CURRENT FUTURE FLOWS Final Revision.Doc
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SEDIIBENG REGIIONAL SANIITATIION SCHEME A STUDY OF CURRENT AND EXPECTED FUTURE SEWER FLOWRATES TO DETERMIINE THE WASTEWATER TREATMENT CAPACITY REQUIREMENTS OF THE REGIION UP TO 2025 FINAL DRAFT NOVEMBER 2008 A STUDY OF CURRENT AND EXPECTED FUTURE SEWER FLOWRATES TO DETERMINE THE WASTEWATER TREATMENT CAPACITY REQUIREMENTS OF THE REGION UP TO 2025 CONTENTS Chapter Description Page 1 INTRODUCTION AND BACKGROUND 1 1.1 Background to the Study Area 1 1.2 Scope of the Study 1 1.3 Overview of the Existing Wastewater Treatment in the Region 3 2 AN EVALUATION OF FACTORS AND TRENDS INFLUENCING CURRENT AND FUTURE SEWER FLOWRATES 5 2.1 Current Demographics and Service Levels 5 2.1.1 Emfuleni Local Municipality 5 2.1.2 Midvaal Local Municipality 7 2.2 Population Growth Projections – Emfuleni and Midvaal 9 2.3 Future Land Use and Residential Developments 10 2.3.1 Emfuleni Local Municipality 10 2.3.2 Midvaal Local Municipality 11 2.4 Anticipated Improvements in Sanitation Levels of Service 12 2.4.1 Emfuleni Local Municipality 12 2.4.2 Midvaal Local Municipality 13 3 CALCULATIONS OF CURRENT AND FUTURE SEWER FLOW RATES 14 3.1 Calculation of Current Sewer Flows 14 3.1.1 Emfuleni Local Municipality 14 3.1.2 Midvaal Local Municipality 15 3.2 Calculation of Future Sewage Flow Rates 16 3.2.1 Emfuleni Local Municipality 16 3.2.2 Midvaal Local Municipality 17 3.2.3 Consolidated Future Sewage Flow Rates 18 4 CONCLUSIONS 20 Current and Future Sewer Flows Rev 01 Figures Figure 2.1 Emfuleni population distribution per settlement type ............................................. 6 Figure 2.2 Midvaal household distribution per settlement type............................................... 7 Figure 2.3 Emfuleni Population Growth ................................................................................. 9 Figure 2.4 Midvaal Population Growth................................................................................... 9 Tables Table 1.1 Overview of Treatment Works in the Study Area ................................................... 3 Table 3.1 2008 Sewer Flows for Emfuleni ............................................................................14 Table 3.2 Current Sewer Flows for Midvaal..........................................................................15 Table 3.3 Projected Future Flows for Emfuleni (AADF – Ml/day) ..........................................16 Table 3.4 Projected Future Flows for Midvaal (AADF – Ml/day)............................................17 Table 3.5 Consolidated Future Flows for the study area.......................................................18 Table 3.6 Sebokeng Catchment Sewer Flows .....................................................................18 Table 3.7 Consolidated Future ADWWF Flows (Excluding Sebokeng and Johannesburg)...19 Current and Future Sewer Flows Rev 01 1 INTRODUCTION AND BACKGROUND 1.1 Background to the Study Area Emfuleni Local Municipality (Emfuleni) and Midvaal Local Municipality (Midvaal) are located along the southern boundary of Gauteng Province in an area known commonly as the Vaal Triangle. These municipalities fall within the Sedibeng District Municipality (Sedibeng), a large district extending along the southern region of Gauteng Province between the adjacent provinces of Mpumalanga and North West. The Vaal River forms the southern boundary of Sedibeng, and also serves as the boundary with the Free State Province. Emfuleni covers an area of just under 990 square kilometres with its main economic and commercial nodes being Vanderbijlpark and Vereeniging. Vanderbijlpark was originally established to house the workers of the Mittal (previously ISCOR) steel company. Evaton, Sharpville and Sebokeng are predominantly residential areas within Emfuleni and also linked to the Mittal steel factory. Midvaal on the other hand, is the largest municipality (by area) in Gauteng Province - covering an area of 2000 square kilometres. Urban areas are located in the towns of Meyerton and Vaal Marina, which are developed around a Central Business District. Residential densities decline from the Central Business District outwards with low- income residential areas being situated on the outer edges of the towns. Lesser-urbanised towns are also found at De-deur, Daleside, Walkerville, Henley on Klip, Riversdale, Risiville, Ohenimuri, Klipwater, Kliprivier, Highbury, Riversdale and Rothdene. Appendix A illustrates a map of the study area. 1.2 Scope of the Study This sewer flow estimation study is a component of the overall larger project entitled “Sedibeng Regional Sanitation Scheme” jointly undertaken by Sedibeng, Emfuleni and Midvaal Municipalities, and implemented by Arcus GIBB and its partners. Current and Future Sewer Flows 1 Rev 01 The primary goal of the overall project is to eliminate polluted discharges into the Vaal Barrage and its catchments. It was generally accepted that a 2 phased approach is required to address the problem of discharges, as follows: PHASE 1 – dubbed short term, was to rectify the most serious shortcomings at the pump stations and at the Rietspruit and Leeukuil works. PHASE 2 – the long-term solution, concentrates on reducing the number of pumpstations to a bare minimum and also rationalising the treatment aspect. The project by Arcus GIBB is geared to Phase 2 – ie. to enable the Sedibeng Regional WWTW to become operational as soon as possible in order to limit non- compliant effluent discharges into the Vaal Barrage. The objective of the project is to carry out a feasibility study into the site selection, and design parameters to construct a Regional WWTW, which will cater for the future requirements of the entire Region up to year 2025. The envisaged benefits of a Regional sanitation scheme will be: Elimination of problematic sewage pump stations as much as possible Scale of economics with regard to the proposed Regional WWTW Improved effluent quality – and hence reduced environmental pollution Reduced operational and maintenance costs Growth and development of the Region –job creation, skills development, and SMME development The objective of this “flows” estimation study is to predict the current and future wastewater generation and hence treatment requirements up to year 2025. This information will inform the site selection and conceptual design components of the Regional WWTW and outfall sewer route selection. In estimating the future wastewater generation this study factors in, amongst other information, the available population figures, census results, growth forecasts, planning information from the spatial development frameworks, water services development plans, information from Housing departments integrated development plans. Current and Future Sewer Flows 2 Rev 01 The above information guided the study team as to where future residential and other developments were likely to take place in the Region. This will have a direct impact on the future demand for wastewater treatment services. Finally, the current and future wastewater flows from areas outside the study area, which contributes to the Sedibeng Region (such as Johannesburg), were analysed. 1.3 Overview of the Existing Wastewater Treatment in the Region The Sedibeng Region is currently being serviced by six sewage WWTW - with three works located in Emfuleni and Midvaal respectively. The diagram in Appendix B points out the geographic location of the treatment works as well as the catchment areas associated with each treatment works. Table 1.1below summarises the design, location and feeder catchments of the six existing treatment works. Table 1.1 Overview of Treatment Works in the Study Area Name of Treatment Treatment Municipality Catchment Comments Works Capacity Areas Evaton, 100Ml/day Sebokeng 100Ml/day Emfuleni Sebokeng, South BNR of Johannesburg, 11Ml/day Rietspruit 25Ml/day Emfuleni Vanderbijlpark, BNR Vereeniging, 20Ml/day Leeukuil 35Ml/day Emfuleni Sharpville, Three BNR Rivers Meyerton, Henley Meyerton 8Ml/day Midvaal 8Ml/day BNR on Klip Package Ohinimuri 1Ml/day Midvaal Ohinimuri Plant Package Vaal Marina 1Ml/day Midvaal Vaal Marina Plant Current and Future Sewer Flows 3 Rev 01 Discussions with Municipal officials indicate a preference for Ohinimuri WWTW to be closed. Also, as per the Client’s instruction, the Vaal Marina WWTW is not analysed in the scope of this study. Hence the Sedibeng region has a total sewage treatment capacity of 168Ml/day (combined Biological Nutrient Removal (BNR) plus Trickling Filters). It is generally accepted that BNR treatment plants are required to meet the DWAF discharge standards. The combined BNR treatment capacity of Sedibeng is 139Ml/day (and 39Ml/day if one excludes Sebokeng). The Sebokeng WWTW is able to meet the DWAF effluent discharge standards. It is also important to note that the Sebokeng WWTW has part of its catchments located across the Emfuleni borders, notably south of Johannesburg and parts of Midvaal. Leeukuil WWTW also receives part of its inflow sewer from Risiville, Duncanville Extension 3, Mackay and Uitgvilt which are areas in Midvaal. Meyerton WWTW receives sewer from Rustervaal and Roshnee, which are areas located in Emfuleni. These inter-municipality flows of sewer are supported by inter- municipality agreements entered into by the respective municipalities. As illustrated in the diagram in Appendix B the area to the west of the N1 in Emfuleni receives no wastewater services. This is because the area is predominantly farmland. Similarly the diagram also illustrates that the majority of Midvaal receives no wastewater