Civil Engineering

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Determining the efficiency of selected vegetated biofilters in reducing nutrients from urban stormwater in the city of Ekurhuleni, South Africa
(Vaal University of Technology, 2021-11) Bvumbi, Mulalo Justice; Rwanga, S. S., Dr.; Ochieng, G. M., Prof.
Over time, the quality standard of stormwater in the City of Ekurhuleni (CoE) has deteriorated due to industrial, commercial, residential and farming activities. Stormwater quality directly impacts the treatment chain of potable water, and therefore, it should be kept in check at all stages. Innovations in the biofiltration process can provide useful, practical solutions to overcome crucial stormwater pollution problems. In 2013, the CoE developed stormwater design guidelines and standards to be implemented for the design of stormwater management, which include the principles of Water Sensitive Urban Design (WSUD) and Sustainable Urban Drainage Systems (SuDS) in particular. The CoE stormwater design guidelines and standards do not provide details on how the city plans to implement SuDS treatment trains to reduce stormwater pollution experienced by the city. This study aimed to verify the efficiency and effectiveness of vegetated biofilters on the stormwater treatment using CoE – Olifantsfontain's natural stormwater and to determine the most suitable vegetation to be used in the region. The CoE experimental case study was conducted to assess the efficiency of selected vegetated biofilters in lowering the concentration of orthophosphate (PO4-3), ammonium (NH4+), and nitrate (NO3-) from Tembisa/Olifantsfontain stormwater. In the experimental setup, six selected plant species were planted into 30 vegetated biofilter columns, namely: Agapanthus praecox (Dryland plant), Carpobrotus edulis (Dryland plant), Stenotaphrum secundatum (Dryland plant), Zantedeschia aethiopica (Wetland plant), Typha capensis (Wetland plant) and Phragmites australis (Wetland plant). The six species were grouped according to general habitats, i.e. three wetland and three dryland plants. Wetland plants were planted into fifteen vegetated biofilters, and dryland plants were also planted on another fifteen vegetated biofilters. The biofilters contained layers of sandy loam soil, coarse and and gravel sand. Each biofilter had a designated inlet and outlet section fitted with a gate valve to control retention time. The raw stormwater consisting of natural nutrient pollutants was applied to each vegetated biofilter through the inlet section. The samples were collected from the inlet and outlet of the six grouped vegetated biofilters during the month of June. All six plant species reduced outflow concentrations of PO4-3 and NH4+ by an average of 99% and 98%, respectively. The results also show that all plant species excluding Phragmites australis were able to reduce NO3- with outflow concentrations being reduced by an average of 58%. From the results obtained, it may be concluded that all the six plant species may be suitable variants to be applied as biofilter material for the purposes of treating urban stormwater in the CoE. The reason is that the determined removal efficiencies for bio-retention fall within 50% – 60% for PO4-3, and 40% - 50% for NH4+ and NO3- respectively. The results also show that if the plant species were applied for SuDs in the CoE, there could be a great improvement in the urban stormwater quality with the consequent improvement in both surface and groundwater quality of the receiving water bodies in the area. Regardless of the nutrient removal by selected plant species, the inclusion of vegetation in a field setting would slow flow rates and thus encourage infiltration into the soil, improve water quality, and support urban biodiversity. In the CoE, all the selected species could be used in the SuDS treatment trains targeting PO4-3, NH4+ and/or NO3-. The case study results provide a informed records for the CoE in the future/intended application SuDs in the upgrade/rehabilitation of its stormwater system.
Effect of land-use change on traffic peak hour factor
(Vaal University of Technology, 2012-01) Phahlane, Motsepe Herbert; Salim, W. R., Dr.; Ndambuki, J. M., Prof.
Growth in land development in South Africa resulted in large increase in traffic volumes. A Traffic Impact Assessment (TIA), as a traffic engineering tool, is commonly used to assess the possible effects of a land development project on the transportation and traffic system. During the TIA process, capacity analysis is performed to indicate the measures of effectiveness of the intersection. Intersection capacity analysis in South Africa by engineers is done on the basis of default values of the Peak Hour Factor (PHF) provided by the Highway Capacity Manual (HCM) or limited traffic counts. However, the default value of PHF may be significantly affected by new developments in the neighbourhood of the intersection. This study aimed at investigating the impact land-use change has on the existing intersection PHF, thus predicting values per land-use type. Intersections with traffic counts conducted before and after land-use change in vicinity were selected and investigated. The results showed that change in land-use has an impact on the existing PHF. They also assist in identifying the appropriate intersections to predict the PHF per land-use type. Intersections were identified and analysed, and this led to the development of a design chart showing the predicted PHF per land-use type selected and measures to consider during traffic analysis. Intersection capacity analysis was performed to compare the results using the predicted PHF and the HCM default values. The results showed that traffic flow rate was adjusted by up to 26% when using the default values, 0.92 and 0.95. The results also showed that the default values could overestimate the volume to capacity ratio and the average delay by up to 15% and 35%, respectively. It was then concluded that the use of HCM default values of the PHF for every land-use type will have an effect of the final roadway design results. The computed PHF values for each land-use type were then recommended to be used to ensure fairness and consistency in traffic analysis.
The evaluation of project management practices relationship with the project performance outcome of reconstruction development programme (RDP) and subsidy housing
(Vaal University of Technology, 2022-06) Tseladikae, Tshepo; Ochieng, G. M., Prof.; Agumba, J. N., Prof.
As citizens migrate from rural to urban locations, coupled with the population growth in South Africa, housing supply remains an imperative task. Regarding this migration and housing need, the South African government, shortly after the dawn of democracy, has been providing housing to its previously disadvantaged citizens due to the apartheid government. The housing typology that the government delivers to its citizens is the Reconstruction Development Programme (RDP) and subsidy housing. The construction industry has difficulties achieving satisfactory project performance, especially with the current delivery of the Reconstruction Development Programme and subsidy housing projects in South Africa. Most housing projects are never completed satisfactorily as contractors either abandon the project or deliver it late. They incur cost overruns and poor quality, making it an expensive and wasteful process for the beneficiaries and the government. As a result, this dissertation investigated the relationship between project management practices (PMPs) usage and project performance outcomes for the RDP and subsidy housing in South Africa. The research design was quantitative in nature, using primary data and the data were analysed using the IBM Statistical Package for Social Sciences (SPSS). The main statistical parameters used to present and analyse data results were mean score, correlation and factor analysis. The researcher used a questionnaire survey to gather the primary data and address the objective of this study, which is a deductive research approach. A convenience non-probability sampling method was used for sampling the participants. The questionnaire was administered to Gauteng-based small and medium contractors undertaking the RDP and subsidy housing projects. A total of 116 questionnaires were returned for analysis. However, one questionnaire was removed from further analysis because it was a large contractor as per the Department of Trade and Industry definition. As per the results, the majority of the respondents were males; 14 percent were females and 86 percent were males. The majority had a minimum qualification of a diploma, which represented 50.9 percent. The challenges faced by contractors were ranked using the mean score. The findings indicated that late payment of contractors was deemed a significant challenge. Furthermore, factor analysis established that the challenges stated were a three-factor model, categorised as project management, environmental and financial factors. The 86 PMPs identified in the literature were analysed using exploratory factor analysis (EFA). The results from the EFA established a ten-factor model in line with the theory of the knowledge areas of the Project Management Body of Knowledge (PMBOK). The mean score was performed to determine the usage level and results showed that one project management practice, namely a bar chart, was used every time in the RDP and FLIP housing projects (mean = 4.25 and Std. Deviation = 0.77), ranking first. Eighty-two other PMPs were used almost every time, as their mean scores were in the range of 3.41 to 4.20. On the contrary, Pareto, flow chart and fishbone were almost never used as they were in the range of 1.81 to 2.60. The final part of the results determined the performance outcome of the project and the relationship between the usage of the PMPs and the project performance outcome. The identified performance outcome measures were analysed using EFA and three components of the performance outcome measures were identified: compliance and financial performance, contractor process and employee satisfaction and contractor process and employee satisfaction. Spearman’s rho correlation, which is non-parametric, was used to evaluate the relationship between the three project performance outcomes and the 10 PMPs. From the results, the hypotheses tested indicated that nine of the PMPs, namely scope, schedule, cost, quality, integration, stakeholder, resources, communication and risk management, significantly correlate with one of the three project performance outcomes. However, the procurement management practice established no significant correlation with any of the three project performance outcomes. In conclusion, PMP has a relationship with the project outcome and each area of project management affects a different aspect of performance; for instance, cost management practices showed a relationship with compliance and financial performance component whereas stakeholder was customer performance component, the following recommendations were made: Relevant PMPs found to correlate with the performance outcomes of the project should be made compulsory for every RDP and subsidy housing project; qualified personnel should be employed to care for a project management role and not be a passive role given to anyone; training in PMPs should be compulsory for all those involved in the construction of RDP and subsidy housing projects.
Flash flood risk management in a South African township: a case study of Alexandra
(Vaal University of Technology, 2022) Fadupin, Adekunle Oluwatosin; Ndege, M., Prof.; Ochieng, G. M., Prof.
Several studies have been carried out on improvement of flood risk assessment and management in South Africa. Despite all these studies, the problem of F lash Flood (FF) persists. This study was designed to determine the most appropriate Flash Flood Inundation Model that could be applied in flash flood risks management in a South Africa Township: a case study of Alexandra. Alexandra Township being a FF prone area was chosen for this study from where a sample of 30 respondents was purposively selected. A survey (Questionnaire) and document search were used to collect relevant quantitative data and qualitatively based secondary information from the sample population respectively. Also, data were collected through in-depth interviews of senior officials in the Disaster Management Services for more well-rounded information. Content analytical method was used to process the qualitative information. The study adopted complementary analytical tools, namely, R-programming and appropriately selected tools from the Statistical Package for Social Sciences (SPSS version 21.0) to analyze the quantitative data and to determine the most appropriate Flash Flood Inundation Model. In search of mitigating the risk of the FF in Alexandra Township, a FF inundation model was determined. People were educated on FF not to build shacks along Juskei River and were trained to prepare for and manage FF. Early Warning messages were sent and community volunteers were trained on managing risks related to FF. The main observed risk factors of FF where building of shacks without abiding by the rules and regulation, blocking of drainage system by illegal dumping of solid waste and growth in population. The major risk factors the respondents agreed to cause FF where annual rainfall intensity (70.0%), poor drainage (56.7%) and human settlement (50.0%). The three Principal Components identified to be contributing to FF in Alexandra Township were terrain, soil texture and poor drainage system. This factors contributed 82.0% of FF risk factors in Alexandra Township. The model revealed that appropriate solid waste disposal, construction of sewers, dredging of Jukskei River, and construction of Gabions along Jukskei River will mitigate flash flood risk and related hazards in Alexandra Township.
Monitoring and modelling of water quality characteristics along a reticulation system: a case study of modimolle reticulation network
(2012-01) Mehlo, Mahlomola; Wanjala, R. Salim, Dr.; Ndambuki, J. M., Prof.
Potable water quality can deteriorate immensely from point of treatment to point of usage. This change in quality along a bulk distribution main may be attributed to numerous factors, such as the ingress of storm water. Furthermore, water utilities experience challenges in terms of the microbiological organisms that are not attributed to operational practices. For example, drinking water bulk distribution mains may be a shelter for these microorganisms that are sustained by organic and inorganic nutrients present within the pipe itself. These microorganisms may be active in the water being transported by the pipe, and can cause a significant drop in the water quality. In order to deal with the problem of deteriorating water quality, sufficient information within the bulk main is required, so that the consumer can be protected from ingesting contaminated water or water of poor quality. Hence, the overall objective of this study was to investigate and model water quality characteristics within the Modimolle reticulation network. Water samples were collected from various points throughout the entire system for quality analysis. Different sampling points were established along the main pipeline as well as within the Modimolle distribution system. Water quality software, EPANET, was then used to model the water quality deterioration for both the bulk line and the reticulation network of Modimolle extension 11. Residual chlorine was the main parameter which was monitored. This study presents results of a research on water quality variation within a long distribution mains conveying water up to 87 km. Results show that raw residual chlorine is constantly depleted along the pipeline, and is therefore unable to be maintained at the required level of 0.2 mg/l, as stipulated by the Department of Water Affairs. This means that if any harmful contaminants should enter the water, the residual chlorine in the water will not be able to protect the consumers from the contaminants.
Optimal modelling of non-revenue water: A case study of Lebohang extension 9 and 10 in Govan Mbeki Municipality, Mpumalanga, South Africa
(Vaal University of Technology, 2023-01-15) Mlangeni, Ready Victor; Ochieng, G. M., Prof.
South Africa was declared a water scarce country with an annual runoff that is estimated to be less than 13 percent against the world average. South African municipalities are in position of providing accurate water balance data which is necessarily to measure the level of NRW. However, majority of them don’t keep accurate records of their input volume or billed consumption. The study done by South African Water Research Commission which analysed 62 system has estimated total water losses (real and apparent) to be 31 percent of total supplied water. (McKenzie: 2014) The global volume of non-revenue water (NRW) or water losses is overwhelming. Each year more than 32 billion m3 of treated water is lost through leakages from the distribution networks. An additional 16 billion m3 per year is delivered to consumers but not invoiced due to various reasons such as of theft, poor metering, inadequate billing systems, or illegal use. In some low-income countries this loss represents 50 -60 percent of water produced, with a global average estimated at 35 percent. Saving just this amount would supply water to an additional 100 million people without further investment in water production and distribution systems. (Simbeye I: 2010) Many studies conducted proved that water loss in South Africa is generally considered high between 30 percent and 70 percent and the cause of these high losses is defined in various studies (McKenzie & Seago: 2007). Many reasons have been tabled as contributing factors to the cause of high level of non-revenue water in general. The reasons include amongst others and not limited to poor planning, pressure management control, insufficient funds, and poor water network implementation. The factors further include inadequate actions in place to address optimization of services, leakage control, inadequate tariff, and collection systems. (Muhamad Shahbani Abu Bakar: 2005) The major challenges towards efficient and effective water delivery to all urban people are usually poor governance, financial constraints, poor network design, poor customer services, and inadequate infrastructure. It is obvious that high levels of NRW result from volumes of water lost through physical leaks or administrative losses from poor customer accounting and billing. This seriously affects the financial sustainability of water service providers. (Simbeye I: 2010)

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