SYDNEY: Design flaws and a series of problems over six years led to the collapse of a mine dam and the loss of 19 lives in Brazil’s worst environmental disaster, mining giant BHP Billiton said Tuesday. A technical report commissioned by the world’s biggest miner and Brazil’s Vale — the co-owners of the mine’s operator Samarco — found a chain of events from 2009 to 2015 caused the November 5 catastrophe, which unleashed a tsunami of toxic waste and buried a nearby village. Samarco is facing billions of dollars in legal claims for clean-up costs and damages. The 76-page report by an expert panel led by Canadian geotechnical engineer Norbert Morgenstern did not assign blame “It is a very detailed, technical report 10 months in the making,” BHP’s chief commercial officer Dean Dalla Valle said in a media teleconference. “Given the legal proceedings, it wasn’t appropriate that we actually try to use this process to attribute blame,” he said, adding that “we have no reason to believe that anyone at BHP had any information that indicated that the dam was in danger of collapsing”.