(1) Minor - affecting area of less than about 50 metres x 50 metres (area less than 0.25 hectare) or resulting in minor public nuisance and inconvenience.

(2) Small - affecting area of more than 0.25 hectares or resulting in some agricultural damage, isolated property damage, or traffic disruption.

(3) Medium - affecting area of more than 10 hectares or resulting in significant property damage or serious traffic disruption.

(4) Major - affecting area of more than 100 hectares or resulting in serious social and economic disruption.