Civil works |
and engineering, was proud to announce the successful completion of the Priest Rapids Right Embankment Improvement Project. This critical infrastructure project, undertaken in
collaboration with Grant County Public Utility District No. 2 (Grant PUD) and IMCO General Construction, enhances the safety and resilience of the Priest Rapids Dam, which is now able to withstand a 7.1-magnitude earthquake. Located in Mattawa, Washington, the Priest Rapids
Above: The Priest Rapids Right Embankment Improvement Project in Washington, US, has recently been completed
Dam plays a crucial role in impounding water for a hydroelectric powerhouse with a rated capacity of 950MW. Over time, concerns arose regarding the seismic resistance of the dam’s right embankment. To address this issue, Grant PUD initiated the Priest Rapids Right Embankment Improvement Project. Stantec’s team worked diligently to design and construct a downstream replacement dam, with the new structure mitigating potential liquefaction risks associated with the existing dam’s foundation. Despite the challenges posed by the project’s complexity, the team managed to stay ahead of schedule and the project was completed a month early. The dam was designed and constructed using roller-compacted concrete (RCC), an alternate construction method for concrete dams that offers many advantages. Stantec has prepared designs for more than 25 RCC dams and rehabilitation structures, including gravity, thick-arch, and buttress dams. “We are thrilled to have successfully completed the Priest Rapids Right Embankment Improvement Project ahead of schedule,” said Mario Finis, executive vice president of Energy & Resources at Stantec. “Our collaboration with Grant PUD exemplifies our commitment to dam safety and community resilience. The project’s success was the result of a strong partnership spanning years of planning and dedication.”
“Completion of the Priest Rapids Right Embankment Improvement Project enhances the protection and preservation of the Wanapum people’s culture who live immediately downstream of the dam,” said Dale Campbell, senior manager of power production at Grant PUD. “This investment in Priest Rapids Dam is strategically critical for our customers as it reduces Grant PUDs public safety and financial risk for the foreseeable future.”
Exploratory work On the other side of the Atlantic, Scotland’s Coire
Glas project continues this global push, with exploratory tunneling paving the way for one of the UK’s most ambitious pumped storage projects in decades. Exploratory tunnelling at the site of what would be the UK’s first large-scale pumped storage scheme to be developed in 40 years is now complete. The completion of a 1.2km long exploratory tunnel is the latest milestone in SSE’s ongoing development of its landmark Coire Glas project in the Scottish Highlands. Located at Loch Lochy in the Great Glen, the
proposed Coire Glas project would have an installed capacity of 1300MW and be capable of delivering 30GWh of long duration electricity storage – enough to be able to provide firm, flexible renewable power
34 | October 2024 |
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for three million British homes for up to 24 hours non-stop.
SSE Renewables hopes to make a final investment decision on the project in late 2025 or early 2026, allowing for main construction to commence in the second half of 2026, subject to being successful in the administrative allocation of an investable cap and floor mechanism. Exploratory works at Coire Glas commenced in December 2022 and are being conducted by STRABAG UK.
In early 2023, SSE announced a £100-million investment boost to further develop Coire Glas to include the construction of a major exploratory tunnel as part of a comprehensive package of site investigation works. SSE’s technical partners, Stantec and COWI, have designed and supervised the unique and complex ground investigation programme which is being delivered by STRABAG. The works included the creation of a tunnel
approximately five metres high and four and a half metres wide which cuts into the hillside around the proposed location of the underground powerhouse complex. Construction of the tunnel will allow the project team to gather accurate information on the geological conditions to inform the detailed design for the main works.
Now that tunnel construction is complete, a
programme of exploratory drilling and testing is continuing to further investigate the ground in the area of the proposed underground powerhouse excavations. “The works progressed to plan, and samples of the materials excavated from within the hillside are currently being analysed,” Mike Seaton, SSE Renewables Director of Development for Coire Glas, said. “This phase of the project is an engineering challenge in itself and we are learning a huge amount as we progress the works. The findings of the tunnelling works, alongside our wider site ground investigation works completed by Fugro in December 2023, will be used to inform the final design, including the detailed design of underground structures, and will be a key consideration in any final decisions related to the project.” “The Stantec team has thoroughly enjoyed working on this stage of the Coire Glas project, delivering award winning work alongside COWI, STRABAG, and SSE Renewables,” said John OrdBusiness Director, Energy, Stantec. “We look forward to continuing our support as it moves into the next phase, defining rock quality more than a kilometre inside the mountain. This important work will inform the design of the main pumped storage scheme, moving the project closer to offering a huge boost for the UK’s renewable energy storage.” “At COWI we’re delighted to have reached the important milestone of the end of the tunnelling phase for the exploratory tunnel,” said Andy Sloan, Managing Director, COWI in the UK. “The joint Stantec/COWI site team have worked tirelessly with SSE Renewables and STRABAG to reach this point and collaboration has been excellent. The Stantec/ COWI team will now move on to supervise the underground drilling, which includes complex testing rarely seen in the UK.”
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