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Engineered products for the protection of hydro dams

Engineered products for the protection of hydro dams

ENGINEERED PRODUCTS FOR THE PROTECTION OF HYDRO DAMS

Bolina is the European leader in marine safety, security and environment booms for inland waterways, ports, dams and critical infrastructure. Bolina has extensive experience in hydro power dam and reservoir protection, ensuring increased operational and cost efficiency through the use of products that protect the environments around which dams and reservoirs are located. Hydro power dams are a crucial part of global initiatives to achieve a more renewable energy infrastructure, and Bolina is proud to be able to contribute to the cause of ensuring that hydro power dams are a viable and long-term alternative to traditional fossil fuels, for the benefit of the planet.

Benefits of products for hydro power dams

Bolina produces a large range of marine and waterway barriers to minimise pollution, protect people and prevent damage to structures adjacent to or directly within aquatic environments, such as hydropower dams. These barriers include products known as booms.

Benefits of products for hydropower-dams
Benefits of products for hydropower dams: Bolina Debris Booms at Kariba Dam, Zambia

‘Booms’ is a catch-all term for a wide range of barriers that prevent the distribution of a number of materials and substances, which may be harmful and/or damaging, one kind of which are debris booms. In the case of hydro power dams, debris booms are able to prevent materials such as plastic, invasive plant life or wood (such as logs or branches) from accumulating and blocking the dams, as well as preventing damage to the dam itself. Damage to the dam can occur as a result of heavy floating objects being carried at speed on the surface of the river impacting the dam’s structure and consequently weakening it. The effect of this is a reduction in the dam’s longevity and an increase in frequency with which the dam will have to be maintained, incurring higher costs over the long-run for the dam’s administrators. Furthermore, obstructions to the dam’s sluice gate as a result of debris accumulation will reduce its capacity to channel water, in turn reducing the dam’s efficiency, which will eventually necessitate cleaning and removal of the obstruction and cause disruption to the dam’s supply and operation – further increasing maintenance costs.

If debris accumulates in a dam’s sluice gate to the degree that clearing is required, this will need to be carried out manually by a team of people, which carries with it an inherent degree of risk, given its location. Reducing the amount of debris that is able to reach the sluice in the first place will reduce the frequency of maintenance, and thus the risk that workers are exposed to. Additionally, preventing long-term, cumulative damage to the integrity of the dam will ensure that the risk of breaches is minimised, and will contribute to the protection of inhabitants living in areas around the river and dam further down-stream.

Plastic pollution is an issue that has begun to receive greater attention amongst the broader population over the last decade, with impactful images of its consequences regularly circulating in the media. Much of the plastic waste that is found in the oceans, however, is in fact deposited by rivers. It is therefore essential that plastic is prevented at the source from being transported into the open oceans, where it has a significant effect on marine life. Bolina is able to ensure that plastic that has been disposed in rivers is collected safely and securely, with minimal disruption to river life, and in doing so, minimise the impact of human activity on marine ecosystems.

The protection of hydro power dams in practice

Protection from debris – Cahora Bassa Hydropower Plant, Mozambique

Hidroeléctrica de Cahora Bassa (HCB) is Mozambique’s pre-eminent hydropower generation company, and it is a major contributor to the country’s socio-economic growth and development. Its main focus is in extending the electricity potential of the Cahora Bassa dam – Africa’s fourth-largest artificial lake.

The protection of hydropower dams in practice
The protection of hydropower dams in practice: Bolina Log Screen Booms at Cahora Bassa Dam, Mozambique

The Hidroélectrica de Cahora Bassa operated hydro power plant provides much of the power to the national grid in Mozambique and as such is a critical installation, being the largest hydroelectric scheme in southern Africa. The water impounded behind the 170-metre-high reinforced concrete hydro dam stretches an incredible 280km upstream and is subject to severe fluctuations in levels due to rainfall and other weather conditions.

As a result, the plant had been experiencing ongoing operational problems with waterborne debris overwhelming the existing boom which had been in place for a number of years and could not hold the debris back. In order to overcome these issues and to increase the reliability of the installation, a new solution was urgently needed. Therefore, Bolina was approached to provide an alternative solution to provide protection to the dam.

For the project, Bolina utilised its LSB600 Log Screen Boom, developed from its highly successful Traffic Control Booms tested to over 60-tonnes. It incorporates a subsurface mesh joined together to provide a seamless barrier for logs and debris, with full articulation provided between units.

The unique tubular backbone of this boom system and the Bolina lug connections make the boom immensely strong without stressing the floats, which are fully demountable with the booms designed for continuous motion and heavy loads.

A total of 380 metres of boom were shipped from the United Kingdom in containers to Cahora Bassa together, with a gate assembly designed by the Bolina team. The gate was included to allow the passage of maintenance boats either side of the boom and was the largest that Bolina had constructed to date.

The work was undertaken by local workers employed by the power company using readily available hand tools. The complete construction of the boom on site only took two weeks and was then simply floated into place and secured in position, utilising the end connections from the previous boom.

The installed boom works as designed, and captures and diverts much more debris than the previous boom. This has both increased the operational efficiency of the plant and reduced the need for the maintenance team to clear debris from around the intakes. 

Ultimately, the principle of our booms is that it is preferable to prevent a problem rather than address the problem once it has already manifested. Prevention is more time-efficient, more cost-effective, safer and more environmentally sustainable. Get in touch to know more!

A version of this piece was first published in Hydropower & Dams, Issue Five, 2021.