Thames Water Research Articles

Earthquake damage mitigation methods for buried pipelines under compressive loads: A case study of the Thames water pipeline

Promoting tensile failure by providing a proper orientation angle between the pipe axis and the fault line is the main seismic design philosophy for buried steel pipelines. However, most of the severe damage and failures experienced by pipelines are mainly due to negative crossing angle and thus compressive loads acting along the pipeline. This paper investigates different earthquake damage mitigation methods such as Carbon Fiber Reinforced Polymer (CFRP) wrapped pipes, Steel Pipes for Fault Crossing (SPF), and corrugated pipes for buried steel pipelines which are mainly subjected to compressive loads. Therefore, the Thames water transmission pipeline, which is a well-known case study, that suffered major and minor damage due to compressive forces in the 1999 Kocaeli earthquake, is considered to simulate and compare the earthquake damage mitigation capabilities of these countermeasures. The numerical studies are performed by using a three-dimensional nonlinear finite element model. The results show that the use of CFRP composites in buried pipelines, regardless of their thickness, wrapping length, or layer orientation, does not have the expected damage reduction effect, but does increase the effective length between major wrinkles or change the type of pipe failure. On the other hand, SPFs and corrugated pipes are more effective in earthquake damage reduction due to their high axial and rotational capabilities.

Analysis of faulting destruction and water supply pipeline damage from the first mainshock of the February 6, 2023 Türkiye earthquake doublet

In 2023, two consecutive earthquakes exceeding a magnitude of 7 occurred in Türkiye, causing severe casualties and economic losses. The damage to critical urban infrastructure and building structures, including highways, railroads, and water supply pipelines, was particularly severe in areas where these structures intersected the seismogenic fault. Critical infrastructure projects that traverse active faults are susceptible to the influence of fault movement, pulse velocity, and ground motions. In this study, we used a unique approach to analyze the acceleration records obtained from the seismic station array (9 strong ground motion stations) located along the East Anatolian Fault (the seismogenic fault of the MW7.8 mainshock of the 2023 Türkiye earthquake doublet). The acceleration records were filtered and integrated to obtain the velocity and displacement time histories. We used the results of an on-site investigation, jointly conducted by China Earthquake Administration and Türkiye’s AFAD, to analyze the distribution of PGA, PGV, and PGD recorded by the strong motion array of the East Anatolian Fault. We found that the maximum horizontal PGA in this earthquake was 3.0 g, and the maximum co-seismic surface displacement caused by the East Anatolian Fault rupture was 6.50 m. As the fault rupture propagated southwest, the velocity pulse caused by the directional effect of the rupture increased gradually, with the maximum PGA reaching 162.3 cm/s. We also discussed the seismic safety of critical infrastructure projects traversing active faults, using two case studies of water supply pipelines in Türkiye that were damaged by earthquakes. We used a three-dimensional finite element model of the PE (polyethylene) water pipeline at the Islahiye State Hospital and fault displacement observations obtained through on-site investigation to analyze pipeline failure mechanisms. We further investigated the effect of the fault-crossing angle on seismic safety of a pipeline, based on our analysis and the failure performance of the large-diameter Thames Water pipeline during the 1999 Kocaeli earthquake. The seismic method of buried pipelines crossing the fault was summarized.

Financial Indicators of Sustainable and Financialised Municipal Water Infrastructure

Organisations that operate utility infrastructure, such as water and electricity, within the municipal context have choices to make in terms of their preferred business model. Such choices include their business goal, implementing agent, and market structure. This study focuses on two of the possible business goals, namely to deliver a ‘sustainable service’ or a ‘financialised service’, defining these terms and exploring the general characteristics of the types of organisations involved in each, such as ownership profiles and exposure to financial market instruments. The study then goes into detail for two relevant case studies, which are Joburg Water, South Africa as a sustainable service, and Thames Water Utilities, England, as a financialised service. It takes a closer look at ten specific financial indicators calculated from the 2021/22 financial statements of Joburg Water and Thames Water Utilities. The study concludes with a tentative proposal for the financial indicators of sustainable and financialised services.

Evaluating the transmission risk of SARS-CoV-2 from sewage pollution

The presence of SARS-CoV-2 in untreated sewage has been confirmed in many countries but its incidence and infection risk in contaminated waters is poorly understood. The River Thames in the UK receives untreated sewage from 57 Combined Sewer Overflows (CSOs), with many discharging dozens of times per year. This study investigated if such discharges provide a pathway for environmental transmission of SARS-CoV-2. Samples of wastewater, surface water, and sediment collected close to six CSOs on the River Thames were assayed over eight months for SARS-CoV-2 RNA and infectious virus. Bivalves were also sampled as an indicator species of viral bioaccumulation. Sediment and water samples from the Danube and Sava rivers in Serbia, where raw sewage is also discharged in high volumes, were assayed as a positive control. No evidence of SARS-CoV-2 RNA or infectious virus was found in UK samples, in contrast to RNA positive samples from Serbia. Furthermore, this study shows that infectious SARS-CoV-2 inoculum is stable in Thames water and sediment for <3 days, while SARS-CoV-2 RNA is detectable for at least seven days. This indicates that dilution of wastewater likely limits environmental transmission, and that detection of viral RNA alone is not an indication of pathogen spillover.

Water Resource Systems Analysis for Water Scarcity Management: The Thames Water Case Study

Optimisation tools are a practical solution to problems involving the complex and interdependent constituents of water resource systems and offer the opportunity to engage with practitioners as an integral part of the optimisation process. A multiobjective genetic algorithm is employed in conjunction with a detailed water resource model to optimise the “Lower Thames Control Diagram”, a set of control curves subject to a large number of constraints. The Diagram is used to regulate abstraction of water for the public drinking water supply for London, UK, and to maintain downstream environmental and navigational flows. The optimisation is undertaken with the aim of increasing the amount of water that can be supplied (deployable output) through solely operational changes. A significant improvement of 33 Ml/day (1% or £59.4 million of equivalent investment in alternative resources) of deployable output was achieved through the optimisation, improving the performance of the system whilst maintaining the level of service constraints without negatively impacting on the amount of water released downstream. A further 0.2% (£11.9 million equivalent) was found to be realisable through an additional low-cost intervention. A more realistic comparison of solutions indicated even larger savings for the utility, as the baseline solution did not satisfy the basic problem constraints. The optimised configuration of the Lower Thames Control Diagram was adopted by the water utility and the environmental regulators and is currently in use.

London's river of plastic: High levels of microplastics in the Thames water column

This opportunistic study focussed on the quantification of microplastics in the River Thames water column, the catchment responsible for draining Greater London. Two sites on the tidal Thames were sampled; one upstream of the City of London at Putney, and the other downstream at Greenwich. Water column samples were collected from June through to October 2017, being taken on the ebb and flood tides, at the surface and a depth of 2 m. Microplastics (excluding microfibres) were identified to test whether the load varied between the two sites in relation to tide, depth and season. Secondary microplastics, films and fragments, contributed 93.5% of all those found at Putney and Greenwich. Site, tide, depth and month affected density, with the combined interaction of month and site found to have the greatest influence on microplastics. Fourier Transform Infrared Spectroscopy analysis showed that polyethylene and polypropylene were the most common polymers collected from the River, suggesting broken down packaging was the primary source of microplastics in these samples. Excluding microfibres, the estimate of microplastics in the water column was 24.8 per m3 at Putney and 14.2 per m3 at Greenwich. These levels are comparable to some of the highest recorded in the world.

Antibiotic selective pressure in microcosms: Pollution influences the persistence of multidrug resistant Shigella flexneri 2a YSH6000 strain in polluted river water samples

Abstract Some urban rivers reach dangerous concentrations of residual antibiotics imposing a certain level of selective pressure on microorganisms to develop various antibiotic resistance mechanisms. In the current work, we have measured the persistence and growth of a multidrug resistant strain of Shigella flexneri 2a YSH6000 under a mock release of lethal concentration of oxytetracycline in microcosms of River Thames water. The water was sampled from upstream (lower levels of pollution) and downstream (higher levels of pollution) of London city centre. In our in-vitro microcosms, in the presence of 160 μ g/mL of oxytetracycline, growth of S. flexneri in the downstream sector was up to 2 log(cfu/mL) higher relative to the upstream sector. This difference in growth is a sum of undefined interactions of different chemicals with the antibiotic. We extrapolated the contribution of two abundant pollutants in downstream sector: iron and phenanthrene. In the presence of selection pressure, iron at a concentration of 6.49 mg/L was found to foster the growth of resistant bacteria while phenanthrene at concentration of 160 μ g/L reduced the growth of the resistant strain. In addition, label free proteomics analysis showed that there are 64 proteins that were differentially expressed by the bacteria exposed to the upstream section versus the downstream sector. In the presence of oxytetracycline, at concentration of 160 μ g/mL, the differences reduced to only a few proteins, demonstrating that environmental stress impacts protein synthesis. Such mock studies contribute to our knowledge of chemicals that reduce growth of resistant strains and aids in the identification of selective biomarkers.

Priority setting for invasive species management by the water industry

The expansion of Invasive Alien Species (IAS) is a growing concern to the UK water industry because of their diverse impacts on water quality, infrastructure and eradication costs. New regulations reinforcing the industry’s responsibilities beyond operational costs, coupled with continued range expansion and establishment of new IAS will increase damages. To tackle IAS effectively, the water industry requires reliable information about which species pose the greatest risk to operations and which areas are most vulnerable to invasion. Here we assess potential biosecurity threats for the 24 water companies in the UK using well-established modelling research techniques such as risk assessment and distribution modelling. Using a consensus approach with environmental managers and water companies, we identified 11 IAS of concern for the UK water industry, including five plants, three crustaceans, two molluscs and one fish. These invaders pose important hazards in terms of water quality, flood protection, human health, integrity of infrastructures, recreational and aesthetic values, amongst others. We used distribution models to predict their potential expansion under current and future 2050 climate scenarios within each of the 24 water companies in the UK. Water companies in the South East of England (Cambridge Water, Anglian Water, Affinity Water and Thames Water) are under the highest risk of invasional meltdown from multiple IAS, both now and under future scenarios. The quagga mussel poses the most serious risk of immediate spread and may exacerbate the impacts of the widespread zebra mussel for the water industry. The information generated in this study can support the prioritization of species and regions at risk, so that funds for prevention and eradication of invasions are well allocated. Ultimately, this study demonstrates that scientific risk assessments, usually restricted to the academic and public sectors, can be extremely useful to guide decision-making by the private sector.

An Analysis of Electricity Consumption Patterns in the Water and Wastewater Sectors in South East England, UK

The water and wastewater sectors of England and Wales (E&amp;W) are energy-intensive. Although E&amp;W’s water sector is of international interest, in particular due to the early experience with privatisation, for the time being, few published data on energy usage exist. We analysed telemetry energy-use data from Thames Water Utilities Ltd. (TWUL), the largest water and wastewater company in the UK, which serves one of the largest mega-cities in the world, London. In our analysis, we: (1) break down energy use into their components; (2) present a statistical approach to handling seasonal and random cycles in data; and (3) derive energy-intensity (kWh m−3) metrics and compare them with other regions in the world. We show that electricity use in the sector grew by around 10.8 ± 0.4% year−1 as the utility coped with growing demands and stormwater flooding. The energy-intensity of water services in each of the utility’s service zone was measured in the range 0.46–0.92 kWh m−3. Plans to improve the efficiency of the system could yield benefits in lower energy-intensity, but the overall energy saving would be temporary as external pressures from population and climate change are driving up water and energy use.

Characterisation and energy assessment of fats, oils and greases (FOG) waste at catchment level

Several of the waste materials that have a negative impact on the sewer system are produced by fats, oils and greases (FOG) discharged from commercial and domestic kitchens. These materials accumulate at different points in the sewer catchment, from kitchens to pumping stations, sewers and sewage treatment works (STWs), and comprise oily wastewater, floating agglomerates and hard deposits. Despite their detrimental effects, these waste materials have a high calorific content and are an ideal feedstock for energy recovery processes. So far, the overall volume of each type of waste and their physical-chemical properties in relation to their collection point are unknown. However, from a management point of view, knowledge on each feedstock quality and volumes is necessary to develop an economic viable solution for their collection and for energy recovery purposes. In this study, FOG wastes collected from households, food service establishments (FSEs), sewage pumping stations, sewers and STWs, were compared to sewage sludge in terms of organic contents and energy potentials. As expected, FOG recovered at source (households and FSEs) were ‘cleaner’ and had a higher energy content. Once mixed with wastewater the materials changed in composition and lost some of their energy per unit mass. Our results showed that around 94,730 tonnes.year−1 of these materials could be recovered from the Thames Water Utilities’ catchment, one of the most populated in the UK. These materials could produce up to 222 GWh.year−1 as biogas, close to double of what is produced with sewage sludge digestion and around 19% of the company energy needs. Finally, even with over six million households in the catchment, the results showed that most of the FOG waste was produced by FSEs (over 48,000 premises) with an estimated average of 79,810 tonnes.year−1 compared to 14,920 tonnes.year−1 from private households. This is an important outcome as recovery from FSEs will be cheaper and easier if the company decides to implement a collection system for energy recovery.

A catchment partnership approach to delivering natural flood management in the Evenlode, UK

Adapting to climate change and its impacts on water resources is one of the major challenges facing the UK. In the first scheme of its kind in the Thames basin, this paper describes how natural flood management (NFM) is being piloted in the Littlestock Brook tributary of the Evenlode catchment. This 5-year scheme (2016–2021) explores the delivery mechanisms and assesses the effectiveness of NFM measures to reduce flood risk in Milton-under-Wychwood, improve water quality and create habitat. It has secured £640 000 from Environment Agency programmes, the Thames Regional Flood and Coastal Committee, other partners and landowners. In 2018, ten field corner bunds were created with a combined storage capacity of 26 000 m3. Woody dams in the brook divert high flows into these flood storage areas. Critical to success is integrated delivery through the Evenlode Catchment Partnership and engagement of the local community. Catchment partnerships deliver a range of environmental, social and economic benefits, and directly support many of the ambitions under the government’s 25-Year Environment Plan and the Water Framework Directive. Collaborative working with Thames Water, the Department for Environment, Food and Rural Affairs, consultants and academics has enabled the project to utilise existing delivery mechanisms and to model and monitor the effectiveness of NFM.

Hydrogen sulphide and VOC removal in biotrickling filters: Comparison of data from a full-scale, low-emission unit with kinetic models

In this paper, data is published on the removal of H2S and VOCs by a biotrickling filter (BTF) demonstration plant, namely a SULPHUS™, which was installed by Thames Water in late 2015. These data, along with some data already published by Sempere et al. (2018), were compared to the predictions of a number of existing and novel models for the removal of a single pollutant by a biofilm.The two widely used models of Ottengraf and van den Oever (1983) were found to be inadequate with sum of squares of errors of 11 and 41 mg2 m−6 respectively. These models are based on zero-order kinetics in the biofilm which according to the M-M kinetic model, are likely to be inaccurate at low pollutant concentration. The odour control unit was designed to produce low emission levels of less than 1 mg m−3 of H2S, rendering the zero-order assumption unlikely to be accurate. A model based on first-order kinetics, which also has some support in the literature, was found to be a better, but not a good, fit to the data with a sum of squares of errors of 4.7 mg2 m−6. A novel model for the BTF based on M-M kinetics was found to be a good fit to the shape of the data with the lowest sum of squares of errors of 2.5 mg2 m−6. This novel M-M model was also identified as the best fit for VOC data from the same unit. Other publications support the M-M approach with a product of saturation constant and Henry’s Law constant of about 50 mg m−3, which is equivalent to an H2S level in the gas phase of about 40 ppmv. Broad agreement was found between the SULPHUS™ experiments and data in the literature for other BTFs destroying H2S under the zero-order regime, at Vmax value of about 0.3 g/m3/s. This paper represents an attempt to harmonise a literature that was previously disparate, which has not previously been attempted.

Evaluation of Sub-National Population Projections: a Case Study for London and the Thames Valley

Sub-national population projections help allocate national funding to local areas for planning local services. For example, water utilities prepare plans to meet future water demand over long-term horizons. Future demand depends on projected populations and households and forecasts of per household and per capita domestic water consumption in supply zones. This paper reports on population projections prepared for a water utility, Thames Water, which supplies water to over nine million people in London and the Thames Valley. Thames Water required an evaluation of the accuracy of the delivered projections against alternatives and estimates of uncertainty. The paper reviews how such evaluations have been made by researchers. The factors leading to variation in sub-national projections are identified. The methods, assumptions and results for English sub-national areas, used in five sets of projections, are compared. There is a consensus across projections about the future fertility and mortality but varying views about the future impact of internal and international migration flows. However, the greatest differences were between projections using ethnic populations and those using homogeneous populations. Areas with high populations of ethnic minorities were projected to grow faster when an ethnic-specific model was used. This result is important for assessing projections for countries housing diverse populations with different demographic profiles. Historic empirical prediction intervals are used to assess the uncertainty of the London and the Thames Valley projections. By 2101 the preferred projection suggests that the population of the Thames Water region will have grown by 85% within an 80% empirical prediction interval between 45 and 125%.

Treatment of discontinuous emission of sewage sludge odours by a full scale biotrickling filter with an activated carbon polishing unit.

A SULPHUSTM biotrickling filter (BTF) and an ACTUSTM polishing activated carbon filter (ACF) were used at a wastewater treatment plant to treat 2,432 m3·h-1 of air extracted from sewage sludge processes. The project is part of Thames Water's strategy to reduce customer odour impact and, in this case, is designed to achieve a maximum discharge concentration of 1,000 ouE·m-3. The odour and hydrogen sulphide concentration in the input air was more influenced by the operation of the sludge holding tank mixers than by ambient temperature. Phosphorus was found to be limiting the performance of the BTF during peak conditions, hence requiring additional nutrient supply. Olfactometry and pollutant measurements demonstrated that during the high rate of change of intermittent odour concentrations the ACF was required to reach compliant stack values. The two stage unit outperformed design criteria, with 139 ouE·m-3 measured after 11 months of operation. At peak conditions and even at very low temperatures, the nutrient addition considerably increased the performance of the BTF, extending the time before activated carbon replacement over the one year design time. During baseline operation, the BTF achieved values between 266-1,647 ouE·m-3 even during a 6 day irrigation failure of the biofilm.

Lee tunnel project – the first step toward a cleaner River Thames

Completed in 2016, the Lee tunnel is the largest-diameter and deepest tunnel ever built in London. The 6·9 km long, 7·2 m dia., 80 m deep storage tunnel for combined stormwater and sewage was also Thames Water’s largest ever infrastructure project. The tunnel has already cut combined sewage and stormwater overflows from London into the Thames by over 40%. In 2023 it will carry nearly all of the capital’s overflows when the £4·2 billion Thames Tideway tunnel connects into it. This paper describes the design and construction of the award-winning project. Innovations included steel-fibre-reinforced concrete slip-formed shaft linings, launching a tunnel-boring machine from a shaft without a back-shunt, full-round shuttered secondary tunnel linings and water-cooled pump motors.

Integrating what and for whom? Financialisation and the Thames Tideway Tunnel

The Thames Tideway Tunnel (TTT), often referred to as the Thames super sewer, is currently one of the largest infrastructure projects underway in any European city. Costing an estimated £4.2 billion, the sewer connects London’s Victorian sewerage network with the Thames Wastewater Treatment Works at Beckton. The latter facility has been described as the UK’s Water–Energy–Food nexus poster child, for its combination of desalination facilities, green energy generation and wastewater treatment. While physically connected to the Beckton plant, the TTT is, paradoxically, designed with an apparent disregard for the water–energy nexus. If the Beckton plant represents a nexus-based vision of integration – what Macrorie and Marvin (2016) refer to as Mode 2 Urban Integration – the TTT harks back to a view of urban integration carried from the Victorian era through to the present moment. What unites the two projects, and what undergirds the transformation of the hydrosocial cycle, is a financial model more focused on the extraction of rents from Thames Water’s consumers. Thames Water’s dismissal of genuinely integrated alternatives appears guided more by the financialisation of the urban integrated ideal than by what is needed to respond to London’s broader environmental needs. Contesting the project, therefore, will involve slicing through the various claims to integration, going beyond the many proposals for evidence-based alternatives, and capturing the transformations being wrought by finance’s entry into infrastructure provision.

Statistical modelling anaerobic digestion for process optimisation and bench‐marking: a case study of E. coli inactivation across all Thames Water conventional sewage sludge treatment sites

AbstractUntreated sewage sludge potentially contains a wide range of enteric pathogens that present a risk to human health. Mesophilic anaerobic digestion (MAD) is the most‐favoured process for sewage sludge treatment in the United Kingdom. It is a well‐established approach to sludge stabilisation, but the mechanisms responsible for pathogen removal are poorly understood. Operational data collected by Thames Water from conventional MAD sites were statistically scrutinised to examine the effects of primary and secondary digestion on the removal of the enteric indicator bacteria, Escherichia coli, by using the IBM SPSS statistical software package for ANOVA, post‐hoc and multiple regression analysis. The results showed that the process temperature conditions at the MAD plants were equivalent to or exceeded the minimum estimated by the analysis necessary to comply with the 2 log10 removal standard for E. coli. The results also showed that primary digestion conditions (specifically temperature) sublethally damaged E. coli and increased decay in secondary digestion and therefore over the whole digestion process.

Consuming water smartly: the significance of sociocultural differences to water-saving initiatives

ABSTRACTThis article explores how strategies to encourage households to consume less water, through education and the installation of smart meters, play out in actual social worlds where the texture and complexity of households, and the individuals within them, have a tendency to be simplified to average or statistical norms. Building on research and critical analysis from earlier studies, particularly in Australia, this research set out to explore Thames Water’s smarter home initiative deploying three frames – affect, habit, and the meaning of home – for thinking through the different responses of householders to the intervention. The study revealed that differences in response to the smarter home visit were articulated across income, education, gender, age, and ethnicity – not as homogenous or fixed categories, but rather as categories which emerged through the smart metering intervention. The research concluded that demand management interventions such as the smarter home visits, conceived as a relatively simple technology-driven behavioural change strategy, are more complex and nuanced in their reception and effects, especially on the user–provider relationship, in the constitution of social differences, and in the definitions of public and private spaces and practices. Acceptance or resistance of these programmes is not knowable in advance of their dissemination. For such interventions to be successful, water companies thus need to recognise the differentiated social, cultural, and economic environments in which their strategies are enacted. A failure to do so can only limit their stated objectives of reducing household water consumption.

Considerations for monitoring of deep circular excavations

Understanding the magnitude and distribution of ground movements associated with deep shaft construction is a key factor in designing efficient damage prevention/mitigation measures. Therefore, a large-scale monitoring scheme was implemented at Thames Water's 68 m deep Abbey Mills Shaft F in East London, UK, constructed as part of the Lee Tunnel Project. The scheme comprised inclinometers and extensometers which were installed in the diaphragm walls and in boreholes around the shaft to measure deflections and ground movements. However, interpreting the measurements from inclinometers can be a challenging task, as it is often not feasible to extend the boreholes into ground unaffected by movements. The paper describes in detail how the data are corrected. The corrected data showed very small wall deflections of less than 4 mm at the final shaft excavation depth. Similarly, very small ground movements were measured around the shaft. Empirical ground settlement prediction methods derived from different shaft construction methods significantly overestimate settlements for a diaphragm wall shaft. The results of this study will help to inform future projects, such as the forthcoming 25 km long Thames Tideway Tunnel with its 18 deep shafts being constructed adjacent to existing infrastructure.

Failure analysis of a welded steel pipe at Kullar fault crossing

Abstract The seismic response of a 2200-mm-diameter welded steel pipe at strike slip Kullar fault crossing in Izmit, Kocaeli during 1999 Kocaeli earthquake is investigated. The pipe was crossing the fault-line with an angle of 55° and suffered leaks due to 3.0 m of right lateral movement of fault, which imposed compressive axial strain in the pipe. The backfill material of the trench was native soil which was non-homogenous (soft and stiff clay) with respect to fault line-soft material on the North side, stiff material on the South side. Field observations revealed two major wrinkles with finger width cracks and a minor wrinkle on the soft soil side of the fault. Large plastic strains and local folding were observed at wrinkles due to compressive strains. The case is known as one of the best documented fault crossing examples. The failure behavior of the Thames water pipe during 1999 Kocaeli earthquake is simulated by utilizing a 3D nonlinear continuum FE model. The numerical model considers contact surface at soil pipe interface and performs large deformation analyses of the pipe. The locations of wrinkles as well as axial displacements/rotations demands due to fault rupture are predicted. It is observed that once wrinkle initiates, strain in the pipe away from the wrinkle reduces after initial local buckling and additional shortening of the pipeline tends to accumulate at the wrinkle causing large plastic strains and rotation demands associated with fault rupture, an observation consistent with field observations and 2005 ALA guidelines.