Consultants from Ernst & Young were brought in last month to assess the alternative to handing the environmental services contract to private firm Enterprise.
A report set to be published today has revealed that the consultants judged that there was “low to medium confidence” that the £45 million of savings identified within the public sector comparator (PSC) could be successfully delivered.
They said that there remained “uncertainty” about whether the workforce would accept the changes that are required.
The privatisation plan sparked massive protests from left-wing groups and council staff at the City Chambers last month and councillors put a decision on hold until further work had taken place to assess the in-house alternative.
Council officials have now re-asserted their original recommendation that councillors accept the Enterprise bid, which would bring about a minimum of £51.4m of savings, possibly rising to £72m.
In today’s report, council chief executive Sue Bruce said: “Ernst & Young were commissioned to undertake an external review of the PSC.
“Ernst & Young have concluded that there is low to medium confidence in the deliverability of the PSC. It should be noted that the work that has been done on the PSC is substantial and that effort should be recognised [and] Ernst & Young conclude that it provides a legitimate comparator to the proposals from Enterprise.
“It is important to note that Ernst & Young highlight that uncertainty remains as to the acceptability to the workforce of new ways of working which are fundamental to the improvement plan.
“They conclude that implementation will involve difficult decisions along with sustained commitment and leadership if the full benefits are to be secured.”
Trade unions sent a formal statement to the council earlier this month pledging that bin men would end their ongoing industrial action, while insisting that they “recognise the need” for new work systems.
Mrs Bruce said that the letter “did not provide a definitive and unambiguous agreement that the workforce supported the changes required”.
Last month, SNP councillors agreed to a delay to the decision but insisted that they still intended to vote for the in-house option, alongside Green and Labour councillors, at a meeting next Thursday.
The Lib Dems and Conservatives have previously indicated support for the Enterprise bid.