The bogland search is to take place before Christmas.
The schoolgirl was last seen in the company of convicted rapist and murderer Robert Howard when she accepted a lift home from a disco in Donegal. Howard was cleared of her murder in 2005 but was jailed for the murder of a 14-year-old girl in Kent.
The bogland to be searched is off the Drumquin Road close to where searches were carried out by a team from Queen's University.
The news comes as it's emerged that a 'secret' inquiry has been held into the Public Prosecution Service's handling of the case against Howard. It's been claimed that the PPS failed to alert the Arkinson family to the inquiry. The findings are expected to be released today.
Arlene's sister, Kathleen, said: "I knew nothing about it - no-one has asked us anything. They could have let us know what was happening. We're entitled to know. Let us have our say on behalf of Arlene. It's been terrible, a long twelve years of our life. Every day we think about Arlene, and now especially coming up to Christmas. All we have is Arlene's picture. They say time is a healer but it's not."
A spokesperson for the PPS refused to comment.
It is understood that the inquiry also examined the former DPP's role in another attack by Howard, when he drugged and raped another teenager living in Castlederg in 1993. The Arkinson family say that they never received a proper answer as to why that case went so badly. Howard received a suspended sentence.
Speaking of the searches, Kathleen said:"Hopefully with the new technology they will find something."