The membrane will be laid out over the equipment, attached to the floor and inflated.
Once inflated, all remaining work on the dome structure happens inside.
Holcim now ships cement to Onehunga from its Westport manufacturing plant. That plant will close in mid-2016 once the new Auckland silo is built.
Consent to Holcim to build the silo was granted on a non-notified basis, meaning the public did not have a say.
The same thing happened with two controversial wharf extensions to Bledisloe Wharf, although this was overturned by Justice Geoffrey Venning after the legality of the consents was challenged by Urban Auckland, a society of architects and planning professionals.
Urban Auckland chairwoman Julie Stout said the dome was a major investment on port land to enable the importation of the North Island's cement needs and the export of iron sands.
"This trade is one of the factors putting pressure on the footprint of the Ports of Auckland. While appreciating the need for cement in the city's growth, the question many Aucklanders have is whether bringing these bulk goods through the centre of our city is appropriate in the long-term," she said.
Until a study on the wider effects of the port on the city is done, "we hope major investment of this kind is put on hold until all other options for Ports operations, including a national ports strategy, have been investigated", Ms Stout said.
The establishment of the Port Future Study began last week with the first meeting of stakeholders and the selection of the Stakeholder Reference Group.
Interested groups and individuals from a broad range of sectors interested in future port development met together for the first time to discuss how the study should be conducted.
Greg McKeown, a former Auckland City councillor, said you had to wonder why these sorts of port developments could not be fully disclosed to the public and councillors, especially as Quay St was recognised as a major gateway to the city.
