Major players in negotiations are poles apart on further funds at present, with the Napier City Council, owners of the land and looking at a new lease with hockey to include the area set-aside for the expansion, having already committed $1m in grants and a $500,000 loan, and Unison already a strong supporter of hockey, and other sports.
Network customer relations manager Danny Gould said Unison would do what it could to help, but it is unable to financially support the cost of the undergrounding he said would be $300,000 to $400,000.
Edmundson said: "We're forever hopeful, but we're going to have to find the money elsewhere."
He said it would be "very much the plan" to lay the turf during the summer, but it is "very much dependant" on finding the money.
The first Park Island pitch was laid in 1991 and the second in 2000, and Edmundson said player numbers had grown each time.
"They are very well used, and very economical to look after, when you look at the cost of maintaining and repairing grass turf," he said.
The new lease is on the agenda for Thursday's council Prosperous Napier Committee, a report from staff noting the year-on-year growth in the game's numbers over the last decade.
Rental on the area of the new turf would not be charged until the turf was in use, the report said.