Feasibility Study for the Thames Tideway Tunnel Project
Introduction
The length of the Thames Tideway Tunnel is 16 miles (25km). A significant section of this length is underneath the River Thames tidal section, which is located in central London. The reason for this tunnel’s construction is the collection, storage, and conveyance of close to the entire collection of rainwater as well as raw sewage that overflows into the Thames River currently. November 3, 2015, marked the day when the Bazalgette Tunnel Limited (BTL) got the go-ahead to be in charge of the tunnel’s construction and maintenance. The company, also called Tideway, was also to oversee the tunnel project’s funding and operation (Jacobs 2016). This company consisted of four investors, namely Dalmore Capital, DIF, Allianz, and Amber Infrastructure. The tunnel’s construction took off in 2016. The project planners expected the project to go for approximately 7 or 8 years. On completion of this project, it is estimated that the primary tunnel’s internal diameter would be about 24 feet. This primary tunnel would commence at -30 meters to -70 meters from west London to Abbey’s Mills east London, respectively, stretching through central London over a length of over 25 km.
In this project, transfer tunnels will be instrumental in linking 24 CSOs that are considered to be among the most contaminated in the city. This linkage is expected to inhibit the number of times that overflowing occurs. This inhibiting would see this number of overflows reduced to four annually on the high side per CSO during commissioning. Notably, factors such as climatic changes and population increase in the city would eventually see this number rising gradually. The sewage that the tunnels collect would end up in the main tunnel, and it flows from Stratford to the East Ham region, where there is a Sewage Treatment Works at Beckton. When the sewage gets to this treatment plant, it undergoes treatment and then discharged into the Thames River (Jacobs, 2016). According to projections, the aggregate cost of capital that the project would require up until completion would be roughly £3.8 billion, plus a top-up of £1.1 billion for the project’s preparations. Notably, this estimate does not include the expenses that the company would incur during operations and project maintenance and financing.
This paper is a report on a feasibility study conducted on the Thames Tideway Tunnel project. The report will include a description of the project, a problem statement, and an explanation of the need for this project. It will also cover a feasibility analysis in terms of economics, technology, legal considerations, and operations. Finally, there will be a discussion of possible alternatives to solving the problem and a conclusion.
Problem Statement
There has been a high level of pollution of the UK’s Thames River among other rivers, stemming from combined sewer overflows (CSOs) as well as runoffs.
CSO pollution: Surface rainwater, industrial and household wastewater, and other forms of spillages collects in a drainage pipe and flows through a combined sewer system and ultimately discharges into a site for sewage treatment. Notably, if the volume of this flow is too high for the pipe, it could cause flooding in the streets and households. Consequently, as per the system’s design, any excess water caused by intense storms as well as discharges prompts discharge of this excess water directly into the river, thereby preventing flooding.
However, this flooding prevention causes pollution in the river. Notably, rainwater mixes with wastewater from households (sewage) and industries in these combined sewers. This mixture then goes into a sizeable interceptor sewer. The idea is for this water to stay on-site for treatment before discharge into the river. However, should the mixed water exceed the interceptor’s capacity, there is an allowance for the excess water to get into an alternative pipe where the pipe directs the water into the river. Therefore, the excess water foregoes treatment, thereby directly carrying pollutants such as metals, EDPs, and nutrients into the river (Jacobs, 2016). According to the PAEC and Water Framework Directive (DEFRA, 2002, p.2), excessive amounts of these pollutants result in eutrophication, drinking water contamination, and damage to the river’s biota.
Runoffs: Stormwater causes runoffs that pollute UK rivers with about 300 pollutant forms. Rivers are exposed, and runoff water from different surfaces can flow directly into them. Notably, most urban areas have insulated surfaces with concrete, among other materials. This insulation facilitates increased rain or stormwater runoffs that enter the rivers (Thames21, 2019). These surface runoffs also carry various forms of pollutants from these surfaces and take them into the river. Therefore, increased surface runoffs equate increased pollutants to the river. Some of the pollutants on urban surfaces include heavy metals such as zinc and lead. Some reports have linked these metal pollutants detected in the Parisian rivers to runoffs and storms (European Commission, 2019, p.14, 31). In other instances, runoffs get into the Thames River directly from roads and agricultural fields. Notably, agriculture involves using fertilizers that are known to have high nitrate and phosphate concentration levels. Reports indicate that 50% of UK rivers’ phosphate deposits come from agricultural fields’ runoffs. Therefore, UK rivers water falls short of the Water Framework Directive of the EU’s good quality standards (DEFRA, 2002, p.2).
Both of these methods of pollution produce either organic (organic carbon and phosphorus from animal manure, food wastes, chemicals from households and pharmaceuticals, polychlorinated biphenyls, and contraceptive pills) or inorganic (heavy metals like chromium, mercury, and cadmium, solid waste, chemicals, inorganic nutrients with nitrates and phosphates) pollutants (European Commission, 2001, p.16-18). All these pollutants have various consequences. For instance, inorganic pollutants can cause eutrophication, which has adverse effects on the river’s biota and thereby having economic implications on humans (European Environment Agency, 2013, p.81, 88). Synthetic organic pollutants have been known to influence fish stock behavior as well as phenotypes (Kidd et al., 2014, p.8898; Aris, Shamsuddin, & Praveens, 2014, p.108). Therefore, reproduction levels of different fish species face a negative impact from these pollutants, which can be a problem for humans as it is a source of food (Aris, Shamsuddin, & Praveena, 2014, p.110). There will be less food, and the fish would also have harmful metals that humans can ingest and cause health problems (European Environmental Agency, 2013; Lindqvist, Tuhkanen, and Kronberg, 2005, p.2225).
Need for the Project
London’s sewerage system’s construction occurred in 1859 and 1865 under Sir Joseph Bazalgette. The target then was to serve a 4 million resident capacity as well as runoff from rain and stormwater. The process’s first cycle gathers water from rain and sewage, then takes it to a lower level interceptor sewerage. This interceptor has a flat tube that directs water into the river as the interceptor fills up. This process served as a failsafe approach for sewage accumulation prevention so as not to food homes. There were 57 CSOs along the banks of the Thames River to facilitate overflowing into the river from over 50 cities across London (Jacobs, 2016). However, by 2012, London reported an approximate population of about 8 million, rendering the system incapable of serving the city (Jacobs, 2016). The city kept growing through the 19th and 20th centuries, which necessitated the development of separate sewage and rainwater infrastructure for the outer suburbs. Overflowing persisted in the early years of the 21st century with an annual average of 50 times. These CSOs inhibited the sewage system to accepting the daily dry weather flow (DWF) up to six times only, with only half the capacity undergoing treatment. The remaining capacity went to storage in storm tanks for sedimentation or precipitation before being released to the river. This situation implied annual raw sewage and rainwater drainage of roughly 39,000,000 m3 into the Thames River. Consequently, discharge reduction became necessary for better river ecology. In effect, this tunnel project purposes of minimizing sewage discharge by approximately 94% to a maximum of four (Jacobs, 2016). As such, the tunnel is designed to intercept the lower sewage of the city before it enters the river to prevent pollution from untreated sewage. Expectations for this project is that it will serve the city’s residents for the next century.
Feasibility Analysis
A feasibility study is important for any project to establish its viability before investing any funds in the project. It discusses the project’s suitability, the anticipated costs, and other available alternatives (Thompson 2). Therefore, it is usually conducted before a project starts. However, in this case, the Thames Tideway Tunnel project is already in progress, due for completion in 2024. These topics will be discussed under economic, technical, legal, and operational feasibility, and alternative solutions sections.
Economic Feasibility
A project is considered to be economically feasible if its expected benefits surpass its costs. A cost-benefit analysis is used in determining a project’s economic feasibility. During the planning phase, estimations of capital requirements for the project stood at roughly £3.8 billion, plus a top-up of £1.1 billion for the project’s preparations. This calculation brought a total of £4.9 billion. According to Ofwat, the approximate bill for each household (for wastewater and water) stood at £370 annually before inflation (Department of Environment, Food, and Rural Affairs 15). This rate was to remain until 2020 in the least. The number of households that the project was to serve was about 820,000. Therefore, the revenue per year from this project would be £303,400,000. However, after 2020, the amount per household in bills was to increase by roughly 15% to come to £425.5 (Department of Environment, Food, and Rural Affairs 15). Therefore, the annual bill for households stands at £348,910,000. These figures imply that the debt of the project, which has private funding, would be repaid in 14 years. However, this period could be shorter if commercial properties are considered in terms of bill payment. Nevertheless, the repayment period is quite long. It is worth noting that as the years go by, the population of the city is continuously increasing, and the changes in climatic conditions could also contribute to increased overflows and runoffs. Therefore, the chances are that by the time the debt would have been repaid, the system might already be getting overwhelmed. Thus, there would be a need for a new project to rescue the situation. There will be a need to take on new debt to fund this new project. Therefore, the tunnel project might not be economically feasible.
Technical Feasibility
Technical feasibility has to do with an assessment of the availability of the required technology and resources. Notably, the project had delivery partners from the west, east, and central London to ensure the completion of this project. From the west, Bam Nuttall, Balfour Beatty Group, and Morgan Sindall participated in the project. From the East, there was Costain, Bachy Soletanche, and Vinci Construction Grands Projects (Tideway). All these brands are engineering and construction companies that deal with geotechnical innovation and development, building design and construction, mobility solutions, and infrastructure development. Notably, the Thames Tideway Tunnel project involves digging an underground tunnel for drainage, which makes it an engineering project. Therefore, it is safe to conclude that the project will have all the required resources and equipment to complete the task based on its partnership with various companies in the engineering and construction sector.
Additionally, Amey is another delivery partner as a systems integrator, whose responsibility is the provision of communication equipment, process control, and software systems that would be employed in operations, maintenance, and reporting across the tunnel’s system (Tideway). Therefore, the project’s technological requirements will also be met. In terms of labor for the project, the partner companies are among the largest contractors of employers in the city, with Ban Nuttall alone contracting about 20,000 workers globally. Therefore there will be sufficient skilled labor supply for the project. availability of labor and all equipment and technology necessary for the project makes the project technically feasible.
Legal Considerations
Legal feasibility entails an assessment of liabilities, contracts, violations, as well as any other legal traps that the technical staff could identify. Notably, the European Commission started proceedings against the UK in 2004, for breach of the EU Urban Waste Water Treatment Directive (Global Infrastructure Hub). This directive requires that any discharge that enters into waterways such as lakes, seas, or rivers has to be treated. As earlier stated, London’s population has increased since the construction of the first tunnel, and now there was pressure on the existing tunnel system to serve the city’s residents regarding industrial and household wastewater and sewage. Climate change has also caused different weather patterns over the years, prompting more intense storms and heavy rains for increased surface runoffs. The result was discharging excess water to the Thames River without treatment to avoid flooding, but this act caused the river’s pollution. This project would solve this problem for the UK, and the government supported the project as a solution to this problem (Global Infrastructure Hub). Therefore, the project is legally feasible.
Operational Feasibility
Operational feasibility involves the determination of the likelihood that the project will be used following its development and implementation. For instance, it assesses the chances of resistance from the public that could negatively affect the application benefits. Notably, there have been increasing health concerns resulting from the consumption of contaminated water and food. In this case, contamination is affecting the river water as well as the biota in the river. Such biota includes fish, which is food for humans. Pollution makes it possible for humans to ingest heavy inorganic metals accumulated in the river’s biota, such as lead and arsenic. Such metals can navigate the food web from the river’s biota to reach humans (Heberer, 2002, p.11). Some human consequences of high exposure to such metals (such as lead) could be cardiovascular and neurological complications or ailments as well as mental problems. Thames River’s outward section has mussels with a 2 jig/g lead accumulation, an amount that is double the stipulated limit. On the other hand, the inner section has worms and clams containing a stipulated 10-35 jig/g value. Notably, research bodies have shown that amount exceeding 5 jig/g in concentration is termed as hazardous (European Environmental Agency, 2013). Lead does not break down easily. Predators can retain 45% of metals from ingested prey (Lindqvist, Tuhkanen, and Kronberg, 2005, p.2225). Therefore, it is easy for animals and humans to ingest these metals that can be harmful to their health. The Counters Creek region located in West London has also been having problems with flooding, and this project could help in addressing this problem (Department of Environment, Food, and Rural Affairs, 2015, p.11). Such concerns have made the project welcome to the residents of London.
Moreover, the project managers brought the public on board before commencing the project. There was a twelve-week allowance for the public to front their opinion on the project, and this period ended in October 2012 (Global Infrastructure Hub). There was also a consultation between the relevant authorities and Thames Water for feedback from stakeholders that the construction would possibly affect. The feedback sought was concerning possible construction sites and proposed tunnel passages. There was an agreement between all the stakeholders and the company before the construction began. Therefore, there would be no reason for any resistance to the project. Therefore, the involvement of all relevant parties and the increasing health concerns make the project operationally feasible.
Alternative Solutions
An alternative to the pollution issue from overflowing could be the Sustainable Urban Drainage Systems (SuDS). Sustainable urban drainage systems refer to the management of surface water with the consideration of water quantity or flooding. Other factors of consideration in SuDS include wildlife and plant biodiversity, water pollution, as well as involved amenities (Thames21, 2019). SuDS utilizes techniques aimed at capturing, usage, absorption, or delaying of rainwater. Usually, people perceive this rainwater as a problem and reject it. Source control is one of the SuDS’s approaches for reducing the water volume that joins the river’s network. The method achieves this objective by intercepting rooftop runoff water for storage. This stored water can be used in the future. It can also be used in subsequent evapotranspiration (in green roofs) or for irrigation.
Another approach is pre-treatment, which includes swales or vegetated ditches (in wales) as well as filter trenches. This approach clears surface water of any waste products before joining the river. There is also the retention approach, which delays surface water discharge into water systems. This approach entails the introduction of retention basins, ponds, and wetlands as storage spaces (Thames21, 2019). Conversely, infiltration as an approach allows the permeation of water to the ground using techniques such as infiltration trenches and soakaways.
This solution would be appropriate for London’s problem since most of this city’s pollution stems from CSOs and runoffs. SuDS can be instrumental in entrapping solid waste present in surface water in before joining waterways. Additionally, it mitigates nutrients (nitrate and phosphate) and contaminants from heavy metals from entry into waterways through runoff delay. The technique achieves this objective by restricting the water volume that enters rivers as well as through retention systems. As a result, infiltration and source control techniques facilitate re-entry of nutrients to the ground as opposed to joining waterways as pollutants. Moreover, as the population increases in the future, there will be increasing pressure on the system’s capacity as well (Thames21, 2019). Projections from studies show that London’s population will reach 10 million by 2030, implying a likely need for another tunnel. Therefore, SuDS could be a better alternative to the pollution and flooding problem in London as opposed to the Thames Tideway Tunnel project.
Conclusion
The Thames Tideway Tunnel project aims to address the problem of pollution and flooding in London. The project commenced in 2015 and is expected to come to completion in 2024. The population of London has been increasing over the years, causing increased wastewater from households and even enterprises. Climatic changes have also caused changes in rain patterns, causing intense storms that intensify surface runoffs. These factors created a pollution and flooding problem, hence the idea of the tideway tunnel. Various companies are partnering in this project, thereby ensuring that all requirements and resources for the project will be available. The relevant stakeholders were also involved in the project planning. Therefore there are high operational feasibility chances. The project is also addressing a problem that the UK faces legally with the EU, thus making the project legally feasible. However, the economic implications suggest that the project might not be viable, especially since there is the alternative of SuDS that is more sustainable as a solution to the same problem. Problems of population increase cannot be stopped. Therefore the tunnel might need modification in the future again. It would be better to invest in a more sustainable option such as SuDS for higher economic benefits.
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