The price paid by the Government to acquire the site for a proposed new prison at Thornton Hall in north Co Dublin was eight times the going rate for land in the area, the Dáil Public Accounts Committee has heard.
Green Party TD Dan Boyle cited figures for land sales in north Dublin ranging from €19,000 an acre to €34,000 an acre. The price paid for Thornton Hall was €29.9 million, or €200,000 an acre.
The figures quoted by Mr Boyle were compiled by Paddy Spain, an accountant with 40 years experience in the estate agency business and a former partner of Lisney and Spain Courtney Doyle.
In a letter to the committee, Mr Spain said he was staggered by the "massive fiasco" that had taken place. The market value of property in the area was €25,000 an acre and the Government could have bought 1,100 acres of agricultural land with the money it spent, not 150 acres.
Minister for Justice Michael McDowell should apologise for the €26 million overspend on the project, the letter said.
However, Department of Justice secretary general Seán Aylward said many of the sites referred to by Mr Spain were too small for a prison. Some were hopelessly unsuited, he said.
"I am not aware of any site as suitable or as close to Dublin as Thornton being sold for less than €200,000 an acre."
Mr Aylward pointed out that four years ago Mr Spain had contacted the department offering to sell land at Hollystown, west Dublin, for a juvenile detention centre for €440,000 an acre.
Committee chairman Michael Noonan said this site was fully serviced, unlike Thornton Hall. From the public gallery, Mr Spain said Mr Aylward was taking this offer out of context. Mr Aylward was "ballyragging" him.
Mr Noonan advised Mr Spain that he was not entitled to make comments from the gallery, but he was welcome to write to the committee.
Mr Aylward agreed that the department sought a 100-acre site but eventually bought all 150 acres at Thornton Hall.
This would allow for lower-scale development, future expansion and a "sterile zone" to prevent drugs and weapons being thrown into the prison. He declined to say how much the prison would cost to build.
