Infrastructure news from around the continenent

UGANDA

Refurbishment of Nalubaale Dam

GIBB was awarded the contract to design and oversee the construction of Nalubaale Dam. Located 3 km downstream from the source of the Nile River in Jinja, Uganda, the Nalubaale hydropower station’s first turbine unit was commissioned in 1954.

Cracks were first noticed in the powerhouse structure in 1964. These were caused by an alkaliaggregate reaction (AAR). Cracks had also developed in the main dam wall and leakages from the reservoir were observed against the downstream face. All repair attempts before 2020 had a limited service life as long as the concrete kept on swelling due to AAR.

Louiza van Vuuren, civil engineer, GIBB, says Eskom Uganda decided to implement a new grouting programme to improve the structural and functional integrity of the dam structure. The grouting approach used by GIBB was based on the GIN (grouting intensity number) method. The acceptable pressures and volumes of grout injected were derived from stability calculations to avoid hydro-jacking of the dam’s concrete during grouting.

“The specifications stipulated that the pressures used for grout injection should be controlled with a pressure transducer, which is fitted to a grout pump equipped with an automatic data acquisition system capable of measuring, displaying, and recording data in real time,” explains Van Vuuren.

In December 2020, the contractor started the drilling and grouting works on a trial section of the dam. This was done to confirm or modify the grouting method (boundary curve, boreholes spacing, stop criteria), the grout mix design and grouting materials, as well as the equipment such as pumps, mixers, sensors and automated control devices, among others.

Primary holes were inspected with a borehole-imaging device to establish typical crack elevations, directions and widths, and to inspect the mass concrete condition. This led to the detection of large cracks of up to 17 mm wide. Crest levelling surveys of the concrete blocks were also conducted to detect any evidence of hydro-jacking.

Due to the grout trial section taking longer than originally anticipated, the project experienced a slow start, compelling the contractor to increase the number of employees on-site – as well as drilling equipment – to catch up with the planned schedule.

NAMIBIA

Shell hits oil and gas in offshore well

Shell has made a significant oil and gas discovery at an offshore well in Namibia, which could spark a wave of investment. Namibia is not a fossil fuel producer, although northern neighbour Angola is a major oil and gas producer.

The discovery at the Graff-1 well, which Shell started drilling last month, has so far shown at least two reservoirs containing what one of the sources described as a “significant amount of oil and gas”. The drilling results have shown one layer of hydrocarbons at least 60 m deep, holding an estimated 250 to 300 million barrels of oil and gas equivalent.

Developing new oil and gas fields in a country with no existing energy infrastructure and regulation, similar to what has happened in Guyana on the other side of the Atlantic in recent years, is timely and costly. Namibia has sought to develop oil and gas fields for decades with no success. But, in recent years, interests in its offshore prospects have attracted many foreign companies, including Exxon Mobil and TotalEnergies following discoveries in neighbouring South Africa as well as Brazil and Guyana, which share geological similarities.

NIGERIA

Dangote projects to be game-changing initiatives

Dr Akinwumi Adesina, president, African Development Bank, has described the Dangote oil refinery and petrochemical plant projects as a “game-changing initiative” that will spur Africa's development and deepen regional integration.

In 2014, the African Development Bank’s board approved a US$300 million (R4.5 billion) loan to Dangote Industries to support the construction and operation of the greenfield crude oil refinery and the greenfield fertiliser manufacturing plant. The two facilities are expected to create 38 000 jobs during construction.

According to Aliko Dangote, president and chief executive, Dangote Group, the refinery, which has the capacity to meet 100% of Nigeria’s requirements for refined products with a surplus for export, is the largest single-train petroleum refinery in the world. The refinery has a capacity to process 650 000 barrels of crude oil per day and it is estimated that by 2023, Nigeria will import zero petroleum oil products – down from approximately $50 billion (R757 billion) in current oil product imports per year.

The refinery includes a 440 million litre water treatment tank farm and a housing estate built for 50 000 staff and their families on-site. The successful completion of the refinery project is expected to have a significant impact on Nigeria’s foreign exchange through import substitution and substantial savings in earnings. Officials explained that the refinery will be commissioned by the end of the year.

The fertiliser facility has two production train lines, with each producing 2 200 tonnes of ammonia and 4 000 tonnes of granulated urea each day. The first train was built and deployed in the second quarter of 2021. More than 300 000 tonnes of urea have been produced and sold as at Q4 2021, primarily to export markets. The second production train line is expected to be commissioned in the first quarter of 2022. The plant now makes Nigeria a net exporter of fertiliser.

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KENYA

Water access in Nyandarua

At a time when most parts of Kenya have been hit by prolonged drought, several farmers’ groups have just received toolkits from the government to start vegetable gardening activities to enhance food security in Nyandarua County.

In addition to this support, the Kenyan government has launched the Kagongo Wendani Irrigation Project in Weru Ward, which will serve over 800 households. This initiative is funded by the Kenyan Ministry of Agriculture under the Small-scale Irrigation and Value Addition Project.

Under the National Agricultural and Rural Inclusive Growth Project, the East African government has implemented an irrigation system in Murang’a County in west-central Kenya. Water pumped from the Maragua River is channelled through 14 km of pipes to serve 457 households, including farming households. Thanks to this US$976 000 (R14.77 million) investment by the World Bank, each beneficiary household has a 100 m3 basin to store excess water that it can use for three months.

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