Windmill collapse cause finally revealed

A cracked blade has been revealed to have led to the collapse of this 300-foot-high windmill near Ocotillo on Sept. 16.

OCOTILLO — The operator of the wind farm near here has released the reason for the September collapse of a 300-foot-high turbine and measures it will take in an effort to prevent further such failures.

“The cause was an external crack that formed in a turbine blade,” Ocotillo Wind facility manager Tony Welsh stated in a Dec. 10 letter released to this newspaper on Jan. 7. “To prevent this from reoccurring, the site team will conduct frequent external blade inspections using drones, in addition to regularly scheduled internal blade inspections.”

Asked how a crack in a blade on the windmill could cause the main tower to collapse, as occurred on Sept. 16, Matt Dallas, a spokesman for wind farm parent firm Pattern Energy, explained Tuesday, “The crack propagated over time, causing the blade to detach, which in turn led to the turbine collapse.”

After the incident, the federal Bureau of Land Management ordered the facility’s 112 windmills shut down while Pattern investigated the cause and developed a plan to prevent further such incidents. The firm was aided in that effort by windmill manufacturer Siemens Gamesa.

County Supervisor Luis Plancarte, whose district includes Ocotillo, said because BLM is the lead regulatory agency his role has been as an informational conduit with residents. He added he has confidence in how BLM has handled the matter.

Noting there have been previous turbine failures, he added, “It’s not the first time, and with how these things work, it won’t be the last.”

BLM approved Pattern’s “return to service plan” in early December and allowed 16 windmills back in service and plans for more as remediation efforts continued. As of Wednesday, 57 windmills were back in service, BLM spokesperson Michele Van Der Linden said.

BLM did not release the plan, a cause or what preventive measures Pattern was to take. That information was obtained in a follow-up inquiry to Pattern.

But BLM’s report made it clear Ocotillo Wind was far from off the hook.

BLM’s “acceptance of return to service plan,” states “This notice does not lift the temporary suspension of operations for the entire project” and outlines further steps Pattern must take.

Imperial County and BLM allowed Ocotillo Wind to open in 2012 despite staunch opposition from some area residents that continues to this day. It provides 265 megawatts of electricity to San Diego Gas and Electric and is viewed by county officials as among the shining stars of the push to make Imperial County a renewable energy Mecca.