UPDATE 4-Samarco dam failed due to poor drainage and design -investigation
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By Marta Nogueira and Stephen Eisenhammer
BELO HORIZONTE/RIO DE JANEIRO Aug 29 (Reuters) - The deadly collapse of a tailings dam last November at the Samarco mine, owned by Vale SA and BHP Billiton, was caused by drainage and design flaws, a report into Brazil's worst-ever environmental disaster showed on Monday.
The 76-page report commissioned by the companies responsible for the spill, which killed 19 people, attributed the dam burst to a chain of events dating back to 2009, but did not assign blame or highlight specific errors in corporate or regulatory practice.
Norbert Morgenstern, a geotechnical engineering professor who headed the investigation, repeatedly told reporters he could not answer their questions when quizzed on whether there was negligence or malpractice on the part of the companies involved.
A separate police investigation has accused Samarco of willful misconduct, saying the company ignored clear signs the dam was at risk of collapsing. Samarco denies any wrongdoing.
BHP Billiton's chief commercial officer, Dean Dalla Valle, said cost-cutting since 2012 was "absolutely not" a factor and there was no evidence anyone had prioritised production over safety.
"We have no reason to believe that anyone at BHP had any information that indicated that the dam was in danger of collapsing," Dalla Valle told reporters in Australia on a conference call from Belo Horizonte.
The report stressed that a change in the dam's design between 2011 and 2012 led to less efficient water drainage that saturated sand in the dam and resulted in liquefaction. Continuación...