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Inspection find problems at Lewis River dams
http://www.columbian.com/news/2010/jun/24/inspection-spurs-alarm-about-dams/
Federal energy regulators are raising alarm about the potential for “catastrophic failure” of spillway gates on three major PacifiCorp-owned dams on the North Fork of the Lewis River.
The concern arises from a 10-year inspection earlier this year by the investor-owned utility that was submitted to the Federal Energy Regulatory Commission in late January. PacifiCorp and the federal agency declined to release the report itself, citing security concerns.
However, it did elicit a strong reaction from federal regulators.
Document
Dam Spillway Concerns Aired
Download .PDF
In a letter dated June 2, FERC Regional Engineer Patrick J. Regan summarized a series of concerns with the report’s findings, including missing or broken bolts and rivets, out-of-plane bending and cracked welds.
“Some of these findings seem a cause for great concern,” Regan wrote in a letter addressed to PacifiCorp Energy official Randy A. Landolt in Portland. “For instance, at Merwin, loss of enough rivets or bolts near a trunnion could cause a catastrophic failure of the gate.”
http://columbian.media.clients.ellingtoncms.com/news/documents/2010/06/23/tainter_gates.pdf
Our review found that the reports did not include an evaluation of these results by
a structural engineer. Some of these findings seem a cause for great concern. For
instance, at Merwin, loss of enough rivets or bolts near a trunnion could cause a
catastrophic failure of the gate. At Swift No.1, fatigue cracking would imply
overstressing of the gate support. In addition, every trunnion mount had broken concrete,
possibly caused by gate movement. At Yale, the out-of-plane bending in several similar
members might indicate overstressing. Also, there was no evaluation of potential
deterioration in the trunnion pins as many dam owners have done.
http://www.columbian.com/news/2010/jun/24/inspection-spurs-alarm-about-dams/
Federal energy regulators are raising alarm about the potential for “catastrophic failure” of spillway gates on three major PacifiCorp-owned dams on the North Fork of the Lewis River.
The concern arises from a 10-year inspection earlier this year by the investor-owned utility that was submitted to the Federal Energy Regulatory Commission in late January. PacifiCorp and the federal agency declined to release the report itself, citing security concerns.
However, it did elicit a strong reaction from federal regulators.
Document
Dam Spillway Concerns Aired
Download .PDF
In a letter dated June 2, FERC Regional Engineer Patrick J. Regan summarized a series of concerns with the report’s findings, including missing or broken bolts and rivets, out-of-plane bending and cracked welds.
“Some of these findings seem a cause for great concern,” Regan wrote in a letter addressed to PacifiCorp Energy official Randy A. Landolt in Portland. “For instance, at Merwin, loss of enough rivets or bolts near a trunnion could cause a catastrophic failure of the gate.”
http://columbian.media.clients.ellingtoncms.com/news/documents/2010/06/23/tainter_gates.pdf
Our review found that the reports did not include an evaluation of these results by
a structural engineer. Some of these findings seem a cause for great concern. For
instance, at Merwin, loss of enough rivets or bolts near a trunnion could cause a
catastrophic failure of the gate. At Swift No.1, fatigue cracking would imply
overstressing of the gate support. In addition, every trunnion mount had broken concrete,
possibly caused by gate movement. At Yale, the out-of-plane bending in several similar
members might indicate overstressing. Also, there was no evaluation of potential
deterioration in the trunnion pins as many dam owners have done.
