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November 2017 Dinner Meeting
November 16 @ 5:30 pm - 9:00 pm
Three Strikes and Out: Natural Hazards Impact Nepal Hydropower Project
Michael P Bruen, LPG, LEG, PMP
Vice President; Project Manager, Senior Tunnel Specialist, and Engineering Geologist
Abstract: From 2014 – 2016, three natural hazards, large landslides, an earthquake and major flooding, significantly damaged the Upper Bhote Koshi (UBK) Hydropower Project, a run-of-the-river hydroelectric project, in the Nepal. MWH / Stantec had been involved with the UBK project since the early 1990s as the owners engineer for the original design development through construction, operation, condition assessments and rehabilitation. This presentation will provide an overview of the challenges of operating a hydropower facility in the mountainous region of Nepal.
The first strike occurred on August 2, 2014 when a massive landslide downstream of the power station knocked out three transmission towers. The landslide, with an estimated volume of 6 MCM, dammed the river, creating a lake that stretched 3km upstream. A total of 156 fatalities were attributed to this event.
The M7.8 Gorkha earthquake less than a year later was the second strike to the project. At the time of the earthquake, the plant went through an unscheduled emergency shutdown and appeared to be undamaged. However, numerous aftershocks including M6.7 and M7.3 events de-stabilized the slopes triggering rockfall above the project facilities and landslides and debris flows throughout the area. It was rockfall debris that rained down on the 2m diameter surface penstock and ultimately ruptured the pipe resulting in an uncontrolled dewatering of the headrace tunnel, releasing more than 50,000 m3 of water that severely damaged the penstock and flooded the powerhouse.
The latest strike, occurred on July 5, 2016 while the project, which was still under repair, was hit by a catastrophic debris-laden flood event that severely damaged the headworks and again flooded the powerhouse. At the time of the event, the Bhote Koshi River peaked at about +3.5m above the top of the dam (2600 m3/s). The flood event was significant as the bed load carried an overabundance of large boulders (4m to 10m diameter). At the headworks, the flood event caused the ultimate destruction of the desanding basin, as the riverside wall failed, and with the river choked off, the river was redirected, eroding the abutment creating a channel that bypassed the dam.
Presently an EPC contract to reconstruct the project is being tendered. The rehabilitation design for the project will include mitigation measures to minimize the impact of future large debris floods precipitated by future GLOF or landslide debris outburst flood (LDOF) events. The design will include raising of the dam crest and slope protection to a higher level on the right abutment, channel widening opposite the powerhouse and in the tailrace, and raising of the flood wall to prevent overtopping and flooding of the powerhouse
Bio: Mike Bruen is a Vice President with MWH now a part of Stantec, and has served in various roles including Senior Project Manager, Senior Tunnel Specialist, or Engineering Geologist specializing in tunnels and underground engineering and construction for wet infrastructure, hydropower, and dam projects. Mike has more than thirty-five years of experience working in North America, Central and South America, Asia, and the Middle East. He has been involved in over 50 tunnels, totaling more than 100 miles of tunnels and up to 33-ft diameter, more than 60 shafts, and caverns worldwide. Selected project experience includes the Tunnel and Reservoir Plan (TARP, Chicago), Lake Mead Intake 3 (Las Vegas), Brightwater Conveyance and Fremont Siphon (Seattle), Deep Storm Water Tunnel System (Dubai), Bath County Pumped Storage Project (VA), the Esti Hydroelectric Project (Panama). In addition to project work, Mike has held corporate as a business line manager, Director of Claims and Risk Management, and Director of Project Management. Recently he was the lead author for the chapter on Water Tunnels for the UCA of SME book, the “History of Tunneling in the United States”.
He has a bachelor’s of science degree from the University of New Hampshire and a masters in art degree at SUNY Buffalo in geology. He is a member of AEG, UCA of SME, ITA, PMI USSD, and the DRB Foundation.