Full interview: Tapping storm waters to keep taps wet
Management of water for household, industry and commercial use is one of the main challenges that urban centres face. Many cities around the world increasingly face water stress because of changing climate conditions. One such city is Cape Town, South Africa. Increasingly, policy makers will have to adopt innovative approaches to maximising the use of dwindling resources like water. This will call for increased use of knowledge from scientific research. In the case of Cape Town, one attempt at keeping the taps wet is to tap storm water. John Okedi, a Ugandan PhD student of water engineering in the University of Cape Town, is working on one such innovation (called storm-harvesting), under the tutelage of Prof. Neil Armitage. The Infrastructure Magazine interviewed John Okedi on his work. Excerpts:
Could you begin by telling us about yourself: Your family background, education, work experience, expertise?
Well, I am your true Ugandan. My father, Valerian Epiyu, is from the eastern part of the country, specifically hailing from Kachonga, Malera sub county, Bukedea District. My mother, Monica Epiyu, is from Kazo, Kiruhura district in the western part of Uganda. Using the law of averages, you could then say that am from the central, but with the African patriarchal lineage, that makes me a proud Etesot. I was born 40 years ago in Entebbe, and largely grew up in Kampala. I went to various schools in the central, western and eastern regions of Uganda including Kiswa primary school in Bugolobi, (Kampala), Nganwa Junior in Bushenyi, Ntare School in Mbarara, St. Peter’s College, in Tororo and Caltec Academy in Kampala.
I joined Makerere University for a civil engineering degree, completing in 2005. After graduation, I worked with the Ministry of Water initially at the head office in Kampala then on an African Development Bank (ADB) funded project that brought piped water, sewerage and solid waste management services to Iganga town. After that project, I joined National Water & Sewerage Corporation as area engineer for Kabale Town for 3 years, after which I took up a job with an American NGO called Water Missions International (WMI). At WMI, I was a field engineer responsible for design and installation of robust low cost water treatment and distribution systems to small communities (around 3000 people). At this NGO, I assisted with installation of various projects in Uganda, Zimbabwe, Burundi and Malawi. After some 5 years of work, the Belgian Government awarded me a scholarship to study water resources engineering at the prestigious Katholieke Universtiet, Leuven (Catholic University of Leuven) and Vrij Universteit Brussels with a 3 months flood management program at the University of Sophia Antipolis in the French Riviera.
On completion of the master’s degree, I returned to Uganda and worked with ILISO consultancy, a South African firm working on various water supply and sanitation projects in Uganda. After about 2 years, I applied and was awarded the prestigious Carnegie Fellowship to study a PhD in civil engineering at the University of Cape Town which I hope to complete in 2018. Along my PhD studies, I teach under graduate courses at the University of Cape Town and the Cape Peninsula University of Technology, both in Cape Town, South Africa.
What is the urban water system problem in the city of Cape Town that you are trying to solve in your PhD studies?
Currently the biggest problem in Cape Town is the long and persistent drought. This has been the case for three years in a row. That has led to a water crisis in the city. The main source of water in Cape Town and indeed South Africa is surface water from dams built on rivers, which rely heavily on above average rainfall at least once in two years. With the extended drought period, Cape Town residents are now counting down to ‘day zero’; the day we will have no water in our taps. Note that Cape Town is a advanced and quite comparable to most European and American cities. So Capetonians expect water to always be in their taps nice and clean to drink with no need to boil. With this water shortage, the city is looking for alternative sources as the current conventional water resources are no longer adequate to meet demand. The city is considering various options including waste water recycling, sea water desalination and groundwater. My research is investigating the potential for storm water (rainwater in urban pipes) as a source that is currently not being considered by the city.
What is the solution you are coming up with?
Conventionally, the practice in urban areas is to convey or transport all stormwater from locations of rainfall incidence to larger water bodies downstream like a sea, lake or swamps outside the city boundary. Then water for use in the city is brought in, sometimes from as far as over 100 km from the city to meet domestic, commercial, industrial and other water needs. For example, the water used in Johannesburg is transported from Lesotho, a neighbouring country.
But since the 1990s, stormwater management experts led largely by experts from Australia, USA and UK began to consider more sustainable approaches of stormwater management and possibility for reuse. Various labels have since been proposed for the new approaches including Sustainable Urban Drainage Systems (in the UK), Water Sensitive Urban Design (Australia) and Low Impact Development (USA). Application of these approaches has been a subject of research for Professor Neil Armitage and colleagues at the University of Cape Town and this culminated into guidelines and framework for planning and installation of the infrastructure.
As Professor Armitage’s PhD student, my task was to take the research further and provide insight into the opportunities and possibilities especially with regard to storage of the stormwater in an urban area. Stormwater is mostly available in the rainy season. Yet water is required all year round especially in the dry period for irrigation. Accordingly, I have considered storage in stormwater ponds with possibility for pre-emptive discharge prior to major storms to control flooding through a system called real time control. With real time control, the stormwater ponds are emptied by opening outlet valves prior to onset of forecasted storms.
A 24-hour lag is adequate for the system to work and the forecasts are sufficiently accurate to this extent. Alternatively, I have simulated the stormwater ponds to function as artificial recharge basin. In this case, the stormwater ponds hold the water long enough to allow for infiltration into a groundwater aquifer. This seems to be the most suitable approach as the aquifers are much larger than the surface water storages with limited evaporation and potential additional treatment through ground filtration. According to my findings, the groundwater approach is the most preferred and cost effective option.
It is said that Cape Town uses 300 million cubic litres of water annually, but it loses about 1,200 million cubic litres in free flow of rain and storm water. Would you say the same proportion of rain water loss applies to Uganda, Kenya, Rwanda, or indeed any East African country?
Cape Town is a city where its water consumption/use can easily be quantified and compared with available rainfall. I would not know exactly how much water is used in the East African countries. But What I can say, is that rainfall in East Africa is twice or three times and in some places four times higher than South Africa.
Secondly, the proposal in my research is more practical in urban areas such as Kampala, Nairobi and Kigali. Thirdly, the approach can only be attractive from a water supply point of view, to a city that is water resource constrained. For example, Professor Armitage has been working on this topic for many years and it had never attracted such political and media attention. It is now due to water shortages that we are finally getting noticed. For a city like Kampala, I doubt they will ever consider it with a source like Lake Victoria, the largest fresh water lake in the world nearby. However, there are other additional benefits of the approach such as water quality improvement, biodiversity preservation and amenity provision for a city that would be interested in such. Due to budgetary constraints and perhaps lack of political will, it’s unlikely that authorities in Uganda would be interested in this approach.
Could you explain this concept of “Storm water harvesting”? Is it relevant to Uganda and other East African countries as a source of water for human use? If so how is it relevant?
In simple terms, stormwater harvesting is an approach where stormwater management infrastructure in a city is retrofitted for stormwater reuse. This can range from a building scale e.g. installation of permeable pavements and green roofs with storage to capture most of the rainfall for reuse. At a neighbourhood scale, this could include drainage through soak pits and infiltration trenches into the ground and later harvested with boreholes. At the city scale, which is the subject of my research, a network of interconnected stormwater ponds to capture and either reuse or infiltrate into the ground for storage. The building scale and neighbour scale would be relevant in East Africa especially in an attempt to minimise house hold water bills and avoid water shortages in case of outages. A warning though, this approach would be fatal if there are many unlined pit latrines. This approach would only be suitable for areas with sound sewer networks and lined septic tanks. For a city like Kampala, the cost benefit analysis would not favour this approach due to an already existing water supply network and an infinite source in Lake Victoria.
How appropriate is your proposed solution to Cape Town urban water system? What features of Cape Town make this solution relevant?
The solution is appropriate for Cape Town as a water supply option only because we are comparing it with other relatively expensive options such as sea water desalination and waste water recycling. However, if other benefits of water quality improvement in the urban rivers, provision of local amenity and biodiversity preservation are considered, the opportunities are immense and should be considered.
What urban water management principles can you take away from your study and apply to other cities in East Africa, say Kampala, for example?
Cities of the future will increasingly need to be self-reliant with regard to food, water and energy. This stormwater management approach would promote sustainability with regard to water. Secondly, demands of the population living in developing cities are changing. People are no longer just satisfied with good roads and painted buildings but now demand for improved ambience and liveability. Well designed, retrofitted and well managed stormwater infrastructure would provide water features, urban parks and fresh air in addition to a water source that city dwellers now demand. With progressive leaders like Jennifer Musisi in Kampala and others, I am hopeful such ground-breaking innovations are achievable.
What is the cost of technology investment to make your idea work in Cape Town?
The capital cost to implement the project in the study area (portion of Cape Town) would be about 300 million rands (UShs 81 bilion) to include water abstraction from the source, water treatment and distribution to 100,000 households. The cost of water would be about 10 rands (Ushs 2,700) per 1000 litres for the groundwater option and 14 rands (Ushs 3,780) for the surface water. The difference is due to the requirement for treatment of the different sources of water. Well as surface water would require a full water treatment train including sedimentation, coagulation, flocculation, filtration and disinfection, the groundwater source would only require the disinfection process. The current lowest water tariff in Cape Town is 16 rands (Ushs 4,320) per 1000 litres and this is due to long distance transmission of water over 50 km.
Would you say, that idea in full, or in part, could work for Ugandan urban areas as well where millions of litres of water literally runs down the drain during the rainy season, yet taps run dry during the dry season?
As already mentioned above, from a water supply point of view, the approach would work well at a building and neighbourhood scale and not the city wide scale. However, the additional benefits of ambience and liveability is incentive for the approach to be attractive to city dwellers are equally strong.
Has similar technology been used elsewhere in the world? Where?
Yes, Singapore is the best example. Other cities in South Korea, Australia, Netherlands, Denmark, USA and UK have implemented the approach.
I am going to bring you back to Uganda where you have lived and worked before. Uganda experiences episodes of water stress for human use in both rural and urban areas. Yet at the same time, the country sometimes suffers from floods from rivers, rain water, etc. What is the problem here, too much and yet too little, at different times? What do you see as Uganda’s biggest water management problem?
I could say the problem is both lack of proper planning and implementation of appropriate technology. But again, everyone outside government says that government is not doing the right thing and their best; but government says they are doing their best. Then it comes down to who do you trust more? I will take it a notch higher though. I believe African countries in general do not demonstrate tat they value life of their citizens much. That is why we ask for money from emergency cases in hospital before administering even the basic first aid to save a life or embezzle Global Fund money meant for TB, HIV and malaria. So when we lose a life to a flood, drought or hunger, I never see the situation given the urgency it requires and no solution is provided to minimise the impact of the hazards in future.
It does not mean that such hazards never happen in developed countries, but when they happened, emergency measures are swiftly implemented and plans are put in place to minimise casualties in future. In summary, I think our governments do not care and do the right thing enough. Secondly, engineers like myself could provide technical solutions but these are short term. This problem really requires a fundamental, multi-disciplinary approach and political will to deliver the change we need and deserve.
Your last word?
Uganda and Africa in general has immense human (numbers and education) and financial resources (natural resource). Many of us have acquired knowledge in various fields and are willing to assist make a difference in our communities even when it is tempting to remain abroad. My advice is for our governments to lead all of us to work together for the common good. Working in silos everyone in their own professional field will not yield much for our countries and continent. The future professionals need to work across disciplines as specialised solutions have failed to work. Engineers need to work with biologist, social workers, and economists with mutual respect and value all contribution.
Thank you for accepting to speak to us and, our very best wishes to you