Quietly Active - Water Sewage & Effluent , May 2009

There has been quiet but active engagement to improve the water-supply situation in Lesotho.

South Africa’s awareness of water issues in Lesotho has been likened to a nodding acquaintance.  Generally there is recognition of the essential water supplies received from the Lesotho Highlands Water Project but little appreciation of the fact that virtually none of this water is available for use in Lesotho itself.  However Lesotho does benefit materially from hydropower generation and is almost completely self-sufficient in this regard.  Royalties paid on the water transferred to South Africa are also a major source of income for the Lesotho exchequer.

Against this background, the government of Lesotho has been quietly but actively engaged in efforts to improve the water supply situation in Lesotho itself with regard to access to safe drinking water.  To this end and stemming from the Millennium Development Goals and World Summit on Sustainable Development 2002, a British company, Parkman, was appointed to undertake a feasibility study to improve the provision of bulk potable water in the Lesotho Lowlands in 2003.

This study was commissioned by the Lesotho Ministry of Natural Resources, through its Commissioner of Water and the Lesotho Ministry of Finance & Planning, and funded by the European Development Fund (EDF) of the European Union (EU).  The final report was published towards the end of 2004.

The Lesotho Lowlands includes the more populous, less mountainous western and southern third of the country, including the capital Maseru and the districts of Butha Buthe, Teyateyaneng, Berea, Morija, Mafeteng, Mohale’s Hoek and Quthing.  In recent years, industrial development was also attracted to these parts of Lesotho, which gave impetus to a latent trend of urbanisation.  This, together with normal population increases, started to put pressure on the limited groundwater and the few instances of river-flow extractions.  Generally households rely on people fetching and carrying untreated water from the rivers except in the more sophisticated urban areas.

The 2004 feasibility study, recognising that dam building in the Lowlands is undesirable, except for the proposed Metolong Dam intended to serve Maseru and environs, recommended the establishment of river-extraction systems to serve the remaining parts of the Lowlands.  For the purpose of the study, the Lowlands is divided into eight supply zones based mainly on catchment areas.  Possible extraction positions were also identified for those zones to be supplied from this source; giving rise to the Lowlands Bulk Water Supply Scheme.  In the case of the central zones, which incorporate Maseru and comprise more that half the Lowlands’ population to be supplied, other studies had previously recognised the best solution was to build the Metolong Dam on the Phutiatsana River.   The feasibility study had also identified three further potential dam sites on other rivers should demand growth require it.

Design team

On the basis of the feasibility study, the government of Lesotho then obtained further EU funding for conceptual and detail design of the scheme and invited proposals internationally.  The duration of the design phase was 18 months.  In the subsequent competitive bidding process, the tender was awarded to Lowlands Water Joint Venture (JV) with the project team working from an office opened by the JV in Maseru. This JV comprised the firms Stewart Scott International (SSI) and its holding company the Dutch DHV group, Jeffares & Green (J&G) of South Africa, Fichtner a German consultancy with experience of EU-funded work, and a Lesotho firm, GWC Consulting Engineers.

The JV was headed by SSI as lead consultant with an engineer from Fichtner - as team leader.  This arrangement was brought about by the requirement that the work had to be done locally in Lesotho and the need for a knowledgeable EU interface.  The work was distributed between the firms with shared responsibility for the design of river intakes, water-treatment works, all pump stations and civil design, while each firm was responsible for all bulk transfer pipeline design in the zones.  SSI for the northern zones (1, 2 and 3), J&G for the central zones (4 and 5) and GWC for the southern zones (6, 7 and 8).  Uniformity of design and coordination were achieved by regular weekly meetings between the three design teams.

Project deliverables

Tenders cover all river intakes, water-treatment works and pipelines.

The first major deliverable on the project was to update projected water demand and river hydrology with confirmed data.

An ‘inception report’ reviewed the feasibility study with the design horizon years from 2020 and 2035.  On its acceptance, conceptual design was undertaken followed by detail design.  This included an environmental impact assessment (EIA) and an extensive public consultation and participation programme.  As a result, tender drawings and documents for design-build contracts were issued.  These cover all river intakes and water-treatment works, as well as conventional construction contracts for all reservoirs and pipelines, to be led by the Lesotho government.  The work to be constructed will comprise 52 pumping stations and a total of 138 reservoirs for the eight different zones, as well as four river intakes with associated treatment plants.  A fifth treatment plant downstream of the planned Metolong Dam, intended to serve Maseru, did not form part of this project but is being designed by members of the same JV.  For operation and management purposes, the original eight supply zones were grouped into five bulk water-supply areas served by several ‘command’ and distribution reservoirs placed strategically.  While the number of pumping stations appears to be significant, most are small and boost supply to more remote areas at the end of the main bulk-water systems, which operate mainly under gravity flow.  Reservoirs and length of distribution pipeline in each area include:


Small reservoirs are, generally, classified as 750 m³ or smaller and usually comprise pressed-steel plate tanks. 
Large reservoirs are typically of the order of 1 000 m³ to 5 000 m³ and are, generally, concrete structures.

There are also several large reservoirs, ranging from 10 000 m³ to 25 000 m³ in volume, serving the main urban centres.

Including the projected price escalation, the value of the works designed for this undertaking amounts to a total of R6 033-million.

Intake design

Intake designs are based on supplying medium-term demand for bulk water to settlements of more than 2 500 people.

With the exception of zones 4 and 5, the system is based on pumping water from the river intakes to the purification works.  From there the treated water is pumped to the command reservoirs.  The treated water then, generally, gravitates to the bulk-storage reservoirs.  As the name of the scheme implies, the works do not include reticulation to individual users.

In the case of zones 4 and 5, the works included in the Lowlands Bulk Water Supply Scheme start with the outflow of treated water from the purification works.  In this instance, the raw water source, the Metolong Dam, its water-treatment works and associated infrastructure form part of a separate project funded by a number of international donors, including the Millennium Challenge Corporation (USA), a consortium of Arabian banks and donor funding agencies, the World Bank, the EU and the government of Lesotho itself.

In three cases, the river intakes are concrete sump structures with submersible pumps and screens to reduce the sand and silt load in the raw water pumped to the purification works.  The screens will be kept clean with regular backwashing by jet pumps designed and programmed into the pumping sequence.  However the process is also expected to require manual cleaning from time to time.  The intake designs were subject to sedimentation studies and modelling by the University of Stellenbosch.  In the case of the Senqu River intake, it takes the form of an intake tower similar to a normal dam intake.  In accordance with normal river-intake design philosophy, the designers positioned the intakes outside river bends where natural scour will assist in reducing the sand and silt load.

Designed for extremes

It is accepted there will be periods of low flow in the rivers during periods of extended drought.  Intake designs have had to take extreme water-level variations into account – for instance, during droughts and floods.  Primarily, the designs are based on supplying medium-term demand for bulk water to all settlements of 2 500 people and above.  For domestic users, this provides for demand of 100 ℓ/capita/day in the urban areas in 2020 and 60 ℓ/capita/day for rural dwellers.  An agreement on these numbers was reached at a stakeholder workshop during the inception report stage of the project.  While the per capita rural-demand figure might be considered a little higher than those used in the region, this figure provides for an allowance to supply smaller settlements en route that do not meet the ‘more than 2 500 people” requirement.

In addition to the domestic and industrial demands, the designs had to contend with the minimum in-stream flow requirements for sustaining the biophysical environment in the rivers affected by the abstraction.  Where appropriate, existing water-supply infrastructure elements were also incorporated into the designs.

Review and funding

The philosophy accepted by the government of Lesotho is to review the capacity of the works again before 2020 against actual demand to determine the eventual expansion requirements up to the year 2035.  The long-term supply may well have to be augmented from other sources.  This issue is being considered by the authorities but does not form part of the project under way.  In all, around 1, 25-million people will benefit from the Lowlands water scheme.  A comprehensive economic and financial evaluation of the scheme has also been undertaken with positive outcomes for financial viability and sustainability.  The financial model is also expected to assist the Lesotho authorities in future decision-making and policy-development processes.  Actual tariffs payable will depend on the type and terms of funding obtained for the scheme.  In addition to the available funding mentioned above, the government of Lesotho is actively seeking further funding required to complete the Lowlands scheme as soon as possible.

Environmental considerations

The EIA for the scheme was a major undertaking in itself.  For the purposes of the EIA, the project area was divided into three regions: north, central and south coinciding with the distribution design areas.  A detailed EIA was done for each region: focusing on abstraction, environmental-flow requirements, water-treatment works, storage reservoirs, pumping stations and pipeline routing.  One of the findings of the environment studies was that there were in excess of 500 hand pumps in the study area but only approximately 40% working.

Benefits from the project quantified in the studies are, among others, R44-million per annum in national health benefits and sustained industrial growth.  Pipe laying alone should yield 240 full-time jobs over the five-year implementation period envisaged with large multiplier effects.  On the social and biophysical sides, negative impacts were identified.  Aspects considered during the social impact assessment included effects on drinking water downstream for humans and livestock, sand mining, fuel wood, wild vegetables, medicinal plants, baptism rituals, fishing and irrigation – the latter two with minor impacts during low-flow cycles.  Mitigation prescribed in the environmental management plan (EMP) includes, inter alia, limiting abstraction to 16 hours per day; sludge should not be returned to rivers during low-flow (dry) periods but sludge-drying beds should be used; careful management of road and street crossings of pipelines; community liaison with regard to blasting; concurrent excavation and backfilling of trenches to limit the period the trench is open; rehabilitation of trenches and other disturbed areas to limit erosion; and the recruitment and management of local and imported labour, considering the risks related to spreading disease, among others.  Key risks identified included the reliability of power supplies for pumping equipment and people reverting to old water sources when faced with water bills.  The EIA concluded the project would resolve significant water shortages and problems, and the benefits far outweighed potential costs, especially if negative impacts were managed well.

National Water Sector Information Management System

An interesting adjunct to the project was the development of a National Water Sector Information Management System (WSIMS) for Lesotho.  This work was undertaken on behalf of the JV by the firm Intermap, represented on the project by Lani Fowles and key expert Michele McDonald.  Establishing a comprehensive, geographically-based management system was thought essential in view of the large numbers of widespread infrastructure elements comprising the scheme, such as the reservoirs and pipeline linkages.  With this as background, an integrated system was developed that would, optimally, support the generation, flow, storage and use of data to ensure sustainability of the scheme.  To this end, the WSIMS is designed to enable all participating water-sector entities to collect, verify, share and store data, information and knowledge in a controlled and hierarchical manner.  Each participant decides, within the framework of legislation, which data and information will be shared by whom.  The large investments made in water-sector infrastructure will require long-term effective and efficient infrastructure management and the WSIMS is intended to become the core information system to support water-sector managers in their efforts in this regard.

The system comprises four sub-systems and takes into consideration core aspects:

 

International water agreements

Another interesting aspect of the Lesotho Lowlands Bulk Water Supply Scheme is that it is being developed in terms of the framework of international water agreements between Lesotho, South Africa, Botswana and Namibia – all with an interest in the Orange River Basin.  The Orange-Senqu River Commission (ORASECOM), charged with the management of this resource, was established in 2000 by the four countries, and comprises three commissioners from each state.

ORASECOM is also affected by and kept informed about the activities of the Joint Permanent Technical Committee between Botswana and South Africa, the Permanent Water Commission between Namibia and South Africa, as well as the Lesotho Highlands Water Commission.

In conclusion, considering all the aspects that had to be taken into account and formed part of the Lesotho Lowlands Bulk Water Supply Scheme, the government of Lesotho and its advisors and consulting engineers should be commended for the successful completion of the design and tender documentation phase of the project.  The remaining challenge for the government of Lesotho will be in obtaining the necessary funding for the implementation of the entire scheme, which will make a major difference to the lives of all the “Lesotho lowlanders”.


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