A water engineer has issued a warning over the plan to relocate the Powerhouse Museum to a floodplain in Parramatta, saying the move will put lives and its "irreplaceable collections" at risk.
Hydrologist John Macintosh, who advised the inquiry into Queensland's deadly Grantham flood, said building a museum at the chosen site adjacent to Parramatta River would create a "flood hazard".
"Speaking plainly, I think it's crazy, it's a crazy proposal to put the museum in that location, pure and simple," he said.
Dr Macintosh's submission to the Upper House inquiry investigating the proposed museum move is the 17th paper to raise concerns about flooding.
As recently as 2015, flood water at the site peaked at 2.8 metres.
"My primary concern is for public safety," he said.
"They're locating a building, which is of interest to the public, a tourist attraction, in a floodplain.
"The intention is to attract people there, which, when it floods, is a hazardous location to such an extent that people could die.
"It's not a place where people will get their feet wet or dirty their shoes, it's a hazard where they could easily lose their lives.
"As an engineer very familiar with flooding circumstances where people have died, you avoid that completely."
Flood mapping shows site vulnerable to one-in-20-year event
Existing flood mapping of Parramatta reveals the entire site is at risk of water inundation to more than four metres and its edge adjacent to the river is vulnerable to a one-in-20-year flooding.
Dr Macintosh marked the location of the site on existing flood maps as part of his submission.
His experience of Grantham — where 12 people lost their lives — has given him heightened awareness of the channels that can form between built structures to create fast and dangerous currents.
"Water flows down those paths to such a velocity to carry people away and drown them, it's those areas that present the real hazard," Dr Macintosh said.
Dr Macintosh also gave evidence at the inquiry into the 2011 Queensland floods, where rising water threatened cultural institutions built along the Brisbane River.
Those museums store their collections on upper levels, well beyond predicted flood marks, but Powerhouse collections include items like vulnerable prints, jewels and fashion items to locomotives, which would be too heavy to store above ground.
Donor wants to donate items 'somewhere else' if plan goes ahead
Jewellery expert Anne Schofield, who has donated hundreds of jewels and costumes to the Powerhouse, is so worried about the risk of moisture and floods she will ask the museum to return everything she has donated.
"I don't want them to go to Parramatta frankly. I'd like to be able to ask for them back if the plan goes ahead, because I didn't donate them to a museum in Parramatta, I donated them to a museum in Harris Street, Ultimo and that's where I'd want them to stay.
"If they're not staying there I'll donate them somewhere else."
Trustees of the Powerhouse Museum have conditionally supported the move. One of those conditions is that "the new site is fit for purpose and appropriate to the construction of a museum", according to chairman Barney Glover.
Professor Glover would not say if Dr Macintosh's report would lead the trust to withdraw its support.
He said in a statement:
"The Trust looks forward to the Government decision on the Powerhouse Museum relocation.
"Until a Government announcement is made the Trust is not in a position to comment."
On Thursday afternoon, Greens MP David Shoebridge's motion to compel the Government to release its business case for the move was passed by the Upper House.
Outspoken Liberals backbencher Matthew Mason Cox crossed the floor to vote for the motion.
Also on Thursday, the Government reaffirmed its commitment to the move. It's expected to announce more details of the plan any day.
