River Thames Clean Up - Past, Present & Future Amy Fairbairn B.Sc (Hons) M.Sc AIEMA Tideway Environmental Assessment Manager Thames Water Utilities Limited Summary Introduction Part 1 – Past to Present Cholera, the ‘Great Stink’ and Joseph Bazalgette! Part 2 – The Current Challenge Dead Fish and Sewage Litter… Part 3 – The Future Working for a Cleaner Thames Conclusions 2 INTRODUCTION - UK Water Companies Northumbrian Thames Water North West Yorkshire Severn Anglian Trent Welsh Thames Wessex South Southern West 3 Our Sewerage Operation Over 13 million wastewater customers 348 sewage treatment works 67,000 km of sewer pipes Treat equivalent of 41 Olympic size swimming pools of sewage every hour in London 4 River Thames in London 5 PART 1 – River Thames Clean up Past to Present 7 Woolwich Bow Eltham Stoke W Shore Ditch Newington a er ll y Riv Hackney Brook B Quagg r o o Islington k rne l le Bou r Ho a Riv E er Rav ens bou rne TY Bourne Waterloo Hampstead ForestHill e West Bourn River Effra Old Rivers of London NottingHill St Counters Creek amf ord Streathamk Bro o ok ro B n o lc a F Roehampton Population Growth & Technology Changes in the 19th Century Cesspits developed and by 1800, 150,000 were serving population of 1 million Rising population (1 to 6 million between 1820 and 1900) due to immigration from the country Flushing toilets were developed but still discharging into cesspits so regularly overflowed Caused unpleasant odour and pollution of drinking water wells - sanitation became a large problem in poor areas 8 Wastewater Crisis in the 19th Century Until around 1800 River Thames fairly clean and supported fishing industry (e.g. salmon and lobster) Old rivers and sewers discharged onto the foreshore – Thames became increasingly dirty and toxic Tides meant buoyant material floated up and down river and deposited on river banks Water quality of River Thames worsened and it began to smell – by 1850 only eels could survive! 9 Public Health Issues Overcrowding continued and death rates increased – spread of disease not properly understood 1831/2 - first cholera epidemic followed by repetitions in 1848/9 and 1854/5 Government knew something had to be done – investigations showed diseases related to poor living conditions and polluted drinking water Public Health Act 1848 - formation of Metropolitan Commission of Sewers Metropolitan Water Act 1852 – abstraction of water from upstream of Teddington Lock (freshwater) 10 Metropolitan Commission 1848 – 1855 Undertook major survey of all sewers in London Principle of intercepting sewers was considered but technically very difficult Involved building canal-like sewers on each bank of Thames to separate the sewers from the river Sewers would convey waste to East London - discharge on ebb tide so foul flow taken out to sea 1853 Joseph William Bazalgette appointed as Chief Engineer at the Commission 11 Plan for Intercepting Sewers Developed intercepting sewer plan further – based on combined system for foul sewage and surface runoff (Combined Sewer Overflows) 82 miles of major intercepting sewers, 2 large storage works, 4 major pumping stations and 4 miles of river embankment! Construction cost estimated to be £3.3million Plan was rejected, mainly on cost and technical grounds 12 Metropolitan Board of Works 1855 - 1889 Basic proposal was accepted in principal in 1856, but many discussions and arguments about details Government ordered further investigations and subsequent plans were rejected June 1858 – business could not continue in the Houses of Parliament because of the ‘great stink’ of the river August 1858 - Prime Minister Benjamin Disraeli agreed Act to enable MBW to obtain a loan and work started 13 London’s Intercepting Sewers Northern High Level Hampstead Stoke Newington Abbey Mills Northern Pumping Station Outfall Islington No Works Bow rthern Outfall Beckton evel dle L ow Level Notting Mid ch Northern L ran Hill B illy ad icc Waterloo P Bermondsey Southern WesternWestern Pumping Branch Outfall Station l Works rn Outfal el Southe ev Crossness L Woolwich ow L Deptford ern vel th Le h u gh c Pumping Station So n Hi n ther a Sou r B Eltham High Level Extension a fr Forest Roehampton f E Hill Streatham 14 London’s Sewers 15 London County Council 1889 - 1964 Quality of river Thames improved MBW replaced by London County Council in 1889 Assessment of system problems and continuing population growth (above Bazalgette’s predictions) resulted in: – Two new interceptors on each side of the river built between 1905 to 1911 – Storm relief sewers between 1879 and 1964 – Primary treatment (sedimentation) at Beckton and Crossness between 1890 to 1900 – Mogden STW commissioned in 1935 16 Changes in the 20th Century By 1950s river was anaerobic again - large extensions at Beckton (1964) and Crossness (1974) Sludge from Beckton and Crossness treatment processes was transported in vessels out to sea until 1998 All 5 Tideway sewage treatment works (Beckton, Crossness, Mogden, Long Reach and Riverside) received secondary (biological) treatment by 1978 17 Tidal Thames Dissolved Oxygen The Recovery 1950-90 1950-59 100 1970 90 1975 80 1980 70 1990 60 50 40 30 20 Dissolved Oxygen % Saturation 10 0 30 20 10 0 10 20 30 40 50 60 Km from London Bridge 18 Cumulative Species Number in TidalThames (Fulham – Tilbury) Cumulative Fish Species Recorded 100 120 20 40 60 80 0 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 19 Fishing on the Thames 20 PART 2 – River Thames Clean Up The Current Challenge Central London Intercepting Sewers HampsteadNorthern High Level Stoke Middle Level No. 2 Newingto Notting Islington n Hill Midd Abbey Mills le Level No 1 Pumping Station Western North ranch ern Lo Bow illy B N w Le iccad o 2 vel Western PPumping Northern No N rthe o Outfall Station Le rn L rth vel N ow er Bermondsey o 1 n O Works 1 Branch ut el No fal Beckton w Lev l ern Lo South High Level ExtensionSouthern Low Level No 2 Roehampton Southern Outfall No 1 Southern High Level Deptford Pumping Southern ch n Sout a Station hern O Outfall 5839-17 26/11/99 r utfall N B h o 2 a Forest ig Woolwich Works Streatham ffr H E n 2 Crossness Hill er o th l N ou e S ev Eltham Lewisham Branch L 22 Tideway Combined Sewer Outfalls and Pumping Stations 23 River Thames & Tideway STWs River Roding River Beam River Ingrebourne River River Lea Beckton Southend Brent Riverside Thames Estuary Mogden Barrier Crossness Gravesend Long Reach 24 London’s Principal STWs Mogden STW Beckton STW 25 Crossness STW London’s Sewers: Current Challenge Acute water quality problems: – Combined sewers reach capacity in heavy rain and discharge into River Thames – Localised impact on quality - severe oxygen depletion under worst circumstances Chronic water quality problems: – Quality of STW discharges establishes background for intermittent discharge issues – Summer/low flows - minimal freshwater dilution, poor mixing, long retention times 26 Typical Oxygen Sag Curve 100 Mogden STW 90 80 Crossness STW 70 Beckton STW 60 50 40 Dissolved Oxygen % Saturation Critical Point 30 -31 -22 -16 -9 -3 3 9 16 22 31 41 51 61 Distance from London Bridge km downstream 27 Combined Sewer Overflows Discharging into River Thames 28 Litter and Dead Fish on the Thames Foreshore 29 Protection of Water Quality in Tidal Thames ‘Tideway Operating Agreements’ with Environment Agency: 1. Enhanced effluent quality – All 5 Tideway STWs operated to produce better effluent quality during summer period 2. Maintain and operate mobile vessels (Bubbler and Vitality) – Oxygenation barges capable of adding 30 tonnes oxygen per day – Use when DO concentration falls, to protect river life Also 2 new skimmer boats to collect litter 30 5839-79 26/11/99 Oxygenation Barges – ‘Bubbler’ & ‘Vitality’ 31 PART 3 – River Thames Clean Up The Future Thames Tideway Strategic Study Carried out between 2001 - 2005 Aim to investigate the issues of combined sewer overflows to the River Thames and identify possible solutions Independently chaired Steering Group with representatives from: – Government – Regulators – Local Planning Authority – Thames Water 33 Tideway Strategy – Agreed Environmental Objectives 1. To reduce the incidence of aesthetic pollution (sewage- derived litter) 2. To reduce health risk to recreational users - preserving and improving water quality for bathing and recreational activities 3. To maintain dissolved oxygen concentrations that support a sustainable fish population 34 Outcomes of the TTSS 1. Improvements to STWs – Increased capacity (more flow to be treated before storm discharges are made) at Beckton, Mogden and Crossness STWs – Improved effluent discharge quality at Beckton, Crossness, Long Reach and Riverside STWs – Improvements will be in place by 2014 2. Tideway Tunnel – Underground tunnel to capture flows from combined sewer outfalls currently discharging into the River Thames – Flows would be transferred to East London for treatment 35 2006 Progress July 2006 – Government requested further assessment of two options (full tunnel and 2 shorter tunnels) Report will be submitted in Dec 2006 and decision expected in early 2007 Assessment to include technical, cost and environmental aspects Principal driver is European Union Commission – improvements of London’s sewerage system to meet requirements of the UWWTD 36 Tideway Tunnel Options Option 1 •34.5km long, 7.2m diameter •85m below ground •Treatment at Beckton STW Option 2 •Two shorter tunnels •Treatment at Beckton STW 37 Summary – River Thames Clean Up Quality of the River Thames has improved greatly over the past two centuries Main drivers have been: – Public health - e.g. cholera epidemics, ‘the great stink’ – European Union – environmental legislation – Public pressure and health risk Implemented through mixture of legislation and regulatory bodies (e.g.