Police searching for for missing airman Corrie McKeague are trawling a landfill site
It could take the team of eight trained search officers up to 10 weeks to sift through rubbish up to eight metres deep, covering around 920 square metres of the dump in Milton, near Cambridge.
A bin lorry linked to the disappearance of Mr McKeague was initially thought to have collected an 11kg load, but police said it was later found to be more than 100kg.
Mr McKeague’s mother Nicola Urquhart said this could "only mean one thing".
The 23-year-old, from Fife, vanished on a night out with friends in Bury St Edmunds, Suffolk, on September 24.
A bin lorry was seen on CCTV near Brentgovel Street in the town around the time Mr McKeague was last seen
A bin lorry was seen on CCTV near Brentgovel Street in the town around the time Mr McKeague was last seen, and it took a route which appeared to coincide with the movements of his phone.
The area of the landfill site where the load was deposited is now being searched, with a digger mechanically excavating mounds of waste and officers in white protective suits raking through it on the ground.
The drastic difference in the lorry's load weight prompted police to swoop on a 26-year-old man, who was not the driver, before he was bailed on March 1.
MISSING RAF serviceman, Corrie Mckeague Mon, January 9, 2017
Corrie Mckeague, of Dungermline, Fife, has been missing since he disappeared after a night out in Bury St Edmunds, Suffolk on September 24. The 23-year-old's girlfriend, April Oliver, 21, of Norfolk, revealed she found out she was expecting his child two weeks after he vanished near RAF Honington where he has been based for three years while training to be a gunner and a medic.
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April Oliver, 21, girlfriend of missing 23-year-old Corrie McKeague (right), who has revealed she is expecting his child
He was arrested on suspicion of perverting the course of justice by misleading officers over the discrepancy, but on Tuesday was told he faced no further action.
Police said correcting the error he provided had placed a "new emphasis on the search".
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Forensic examinations previously found no traces of Mr McKeague in the lorry.
Detective Superintendent Katie Elliott said she does not believe there was a "deliberate attempt to mislead" the investigation, and that the focus had to be on finding Mr McKeague.
8,000 tonnes of bulk material have been moved to make the area safe to search
The team will search around 920 square metres of the dump at Milton
She said: "We now know the weight of the waste collection from the 'horseshoe' on the night Corrie went missing was over 100kg, when the original information we were given indicated that this was 11kg, and this makes our search of the landfill the next logical step to try to find Corrie.
"There was no intention to mislead the investigation, however our discovery, through persisting with this through our inquiries and evidence gathering, now puts a new emphasis on the search.
"The search of the landfill is a huge undertaking, and still may not provide the answer as to what happened, but now, with new information uncovered by the officers working on the case, this is the priority."
The six-month investigation has cost more than £300,000 to date and the search of the landfill site could cost more than £500,000 if it runs to 10 weeks.
It could take the team of eight trained search officers up to 10 weeks to sift through rubbish up to
A digger is manually excavating the site with officers raking through on the ground
It follows work to move 8,000 tonnes of bulk material to make the area safe to search.
Ms Elliott said it was a "dreadful" time for the family of Mr McKeague and her thoughts are with them.
Corrie’s mother Ms Urquhart said she hoped her son would be found quickly on a social media page called Find Corrie.
She wrote: "With the weight of the bin that was lifted the night Corrie went missing has been incorrect and the true weight is over 100kg.
"This can really devastatingly only mean one thing.
"I can only pray that Corrie is found quickly and that we are able to get answers as to how this could have happened.
"Please can I ask everyone on here to try really hard not to speculate just now. Each second waiting to find Corrie is torture enough.
"This page was set up to find Corrie. We still need to do this.
"From myself, Makeyan and Darroch thank you for your neverending support more than ever."
She told BBC's Good Morning Scotland programme that her focus was on finding Mr McKeague.
She said: "My absolute focus is on finding Corrie; once I've found Corrie then all the questions will come as to how this happened, how he's ended up there, how the investigation's gone, what things have been done.
"Hindsight's a wonderful thing – this isn't the time for it. Finding Corrie right now is the only thing we need to be thinking about."