KiwiRail chief operating officer Todd Moyle spoke to Susie Ferguson on Morning Report and said they were able to recover the wagon and containers last night.
He said recovering the locomotive today will be more of a challenge.
"We are trying to float it this morning with 10 airbags. Then we will take it about 50 minutes around the corner to a point we can lift it."
Two large cranes will be on-site to lift the locomotive once it is at the right location.
"It is a complex move. I'm confident we can do it. We have very experienced contractors supporting us."
About 15 to 20 litres of diesel has reportedly leaked into the harbour from the locomotive but Moyle said this is minimal.
"There's been very very limited discharge. It's very well contained, we've got contamination booms all around that area and we are able to go in with the harbour masters and collect that material and skim it off the top.
"It is something we're absolutely conscious of and are managing well."
The moving of the locomotive once it has been floated is expected to begin at about 2pm and there is a five-hour window between ferry sailings to make it happen.
"We want to minimise the impact to sailings, we understand the acute pressure on freight at the moment. Once we've got the locomotive floated it's probably a two to three hour operation."
It is too early to say whether anything can be salvaged from the locomotive, wagon or containers but Moyle said they will see when everything is out of the water.
- RNZ
