A NSW Parliament upper house inquiry has heard the proposed Parramatta Powerhouse Museum development is at serious risk of significant flooding.

Ray Hadley has been fiercely campaigning against the destruction of Willow Grove and St George’s Terrace – both 19th century heritage-listed buildings – to make way for the new site.

“There’s another dozen sites they could use. It’s insanity that they want to knock these old buildings over,” he said.

Ray reported leading flood experts provided “devastating evidence” of inundation if the development was to go ahead.

Artefacts stored in the lower levels would be washed away into the Parramatta River.

Powerhouse Museum Alliance heritage consultant Kylie Winkworth told Ray Hadley the group is “very concerned” the site poses a risk not just to the objects on display, but also to visitors due to improper evacuation provisions.

“It’s risky, dangerous and reckless to put a museum that’s going to attract an average of 5500 visitors a day on that site.”

Click PLAY below to hear the full interview