The company said the offering, open to professional and sophisticated investors, had the support of its bank.
Coffey managing director John Douglas said the bond offering was in line with the focus on debt reduction, which had seen gross debt fall to $77 million in June 2014 compared to $88.7 million in the previous year.
The deficit is down from a high of $150.8 million in the 2011 financial year.
“Driving down debt was one of our key achievements in FY2014 and we are committed to building on this strength,” Douglas said.
“The bond issue will deliver a more balanced debt profile managed over a longer timeframe.
“It diversifies our funding sources and gives us greater certainty over the short to medium term.
“Together with our recent return to profit, this gives us the right base on which to grow when opportunities emerge.”
The bond offering comes at a time of continued weakness for mining consultants.
Soft conditions and project deferrals in the mining sector have seen a number of companies post weaker results.
When the offering is completed, Coffey’s bank facilities will be reduced by the amount raised and extended a further 18 months from February 2016 to September 2017.
The senior, unsecured bond offer will be subject to a minimum subscription of $50,000 with Coffey indicating a term of five years.
The lead arranger for the transaction is FIIG Securities.