<a href=”http://www.expressdrainagesolutions.co.uk/news/infographic-victorian-sewers-london-thames-tideway/“><img src=”http://www.expressdrainagesolutions.co.uk/images/misc/victorian-sewer-thames-tideway.jpg” alt=”Infographic on London’s Past, Present & Future Sewer Systems”/></a>
The Victorian Drain System
The Victorian age is regularly cited as a landmark era in construction, engineering and industry, with improvements to many areas of society taking place to support the swelling populations of Britain’s major cities.
Effective drainage was one such development, brought about more out of necessity than anything else. As London expanded to record sizes throughout the middle of the 19th century, the amount of raw sewage that was being deposited directly into the Thames reached catastrophic proportions. As the river was also the main source of drinking water for the capital, this resulted in waterborne diseases becoming rampant, with one particularly bad cholera epidemic killing over 10,000 people in 1853.
It wasn’t until 1858 however, during the summer that became known as the ‘Great Stink’, that any action was taken to rectify the situation. That action came in the form of Joseph Bazalgette, a top engineer, and his revolutionary design for a sewage system. Called upon by the government to carry out the work, Bazalgette and his team constructed 85 miles of intercepting sewers that ran parallel to the Thames, as well as 1,100 street sewers, at a cost of £4.2 million – a phenomenal figure that roughly equates to somewhere between £50 -£60 billion today.
In another major achievement for Victorian engineering, the entire project was completed in just 11 years between 1859 and 1870, and remains in use to this day. However, this is where new problems have arisen.
The Present Day
As effective and pioneering as Bazalgette’s system was, it was only designed to cope with the sewage needs of a city with a population of 2.5 million. By the end of its construction, that figure had already reached 4 million, and today it is over twice that amount. The 150 year old Victorian sewers that still run under the capital cannot cope with present day demands, and sewage is regularly spilling over into the Thames – up to 39 million cubic metres in an average year – with only 2mm of rainfall needed to cause the overflow.
It’s not only the obvious negative impact on health that is a concern, but also the financial implications of having such unsanitary water supply. If found to be in breach of the Urban Waste Water Treatment Directive, the state of the Thames could incur millions in hefty fines from the EU – a cost passed on to the British taxpayer.
Back in 2000, the Thames Tideway Strategic Study was introduced to assess the river’s compliance with this EU initiative, and discovered that simply preventing the untreated sewage discharge alone would not be sufficient to meet the new regulated standards. This put into motion a series of necessary improvement to London’s sewage system as a whole, which are now beginning to take effect.
One such solution that was given the go-ahead this year, the Thames Tideway Tunnel, will see a major new sewer built under the river to act as a storage and transfer tunnel, taking the strain from the aging Victorian system and protecting the water from contamination. The proposed route for the tunnel will begin in the West London area, roughly following the river to Limehouse before heading north east to Abbey Mills Pumping station near Stratford. Everything stored in the tunnel will be pumped to Beckton Sewage Treatment Works for processing, eradicating any risk of it ending up in overflowing into the Thames.
A second initiative has been introduced in the form of major improvement work at London’s 5 principal sewage plants – Mogden, Crossness, Beckton, Long Reach and Riverside. The £675 million project began back in 2010, and aims to increase dramatically the amount of sewage each can treat. Improvements to the standard to which sewage can be treated will also be carried out, helping to both increase the cleanliness of the water system and help meet the EU guidelines.
A further tunnel, the Lee Tunnel, has also been given the green light, and will act as a capture point for overflows from the 35 most polluting combined sewer overflows (CSOs). Although focusing on improving sanitation along the Lee, the tunnel will have a positive effect on both those who use this water supply and also the rest of London, as it flows into the Thames at its most southern point. The tunnel itself will also link to the Thames Tideway Tunnel, shortly before it discharges into Beckton Sewage Treatment Works.
These improvements echo similar work being carried out in Paris, Helsinki, Stockholm and Washington DC, and represent a long-overdue updating of Victorian sewer engineering work that has, to its credit, held up reasonably well up to this point under the circumstances.