The other problem is that the mines move due to the type of ground.
As for de-mining expertise, I think you will find that the RE teams knowledge and experience is very high on this front.
http://en.wikipedia.org/wiki/Mine_clearance
Currently, the main methods used for humanitarian demining on land are manual detection using metal detectors and prodders, detection by specially trained mine detection dogs, and mechanical clearance using armoured vehicles fitted with flails, tiller or similar devices. In many circumstances, the only method that meets the United Nations’ requirements for effective humanitarian demining, the International Mine Action Standards, [1] is manual detection and disarmament
Very good over view and answers a number of your questions Panzerknacker. Go down to Landmine Situation.