In the interim, the landfill has been shored up by boulders, but a final decision on the rubbish is yet to be made by the Westland District Council.
All options will be expensive, ranging from more than $300,000 to $2.8 million.
Rubbish from the landfill, which was closed earlier this century, was strewn over the Fox riverbed and 21km out to the Tasman Sea after a severe storm in March.
District council group manager of district assets David Inwood said any further rock-protection work would only be an interim solution "when taking into consideration that New Zealand's largest active landslide is at the head of this valley and the fact that 60m of land has already been lost to the Fox River that exposed the closed landfill".
Indications were this would cost more than $300,000.
Having the remaining landfill material removed would require significant consent applications and compliance with national environmental standards for contaminated soil.
The cost of removal and relocation to either a new site, yet to be identified, or to the council's consented landfill at Butlers was expected to cost about $1.8 million.
There would also be an additional cost of $1 million to create a new cell, as the transfer would use most of the landfills remaining life.
The council had obtained technical support from experts in this field and was working through this process.
Both options were being considered by the council with input from the Department of Conservation and the West Coast Regional Council as resource consents would be required for any future action, Mr Inwood said.
