Henry Williams is a resident of the Lenten Pool area of Denbigh, who heard the explosions caused by John Larsen, near to their homes earlier this year.
He said he thought it was somebody letting off fireworks, until one Sunday morning when "big damage" had been done to some cars - "and that's when I felt a bit worried."
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Rain clipping the far north through the evening but elsewhere staying dry with some sunny spells.
Public Health Wales figures show 25 more cases of the virus have also been confirmed.
Photos taken on Saturday morning show Roald Dahl Plass strewn with empty beer bottles and discarded canisters of laughing gas.