If stock arrives earlier installation will be brought forward.
"Spring thanks everyone for their time and efforts to date and looks forward to working with you all as we fulfil the installations."
Project Waireka spokesperson Missy Biddle said she was delighted with the news.
"We are finally there with the contract agreement, what a relief and celebration time is in order."
Missy said she thanked everyone who has worked on and supported Project Waireka.
Ruapehu District Council chief executive Clive Manley acknowledged how long the process had taken.
"Council appreciates there was some frustration with how long the contract negotiations took however it was important to ensure that the interests of the two Project Teams, the Raetihi community and ratepayers were protected," he said.
He thanked people for getting Project Waireka "to this point and we look forward to doing all we can to ensure that the next phase is a complete success."