bankside vegetation captures that which is generally known as 'rag'. This includes the nappy liners, the wet wipes, condoms, tampons, dental floss etc.

 This is additional to the daily dosage from the many misconnections polluting every outfall along it's nine mile course. see previous posts on sewage spills and dead fish and rag removal (21.2.16,19.4.16 and 2.5.16) and related Flood risk position and catchement approach (10.3.16, 19.3.16).

Ammonia testing
Testing for e-coli
 Yesterday, in attempt to quantify elements of the impacts of sewage, we were joined by Theo from the charity London Waterkeeper http://londonwaterkeeper.org.uk/

Theo worked at Thames21 for 12 years. During this time he set up the ‘Love the Lea’ campaign to make members of the public aware of the problems facing London’s second river. He established its water quality testing laboratory.

Testing strips from LaMotte
Elliot at the outfall
We took samples from eight different sites along the Hogsmill from the confluence with the Bonesgate to Middle-Mill at Hogsmill Community Garden. We found raised levels of ammonia at two sites and await the results of the e-coli test samples.

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