(Footage of workers getting ready to go out into the mine fields)
HALO TRUST GROUP LEADER: Attention. Attention.
RICHARD LINDELL: It is 6am and this group of workers are already on the move. This has the look and feel of a military operation, with discipline and focus to survive the day ahead. Almost a quarter of the workers here are women taking on one of the most dangerous jobs in the world.
THERARASA NITHYANANTHI (Translation): I do have fears while doing this work. I try to do my work carefully and safely.
RICHARD LINDELL: Therarasa Nithyananthi is one of the estimated 90,000 war widows in the north and east of the country. Work is scarce and manual labour doesn't provide the job security or the $200 a month salary she's paid to clear mines.
THERARASA NITHYANANTHI (Translation): I needed to work because I have four children. My husband's no more and we were struggling to make ends meet.
RICHARD LINDELL: Her job is made more difficult by the nature of the conflict. Both sides laid mines during the almost three decade long civil war.
Of course one of the major problems you have is that the LTTE (Liberation Tamil Tigers of Eelam) didn't map any of the minefields they laid, so it must make the job that much more complex.
BARTHY DIGBY, LOCAL MANAGER, HALO TRUST: Sure. We depend on initially depend on local information for the location of the minefield.
RICHARD LINDELL: While the Sri Lankan army mapped their minefields the Tamil Tigers did not. It means all uncleared areas pose a threat and that the miners must map their progress as they work.
Here at Killinochchi, the scene of some of the fiercest battles of the war, minefields have still being discovered.
BARTHY DIGBY: So as people are pushing further back into the jungle, into their own land, new information is arriving. And we just have to react to that in terms of surveying, marking and then clearing where necessary.
RICHARD LINDELL: Work at this site started three months ago and so far 200 mines have been removed.
BARTHY DIGBY: So each of the 30 centimetre yellow sticks marks a mine found and removed through our clearance. This whole area around you is now cleared.
RICHARD LINDELL: But a large swathe of this farmland is yet to be cleared. This is slow painstaking work; using basic tools these women are reclaiming their land in 50 centimetre strips.
There are no definitive figures as to the amount of mines laid during the war, but it is estimated that there are over 100 square kilometres of minefields still to be cleared with potentially hundreds of thousands of mines.
Now 100 square kilometres may not sound a lot, but this de-miner will clear just 20 square metres a day.
Sri Lanka's north has one of the highest concentrations of landmines in the world. But clear marking by the military and aid groups has kept the casualty rate low compared to other conflict zones.
Nine deaths and 38 injuries were reported in 2010, but there is a social and economic cost. Minefields lay waste to valuable farmland and prevent thousands of displaced people returning to their homes.
KANESAN KRISHNAVENY, SECTON COMMANDER, HALO TRUST (Translation): I'm helping to make areas safe for people to live, do cultivation and for cattle to move around. I feel happy because people are benefiting.
RICHARD LINDELL: Kanesan Krishnaveny is the section commander of this team. Her wage supports her four siblings and parents.
While she has been promoted and had success here, is hasn't filled her with confidence about the future.
KANESAN KRISHNAVENY (Translation): I haven't thought about what I'll do after a leave this work. It will be difficult to find a job once I leave here.
RICHARD LINDELL: In the meantime, aid groups say there's another decade's worth of work clearing the most dangerous legacy of Sri Lanka's civil war.