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generation, the project will strengthen Nepal’s energy security and stability.
Switzerland
Forces Motrices de la Gougra proposes new headrace tunnel to boost hydropower production Forces Motrices de la Gougra SA has launched a consultation on constructing a new headrace tunnel between Vissoie and Niouc in the Val d’Anniviers. The proposed tunnel would replace the existing one to improve water flow efficiency and fully utilize the production capacity of the Navizence power plant. The company has submitted a construction permit application to the canton of Valais for the project. The new tunnel would replace the current conduit connecting the Vissoie compensation reservoir to the pressure line that supplies the Navizence plant in the Rhône plain. The existing non-pressure tunnel, built in 1908
and renovated in 1950, is a bottleneck in the system, limiting water flow to 10.8m3
/sec. Other
components of the hydropower network are designed for a higher capacity of 15m3
/sec. The
Navizence plant, which was fully renovated in 2013, was also built for this increased capacity. The new pressure tunnel would align with this standard, allowing for greater efficiency. It would increase the Navizence plant’s capacity from 50MW to 70MW and generate an additional 20 GWh of electricity annually –enough to power nearly 4,500 households. This would bring the total annual production of the system to approximately 660 GWh. The new pressure tunnel will be built east of the current tunnel and excavated using a tunnel boring machine. It will stretch 8,200m and is expected to cost around CHF 100 million. Under the Federal Energy Act, the project qualifies for investment contributions from the Swiss Confederation, which supports major hydropower renovations. The shareholders of Forces Motrices de la Gougra SA – Alpiq (54%), Rhonewerke (27.5%), and the municipalities of Anniviers (7.71%), Sierre (7.5%), Chippis (1.79%), Chalais (0.5%), and Oiken (1.0%) – will decide on proceeding with the project based on investment aid approval and profitability assessments. If approved, work is expected to begin in 2027 and take approximately five years to complete. The facilities are licensed for hydropower generation until 2084. To offset environmental impact, Forces Motrices de la Gougra has agreed to support a forest revitalization project between Pramin and Soussillon in the Bois de Finges. This area is listed in the Federal Inventory of Landscapes and Natural Monuments of National Importance. The initiative has already received approval from the Federal Office for the Environment and cantonal authorities. The Vissoie–Niouc project is part of broader upgrades to Forces Motrices de la Gougra’s infrastructure. Built in the 1950s, the main
facilities have undergone renovations to ensure long-term production of renewable energy. The Navizence power plant was modernized in 2013, and the Mottec plant’s refurbishment was completed last year. Work is also ongoing to replace machinery at the Vissoie plant. In addition to these upgrades, studies on raising the Moiry dam – a project under the Swiss Confederation’s Hydropower Round Table – will continue through 2025.
US
USBR awards $115.9 million contract for Hyrum Dam spillway replacement The US Bureau of Reclamation (USBR) has awarded a $115.9 million construction contract to AMES Federal Contracting Group of Burnsville, Minnesota, for the replacement of the spillway at Hyrum Dam in northern Utah. Hyrum Dam, constructed in 1935 on the Little Bear River, stores water in Hyrum Reservoir for irrigation and municipal use. The 90-year-old concrete spillway is approximately 1,100ft long and includes a stilling basin at its base, with walls ranging between 11 and 19ft high. “The spillway at Hyrum Dam is used every
year to release excess water downstream, and though continuous maintenance has occurred on the spillway since its construction, the 90-year-old structure is in need of replacement,” said Wayne Pullan, Upper Colorado Basin Regional Director for USBR. Construction is scheduled to begin later this year. In preparation, USBR has started work to replace the dam’s original 24-inch outlet works piping with 36-inch piping. The upgrade will increase the outlet’s discharge capacity from 50 to 200 cubic feet per second. “Working with our project partners,
Reclamation will continue to take every precaution at Hyrum Dam,” said Rick Baxter, Provo Area Office Manager. “That includes our current work to expand the size of the dam’s outlet works so more water can be conveyed through the outlet and alleviate additional stress on the existing spillway until a new one is built.” Over the years, USBR has conducted regular
maintenance and limited releases through the aging spillway. During high-flow events, agency staff have performed around-the-clock monitoring and staged equipment nearby in case emergency repairs were needed. The South Cache Water Users Association is
responsible for operating and maintaining the dam. The construction contract follows years of coordination between USBR and its partners.
Lesotho TCTA completes maintenance on LHWP Tunnel North and Ash River Outfall The Trans-Caledon Tunnel Authority (TCTA) has announced the completion of maintenance work on the Lesotho Highlands Water Project
(LHWP) Tunnel North and the Ash River Outfall. The work was finished on schedule by the set deadline of 31 March 2025. TCTA Chief Executive Officer Percy Sechemane confirmed that work on the South African section of the delivery tunnel was completed as planned. “From the outset of this project, TCTA maintained steady progress despite numerous challenges that could have caused delays, such as elevated moisture levels in the tunnel,” he said. The six-month maintenance programme began on 1 October 2024. At the time, South Africa’s Minister of Water and Sanitation, Pemmy Majodina, expressed satisfaction with the preparations for the tunnel closure and the planned work, in a joint statement with Lesotho. Sechemane noted that while the South African portion was completed on time, the Lesotho Highlands Development Authority, responsible for the Lesotho section, requested an extension due to earlier delays. “We commend their efforts to accelerate progress and minimise the impact of these delays on water delivery to South Africa,” he said. The full maintenance programme is expected
to be completed by the end of April 2025. As of 3 April 2024, the Department of Water and Sanitation reported the Vaal Dam at 107.3% capacity.
Switzerland
Main construction work on Gigerwald Dam renovation completed on schedule Axpo and Kraftwerke Sarganserland AG (KSL) have completed the main phase of the partial renovation of the Gigerwald dam in the canton of St. Gallen. The final concrete pour was carried out on 2 April 2025, marking the end of structural work to raise the bottom outlet and headwater intake. With the temporary dewatering system closed, the reservoir is being refilled. The project, which required several years of
planning by Axpo and Lombardi Engineering Switzerland, focused on addressing silting issues by relocating key intake structures around 20m higher. This adjustment ensures continued operational safety of the dam and the associated power plant in Mapragg. “Thanks to the good preparation and the
great commitment of everyone involved, we were able to complete the work on schedule, according to plan and without any major incidents,” said Axpo project manager Erich Schmid.
Construction at Gigerwald Dam began in June 2024 with site preparation. The reservoir was drained in September to expose the intake structure. Core construction activities were carried out during the winter months, when water flow is lower and production losses are minimized. Up to 50 workers were deployed in two shifts, six days a week.. Marti Group was involved in the preparation
and execution.
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