Case Study: La Gogue Dam, Seychelles
As part of the Race to Resilience campaign, ICSI is compiling case studies of best practice climate-resilient infrastructure in an effort to showcase human-centric and sustainable infrastructure projects around the world. The below interview was conducted with Erna Victor of Public Utilities Corporation (PUC).
Project Name: La Gogue Dam
Location: La Gogue Dam is located in the North of Mahé, the main island in the Seychelles, a small island developing state (SIDS) with a population of about 100,000.
Description: The dam is the largest of two in the country and is the main water store for the island which houses the majority of the country’s population. The dam is operated and managed by the Public Utilities Corporation (PUC), a state-owned company. The raising of La Gogue Dam is one of the major civil engineering projects being undertaken by PUC and includes the following main components:
- Raising of the dam’s embankment by 6m; the full storage capacity will be increased by 600,000 m³;
- Seepage control measures for the natural north and south saddles;
- The construction of a new spillway on the right embankment;
- The raising of the intake tower by 6m;
- Replacement of all ductile iron pipelines, valves, and fittings that are housed in the intake tunnel; and
- Construction of temporary and permanent roads.
What need is this project meeting?
The main aim of the project is to increase the storage capacity of La Gogue dam by 60% (from 1Mm³ to 1.6Mm³) as part of a nationwide effort to improve raw water storage systems and thus improve climate resiliency. This will lead to a reduction in the need for water-rationing during dry seasons due to insufficient supply to match the increasing demand. It will also support the tourism industry (the country’s main economic driver) and manufacturing/industries e.g. fisheries/beverages. Access to clean water supply throughout the year will also be a contributing factor to the maintenance of high social development indicators, such as gender equality or quality of life.
What is your organisation’s role in the project?
The PUC is the implementing agency of the project and is responsible for the management of the supervision and works contracts, and ensuring the works are undertaken to the required standard to achieve the expected outcomes.
What are the key social, environmental, and economic outcomes you hope to achieve with this project?
The increased storage capacity will improve water supply services during dry periods and will also lead to a reduction in energy costs from the operation of desalination plants (though these will still act as back-up). The increased water production capacity will help to reduce the dependency of households on bottled water during dry periods. The establishment of a catchment and buffer zone (no-development zone) around the dam will also help to ensure the dam’s security from contamination.
This project has helped to create job opportunities during the implementation stage, and will continue to do so through the operation and maintenance of the dam. Gender equality has been prioritised throughout the consultation process by targeting women engineers for on-job training and offering project management and dam construction training for both men and women.
The project will also lead to improvements in sanitation facilities in schools (in addition to water tanks) and a reduced need for additional efforts in getting water for households.
The increased water supply of the dam will support growth in the tourism industry, which is a main contributor to the country’s economy, as well as other industries reliant on water.
Does the project benefit urban, rural and/or coastal communities?
The project is expected to benefit the inhabitants of Mahé island as the demand for water is expected to increase by 130% by the year 2030. That includes the water demand of industries and tourism establishments.
What hazards will be mitigated by the project?
The additional storage capacity will allow for clean water supply throughout dry periods, thereby mitigating prolonged droughts and reducing the risk of diseases associated with lack of sanitation. Additionally, the establishment of the no-development zone around the dam will mitigate the risk of contamination of the dam which is notably the country’s main water store.
How has the project been financed? Did the funding and financing process explicitly consider sustainability and resilience outcomes? Were there any lessons learnt on how to finance similar projects?
The project is being financed under a loan from the African Development Bank (AfDB) through the Government of Seychelles (GOS). Prior to financing approval, the AfDB conducted an in-depth assessment of the expected outcomes, particularly their feasibility and performance indicators.
Lessons learnt include ensuring that the implementation of highly technical projects is supported through capacity building within the implementing agency due to a lack of expertise in dam construction projects. Therefore, project management training, technical assistance, and an experienced technical firm were included in the project’s implementation.
In addition, delays in procurement processes caused delays in project implementation. These were addressed through expediting procurement processes.
How has climate resilience of natural systems been embedded in this project?
The dam is being raised by 6m, determined as the maximum feasible height. This is expected to have a major impact on the country’s resilience to climate change as it addresses water supply constraints to the central and northern regions of Mahé during extended dry periods.
Does the project include elements of carbon mitigation?
The project addresses carbon mitigation in several ways. Firstly, the material (soil) used during the raising was sourced from borrow areas identified in close proximity to the project site, reducing the need for material transportation. Similarly, rock fill was optimally sourced on site and only the required difference sourced from a local quarry 15km away.
In addition, areas cleared of vegetation were restricted to housing permanent structures and borrow areas to limit the impacts of the carbon absorption by vegetation. The borrow areas and other areas left bare from temporary works are being restored with vegetation.
Lastly, as water bodies act as carbon sinks, the dam will have an increased absorption capacity due to increased storage. The added storage will also decrease the amount of energy used for the operation of desalination plants during dry periods which can reach up to 12KWH/m³ per month. (Note that Seychelles depends on mainly fossil fuels for energy production.)
What kind of contribution have local communities had in the planning, design, and implementation of this project?
Consultations and meetings with relevant stakeholders took place during the appraisal mission (prior to signature of financing agreement) as well as during the preparation of the Environmental and Social Impact Assessment (ESIA). The stakeholders involved were the residents of Anse Etoile and Glacis districts, who would be directly affected by the impacts of the project, as well as the two districts councils, represented by members of the National Assembly.
Issues raised during consultations and meetings were:
- Close consultations should be continued with PUC during implementation
- Propose disaster-preparedness emergency plan and train experts in handling emergencies, and
- Door-to-door communication with households close to the dam.
The design of the project has accommodated these three areas of intervention. The consultation process was continued through regional public meetings on Mahé, detailing the relevant works under the project prior to commencement. This was further supplemented by door-to-door visits with households within a close vicinity of the dam as raised in previous consultations.
During the implementation of the project, there have been regular updates to the public via media outlets and the project team remains open to receiving queries/comments/complaints from the public and other stakeholders. Note that public consultations will be held to present the emergency preparedness plan to stakeholders upon finalisation.
What challenges have you faced during the implementation of the project?
There have been a number of challenges to overcome during the course of the project’s implementation. There were protests from local transport service providers who wanted to have participation in the project. This led to delays in implementation as well as additional costs through claims. An agreement was reached that these providers would provide offsite transport.
Adverse weather conditions (heavy rainfall affecting implementation of earthworks and concrete works) led to extensive delays and a prolonged implementation period, as did the COVID-19 pandemic as shipments of necessary materials and equipment were delayed.
Additionally, unexpected ground conditions required the implementation of additional measures to control seepage on the right embankment, and address slope stability issues on one of the dam’s natural saddles.
How are the outcomes and projected impacts going to be measured and evaluated?
The outcomes and impacts will be measured by the:
- Number of days of water restrictions in the North of Mahe island
- Water production capacity in the North of Mahé island
- Number of days reliant on desalination plants for water supply
- Number of direct jobs created during and after project implementation
- Total storage capacity of the dam
- Developed Emergency plan
- Area gazetted as no-development zone
- Number of relevant staff trained on dam management