I started my career in dams in 1984, having graduated from the University of Birmingham (UK) and venturing out to South Africa to work for the then Department of Water Affairs and Forestry. Over the following 10 years, I gained some incredible experience in the design and construction of dams, and particularly the first two Roller Compacted Concrete (RCC) arch dams in the world, Wolwedans Dam & Knellpoort Dam. Since then, I have been involved in dam projects in a further 35 countries, retaining a particular focus on RCC and arch dams. The summit of my dam design involvement to date was as chief dam designer for the construction design and implementation of the 275m double-curvature conventional mass concrete arch Yusufeli Dam, currently in the process of first impoundment in Turkey.
Having had a role in most of the non-Chinese technology RCC arch dams constructed around the world to date, I received the ICOLD Innovation Award in 2018 for my work in developing the understanding of early stress-relaxation creep (SRC) in RCC dams, which technology was recently put to use in demonstrating that Gross Dam in Boulder, Colorado could be raised in RCC and converted from a curved mass concrete gravity dam into an arch-gravity dam without having to post-cool the new concrete and grout contraction joints. The related understanding implies a different methodology for the thermo-mechanical analysis of RCC dams, compared to that traditionally applied for conventional mass concrete dams.
After comparing prototype and modelled behaviour on Wolwedans Dam in South Africa, I was fortunate to be able to take my observations into the design of Changuinola 1 Dam, another RCC arch-gravity dam, in Panama. Expecting the same low SRC characteristics of the fly ash-rich RCC that were observed at Wolwedans, I included comprehensive instrumentation in Changuinola 1 during construction, which was completed in 2011, to enable a definitive measurement of the expected effects. Subsequently being involved in the safety monitoring of the dam over the following 10 years, I was able to fully substantiate and replicate in modelling the significant and quite surprising structural consequences of low SRC in horizontally-constructed RCC.
Wolwedans Dam and Changuinola 1 Dam are two of the 20 RCC dams, of over 900 to have been constructed to date, that have been recognised as “International Milestone RCC Projects”.
While the Yusufeli Dam project presented many challenges, the two biggest were undoubtedly the very complex and heterogenous foundation conditions and adapting and controlling very rapid concrete post-cooling to allow each stage of contraction joint grouting to be achieved sufficiently rapidly to keep up with the record-breaking average monthly concrete placement rate of 140 000 m3. The development of a very detailed finite element foundation model and procedures to improve and verify the improvement of the foundation rock mass has so far meant a very accurate alignment of predicted and measured behaviour during impoundment.
On a substantially smaller scale, I have been extensively involved in the development of rubble masonry concrete (RMC) arch dams, which is a labour-based construction technology that brings together a 19th-century material with modern structural analysis to present an extremely cost-effective and durable dam type in an environment where low-cost labour is abundant, as is the case in many countries across the developing world. No other dam technology puts more of the project capital cost back into local labour wages and local skills development. Over the past 25 years, we have implemented more than 18 RMC dams, with several more currently in the pipeline.
Dam engineering
Having started ARQ Consulting Engineers in South Africa in 1993 with two partners, I was responsible for the company’s operations in dam engineering for almost thirty years. More recently, I have taken on more specialist and expert roles, although I still work with the ARQ Dams team in South Africa on more interesting and larger projects.
I have served on the ICOLD Committee for Concrete Dams for 10 years and enjoyed very much contributing as lead author to the 2020 ICOLD Bulletin 177 on RCC Dams.
Having served two terms as Chairman of SANCOLD, I regard my election in 2022 as ICOLD Vice-President for the Africa zone as an opportunity to use my voice to increase awareness of worsening capacity and dam safety problems in Africa. I do not believe the most common manner in which we have been developing and implementing projects in Africa over the past several decades is at all appropriate and I believe that we are running out of time to acknowledge the related changes that need to be made.
Change is needed
It is predicted that the population of Africa will double by 2050, implying that 2.5 billion people, or 25% of the planet’s population will live in Africa. This means that we are going to need to substantially increase water storage for food production and domestic and industrial use, not to mention power production. This will require not only the development of high-quality and durable dam projects, but just as importantly, the development of the local capacity to operate and maintain these projects. Additionally, it is critically important that the development of new projects must be used to progressively develop local capacity to enable the local planning and management of large-scale water infrastructure projects and programmes.
The worst-case scenario for any project is for the host country to be left with a facility that does not fully serve its intended purpose, or achieve its target production capacity and for that project to be implemented by a foreign contractor, who imported all his labour, materials and equipment from his home country. In this situation, very little of the project implementation goes to uplift the local economy during construction, while the host country is not only unable to fully service the capital debt through scheme operation but is left without the necessary local skills and institutional capacity to manage and maintain the new project, let alone plan the subsequent one.
We simply cannot continue this approach any longer and we need to look to different project implementation models, which need to go beyond the infrastructure and look at the human and institutional needs. In many African countries, project development should always be extended to look at and plan for the institutional needs not only to run the proposed project, but to establish a planning system for ongoing national bulk water storage infrastructure development. In the process, we should do our utmost to support and develop national committees with ICOLD membership, to ensure sustainable dam safety.
We also need to look closely at our dam safety systems, regulations and legislation. While the dam safety legislation implemented in South Africa in 1986 has served the country very well over the intervening years and is generally well regarded around Africa and the world, it was developed on a premise that no longer exists. When the legislation was drawn up, several dams were under construction in the country at any time and experienced dam designers and constructors were plentiful. The legislation was consequently based on using the related skills and experience to maintain dam safety. Almost 40 years later, very few new dams are constructed and skills and knowledge in dam design and construction are becoming progressively scarcer. Consequently, we need to redevelop the existing system around the available skills and specific dam safety training, rather than design and construction experience. Many related situations and issues exist around the world and we, as ICOLD, need to try to understand and pre-empt the changing needs and requirements.
This article first appeared in International Water Power magazine.
