Whichever way it goes will set a precedent, because it could be the first time seabed mining is consented in New Zealand waters.
Other companies with seabed mining projects will use it to assess their own chances, Kiwis Against Seabed Mining chairwoman Cindy Baxter said.
According to TTR executive chairman Alan Eggers the mining company wants confirmation the EPA used a legally correct approach to grant the consents.
He said they were granted with a long list of conditions designed to protect the environment and existing interests - especially the interests of iwi.
The matter is set down for hearing in the Appeal Court on September 24, 25 and 26.
The many groups that oppose mining will also be in court, seeking to strengthen legal barriers to seabed mining.
The groups include KASM, Greenpeace, Forest and Bird, South Taranaki tribes Ngā Rauru and Ngāti Ruanui, the Taranaki/Whanganui Conservation Board and fisheries interests such as Talleys Group, Te Ohu Kaimoana and Cloudy Bay Clams.
The same groups - an unusual mixture of fishing, conservation and iwi interests - opposed the project in earlier hearings.
"Nobody has dropped out," Baxter said.
The High Court judgement only gave weight to one of the opponents' objections to mining - that it relied on "adaptive management", a process of learning by doing where the results of an action are uncertain.
The groups want to test other possible barriers. One is that the precautionary principle has to be applied under international law.
Another questions the way the EPA hearing was managed, and that the consents were granted on the chairman's casting vote.
Some of the groups would like to know why the negative economic costs of the mining and its effect on the coastal marine environment were not taken into account.
The result of the appeal will be of great interest to Chatham Rock Phosphate, which wants consent to mine the Chatham Rise off the Canterbury coast.
A Niwa study found that its ancient corals and teeming sea life have already been badly damaged by bottom trawling, Baxter said.
There are also companies that want to mine iron sand off New Plymouth and Waihi Beach, and TTR has permits to explore iron sand mining in a bigger area of the South Taranaki Bight, with some of it closer to the coast.
Its website says it has spent more than $65 million on the mining project so far.
