it all up
For years, NPA in Sri Lanka provided assistance to the Tamil demining groups and authorities, helping them to refine their own systems and so meet the requirements of the International Mine Action Standards. Uniquely, they achieved this without losing the low-cost features that are essential to any locally sustainable method. NPA also supported a similar process in government controlled areas, working with both the army (in co-operation with RONCO) and civil demining groups. Their civil partners were the Melinda Morigoda Institute for People’s Empowerment, HORIZON and SARVATRA – the first was a local Sri-Lankan NGO moving into Humanitarian Demining and the two others were demining branches of development NGOs based in India and staffed by experienced deminers.The clean up after “Gulf War 1” was a little more than twenty years ago – but it was the first time I heard about the use of rakes to find mines. Back in those days Royal Ordnance were active in Kuwait alongside deminers from many countries. Referred to rather disparagingly as TCNs (Third Country Nationals) deminers from India and Pakistan used rakes to expose mines in the desert. I am told that Royal Ordnance gave the rakes a try but did not take them up. The threats included V69 bounding fragmentation mines with tripwires and tilt-sensitive fuzes, so their rejection made good sense. A lot of TCN accidents during 1991-93 are on record, but the reports did not include much detail.
The idea of clearing mines with rakes was discredited and the potential was ignored by mainstream groups in Humanitarian demining. I was among those who dismissed the use of rakes as obviously dangerous. I was wrong.
The SL army raking in 2001In Kosovo in 2000 and 2001, leaf-rakes were used under Luke Atkinson’s direction (with the demining group Danish Church Aid) to remove the forest leaf-litter and expose PMA-2 and PMA-3 mines in well defined mine-belts. The rakes set off no mines. Detecting minimum-metal AP mines with metal-detectors in those areas was a hit and miss affair, as the accident record shows. Exposing them with the rakes was faster and safer.
At the start of the new millennium in Sri Lanka, demining was being conducted on both sides of the border between government and Tamil forces. With limited funds and extensive human resources, both sides used a low-cost, labour intensive “raking” technique. The Tamil’s Humanitarian Demining Unit (HDU) managed demining in Tamil controlled areas. They used short-handled rakes without marking the area, without imposing any safety distance and without wearing any PPE. Across the border, Government forces wore PPE, but paid similarly scant attention to the concept of safety distances and area marking. Clearance on both sides of the border was “successful”, but there were severely disabling casualties and the random method meant that the ground had not been thoroughly cleared.
When NPA were invited to advise the HDU in 2002, it would have been easy for them to dismiss the rakes and impose metal-detector drills. The cost of importing hundreds of metal-detectors would have been high, but many saw no alternative. However, Luke Atkinson was made the NPA programme manager. He saw that the raking was potentially as thorough as sieving the ground and so would be very attractive if it could be controlled within a marking and safety package that would be effective in preventing missed mines and accidents. NPA looked at ways to refine the tools and to control rake-use within site marking and supervision regimes that would create an entire system that would be accepted within mainstream demining. That system is the Rake Excavation and Detection System, known as REDS.
The REDS uses two simple raking tools to excavate and sift the ground to the required depth. Conventional demining site markings are used, and side of lane depth trenches allow effective QA of depth. A “Base-trench” across the front of the lane marks the extent of the processed area. Loose soil is brushed from the uncleared area into the Base-trench, and then packed to the rear of the trench. When the use of the Brush-rake becomes ineffective, the Harrow-rake is used to scarify the ground, allowing the Brush-rake to be used again. The Base-trench rolls forward as work progresses, which can be surprisingly fast in ideal ground conditions.
The Brush-rake has flexible tines that exert little pressure in any one place on the ground. Tens of thousands of mines were exposed using it, and none detonated. The Harrow-rake is heavier and is used to both scarify the ground and to lift shallow mines to the surface. If used incautiously, mines can be initiated by hitting the rake-head on the ground. This happened several times in Sri Lanka, but no serious injuries occurred. The long handle on the Harrow-rakes keeps the deminer at a distance from the blast, and the PPE that is part of the REDS system completes the protection against small anti-personnel blast mines very effectively.
The Brush-rake in use in 2004
Harrow-rakes in use in 2004
The early design of Harrow-rake head was very cheap and worked adequately in loose, sandy soils. It was revised for use in harder soils by Norwegian People’s Aid (NPA) and SARVATRA - a demining NGO from India who were working in government controlled areas of Sri Lanka. Their revision of the Harrow-rake uses a material with a proven record of maintaining integrity in AP mine blasts (low-grade Stainless Steel). The tools dig into and cut the ground without the need to apply any downward pressure and can be refurbished periodically to have a very long life. Locally made, they cost rather more than the original rake-design, but do not cost as much as three sets of batteries for a metal-detector.
The heads of the SARVATRA/NPA Harrow-rakes
NPA and SARVATRA refined the design further, to make the REDS applicable on even harder ground and to make refurbishment a simple field exercise.
Because the REDS system sieves the ground, it gives the kind of complete confidence of clearance to the required depth that metal-detectors and other area-excavation techniques cannot achieve. [This conclusion is among the results of GICHD comparative trials of manual demining systems which took place in Mozambique during October/November 2004.]
The main limitation of the REDS system was the time that it can take to complete when there is dense undergrowth or the ground is hard with complex root systems.
There was a need to turn the jungle into loosened ground so that REDS could be used efficiently in a wider range of conditions.
Typical Sri-Lankan jungle
Ideal ground for REDS
To solve this problem, mechanical means of preparing the area were devised by NPA in collaboration with SARVATRA.
SARVATRA adapted construction-site machines to provide the platform for vegetation cutters. The platforms are low-cost earth moving machines with hydraulic arms designed to carry excavation buckets for use on building sites. The hydraulic arm reaches out into the minefield while the machine stays on safe ground.
The first set of teeth cuts undergrowth and roots.
The second set of teeth rakes to the
At a unit cost of less that US$30,000, the machine cost less than a good 4x4. Unlike large flails, they did not turn the ground into dust, destroy mature trees or disrupt patterned mine belts. The use of widely used plant machinery meant that spare parts were widely available, servicing was simple, operation was straightforward, and the machine could be converted back to conventional uses by retrofitting its original tools in a matter of minutes. This versatility was unique and guaranteed that the machines did not have to be scrapped when their demining role was over.
Of course, the peace process in Sri Lanka failed and its great supporter, NPA was thrown out. But Sarvatra kept working and has twenty of their machines before they left. The success of the machine was so obvious that five different NGOs were using it by the end, many hired from Sarvatra.
NPA took the rakes on to Jordan, modifying REDS for that environment with complete success. When they cleared the Jotdan/Syria border, they used metal-detectors to find the mines and the REDS rakes to expose them. Meanwhile DDG moved the REDS system into Sudan (where NPA followed) and I last heard of the REDS system being used with great success is Libya in 2011.
So after many years spinning in a backwater, the simple low-cost rake drifted into the mainstream of demining technology. Both hand-held and mechanised, rakes are sustainable, cost-effective and (used in a well designed system) give total confidence of clearance to depth. I wish that the same were true of metal-detectors.
Thanks to NPA Sri Lanka and to SARVATRA for showing me something “new”. Individual thanks to Mr Brar and Mr Petri (SARVATRA); Luke Atkinson and Jan Erik Stoa, (NPA).