Brazil's Vale says poor drainage, intense rain helped facilitate Brumadinho disaster

The Brumadinho tailings dam disaster in Brazil earlier this year that killed more than 250 people was facilitated by several factors, including poor internal drainage and intense rain, the dam's operator Vale said on Thursday.

Citing an internal report compiled by a panel of experts, Vale said it was a unique event with no warning that the dam was unstable, and that no seismic activity in the area was recorded on the day, according to a securities filing.