8. Recommended Projects
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8. RECOMMENDED PROJECTS 8.1 Overview Section 6 of this Infrastructure Master Plan describes each of the water supply systems within the Umgeni Water area of operation, discusses the constraints identified within each one, and makes recommendations on the water supply infrastructure that is required to alleviate these constraints. Figure 8.1 illustrates the systems and subsystems that each of the recommended projects belongs to, and should also be read in conjunction with Figure 6.1. This Section links directly to Section 6, and describes each of the recommended infrastructure projects of significance in more detail. In particular, projects currently being implemented, or are close to implementation, are discussed. A summary of the areas that will be supplied by these proposed projects are shown in Figure 8.2. The projects per WSA are summarised in Figure 8.3, Figure 8.4, Figure 8.5, Figure 8.6 and Figure 8.7. Also included in this Section, are descriptions of new infrastructure projects that have been identified to expand the area of supply. These projects are often planned to be linked into existing supply infrastructure and their future demands could impact on the existing infrastructure. These potential impacts are discussed in Section 6. It is important to note that the implementation of these projects is influenced, and driven, by a host of factors besides purely technical requirements. These factors include financial constraints, corporate strategy, politics and local government priorities, to mention but a few. All these factors carry their own weight in the decision making process and cannot be ignored. Hence the actual implementation and timing thereof, could well vary from what is mentioned for these projects. Finally, all planned new wastewater works (WWW) or proposed upgrades to WWW that Umgeni Water is responsible for are included at the end of this section. These proposals should be read in conjunction with Section 7. As previously mentioned in Section 7, Umgeni Water has recently taken over the operation of all the WWW within the uMgungundlovu District Municipality. Umgeni Water is assessing the nature of infrastructure development and/or rehabilitation required at these works. This assessment is currently taking place and therefore there are no definitive plans to report on at this stage. However, the Darvill WWW is in the process of being upgraded and the detailed design for the upgrade of Mpophomeni WWW has been completed and these two WWW are therefore discussed in detail. 408 Figure 8.1 Recommended projects per system. 409 Figure 8.2 Areas that are anticipated to be supplied by Umgeni Water’s proposed projects. Figure 8.3 Proposed projects within uMgungundlovu WSA and the areas anticipated to be supplied. 410 Figure 8.4 Proposed projects within eThekwini WSA and the areas anticipated to be supplied. Figure 8.5 Proposed projects within Harry Gwala WSA and the areas anticipated to be supplied. 411 Figure 8.6 Proposed projects within Ugu WSA and the areas anticipated to be supplied. Figure 8.7 Proposed projects within iLembe WSA and the areas anticipated to be supplied. 412 8.2 uMkhomazi System 8.2.1 uMkhomazi Water Project Planning No. 114.0 Project No. UI0530 Project Status Detailed Feasibility Project Description With the commissioning of Phase 2B of the Mooi-Mgeni Transfer Scheme (MMTS-2), the water resources available in the Mooi and Mgeni catchments, to augment the Mgeni System, are now fully utilised (Section 5.4.4). The MMTS-2 increased the safe assured yield of the Mgeni System to 394 million m3/annum. Over recent years, eThekwini Municipality has put considerable effort into optimising the operation of its distribution systems that are served by the Lower Mgeni System. Amongst other things, this has led to them implementing new infrastructure in order to undertake a significant load shifting exercise. eThekwini Municipality’s Western Aqueduct project, which is expected to be fully commissioned in mid-2018, will represent the most significant of these load-shifting operations. The intention is for those areas currently being served under pumping from the Lower Mgeni System (viz. from Durban Heights WTP) to be transferred onto the Upper Mgeni System, and served under gravity from Midmar WTP via the Western Aqueduct (WA). This will result in the full utilisation of the Upper Mgeni resource by 2018. After the implementation of MMTS-2, further water resource developments within the Mooi-Mgeni system are not considered to be beneficial. Further augmentation of the Mgeni System will then be required. Water resource development on the uMkhomazi River has been identified as the next major project to secure long-term water resources for eThekwini’s Western Aqueduct supply zone. During the late 1990’s, the then DWAF (now DWS) and Umgeni Water jointly commissioned a pre-feasibility study to investigate various options for developing the uMkhomazi River’s water resources, such that they could be utilised to augment those of the Mgeni River System. A two-phased scheme was proposed, and the overall project area is shown in Figure 8.8. Phase 1 of the proposed uMkhomazi Water Project (uMWP-1) will involve the construction of Smithfield Dam, located along the central reaches of the uMkhomazi River midway between Lundy’s Hill Bridge and Deepdale. Smithfield Dam will be the primary impoundment, whilst for Phase 2, a second dam (Impendle Dam) will be constructed upstream of the Smithfield site (just downstream of the uMkhomazi River/Nzinga River confluence). Phase 2 would only be implemented once the yield of Phase 1 (Smithfield Dam) has been fully utilised. 413 Figure 8.8 uMkhomazi Water Project. Succinct details of the proposed potable water infrastructure are as follows: Water treatment plant design: In order to meet the proposed phased increases in demand as well as a requirement to provide support to the Mgeni System, the capacity of the uMWP-1 WTP is proposed to be 500 Ml/day. A further 125 Ml/day phase would be required in 2044. The proposed WTP layout (Figure 8.9) was constrained by the requirement for gravity supply in the overall system between Smithfield Dam and the Umlaas Road tie-in, as well as a requirement to keep the WTP footprint to a minimum. The proposed plant layout combines features of accessible and compact unit process configuration, minimum lengths of interconnecting pipework, minimum volume of excavation and ease of future extension. The recommended WTP processes are pre-chlorination, coagulation/flocculation, high-rate clarifiers, rapid gravity filtration, granular activated carbon (GAC) filtration, final chlorination and sludge treatment. Figure 8.9 Layout of Water Treatment Plant. Potable water reservoir: The potable water reservoir was sized to accommodate a minimum of six hours of the daily WTP capacity. Based on the WTP phasing discussed above the first 500 Ml/day WTP phase would require 125 Ml of storage, with a further 31.25 Ml/day required when the next 125 Ml/day WTP phase is constructed in 2044, i.e. a total of 156.25 Ml of storage for the uMWP-1. The reservoir for the uMWP-1 would require a footprint of 2.2 hectares. In light of a requirement to keep the WTP footprint to a minimum, it was proposed that potable water storage be constructed beneath various WTW structures. Potable water pipeline: The potable water pipeline (Figure 8.10) was designed to accommodate an average annual daily demand of 602 Ml/day; equivalent to the 1:100 year yield of the Smithfield. The peak design capacity was 753 Ml/day. Pipelines ranging from 2 820 mm diameter (15.1 km) to 2 540 mm diameter is proposed to convey the peak demand of 753 Ml/day. 415 Figure 8.10 Layout of pipeline. Key information on this project is summarised in Table 8.1. Table 8.1 Project description: uMkhomazi Water Project. Project Water Resource Components (to be developed by DWS): Components . Smithfield Dam – having a storage capacity 251 million m3 (31% of MAR), earth core rockfill dam. A Transfer Tunnel – 3.5 m bored diameter (3.0 m lined diameter), concrete-lined (where necessary), overall length of 32 km. Balancing Dam – located at the outlet portal of the tunnel in the vicinity of Baynesfield Estate. 3km of 3 000 mm Raw Water Pipeline. Potable Water Supply Components (to be developed by Umgeni Water): . Water Treatment Plant (WTP) – to be located near Baynesfield Estate with an initial capacity of 500 Ml/day and allowance for further module to increase capacity to 625 Ml/day. 156.25 Ml potable water storage reservoir at WTP. Bulk Potable Water Pipelines –2 820mm diameter (15.1 km) and 2 540 mm diameter (4.6 km) gravity mains from the WTP to ’57 pipeline. Capacity 625 Ml/day Institutional Arrangements DWS will plan, develop and own the water resource and raw water infrastructure up to the WTP. The operation and management component of this infrastructure will be decided at the time of commissioning. Umgeni Water will design, build, own, operate and maintain all water supply infrastructure from (and including) the WTP. Umgeni Water will purchase raw water from DWS as per a revised raw water agreement and sell potable water from this system to eThekwini, the Msunduzi and uMgungundlovu municipalities, as per the existing bulk water supply agreements. 416 Beneficiaries The scheme will primarily serve the eThekwini Municipal area and to a lesser extent portions of uMgungundlovu District Municipality. Assuming 200 l/person/day, the estimated number of beneficiaries from the anticipated capacity of 625 Ml/day may be 3 125 000 people. Implementation The project is divided into three components: Module 1: Technical Feasibility Study: Raw Water (Appointment by Department of Water and Sanitation).