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 Old Rivers of London

Hackney Brook Hampstead H Stoke o le Newington B o u T r Islington

Y n Bow e W B

W o a l

u l

e S s r B

t n t r a B e Shore Ditch

m o o

u o Notting k f r o n r C e d Hill o B u n r t o e Waterloo o r k s C r Earl e e k Woolwich Q u a gg R R y i R v i e v iv r e e r r E

Roehampton f R Eltham f r Forest a a v

e Hill n s b Streatham o Fal u con Br r ook n e

7 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 Fish Species Recorded in Tidal Thames (Fulham – Tilbury)

120

100

80

60

40 Cumulative Species Number Species Cumulative 20

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

evel igh L ern H North Stoke Hampstead 2 Newingto Abbey Mills No. Northern vel Pumping Station e Le n Outfall iddl M Islington Works Bow Beckton evel No No 1 orthern Low L rthern evel N o 2 Outf dle L h N all Notting Mid nc Northern Low ra Level No 1 Hill y B ill ad cc Western Pi Bermondsey Southern Branch Western Pumping Outfall Station 1 Southern Outfall No 1 No el Works ev L 2 2 Crossness ow No tfall No L vel hern Ou rn Le Deptford Sout he Low Woolwich ut hern el So out Lev Pumping S igh h rn H Station ig the H 2 ou h S c n o n r N Eltham a e l High Level Extension r th e B Forest u v o e Roehampton a S L ffr Hill E Streatham Lewisham Branch

5839-17 26/11/99 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 Dissolved Oxygen 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. Environment Agency)

38 Further Information

„ Thames Tideway Strategic Study:

http://www.thamestidewaystrategicstudy.co.uk

„ Thames Water Utilities Limited:

http://www.thameswater.co.uk

THANK YOU

39