The investment case for Christchurch's multi-use arena is before the City Council today

It says to be competitive and attract international and national events, the arena would need a roof, a minimum 25-thousand seats, a fixed rectangular turf and high quality acoustics.

It's projecting the arena would cost almost 475 million dollars to build.

The council has allocated 253-million towards the project, with the Crown signalling it would contribute 220-million.

The net operating cost is anticipated to be 4.2 million dollars per year, with the Council providing 4.1 million from its Long Term Plan.

If the arena doesn't proceed, rates savings of about 2.9 per cent could be made.