A general studies session at school taught us that we should not idly flick through a new book but go straight to the contents. This would give a good idea of the subject matter and of the book’s structure.
Applying this well-proven guidance to the third edition of ‘Groundwater Lowering in Construction – A Practical Guide to Dewatering’ by P.Cashman and M.Preene reveals a book with an eye-watering 918 pages and 28 chapters – enough to make you think of table props and door stops. But you’d be wrong. Totally comprehensive in scope and coverage, the book will likely become – if not already – the standard work on subsurface dewatering on small- to medium-sized projects.
Although practical, the book is not short on theory or analysis. Aimed mainly at MSc students in civil engineering/ tunnelling, engineering geology and hydrogeology, it should also be of value to consultants, contractors, clients, dewatering practitioners and advisors.
Also finding the book of value are likely to be pragmatic temporary works engineers who seek practical and economic completion on small- to medium-sized projects but want to avoid sophisticated, time-consuming techniques when simpler methods will give usable results. No doubt they will warm to the many practical, analytical methods. These are based on successful international field experience and have been regarded as adequate for most temporary works’ assignments. The authors acknowledge however, that groundwater-lowering systems for large-scale or long-term projects may require more sophisticated methods of analysis.
Principles, Construction and Design
There are three broad subdivisions: principles, construction and design. Principles covers the groundwater flow that can occur in civil engineering excavations. It also features a fascinating, albeit brief, historical overview.
Despite ubiquitous software and sophisticated numerical modelling tools available to practitioners, the basic principles – like Platonic forms shining brightly in the darkness – remain constant and immutable. So, if that means referring to Darcy’s law of 1856 – which describes the flow of a liquid through a porous medium – the authors show that doing so can be instructive. Typical headings in this section include the hydrological cycle, aquifers and aquitards. Other chapters include groundwater flows, the objectives of groundwater control and their practical application.
The section on design is much enlarged from that of previous editions; it includes extra detail on groundwater control in tunnelling (also shafts and passages), and permeability assessments. Also included are the main methods for lowering groundwater, site investigation requirements and simple, empirical design methods for assessing discharge flowrates to determine the number of wells required.
The third and final part is devoted to the practical application of groundwater control methods, including the complete lifecycle of a groundwater control scheme, monitoring, maintenance and decommissioning. Near the end are 11 case histories from the Cashman and Preene casebook.
Pat Cashman started writing this book nearly 30 years ago; Martin Preene’s updated third edition turns an already excellent work into a practical book that could well become the bible on the control of groundwater in the field. Its scope is enormous but this mighty tome pulls it off deftly, so that it should be an asset to those whose professional lives are driven by its contents. Ultimately, in the words of J P Powers, the reader of this book “will be the person who understands the theory and respects it, but who refuses to let theory overrule judgement’ (Powers et al., 2007).
‘Groundwater Lowering in Construction – A Practical Guide to Dewatering’, third edition by Pat M Cashman and Martin Preene is published in August 2020 by CRC Press.
