"They're a big club and they have more resources than some of the other clubs and they were already reviewing their future."
Once a venue was chosen a formal proposal would be drawn up, he said.
"We are checking out what venues will work and then we are looking at putting together a proposal for a brief for the vision of the complex."
It was envisaged that the complex would incorporate a gym, room for passive sports and activities such as yoga and bridge and space for meetings and administration, as well as room for traditional sports, he said.
"We want to really see this facility being a community resource so, ideally, the building would be able to be used for meetings and potentially civil defence and things like that.
"The vision is for a wider usage than simply sport. We see this facility complementing the events centre and enriching the community."
The group submitted an outline of its vision to the council's Long Term Plan this year.
Although the costing had not been completed, the ballpark figure was expected to be about $3 million-$4 million, Mr Osborne said.
The trust aimed to meet its funding needs from lottery grants, trusts, sponsorship and donations, and would potentially seek a lease of land from the council.
The trust would consult other sports clubs before moving ahead with its plans, he said. "It's a big investment - we've got to get it right."
Sports on board so far included rugby, football, tennis, netball, swimming, athletics and squash.
Newly appointed trust chairman and Carterton Rugby Club president Steve Hurley, who recently took over from Elaine Brazendale, said the trust would need to further gauge interest from the sporting community.
"We are going through the process of crystal ball-gazing and putting some ideas and plans together, and then each sporting code in Carterton will get a chance to decide if they want to be involved," he said. "It's not going to be a quick fix. It's going to take time."
Mayor John Booth said the council supported the trust's vision but additional consultation with the community would be required once a proposal was completed.
"It's up to them to bring back something to us that we could look at with the community," he said. "We support them going away and doing a study and coming back with options but it has to be thorough process, that I want the community to be part of, so that we can do something that could be really beneficial for the Carterton community."
The trust aims to complete its proposal by the end of the year.