Where does pollution come from?

East London’s rivers are some of the most polluted in Britain, running with high levels of e-coli sewage bacteria, waste water from people’s homes and poisonous oils and chemicals from our roads. This polluted water flows down the Lea Valley past the homes of thousands of people, reducing the quality of the rivers they enjoy.

Pollution Sources:

1.     Sewage
One of the biggest single polluters of the Lea are overflows from Deephams Sewage Treatment Works. This is sewage from all business and homes in North East London*. It needs upgrading so it will meet the new discharge permit that comes into force in 2017. At the moment it is too small to deal with the sewage from people in North East London and rainwater. The wet weather flow can be up to 6 times greater than the dry weather flow. There is a plan to upgrade the Sewage Works by 2021 so that the effluent it discharges is less polluting. It will also be able to process the waste water from more people. To prevent rain water getting into sewers and taking up valuable space at Deephams Sewage Treatment works we need a network of sustainable drainage systems (SuDS) which will hold rain – reducing the risk of sewers overflowing into local streets, and extending the life of the upgrade.

http://www.deephamsconsultation.co.uk/what-we-are-doing/why-we-need-the-upgrade/

Solution – Natural Drainage
The long-term, cost-effective solution is to build natural drainage systems across North East London and upgrade the sewage works. These Sustainable Drainage Systems will reduce the amount of water that enters the sewer drains and give the sewage works more time to process the waste water. Wetlands, wet woodland and water butts are all part of the toolkit. Evidence shows that in most cases using natural drainage will be cheaper than conventional approaches. We need the Greater London Authority’s body for surface water, Drain London, to do much more. Drain London needs to promote natural drainage and devise its introduction across the Deephams Sewage Treatment catchment.

2.  Misconnected pipes
Up to 10% of homes are misconnected. This means waste water from washing machines, showers or toilets is going down the drainpipe instead of into the sewer pipe. Drainpipes are just meant for rain – many lead to local rivers. With thousands of properties polluting their river it adds up to a heavy burden on the environment.

Solution – more checks by Building Control Officers
Too many misconnections are missed by Building Control Departments and approved inspectors. They check on home improvements like extensions and larger developments. This is the easiest time for pipes to be sorted out, but they are not checked often enough. If these checks identified a misconnection they could refuse to sign off the work until it was put right. While many misconnections are blamed on dodgy builders or unofficial work, we have evidence that too often Building Control officers don’t check the pipes on jobs they are inspecting. Making the system work properly is the best way to reduce this problem (with residents, plumbers and builders increasingly understanding what they need to do).

3.  Road run-off
There are more than 2.5 million private cars in London, added to that are the buses, lorries, taxis and vans using our roads. Research on private cars shows that about 16% of them leak oil. That means that in London 291,635 gallons of oil a year drips onto the roads (1,325,799 litres). When it rains this gets washed into our rivers along with any other chemicals that have been dumped plus grit and dirt. The pollutants are poisonous, and cancer causing.

Solution – Rain gardens in car parks
We need to intercept this dirty water before it reaches the river. The easiest way to start this is by digging up unused spaces in car parks planting them with vegetation. The rainwater that washes the oil off the car park can be directed into a rain garden to be cleaned before it flows into the river. This can be done in any car park that drains to a river; supermarkets; outside offices; schools; cinemas; sports grounds etc.

*The sewage from the following areas flows to Deephams Sewage Treatment Works: LB Enfield, eastern half of LB Barnet. Northern part of LB Waltham Forest. Northern half of LB Haringey. Part of LB Redbridge. Western fringe of Epping Forest DC. Southern part of Broxbourne DC. Part of Welwyn Hatfield DC (Cufley).

References:
Deephams Sewage Treatment Works http://www.deephamsconsultation.co.uk/what-we-are-doing/why-we-need-the-upgrade/

River Pollution in London, GLA http://data.london.gov.uk/datastore/package/state-environment-report-london-june-2011

Natural Drainage research paper funded by Defra http://www.cambridgeshire.gov.uk/NR/rdonlyres/C4B8671D-CD62-4BC7-89E8-40288948A5FB/0/FinalMonitoringReportMainReport.pdf

Drain London http://www.london.gov.uk/priorities/environment/water-management/rainwater-drainage

Rain gardens http://raingardens.info/

Oil from cars http://www.burningman.com/preparation/event_survival/oildrips.html

Road run-off pollution by Polycyclic Aromatic Hydrocarbons and its contribution to river sediment. Andreas Krein and Marcel Schorer http://www.deepdyve.com/lp/elsevier/road-runoff-pollution-by-polycyclic-aromatic-hydrocarbons-and-its-0kuqbUYpWx

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