Most of the spilled oil was contained within berms .
About 1 % of the oil , about 40 barrels ( 6.4 m ) , sprayed into the air and coated nearby snow and trees .
Most of the spilled oil was contained within berms but about 1 % of the oil , about 40 barrels ( 6.4 m ) , sprayed into the air and coated nearby snow and trees .