In this part—
"contamination incident" means—
(a) an incident involving contamination of the environment that the administering authority is satisfied has caused or is likely to cause serious or material environmental harm; or
(b) the carrying out of an activity on contaminated land, the happening of an event on contaminated land, or a change in the condition of contaminated land that the administering authority is satisfied has caused or is likely to cause other land to become contaminated land; or
(c) a combination of matters mentioned in paragraph (a) or (b) .