John W. Davies

This new edition of a well-established textbook covers the health, environmental, and engineering aspects of the management of rainwater and wastewater in areas of human development. Urban Drainage deals comprehensively not only with the design of new systems but also with the analysis and upgrading of existing infrastructure. Keeping its balance of principles, practice, and research, the fifth edition has had the most comprehensive update of any edition so far. It includes a new chapter on urban drainage planning, some significant restructuring of others and the introduction of new topics, including emerging contaminants, wastewater surveillance, AI, digital twins, and cyber-physical security. It also addresses current concerns about climate change impacts and intermittent wastewater pollution, and new ideas about sustainable and resilient systems. In all cases, the aim is to provide comprehensive, authoritative, and evidence-based content prioritising innovation, improved methods, and solutions. This is an essential text for undergraduates and graduate students, lecturers, and researchers in water engineering, environmental engineering, public health engineering, engineering hydrology, and related non-engineering disciplines. It also serves as a dependable and up-to-date reference for drainage engineers in water service providers, local authorities, and consulting engineers. Throughout the text, extensive examples are used to support and demonstrate the key issues.

Chapter 11 considers the alternative to pipe-based systems, namely, Sustainable Drainage Systems (SuDS), including their wider benefits beyond water quantity and quality control. The chapter describes the common types of SuDS components in turn, gives guidance on aspects of their design including multiple benefits, and explains how they can be linked together. The importance of addressing public concerns and engaging affected communities is also included. A range of issues and challenges still surround SuDS and their implementation, and these are also considered. The chapter concludes with site runoff control – how to achieve it and what the relevant standards are.

Chapter 3 is concerned with the generation and characteristics of wastewater. It collates quantity and quality information on the various sources of wastewater and discusses their relative importance. This includes domestic sources of wastewater, non-domestic, and the contribution of sewer infiltration and inflow. Wastewater quality issues are also covered. The emerging topic of wastewater-based epidemiology is also presented.

A thorough understanding of hydraulics is needed in the design of new drainage systems and in the analysis and modelling of existing systems. This chapter covers the fundamental hydraulic principles as applied to urban drainage including pipe flow, part-full pipe flow, and open-channel flow. Further aspects of hydraulics are developed for specific applications in later chapters.

In this first chapter, which forms an introduction and scene-setter for the whole book, we introduce exactly what urban drainage is and, in particular, its relationship with urbanisation and climate change. The rest of the chapter introduces in turn the particular need for this infrastructure system, the history of its implementation, and then some diverse geographical examples. The various types of urban drainage systems are introduced, explained, and placed in the wider setting of urban water systems. The chapter concludes with a discussion of the changing context and drivers affecting the development of urban drainage and the future challenges it faces.

This chapter gives an overview of the elements that make up any piped urban drainage system operating under gravity, including building drainage and other main system components. The key stages in the design process are also described, including the requirements for adoption. Further details on specific system types and components are developed where appropriate in later chapters.

This chapter deals with the physical fabric of sewer systems by looking at their construction and rehabilitation. It begins with an overview of construction followed by a description of materials and jointing methods for sewer pipes. The concept of structural design is introduced as is site investigation, an important prerequisite for construction. Specific construction methods are presented in turn: open-trench, tunnelling, and trenchless methods. For rehabilitation, the chapter first considers the context and then describes the various methods of rehabilitation, both structural and hydraulic.

This chapter covers the important topic of pumped systems. The general arrangements of typical pumped systems are presented, followed by a detailed discussion of hydraulic design. The pipe carrying the pumped flow, the rising main, is also considered. The different types and characteristics of the pumps themselves are discussed, and the design of pumping stations is described. Also covered in this chapter are alternatives to gravity flow for a whole sewer system, and the contribution of pumping to energy use and greenhouse gas emissions.

Chapter 5 focuses on the generation and characteristics of stormwater, with many of the concepts underlying the design and analysis techniques described in later chapters. The chapter begins with an explanation of the mechanisms of runoff generation, followed by a discussion on overland flow processes. Stormwater quality issues are also dealt with, and the chapter concludes with the important problem of sewer misconnections.

This chapter deals with the special characteristics of combined sewers, and, in particular, with combined sewer overflows (CSOs). The chapter begins with a discussion on how flows are accommodated in combined sewers, then a description of the specific role of CSOs leading to a discussion on how and to what extent pollution is controlled using this system. Various CSO designs are explained, their details are described, and their performance is highlighted. The chapter concludes with a discussion of the management of CSOs including their problems and potential solutions.