Review of Wastewater Collection System Modeling and Design by T. M. Walski, T. E. Barnard, E. Harold, L. B. Merrit, N. Walker, and B. E. Whitman: Haestad Methods, Inc. Waterbury CT., 2004; ISBN 0-9657580-9-5; 605 pp. Price: $195, students $75, professors $30.

This is a comprehensive text of 605 pages on the modeling and the design of wastewater collection systems by a team of seven authors who have extensive experience on the subject. It is intended for designers, managers, and students. The presentation is didactic and well organized and attempts to link theory and practice. Each chapter has a number of solved and proposed problems. The latter problems are intended to reinforce student knowledge. The proposed problems can also be completed by professionals for continuing education credit. The illustrations are excellent, and 27 cartoons taken from The New Yorker magazine add a touch of humor.

Chapter 1, the introduction, in addition to providing a general background and laying the groundwork for the book, also includes an excellent historical perspective. Chapters 2, 3, and 4 are concerned with the traditional hydraulics of wastewater collection systems. Chapter 2 emphasizes steady flow, Chapter 3 gives a good summary of unsteady flow, and Chapter 4 focuses on force main and pumps. Hydraulic fundamentals are very well treated. An attempt is made to promote the tractive force as an alternative approach to the traditional minimum velocity as a design method for self-cleansing sanitary sewers. This is a welcome initiative, which is based on a more physical process. As the British methodology (Butler et al. 1993, and references therein) is exceedingly cumbersome, the authors attempt to provide a simplified method. Unfortunately there are very few verified experimental data available, and the authors only rely on one data set.

Chapter 5 presents an overview of the development and application of computer models for sewer systems. The sequence of tasks in the modeling process is presented: the definition of objectives; the development of alternatives; the definition of scale; the selection of software; the acquisition of physical, operational, and loading data; the building and calibration of the model, its sensitivity and validation; the running of the model; and the development of a problem solution.

The following three chapters are concerned with obtaining some of the inputs for the models. Chapters 6 and 7 deal with the loadings, namely, the dry and wet weather flows. Chapter 6, on dry weather wastewater flows, provides important input data for the hydraulic design of new sanitary sewers. Perhaps more could have been said about the composition of dry weather flowsand sewer solids. Chapter 7 on wet weather wastewater flows is particularly important in the design of combined sewers. Classical hydrologic models for the estimation of surface runoff from contributing watersheds are described in some detail.

The next two chapters deal with the acquisition of data that are needed for the calibration and verification of models. The techniques of flow and precipitation measurement are presented in some detail in Chapter 8. After a discussion of classical flow measurement devices, modern techniques are presented such as pressure transducers, ultrasonic devices, electromagnetic velocity meters, radar Doppler measurements, and radar imagery for rainfall distributions. Chapter 9 discusses the model parameters that can be adjusted during calibration, a reasonable range of these parameters, and the data against which the model will be calibrated such as velocities and water elevation in the sewer system. Perhaps some measures of statistical goodness of fit of the model could have been included.

The following two chapters are concerned with the design of new sewers and the evaluation and rehabilitation of existing ones. Chapter 10 gives consideration to materials, initial planning, network layout, horizontal and vertical alignment, hydraulic design, and a brief introduction on system optimization. The material on system optimization could be expanded in a future edition. Models can be used to simulate existing conditions to locate and evaluate malfunctions such as overflows and surcharging. They can also be used to evaluate the merits of rehabilitation strategies. These are discussed in detail in Chapter 11.

The next two of chapters are concerned with pumps. Chapter 12 focuses on the details of the hydraulic design of pump stations and force mains while Chapter 13 covers low-pressure sewers in which individual pumps are located at each customer.

Chapter 14 presents an introduction to the integration of Geographic Information Systems (GIS) with hydraulic sewer models which has become essential for the design of sewer and other utility networks. The use of GIS for modeling, analysis, and visualization keeps expanding rapidly.

The last chapter covers U.S. laws and regulations that apply to the design, construction, management, and rehabilitation of sewer systems. Several paragraphs are devoted to the Clean Water Act, the National Pollutant Discharge Elimination System Permit (NPDES), the combined sewer overflow (CSO) policy, the sanitary sewer overflow (SSO) rule, and total maximum daily loads (TMDLs). Similar considerations are discussed for Canada and the European Union.

This reviewer would have liked to see more attention given to recent trends overseas, such as the concept of the integrated design and analysis of drainage systems, treatment plants, and receiving waters and associated software (Harremöes and Rauch 1996) initiated under the guidance of the late professor Paul Harremoës at the Denmark Technological University. Also, the concept of a sewer as a reactor (Hvitved-Jacobsen 2001) suggested by Hvitved-Jacobsen would have been worth mentioning.

In summary, the book provides an excellent and practical up-to-date reference for students and practicing engineers involved in the design, construction, management, and rehabilitation of wastewater systems. No particular software is proposed or discussed in the body of the text. However, a CD-Rom accompanies the book. It contains a 25-pipe version of Haestad Sewer CAD program that can be used to work some of the exercises. The CD-Rom also includes the program’s user guide and an examination booklet that can be used to obtain continuing education credits.