Thames Tideway Tunnel proposed route and sites

The Thames Tideway Tunnel is a

combined sewer A combined sewer is a type of gravity sewer with a system of pipes, tunnels, pump stations etc. to transport sewage and urban runoff together to a sewage treatment plant or disposal site. This means that during rain events, the sewage gets dil ...

under construction running mostly under the tidal section (estuary) of the

River Thames The River Thames ( ), known alternatively in parts as the The Isis, River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the Longest rivers of the United Kingdom, se ...

across

Inner London Inner London is the name for the group of London boroughs which form the interior part of Greater London and are surrounded by Outer London. With its origins in the bills of mortality, it became fixed as an area for statistics in 1847 and was ...

to capture, store and convey almost all the raw

sewage Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produced by a community of people. It is typically transported through a sewer system. Sewage consists of wastewater discharged from reside ...

and

rain Rain is water droplets that have condensed from atmospheric water vapor and then fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides water f ...

water that currently overflows into the estuary. These events occur when rainfall volumes exceed the capacity of Bazalgette's and other engineers'

London sewerage system The London sewer system is part of the water infrastructure serving London, England. The modern system was developed during the late 19th century, and as London has grown the system has been expanded. It is currently owned and operated by Thames ...

. The tunnelling phase of the project was completed in April 2022. Bazalgette Tunnel Limited (BTL) is the licensed infrastructure provider for its finance, building, maintenance and operation. It has as investors:

Allianz Allianz ( , ) is a German multinational financial services company headquartered in Munich, Germany. Its core businesses are insurance and asset management. The company is one of the world's largest insurers and financial services groups. Th ...

, Amber Infrastructure, Dalmore Capital and DIF. Since the licence award, it also trades as Tideway. On 3 November 2015, the award was made by

Ofwat The Water Services Regulation Authority, or Ofwat, is the body responsible for economic regulation of the privatised water and sewerage industry in England and Wales. Ofwat's main statutory duties include protecting the interests of consumers, secu ...

, ensuring the start of the project. Started in 2016, the construction aimed to be completed by 2024. The

COVID-19 pandemic The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identi ...

has delayed this to early 2025. Once constructed, the main tunnel will have an internal diameter of and will run from at Acton in the west of London for over across the full width of Inner London finally reaching at Abbey Mills in the east. This tunnel will connect 34 of the most polluting

overflows (CSOs) and has been forecast to lead to 3.7% of existing overflows – on a maximal four days per year – at time of commissioning. This may rise, gradually, due to

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

and population growth, but will be cut by the installation for streets, car parks and large roofs, and even for building roofs, of separate surface water drainage, which gives owners a little-mentioned annual saving, and is obligatory for all new development under planning law, which imposes

sustainable urban drainage system Sustainable drainage systems (also known as SuDS,Stratford to East Ham Lee Tunnel for onward delivery to

Beckton Sewage Treatment Works Beckton Sewage Treatment Works, formerly known as Barking Sewage Works, is a large sewage treatment plant in Beckton in the east London Borough of Newham, operated by Thames Water. Since construction first began in 1864, the plant has been exten ...

. Following treatment (to the extent currently possible given the greatly increased amount of diluting rain) water will then be released into the saline Thames Estuary. The estimated capital costexcluding financing, operations and maintenance was £3.8bn with an additional £1.1bn for preparatory works. Due to the COVID-19 pandemic, additional costs of £233m were incurred. The 2021-22 annual report gave an updated cost of £4.3bn. Its outfall, the

Lee Tunnel The Lee Tunnel, also known as the Stratford to East Ham deep tunnel, is a paradigm overflow sewer in East London for storage and conveyance of foul sewage mixed with rainwater. It was built as part of the Thames Tideway Scheme and runs from ...

, runs deep under the

London Borough of Newham The London Borough of Newham is a London borough created in 1965 by the London Government Act 1963. It covers an area previously administered by the Essex county boroughs of West Ham and East Ham, authorities that were both abolished by the s ...

Background

Built between 1859 and 1875, Sir Joseph Bazalgette's original

was designed to capture both rainwater runoff and the sewage produced by four million people. As a failsafe, to prevent sewage backing up and flooding people's homes, Bazalgette's system had the ability to overflow into the Thames via 57

overflows (CSO) along the banks of the river. In 2001, London's population density was 18,457 people per square kilometre, compared to just 6,825 per square kilometre in Bazalgette's day. As the population has grown, so has development involving the building on and paving over large areas. This has altered the natural drainage of the sewerage catchment so that now most rainfall and surface water run-off goes directly into London's sewers, rather than being naturally absorbed into permeable ground. An area twice the size of Hyde Park has been lost to hard surfacing every year up to 2001. In the 2011 census returns (that is, omitting residents who did not disclose their residence)

Greater London Greater may refer to: *Greatness Greatness is a concept of a state of superiority affecting a person or object in a particular place or area. Greatness can also be attributed to individuals who possess a natural ability to be better than al ...

hosted just over 8.1 million residents and Thames Water in a leaflet of that year explained how its works and how sewers needed expansion. The older inner boroughs have combined sewerage systems which cannot cope with the extra hard standings. As London continued to grow the new developments and suburbs were equipped with separated foul water and rainwater drainage pipe work. Extending such separate systems would stop sewage flooding of homes and businesses, as well as into the rivers and the estuary, would reduce carbon emissions, and be cheaper in the long term, than the multitude of pumped water tanks otherwise needed to stop homes flooding plus the Tideway tunnel. Pipes would be laid in a number of streets in each Borough each year over say twenty years, limiting traffic diversions. By 2011 overflows into the river took place more than once a week and as little as 2mm of rainfall can trigger a discharge. The mean total of this was , that is 39 million tonnes, of storm sewage entering the river. These discharges, a mixture of raw sewage and rainwater, needed to be cut to comply with the EU's Waste Water Treatment Directive (UWWTD). If cut to such levels, it would thus restore the ecology of the river to that of 1865–70 or better, that is, before such unmitigated growth took place.

Options assessment

Instigated in 2001, the Thames Tideway Strategic Study,Thames Tideway Strategic Study – Executive Summary
(2005). Accessed 17 January 2014 conducted by a group comprising Thames Water, the

Environment Agency The Environment Agency (EA) is a non-departmental public body, established in 1996 and sponsored by the United Kingdom government's Department for Environment, Food and Rural Affairs, with responsibilities relating to the protection and en ...

, DEFRA and the

Greater London Authority The Greater London Authority (GLA), colloquially known by the metonym "City Hall", is the devolved regional governance body of Greater London. It consists of two political branches: the executive Mayoralty (currently led by Sadiq Khan) and t ...

, was intended to assess the impact of the CSO discharges into the Thames and to identify objectives and propose potential solutions, while keeping costs and benefits in mind.

Outcomes

After four years, the Thames Tideway Strategic Study report was published in 2005, and outlined the following objectives: # To protect the ecology of the Tideway; # To reduce aesthetic pollution due to sewage-derived litter; and # Protect the health of recreational water users

Potential strategies

Four potential strategies were discussed: # Adoption of source control and sustainable urban drainage; # Separation of foul and surface drainage and local storage; # Screening, storage or treatment at the discharge point to river; and # In-river treatment After superficial evaluation of alternatives it was decided that only one strategy, the screening, storage or treatment at the point of discharge, would meet the estuary objectives fully. The remainder were found to be either impractical or insufficient to provide a solution, although the evidence from the outer London Boroughs is that separated storm drainage can sustainably prevent all pollution. In a 2006 report commissioned for Ofwat, Jacobs Babtie strongly recommended using the computer model of the existing system to do detailed studies of the effects of laying separate storm water pipes, but their advice and that from Ofwat in 2007 concerning the poor value of the tunnel was not followed. A number of parties questioned the integrity of the TTSS study, in particular the dismissal of separation and future SUDs/ blue-green infrastructure as a solution. Some groups that opposed the tunnel stated that it is an unsustainable 19th-century solution to a 21st-century problem. They argued that rainwater from roads should be sent directly to canals, rivers or the estuary, and that landowners could install soakaways for their roof run off, making them eligible for discounted water treatment bills. This would reduce pressure on the foul system and take away the need for the tunnel. In November 2010 the draft National Policy Statement for Waste Water (NPSWW) was issued, and eventually published largely unaltered, despite Parliamentary objections that it promoted the Tideway Tunnel as the only solution.

Screening, storage and treatment

The three-part solution to implement screening, storage and treatment was collectively known as the London Tideway Improvements.

Stratford to Beckton: Lee Tunnel

This earliest phase was the

: a deep, broad storage and conveyance tunnel dug and lined from Jenkins Lane, Beckton to Abbey Mills, Stratford, sloping down the reverse way. This tunnel, running down to deep from Abbey Mills to

Beckton Beckton is a suburb in east London, England, located east of Charing Cross and part of the London Borough of Newham. Adjacent to the River Thames, the area consisted of unpopulated marshland known as the East Ham Levels in the parishes of Barki ...

is forecast to capture , or 16 million tonnes annually from the greatest-polluting CSO point in London. Thames Water awarded the £635 million construction contract to the MVB joint venture of Morgan Sindall, VINCI Construction Grands Projets and Bachy Soletanche, in January 2010. Construction began in 2010 and on 28 January 2016 the

Mayor of London The mayor of London is the chief executive of the Greater London Authority. The role was created in 2000 after the Greater London devolution referendum in 1998, and was the first directly elected mayor in the United Kingdom. The current m ...

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, confirmed the tunnel open.

Sewage treatment works modernisation

The second part was the £675 million project to modernise and extend London's five major sewage treatment works to treat more sewage, thus greatly reducing the need for storm discharges to the river: *

Mogden Sewage Treatment Works Mogden Sewage Treatment Works is a sewage treatment plant in the Ivybridge (Isleworth), Ivybridge section of Isleworth, West London, formerly known as Mogden. Built in 1931–36 by Middlesex County Council and now operated by Thames Water, it is th ...

– a £140 million upgrade to extend treatment capacity by 50% * Crossness Sewage Treatment Works – a £220 million upgrade to extend treatment capacity by 44%; *

– a £190 million upgrade to extend treatment capacity by 60%; * Riverside Sewage Treatment Works – an £85 million upgrade to improve water quality and produce renewable energy on site; * Long Reach Sewage Treatment Works – a £40 million upgrade in

Dartford Dartford is the principal town in the Borough of Dartford, Kent, England. It is located south-east of Central London and is situated adjacent to the London Borough of Bexley to its west. To its north, across the Thames estuary, is Thurrock in ...

; These intend to improve the standard to which the sewage is treated, thus improving the

Tideway The Tideway is a part of the River Thames in England which is subject to tides. This stretch of water is downstream from Teddington Lock. The Tideway comprises the upper Thames Estuary including the Pool of London. Tidal activity Depending on ...

's water quality.

Acton to Stratford

The final part is the Thames Tideway Tunnel. When built, it intercepts the outflows from London's most polluting CSOs, stores them and directs (conveys) them to sewage treatment works for processing.

Thames Tideway Tunnel planning and consultation

Initial design and phase 1 consultation

Following the Thames Tideway Strategic Study,

Thames Water Thames Water Utilities Ltd, known as Thames Water, is a large private utility company responsible for the public water supply and waste water treatment in most of Greater London, Luton, the Thames Valley, Surrey, Gloucestershire, north W ...

consulted with relevant authorities to get feedback from stakeholders who would potentially be affected by the construction of the Thames Tideway Tunnel. Thames Water sought feedback on the proposed tunnel routes and potential locations of construction sites. Three tunnel routes were considered: # River Thames Routesuch an alignment, broadly, would followed the river from west London to Beckton STW and would cut across the

Greenwich Peninsula The Greenwich Peninsula is an area of Greenwich in South East London, England. It is bounded on three sides by a loop of the Thames, between the Isle of Dogs to the west and Silvertown to the east. To the south is the rest of Greenwich, to the s ...

, reducing the length of the tunnel where there are no CSOs to be intercepted. #

Rotherhithe Rotherhithe () is a district of south-east London, England, and part of the London Borough of Southwark. It is on a peninsula on the south bank of the Thames, facing Wapping, Shadwell and Limehouse on the north bank, as well as the Isle of D ...

Routea similar alignment, but this would have cut additionally across the Rotherhithe Peninsula, reducing the length of the main tunnel by approximately but requiring longer connection tunnels from some CSOs. # Abbey Mills Routethis route would connect the Thames Tunnel to the head of the Stratford to East Ham part at Abbey Mills Pumping Station. This would follow the same route but deviate north-east to Abbey Mills. The main tunnel length would be about less than the River Thames Route and save about £900 million.

Route and sites selection

A long list of 373 potential sites was created using a desktop survey of the land on either side of the 34 most polluting CSOs (as identified in the Thames Tideway Strategic Report). These sites were then further evaluated against more detailed planning, engineering, environmental, property and community considerations resulting in a shortlist of sites. The three tunnel routes, as well as the shortlist of sites, were then put out for consultation between September 2010 and January 2011.
/ref> In total 2,389 feedback forms (both online and hard copy), 480 pieces of correspondence and five petitions were received. In response to the comments received, changes and improvements to some of the sites, including the potential use of alternative sites and alternative technical solutions, were considered. Based on this a round of interim engagement took place from March to August 2011. Residents around 11 specific sites were sent letters explaining that these sites were being considered as alternative sites, and invited to attend drop-in sessions to pose questions and gain a better understanding of the project. In total ten two-day sessions and one community liaison meeting were held. These were attended by over 800 people. In all 168 comment cards and 147 pieces of site specific correspondence were received and considered. Based on this first round of consultation and interim engagement it was recommended that, for the project to be as cost-effective as possible and cause the least disruption, while still meeting the requirements of the UWWTD, the preferred scheme for the Thames Tideway Tunnel would need to involve: * the Abbey Mills route * a main tunnel long with an internal diameter of ; * direct interception of 21 CSOs; * indirect interception of a further 12, and a local solution for the remaining CSO; * selection of five out of 52 possible access shafts to be built including three to be combined with CSO interception; and * selection of seventeen out of 71 CSO alternate positionings from the final shortlist. The new preferred route and sites were then sent out for a second round of public consultation and feedback.

Phase 2 and targeted consultation

The second phase of consultation was carried out between November 2011 and February 2012 when local authorities, land owners, local businesses and communities were consulted on: * The need for the project and whether a tunnel was the most appropriate solution * The preferred tunnel route (including the detailed alignment of the tunnel) * Preferred sites and permanent works (taking into account the feedback received from the first phase of consultation such as the move from greenfield to brownfield sites) * Detailed proposals for the preferred sites (again taking into account feedback from the phase one consultation) * The effects the project would have (as outlined in the preliminary environmental information report) A total of 1,374 feedback forms (online and hard copy), 4,636 pieces of correspondence and nine petitions were received. Following this consultation, and taking into consideration all the feedback received, the proposed route was finalised as the Abbey Mills route and the preferred construction and drive sites were identified. Several sites were also identified as needing further, targeted consultation which resulted in further refinement and improvement of designs at those sites.

Site list and type

Thames Tideway construction site, Putney

* Acton Storm Tanks – main tunnel reception and CSO interception *

Hammersmith Hammersmith is a district of West London, England, southwest of Charing Cross. It is the administrative centre of the London Borough of Hammersmith and Fulham, and identified in the London Plan as one of 35 major centres in Greater London ...

pumping station – CSO interception and connection tunnel drive site *

Barn Elms Barn Elms is an open space in Barnes in the London Borough of Richmond upon Thames, located on the northerly loop of the River Thames between Barnes and Fulham. The WWT London Wetland Centre (105 acres of what were once reservoirs) li ...

– CSO interception and connection tunnel drive site * Putney Embankment foreshore – CSO interception and connection tunnel drive site * Carnwath Road riverside – main tunnel drive and reception and connection tunnel reception site * Dormay Street CSO- interception and connection tunnel drive site *

King George's Park King George's Park is a main park spanning Wandsworth and Southfields, South London. Summary The park was originally called Southfields Park and was laid out in 1922. It was officially opened by King George V in 1923. The park is about long, ...

– CSO and connection tunnel reception site * Falconbrook pumping station – CSO and connection tunnel drive site * Cremorne Wharf Depot – CSO interception and connection tunnel drive site *

Chelsea Embankment Chelsea Embankment is part of the Thames Embankment, a road and walkway along the north bank of the River Thames in central London, England. The western end of Chelsea Embankment, including a stretch of Cheyne Walk, is in the Royal Boroug ...

foreshore – CSO interception and connection tunnel drive site * Kirtling Street – main tunnel double drive site * Heathwall pumping station – CSO interception and connection tunnel drive site *

Albert Embankment Albert may refer to: Companies * Albert (supermarket), a supermarket chain in the Czech Republic * Albert Heijn, a supermarket chain in the Netherlands * Albert Market, a street market in The Gambia * Albert Productions, a record label * Alber ...

foreshore – CSO interception and connection tunnel drive site *

Victoria Embankment Victoria Embankment is part of the Thames Embankment, a road and river-walk along the north bank of the River Thames in London. It runs from the Palace of Westminster to Blackfriars Bridge in the City of London, and acts as a major thoroughfar ...

foreshore – CSO interception and connection tunnel drive site * Blackfriars Bridge foreshore – CSO interception site *

Shad Thames Shad Thames is a historic riverside street next to Tower Bridge in Bermondsey, London, England, and is also an informal name for the surrounding area. In the 19th century, the area included the largest warehouse complex in London. Location Th ...

pumping station – system modification site * Chambers Wharf – main tunnel drive and reception site * Earl pumping station – CSO interception site *

Deptford Deptford is an area on the south bank of the River Thames in southeast London, within the London Borough of Lewisham. It is named after a Ford (crossing), ford of the River Ravensbourne. From the mid 16th century to the late 19th it was home ...

Church Street – CSO interception site *

Greenwich Greenwich ( , ,) is a town in south-east London, England, within the ceremonial county of Greater London. It is situated east-southeast of Charing Cross. Greenwich is notable for its maritime history and for giving its name to the Greenwich ...

pumping station – CSO interception and connection tunnel drive site *

King Edward Memorial Park King Edward Memorial Park is a public open space in the London Borough of Tower Hamlets, on the northern bank of the River Thames. It was opened in 1922 in memory of King Edward VII. With an area of 3.3 hectares, it is the 11th largest par ...

– CSO interception site * Bekesbourne Street – system modification site * Abbey Mills pumping station – main tunnel reception site

Proposed design and construction

To build the Thames Tideway Tunnel, four

tunnel boring machine A tunnel boring machine (TBM), also known as a "mole", is a machine used to excavate tunnels with a circular cross section through a variety of soil and rock strata. They may also be used for microtunneling. They can be designed to bore thro ...

s (TBMs) were needed to excavate the main tunnel plus two others for smaller connection tunnels. It also required two types of construction sites: main tunnel sites, where the TBM was either launched or received, and CSO sites, where interception tunnels and a connection culvert were built to connect the existing sewer to the new tunnel. Construction of the shafts at the CSO sites, to transfer flows from the existing sewer to the tunnel, would vary depending on the depth, the amount of flow they need to carry and the geology. The shaft would be a concrete cylinder with an internal diameter of and deep. Ventilation structures at CSO sites to allow air in and out of the shaft were also required. Construction at these sites was expected to take between 2½ and 3½ years and once complete each site would be landscaped. At the main drive sites, four main activities took place: shaft construction (where a concrete cylinder in diameter and about deep was constructed), tunnelling preparations (preparing the site for arrival of the TBM), TBM assembly and lowering into the shaft, and then driving the TBM to excavate the main tunnel. As the TBM moved forward, precast concrete segments were brought in and fixed together to create the tunnel wall. Excavated material would be transported out the tunnel via a conveyor belt and processed before being taken off-site. In order to minimise disruption, Thames Water committed to use the river as much as possible to transport materials both in and out of the construction sites. At the main tunnelling sites, work was expected to occur 24 hours a day. In 2017, the public voted on a short-list of 17 to name the six TBMs. They were named after female pioneers of their fields linked to where each began to dig. One began tunnelling from

Fulham Fulham () is an area of the London Borough of Hammersmith & Fulham in West London, England, southwest of Charing Cross. It lies on the north bank of the River Thames, bordering Hammersmith, Kensington and Chelsea. The area faces Wandswor ...

in 2018, the Rachel Parsons, after the engineer and advocate for women's employment rights, who set up the first women-only engineering company in Fulham. The others were

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Audrey ‘Ursula’ Smith and

suffragist Suffrage, political franchise, or simply franchise, is the right to vote in public, political elections and referendums (although the term is sometimes used for any right to vote). In some languages, and occasionally in English, the right to v ...

Millicent Fawcett for the Central area and

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for the Frogmore Connection Tunnel from Wandsworth to Fulham. The TBM for the east section from Bermondsey was named after doctor Selina Fox who set up Bermondsey Medical Mission for Southwark's poor and disadvantaged residents. The machine for the Greenwich Connection Tunnel was named after Annie Scott Dill Russell, the first female scientist to work at the

Greenwich Observatory The Royal Observatory, Greenwich (ROG; known as the Old Royal Observatory from 1957 to 1998, when the working Royal Greenwich Observatory, RGO, temporarily moved south from Greenwich to Herstmonceux) is an observatory situated on a hill in G ...

Planning application

In October 2012, the deadline of the tunnels' Section 48 consultation closed. This lasted 12 weeks and was the last opportunity for the public to have their say on the updated proposal. The Application for Development Consentfor the final, detailed plan for the constructionwas delivered to the

Planning Inspectorate The Planning Inspectorate for England (sometimes referred to as PINS) is an executive agency of the Department for Levelling Up, Housing and Communities of the United Kingdom Government with responsibility for making decisions and providing r ...

on 28 February 2013. It included a relatively recent quite inaccurate study of Separation. The Inspectorate then had 28 days to decide whether the application was valid and whether the consultation undertaken was adequate. On 27 March 2013, it was decided that the application was valid and that Thames Water's consultation for the project had been adequate. All the application documents were made available in their own section of the Planning Inspectorate's National Infrastructure website. Thames Water also made the documents available for scrutiny at six public places along the route, three either side of the river. On 3 June 2013, it was announced that the Secretary of State for Communities and Local Government had appointed inspectors Jan Bessell, Libby Gawith, Emrys Parry, Andrew Phillipson and David Prentis as the examining authority to consider any matters arising. As part of this process, interested parties were able to make representations. A preliminary meeting, open to those who had registered an interest, began on 12 September 2013 at the

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. Chaired by the

, this determined how the examination would be carried out, including consideration of more detailed hearings on site-specific matters, as well as project-wide issues. While the inspectors gave a commitment to consider the alternatives to the tunnel, in the event they were not reviewed as part of the examination. Government legislation and the NPSWW required that all efforts be made to reduce carbon emissions in new projects, but the examiners did not manage to study this issue. Once the Inspectorate concluded its examination of the application, a recommendation on whether or not to issue a development consent order would be submitted to ministers to make the final decision.

Planning acceptance

On 12 September 2014, the UK Government approved the plans, overriding some of the findings of the Planning Inspectorate. The decision gave rise to at least three Judicial Reviews.

Funding and delivery

The budget for the scheme steadily increased since it was first estimated. For example, the budget in 2004 was estimated at £1.7bn, which included the East Ham to Stratford part and sewage treatment works upgrade costs. In the words of the

Consumer Council for Water The Consumer Council for Water (CCWater) is a non-departmental public body whose sponsor department is Defra. CCWater is independent of both the regulator, Ofwat, and the water companies. CCWater represents the interests of water and sewerage ...

in 2011:

"The estimated cost of the project has escalated, from £1.7bn in 2004 (including Stratford to East Ham part and sewage treatment civil engineering construction movements (STW) costs) to £2.2bn in 2007 (also including Lee Tunnel and STW costs) to £3.6bn now for the shorter Thames Tunnel as far as Abbey Mills, plus some £1bn for the Lee Tunnel and upgrade of works at Beckton. The total costs of all the Tideway schemes have therefore increased from £1.7bn six years ago to £4.6bn today (all costs at relevant year prices). There is no guarantee that the current estimate will not be subject to further escalation."

Less than a year later, in November 2011, a further £500 million was added to the estimate. Following detailed analysis it was decided that the best means to deliver the project would be through a regulated infrastructure provider (IP) as this would maximise value for money. The IP, originally to be formed through a competitive process starting in the spring of 2013, would hold its own license from the industry regulator,

, and would build, manage and maintain the tunnel. In January 2013, it was announced the IP was to be delayed because Thames Water as main funder sought state financial assurances. This was a polemic. Opponents argued the government should not bear any such risks; Thames Water have noted the government faced EU fines if the work was not done. In a letter to the ''Financial Times'' in November 2012, Sir

Ian Byatt Ian or Iain is a name of Scottish Gaelic origin, derived from the Hebrew given name (Yohanan, ') and corresponding to the English name John. The spelling Ian is an Anglicization of the Scottish Gaelic forename ''Iain''. It is a popular name in S ...

(former Director General of Ofwat) and politician Simon Hughes MP stated:

If Thames is unwilling to make a rights issue, the owners, Macquarie, should be expected to return funds to the utility. If they do not, Thames should go into special administration (allowing for continued service to customers) and another company or financier allowed to take over its activities.

However, procurement for main contractors (who would eventually be contracted to the IP) for up to three packages of work valued at around £500m each started in the summer of 2013. On 29 July, Thames Water announced that a contract notice for work on the tunnel had been published in the

Official Journal of the European Union An official is someone who holds an office (function or mandate, regardless whether it carries an actual working space with it) in an organization or government and participates in the exercise of authority, (either their own or that of their su ...

(OJEU). Following prequalification questionnaires, Thames Water invited shortlisted contractors to tender between November 2013 and April 2014. The successful contractors for the three main tunnelling contracts were announced in February 2015: *West: Joint venture of

BAM Nuttall BAM Nuttall Limited (formerly known as Edmund Nuttall Limited) is a construction and civil engineering company headquartered in Camberley, United Kingdom. It has been involved in a portfolio of road, rail, nuclear, and other major projects worldw ...

, Morgan Sindall and Balfour Beatty Group *Central: Joint venture of Ferrovial Agroman UK and Laing O'Rourke Construction *East: Joint venture of

Costain Costain is a surname of English, Scottish and Manx origin. When originating in Scotland and northern Ireland the surname is an Anglicisation of the Gaelic ''Mac Austain'', meaning "son of ''Austin''". The English surname is a reduced form of '' ...

, Vinci Construction Grands Projets and Bachy Soletanche In August 2015, the independent investors to finance and deliver the scheme were confirmed. Bazalgette Tunnel Limited, a new special-purpose company appointed to take the project forward, received its licence from Ofwat as a new regulated utilities business, separate from Thames Water. The special-purpose company is backed by pension funds and other long-term investors represented by

, Amber Infrastructure Group, Dalmore Capital and DIF. The funding scheme used was later called the Regulated Asset Base (RAB) model, and be used in the nuclear industry. If the cost overruns by more that 30%, the government would have to provide additional equity finance.

Planned timeline

*2014: Planning decisions and approval *2015: Main works and financing contracts awarded *2016: Primary work completed; Main works preliminary construction begins *2018: Tunnelling begins *2019: Secondary lining begins *2022: Tunnelling ends *2024: All works completed (now scheduled for 2025). In August 2020, during the

, a project lockdown and revised working practices meant the project was delayed by nine months and had incurred additional costs of £233m (taking the estimated project cost to £4.133bn). Completion was targeted for the first half of 2025.

Controversy

Since the initial proposal, questions focussed on the cost, the location of construction sites, duration, disruption, and whether a tunnel was the correct solution for London and for Thames Water customers. ''Cost and reward to the business owners'' The £4.3bn cost of the Thames Tideway Tunnel project is to be funded by

customers. This has angered customers who dispute an accounting practice confirmed by the industry regulator.

confirmed the extent of leveraging on the balance sheet, reducing tax due and allowing annual payouts of fairly typical levels of dividendsmoney some customers feel should have cut the cost of the scheme. Thames Water maintains it has done nothing unusual by making tax-deductible investments in the natural and proper domain of its business which reduces tax; this is conventional practice. It explains the money raised was used for essential maintenance and upgrade works. The earliest customers’ bills would be affected was 2014–15, with charges rising gradually after that. The project was estimated to add up to £70 to £80 (excluding inflation) to average annual wastewater bills from around 2019. However, these figures were subsequently revised downwards. In August 2015, the impact was expected to be around £20 to £25 per year by the mid-2020s. ''Disruption'' Some people who live alongside proposed sites were concerned about the noise, disruption and potential loss of public space resulting from construction. To address this Thames Water put together a Code of Construction Practice to outline site-specific and project-wide requirements and measures to minimise the impacts of the construction and ensure that best practice standards and requirements across all sites and contracts. The Code also covered transport (both road and river transport), noise and vibration mitigation, air quality and water resources, land quality, waste management and resource use, ecology and conservation and historic environment. In the report that concluded its inspection of these documents, the

found that Thames Water had "underestimated of impacts on those that have been identified as having a significant effect and underestimated the number of receptors experiencing a significant effect" (12.97) and concluded "We do not consider that hames Water'sproposals meet the first aim of the NPS test to avoid significant adverse impacts on health and quality of life from noise" (12.357). ''The need for a tunnel'' Some people prefer an option that Thames Water's studies show would be up to three times more expensive. This is a sustainable urban drainage system (SUDS) under Central London streets and open spaces with small pumping stations in places of low gradient. They outline the added benefits of building

green infrastructure Green infrastructure or blue-green infrastructure refers to a network that provides the “ingredients” for solving urban and climatic challenges by building with nature.Hiltrud Pötz & Pierre Bleuze (2011). Urban green-blue grids for sustainab ...

, particularly uncovering streams and rivers in some places in inner London Boroughs where they were culverted in the past. Their most progressive arguments are for replacing paved, impermeable surfaces in London with

permeable Permeability, permeable, and semipermeable may refer to: Chemistry *Semipermeable membrane, a membrane which will allow certain molecules or ions to pass through it by diffusion *Vascular permeability, the movement of fluids and molecules betwe ...

options and implementing

green roof A green roof or living roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and draina ...

s, swales and water butts to promote the infiltration of rain-water, preventing it from reaching the combined sewer system, thus reducing peak flows and limiting the number of CSO overflows. Some of these advocates denounce Thames Water's 2011 five theoretical case studies of the solution (finding the threefold cost), citing householders' assistance such as emptying water butts, gardening more, and not using land for parking, and say this could be the cheapest option. Green infrastructure would have further benefits for London in addition to addressing the rainwater overflow problem, such as: # Increased resilience to drought and floods, # Reduction in urban

air pollution Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different type ...

, #

Climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

mitigation – contrasted to the tunnel's significant

carbon footprint A carbon footprint is the total greenhouse gas (GHG) emissions caused by an individual, event, organization, service, place or product, expressed as carbon dioxide equivalent (CO2e). Greenhouse gases, including the carbon-containing gases carbo ...

, # Enjoyment, aesthetics and health benefits of green spaces and nature, # Reduced

urban heat island An urban heat island (UHI) is an urban or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. The temperature difference is usually larger at night than during the day, and is most apparent ...

effects with an associated reduction in cooling load and carbon emissions, # Improved urban

biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic ('' genetic variability''), species ('' species diversity''), and ecosystem ('' ecosystem diversity'') ...

. # Earlier avoidance of EU fines for not meeting water standards than under the scheme. ''Continued overflows forecast'' The annual number of CSO discharges is set to fall from average of 60 a year to under five. The Environment Agency is satisfied predicted Tideway water quality after such discharges will be acceptable. When both the tunnels are operational, the overflows occur after sustained periods of intense rainfall and after the tunnels have captured the most damaging ‘first flush’ from the foul sewers. The remaining total overflow is an average of 2.6 million cubic metres per year, on 2011 estimates.

References

External links

* {{Major Development Projects in London, state=collapsed London water infrastructure Proposed infrastructure in London Proposed tunnels in the United Kingdom Thames Water Tunnelling organizations 2024 in the United Kingdom 2020s in London 2020s architecture Nationally Significant Infrastructure Projects (United Kingdom)