Christchurch City Council has announced Southern Demolition and Salvage Ltd will carry out the job.
The council's head of three waters, Helen Beaumont, said crews would be working 12 hours a day, six days a week to get the job done by September - three months earlier than expected.
"Southern Demolition undertook the trial removal of the material for us in December 2021 so they are aware of the huge job ahead of them. They are going to pull out all the stops to complete the removal work as quickly as possible.
"It's a complex task as the trickling filters have eight metre-high (three-storey) concrete walls and there is about 26,000 cubic metres - about the volume of 10 Olympic swimming pools - of material to remove."
Normally, the council would look for tenders for a project of this size, but the impact on local communities caused the council to make a direct appointment, she said.
But Beaumont warned the putrid odour may get worse before it gets better.
"Unfortunately, there are days when the smell could get worse as material deep inside the trickling filters gets exposed to the elements and starts rotting.
"We know this is the last thing that residents want to hear but at least we now have clear timeframes on when the work will be completed."
The cost of removing the material from the trickling filters will be funded from an interim insurance payment the council has received.
The material will be loaded into sealed bins and transported to the Kate Valley landfill where it will be treated as hazardous waste.
- RNZ
