The twisted steel and concrete remains of the CTV building have been preserved at a Christchurch landfill site for future forensic structural examinations, it emerged today.
The royal commission of inquiry was told a government engineer tasked with trying to find out why the building failed in the magnitude-6.3 quake in February last year released the debris once he was done sifting through it.
The Christchurch City Council confirmed the building material is now piled up at a secure landfill compound surrounded by a 2-metre fence, patrolled by security guards 24 hours a day.
In the disaster's aftermath, the "sensitive material'' was moved to a Civil Defence storage facility - at the request of the Coroner - before being shifted to Burwood Resource Recovery Park (BRRP) at Landfill Rd.
The Canterbury Earthquake Recovery Authority (Cera) said the site, which has been blessed, is not open to the public, but those with an interest in the material - including the Coroner, police, the Canterbury Earthquakes Royal Commission, building owners and bereaved families - can request access through them.
Cera also confirmed to APNZ that engineers giving evidence to the royal commission hearing into the building collapse, which killed 115 people, have received approval to visit the site.
Today, as the hearing enters its third week, evidence came from structural engineers Clark Hyland and Ashley Smith who investigated the collapse for the Department of Building and Housing (DBH).
Their technical report, released in February, identified three "critical factors'' in the six-storey Christchurch building's failure - brittle columns, intense ground shaking, and the asymmetrical layout of shear walls.
They also concluded that the concrete office block did not meet design and construction standards when it was built in the 1980s.
Giving evidence together, Mr Hyland and Mr Smith told how the building's damage was "relatively minor'' after the magnitude-7.1 quake of September 4, 2010, and was destined to come down on February 22, regardless of how damaged it was.
They found its connections were not strong enough, or ductile enough, to stand up to the vicious shaking, while also highlighting problems over its concrete strength and shear walls.
Part of their task in trying to establish the Madras St building's failures involved sifting through its tonnes of rubble, documenting what they found, and taking notes and photos.
Mr Hyland and Mr Smith then "secured and retained'' all of the pieces they examined, which were then dumped at a separate zone at the Burwood landfill site, for future forensic examinations.
The revelations came as the co-authors of the DBH report faced tough questioning from Hugh Rennie QC, counsel for Alan Reay, director of Alan Reay Consultants Ltd, which designed the doomed building in the 1980s.
After the DBH report was released earlier this year, Mr Reay released a statement, criticising its contents as being "technically inadequate''.
Mr Rennie today quizzed them about whether they were qualified to do the job, and whether they considered enlisting the professional help of a Californian forensic structural engineer to assist them.
They did not and said they were confident they reached the right conclusions.
Mr Rennie also accused them of being close-minded, dismissing other "likely scenarios'' for the collapse, including the failure of concrete floor slabs.
The commission hearing - due to last eight weeks - continues tomorrow.