Like many farms our drainage system is the old clay pipe version from the 70's. We can't afford new drains so we are thinking about buying an old single leg mole plough and then moving land going into spring cropping. The problem is depth of the clay drainage system. Obviously we can dig down and find a few pipes in each field to get an idea but obviously they had no gps in the 70's so we are concerned about damaging the system in place. How does everybody else play this?