She does not intend to take a loss, but said she was not organising the event, which will likely take place on December 14 and 15 if approved, to make money.
"I'm just very passionate about it. My long-term vision is to grow this sport in New Zealand."
This month she presented her proposal, which she said has the support of the Takapuna Business Association, to the Devonport-Takapuna Local Board.
Board chairman Grant Gillon said board members were "intrigued" by the idea.
"The board thought this is quite exciting and could raise the profile of Takapuna, but she has to make a formal application."
Concerns included the commercial level of the proposal - it must fit in with the board's policy of not allowing commercial activity on the beach, Gillon said.
Calway is working with the events team at Auckland Council to ensure the proposal met the policy, and will take her proposal back to the board for approval once that is completed.
The event would be zero waste - she was working with a local school, which was the event's charitable partner and would be involved in the clean-up as a fundraiser, Calway said.
An equine vet and St John Ambulance workers would also be at the event, and safety measures would include separating horses and spectators.
Divots - wedges caused by hooves - would be stomped out by spectators at halftime, as was tradition, and the incoming tide would restore the beach to its natural setting.
Beach polo, which began in 2004, was played on smaller arenas than field polo, and the arena would be 50m x 25m, Calway said.
There would be a catered sponsors' area on Gould Reserve, and also space for other spectators, but Calway was not sure yet if entry to the event - which she hoped would become an annual tradition - would be free.
There were a lot of costs, including insurance and measures to cover health and safety requirements.
Whatever the final plans, should her plan win approval, it would keep its "air of aristocracy", Calway said.
That gave polo its point of difference from other events, and she believed punters wanted that.
"Who doesn't want to roll with that? Champers, oysters, good music and wearing a nice flowery dress with your mates or your clients?"
Calway is also behind another beach polo event planned on Waiheke Island's Onetangi Beach next March.
The event is waiting on approval from the Waiheke Local Board, but Calway said that was expected to go through once the board completed its policies on the use of commercial use of public space.
