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Thukela Water Project

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Synopsis +
Background +
Introduction +
Inter-Basin Water Requirements and Resource availability +
Feasibility study +
Investigations +
Findings & Conclusions +
Implementation Time Line +
Reports +
Decision support phase +
Thukela Water Project --> Feasibility study

INVESTIGATIONS

It is envisaged that all components of the TWP will be constructed over a period of about 8 to 10 years. The aim of the TWP is to increase the delivery rate of raw water to the VRS, via the Drakensberg Pumped Storage Scheme, by 15 m3/s. Depending on operating regimes, this could add up to more than 450 million m3 of additional water being transferred per annum.

The estimated capital and compensation costs (excluding financing and operating costs) for the TWP amount to just less than R 5 000 million in March 1998 terms.

The following main elements of infrastructure will be required in the scheme (see diagram below):

  • Jana Dam in the Thukela River situated approximately 30 km south-west of Ladysmith and 15 km downstream of the confluence of the Thukela and Klip Rivers.
  • Mielietuin Dam in the Bushman's River, situated between Weenen and Estcourt, and immediately upstream of the western boundary of the Weenen Nature Reserve.
  • 120 km of pipeline aqueduct linking the proposed dams to the existing Kilburn Dam at the foot of the Drakensberg Pumped Storage Scheme.

Due to future uncertainties (e.g. the determination of the Reserve) information has been made available to decision makers within a range of project component sizes from which to eventually select an optimum scheme. A reference scheme size has been suggested at feasibility level.

LONGITUDINAL CROSS SECTION THROUGH THE SCHEME

: Pump Station : Mielietuin to Junction
: Dam Wall : Junction to Kilburn
: Break-pressure Tank : Kilburn to Sterkfontein
: Jana to Junction

 

COMPONENT MAIN RESERVOIRS JANA DAM MIELIETUIN PUMP STATIONS AT DAMS JANA TO MIELIETUIN
    DAM   COLENSO TO COLENSO
        JUNCTION JUNCTION
Cumulative catchment area (km2) 6 600 1 350 Design discharge (m3/s) 10 5
Cumulative mean annual runoff (million m3) 1 446 288 Dam wall level - minimum (masl) (note a) RL 737 RL 957
Storage in catchment upstream (million m3) 863 60 Terminal elevation (masl) (note e) RL 1088 RL 1088
Total storage in dam reservoir (million m3) 1 500 350 Number of main pumps (VSD) (note f) 5
Full supply level (masl) (note a) RL 860 RL 1025 Number of HL booster pumps (FS) (note f) 5 -
Type of dam (note b) RCCG RCCTH Number of LL booster pumps (FS) (note f) 5 3
Height of dam (m) (Planning definition) (Note c) 160 87      
Spillway length (m) and type (note d) 165 FOCS 69 FOCS      
Spillway flood peak discharges (m3/s) (Attenuated)     AQUEDUCT PUMPING STATIONS RUSTENBURG BETHANY PS
   1:200 4 400 825   PS TO TO KILBURN
   Regional Maximum Flood 6 900 1 700   BETHANY DAM
   Peak Maximum Flood 12 800 4 200 Forebay water level - minimum (masl) (note a) RL 1061 RL 1211
   Total freeboard (m) 11 9 Main pumps elevation (masl) RL 10 50 RL 1200
Construction volumes in wall and tailpond dam     Terminal elevation (masl) (note e) RL 1217 RL 1260
Excavation (all materials incl rock) (million m3) 3.08 0.34 Number of main pumps (FS) (note f) 7 6
   Drilling & grouting (m) 50 550 24 300 Number of booster pumps (FS) 7 -
   Concrete (million m3)          
   Roller compacted 2.96 0.47      
   Mass (20 MPa) 0.6 0.01      
   Structural (25 MPa) 0.14 0.02      
   Reinforcing (metric tons) 12 000 1 920      
   Dam wall construction period (years) 5 3      
           
AQUEDUCTS (Pipeline) JANA TO MIELIETUIN JUNCTION TO RUSTENBURG PS RUSTENBURG BETHANY
  COLENSO TO COLENSO   PS TO  TO KILBURN
  JUNCTION JUNCTION   BETHANY DAM
Design discharge (m3/s) 10+ 5- 15 15 15
Pipeline nominal diameter (m) 2.4 1.8 3.0 3.0 3.0
Length of pipeline (km) 25.6 19.6 24.6 22.4 29.4

 

NOTE:  

a

masl = metres above mean sea level
  RL = Reduced level

b

RCCG = Roller Compacted Concrete Gravity Section
  RCCTH = Roller Compacted Concrete Thick Arch Section

c

Planning definition : Height of Fully Supply Level above river bed level

d

FOCS = Free Overflow Central Spillway

e

Terminal elevation : at next forebay/pumpstation
  VDS = Variable speed drive motor
  FS = Fixed speed drive motor
  HL = High level (eg Jana pump elevation RL900)
  LL = Low level (eg Jana pump elevation RL780)

 

Jana Dam

The Jana Dam site is situated in the Thukela River approximately 30 km south-east of Ladysmith and 15 km downstream of the confluence of the Thukela and Klip Rivers. The site is remote and the terrain rugged with steep valley sides.

The Roller Compacted Concrete Gravity structure will be founded on competent sandstone/dolomite formations. Adequate sources of aggregate are located immediately upstream of the wall and well below the full supply level of the reservoir.

A central stepped ogee spillway with the possibility of a gated side channel spillway down the left abutment has been proposed. A model study of the spillway will need to be undertaken during the Design Phase in order to refine the design details by evaluating the hydraulic performance of the spillway and the competence of the downstream river bed and banks during major flood events. An option seriously considered during the Feasibility Study is the creation of a plunge pool behind a 40 m high tail pond dam.

The capital cost, i.e. excluding design, supervision, compensation and environmental costs, of Jana Dam has been estimated to be between R 1.2 and R 2 billion, depending on the final size and type of dam to be constructed.


Aerial view of dam site at Jana

Jana & Mielietuin Dam Locality Map

Mielietuin Dam

Proposed Mielietuin Dam site

The Mielietuin site is situated between Weenen and Estcourt at a narrowing of the Bushman's River valley immediately to the west and upstream of the Weenen Nature Reserve. The area in which the site is located is reasonably accessible and the basin is relatively flat. The gradients of the valley sides are only steep in the immediate vicinity of the wall site.

Exploration drilling has revealed a massive, competent, unweathered dolerite sill underlying the wall site. Once out of the 90 m deep gorge, the more gently sloping flanks are capped with shallow sandstone. Rock formations suitable for construction aggregates are readily available to construct a Roller Compacted Concrete Arch dam, with an uncontrolled central ogee spillway and Roberts splitters discharging into a tail pond. Although outlet works will be included in the wall itself, intake works for transferring water will be in a separate tower situated about 1 km upstream of the wall.

The capital cost, i.e. excluding design, supervision, compensation and environmental costs, of Mielietuin Dam has been estimated at between R 300 and R 400 million depending on the final size of dam to be constructed.

Aqueducts

An open canal was originally proposed to convey water from the storage dams to Kilburn Dam. However, affected parties in the Thukela River Catchment voiced their concerns, primarily environmental, over this method of conveying water. A steel pipeline was investigated as an alternative during the Feasibility Study.
 

View of open canal
The open canal would have a length of 183 km with three booster pumping stations en route. In contrast, the route of the steel pipeline would be more direct (121 km) and only two booster pumping stations would be required. Although the less expensive steel pipeline is presently the recommended alternative, the open canal remains an option.

Aqueducts will link the proposed dams and the existing Kilburn Dam from which water will be transferred to the VRS via the existing Drakensberg Pumped Storage Scheme. Three aqueduct options were investigated, viz:

  • A single pipeline ranging from 1.6 to 3.4 m in diameter or double pipeline along the same route.
  • Open canals (with limited lengths of tunnel, pipeline and inverted siphons).
  • A combination of open canals and pipelines.

The overall length of the pipeline option from Jana and Mielietuin to Kilburn Dam would be 121 km. This length includes a deep cut or tunnel (approximately 1 km long and 20 m deep) about 12 km east-south-east of Kilburn Dam.

A 30 m fenced construction servitude is envisaged. A permanent unfenced servitude of approximately 20 m would be required after construction, without a permanent service road. The pipeline will be covered by approximately 1.8 m of soil. Large on-site construction housing camps are not envisaged. Accommodation for the work force should be situated in existing towns wherever possible.

The construction time associated with a pipeline aqueduct is likely to be about three years. The aqueduct can be sub-divided into a number of contracts, probably five. Pipe laying would proceed at a rate of about three weeks per kilometre. The construction of the pipeline aqueduct would also include the construction of valve chambers, crossings under roads and railways, scour outlets and river crossings, water hammer protection devices, flow metering equipment and inspection access facilities. There would be a pump station at each dam plus two intermediate pump stations along the route of the pipeline.

Importantly, because of spare capacity at Eskomís Drakensberg Pumped Storage Scheme, no additional pumping capacity is required to transfer water from Kilburn Dam to the VRS. Not only does this increase the efficiency of the use of existing infrastructure, it represents a significant capital saving.

Construction of the TWP could take eight to ten years to complete. The date of commencement would depend on the growth in water demand in the VRS, and the suitability of the TWP when compared to other strategic alternatives.

Regional Development

By deciding to base the TWP Feasibility Study Office in Ladysmith, the DWAF has gained the benefit of understanding the institutional and social dynamics that drive the uThukela Region.

The TWP Project Management Team has played an important role in establishing various regional development and economic forums within the uThukela District Municipality. These forums and other business and labour organisations have been empowered with the necessary knowledge to be in a position to capitalise on and optimise spin-offs that could accrue to the uThukela Region as a consequence of the TWP.

Numerous benefits have been identified by a dedicated KwaZulu-Natal based team during the course of the feasibility investigations. These opportunities can be grouped as follows:

  • Community development and social welfare
  • Tourism
  • Commercial and industrial
  • Agriculture
  • Skills training and capacity building
  • Labour enhanced construction
  • Materials procurement
  • Logistics and communications
  • Electrification
  • Roads and transport
Numerous benefits have been identified by a dedicated KwaZulu-Natal based team during the course of the feasibility investigations. These opportunities can be grouped as follows:
  • Community development and social welfare.
  • Tourism.
  • Commercial and industrial.
  • Agriculture.
  • Skills training and capacity building.
  • Labour enhanced construction.
  • Materials procurement.
  • Logistics and communications.
  • Electrification.
  • Roads and transport.

It is considered highly probable that the National Government can realise many of its policy objectives such as poverty alleviation, local economic development, job creation and empowerment through regional development opportunities arising from the TWP.

Another important component of facilitating regional development was to gain a thorough understanding of bulk water supply for domestic and industrial use in the greater Ladysmith/Emnambithi area. This investigation was necessary in order to take full cognisance of future water requirements of this area, the main in-basin water user. The product of this investigation, funded by the DWAF, was a comprehensive assessment of the bulk water supply options for the area.

However, it is evident that a special effort will be required to ensure that the benefits arising from the TWP are optimised for the people of the uThukela Region and KwaZulu-Natal. This can be achieved by close co-operation between the DWAF, the uThukela District Municipality, the Provincial Office of the Department of Land Affairs, the KwaZulu-Natal Department of Traditional Affairs and Local Government, the KwaZulu-Natal Department of Agriculture and Environmental Affairs, the Implementing Agent, and local business and labour organisations. This is necessary in order to align with existing development plans and even to formulate specific TWP spin-off strategies, for example, procurement policies, SMME policies and incentive schemes.

Environmental Aspects

During feasibility level environmental investigations, nothing was found to indicate that the TWP should immediately be abandoned or that there was high risk in proceeding to the next phase of investigation which will include an Environmental Impact Assessment and Reserve Determination.

The TWP is a large and complex development intervention originating from policy level decisions within National Government. These policies relate not only to strategic water supply. Other policies such as poverty alleviation, job creation, land reform, economic empowerment of previously disadvantaged people, and the establishment of equity in resource access have also been considered.

It is a project that will have profound effects at various levels and in many different ways over a long period of time, and will directly affect the quality of life of large numbers of people. There is, therefore, a specific onus on the DWAF to ensure that environmental considerations are accorded appropriate recognition and respect in the administrative processes and planning activities which they undertake.

The environmental feasibility of the TWP was, therefore, assessed at three levels:

  • National strategic policy level.
  • Regional level.
  • Site specific level.

The environmental investigations showed the following to be of particular importance:

National strategic policy level

  • The Reserve (basic social and natural river water requirements for the Thukela River and its tributaries) has not yet been determined.
  • A formal strategy is currently being developed for the management of the water resources of the Thukela River as part of a national water resource management strategy.
  • A decision not to augment the water resources of the VRS would potentially simulate trends synonymous with a slump in the national economy. There would be job losses and increasing levels of unemployment, a reduction in disposable incomes, and a shortage of funds (through taxes) for national development initiatives.
  • Implementation of the TWP would require political support at National, Provincial and Local Government levels.
  • The ramifications of negative international and domestic sentiment regarding big dams should be considered in the decision making process.
  • Issues around the effects of AIDS are not yet fully understood.

Regional level

  • A comprehensive understanding of the sediment movement processes in the Thukela River, their cause and effect, is essential and of fundamental importance to a full understanding of the feasibility of the TWP. In the Feasibility Study, work on the subject was started but much still remains to be done.
  • The TWP presents a unique opportunity to stimulate and kick start considerable development and economic empowerment in the Thukela Region. However, this is unlikely to occur if comprehensive regional development plans and spatial planning for regional and local government structures are not implemented. To do this effectively will require proactive participation of all institutions to accept joint responsibility in social upliftment programmes. There is a significant opportunity for effective liaison, communication and joint action by National, Provincial and Local Government Departments.
  • Unacceptable levels of crime and security may occur as a result of poverty, AIDS-orphans, migration and easier access throughout the region, related to the implementation of the TWP and the investment in infrastructure and other services. To combat this will need policing, combined with integrated regional development planning and implementation. There will also have to be effective communication, liaison and joint action by National, Provincial and Local Government Departments.

Site specific level

  • Initial investigations have revealed that the construction of a dam at Jana and flooding of the basin will bring about the loss of a large contiguous area of Northern Valley Bushveld, which is endemic and a threatened veld type in KwaZulu-Natal.

The loss of this habitat and potentially of certain fauna makes this issue important, specifically because of legal principles in NEMA, and international agreements on biodiversity, of which South Africa is a signatory.

  • Flooding of the impoundments will cause economic, physical and cultural disruption to landowners, farm labourers and communities currently resident in the potential dam basins.

Approximately 74 private land-owners, 40 labourer families, 2 tenant families and up to 450 households along the aqueduct route and, to a lesser extent, in the in the dam basins could be affected either economically or physically. Both communal subsistence agriculture and commercial farming enterprises will be affected. This includes arable and grazing land.

  • Resettlement is a highly emotive and sensitive issue. The process will have to be planned carefully, transparently and inclusively. If not handled properly, it has the potential to substantially disrupt the implementation of the TWP.

All of the negative impacts can be investigated and managed satisfactorily. So too can positive impacts be enhanced by special intervention.

Although a significant amount of environmental baseline assessment has been conducted during the Feasibility Study, it is intended that a comprehensive Reserve Determination (in progress) and full Environmental Impact Assessment (in the future) will complement existing information.

Financial and Economic Viability

Financial and economic cost benefit and sensitivity analyses have been undertaken as part of the TWP Feasibility Study. Variables considered were the following:  the affect of using different discount rates, the affect of different values of water for estimating the benefit of the water transferred, the affect of increasing the capital cost of the TWP, and the minimum water transfer rate necessary to ensure break-even between costs and benefits.

Results show that the benefit cost ratios are all significantly greater than one over the full range of sensitivity tests. This is considered favourable and from a financial and economic cost benefit perspective, the Thukela Water Project is viable, yielding acceptable rates of returns.

Macro Economic Impact Analysis

A social accounting matrix has been developed to estimate the macro economic impact of the TWP. Importantly, it has been assumed that the benefits or forward linkages arising from the supply of water to the VRS would be the same, irrespective of the source of water. This analysis was, therefore, focussed on the macro economic impact that the TWP would have on the uThukela Region and the Province of KwaZulu-Natal.

A summary of the major impacts is as follows:

Gross Geographic Product
Economic activity measured in terms of Gross Geographic Product should increase by at least 10 % in the uThukela Region and 0.5 % in KwaZulu-Natal. However, if a special effort is made to comply with Government objectives to stimulate the local economy through pro-active intervention, then these anticipated impacts could increase significantly.

Employment
Assuming traditional construction methods are employed, i.e. machine intensive, it is estimated that more than 4 000 construction jobs will be created in the uThukela Region and an additional 2 000 jobs in KwaZulu-Natal. However, if a diligent effort is made to enhance the labour content of construction practices, then the number of job opportunities created could be significantly greater.

Factor payments (labour)
Skilled and semi-skilled labour constitutes a high percentage of the direct and indirect workforce required for the construction of the TWP. By inference, if appropriate training is not provided for the local economically active workers, then the advantages of the proposed scheme could be somewhat negated.

Commodities
The demand for various commodities, for example, construction materials, and intermediate and consumer goods, is anticipated to be high, creating opportunities for the manufacturing, commercial and service sectors. However, it is believed that the entrepreneurial sector in the uThukela Region and KwaZulu-Natal will require assistance to capture this demand to ensure that the source catchment optimises benefits arising from the TWP.

Enterprises (capital)
As can be expected, almost two thirds of the enterprises employed during the construction of the TWP will fall into the civil engineering sector. It is estimated that 10 % of the total benefits accruing to enterprises will go to emerging contractors.

This is considered reasonable given the type of construction activity to be undertaken. However, the social accounting matrix indicates that by using traditional implementation methodology, only a small percentage of the various benefits will accrue to local community-based businesses. This is considered unacceptable and, therefore, proactive intervention will be required to achieve Government objectives.

Households (income)
It has been noted that, during the construction phase, the distribution of income between rural and urban households, will be urban orientated. This phenomenon requires investigation and, if necessary, counter measures will need to be formulated in support of predominantly rural communities in the uThukela Region. With regard to the distribution of income groups, equity was found in the projections for the construction phase. Importantly, however, income distribution during the operational phase tends towards the lower income groups.

Financial Arrangements

At this stage in the project cycle, only a superficial analysis of possible institutional and funding options has been undertaken, mainly to gain a perspective on how various models will impact on the timing of the TWP.

Various models, ranging from Government as the sole implementing agent, through a public private sector initiative to a mainly private sector undertaking, have been considered. However, more detailed analysis will be required with the involvement of the Public Private Sector Partnership Task Team of the Department of Finance. 

FINDINGS AND Conclusions + - To the top

Arising from the Feasibility Study, it can be concluded that the Thukela Water Project:

  • Is technically, environmentally (natural and social) and economically feasible.
  • Up to 15m3/s (about 450 million m3/a) can be transferred out of the Thukela River catchment, in addition to the existing transfer to the VRS via the Thukela Vaal Project at the Drakensberg Pumped Storage Scheme, without negatively affecting existing and projected long-term water use in the Thukela River Catchment, while also maintaining the sustainability of riverine ecosystems.
  • The most attractive means of transferring water from the Thukela River to the VRS is to develop the proposed TWP comprising major dams at Jana in the Thukela River and at Groot Mielietuin in the Bushman's River, a pipeline from the two dams to the existing Kilburn Dam at the Drakensberg Scheme, pumping stations and associated infrastructure.
  • The proposed project is a cost-effective means of augmenting water supply to the VRS, benefiting from the capacity of the existing Drakensberg Scheme to lift the additional water required over the Drakensberg mountains to the VRS.
  • The project can be implemented at any time to provide additional water to the VRS (when required).
  • The development proposals are situated in the relatively poor uThukela Region of KwaZulu-Natal; the local and regional economy can enjoy potentially large benefits from investment of the capital amounts and the creation of temporary and permanent employment opportunities.
  • Development and operation of the project can be managed in a way which can make a major contribution to achieving Government objectives such as poverty alleviation, employment creation, equitable access to resources, integrated rural development and co-operative governance.
  • The TWP is a strategic development option which will have consequences, both negative and positive, in the source basin, in the VRS and throughout the national economy.
  • The two major dams comprising the development proposals are significant in size and technically complex by world standards, and will be subject to local, regional and global scrutiny for compliance with current best practice world-wide and for irrefutable evidence that they represent the best available response to the growing water demand in the VRS.
  • Conceptualisation, planning, design, evaluation, implementation and operation of the TWP will be the focus of ongoing interest and scrutiny from all quarters and the relevant information must be made readily accessible to facilitate evaluation.
  • At a regional level, the development proposals will have major temporary impacts during the construction phase as people move into the region with negative social consequences. Training and skills development for local job seekers should increase dramatically. Business and commercial opportunities in the region are expected to expand. Infrastructure, such as roads and electricity supply, will be developed and environmental disturbances such as noise, dust and loss of sense of place will occur.
  • Permanent consequences of the project at a regional level will be some increase in employment opportunities, expanded road and other infrastructure, expanded opportunities for tourism business and commerce, and a significant change in the flow regime of the Thukela River.
  • At a local level, construction of the project will have severe negative consequences for a limited number of people directly affected by the works, negative impacts on the environment as work areas are disturbed and destroyed, an invasion of the privacy and lifestyle of some people close to the work areas, and positive consequences for those who are employed on the works (perhaps for the first time in some recently established land reform settlements).
  • The project will cause permanent negative local impacts as inundation of the dam basins, particularly the dam at Jana, destroys highly valued valley bushveld ecosystems, some people will have to be relocated to make way for the dams and aqueduct, commercial farmers and tourism operators will have to sell their properties, the sense of place wilderness-like areas would be destroyed and the sediment regime and river morphology downstream of the main dams could be disturbed if adequate mitigatory measures are not implemented.
  • Negative consequences of the TWP can be mitigated and managed in an affordable and sustainable manner to avoid, minimise, and in some cases only compensate for damage done. Similar affordable impact management strategies can be employed to significantly expand and add value to the many positive opportunities which will be derived from development of the project.
  • Finalisation of project details is dependent on determination of the Reserve for the Thukela River, the outcome of a comprehensive Environmental Assessment and associated Environmental Management Plan.
  • In order to meet the selected target date for delivery of additional supplies into the VRS, it will be necessary to confirm the selection of the TWP from among the alternative strategic options not later than ten year before this augmentation date.
  • Implementation of the TWP at a 1998 capital cost of R 5 billion could probably be beyond the means of the SA Government's expenditure budget and it will be necessary to set up an appropriate implementing agent, probably in some form of partnership with the private sector, to raise the necessary funding,  design and construct the project and operate the system for a period of time. This institutional development would be the critical path to successful implementation to meet the desired target delivery date.

In summary, the Feasibility Study has identified and classified all aspects and issues associated with the future construction of the project in sufficient detail to enable decision makers to compare the Thukela Water Project with other strategic augmentation alternatives. At this stage, further refinement is occurring as part of the recently launched Decision Support Phase.

IMPLEMENTATION TIME LINE - To the top

The implementation time line indicated alongside has been used during the Feasibility Study as being the soonest that VRS water augmentation would be required.
PROJECT TIME LINE FROM RECONNAISSANCE TO IMPLEMENTATION

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