Burying the exit wand deeper is the typical answer to this question. However we see in your details that you already have the wand buried 3 feet deep and the sensor is still being triggered fairly easily. Our next suggestion if that is not working is to add resistance to the ground lead of the exit sensor. This can be done with a potentiometer. You had also asked in your details if putting the sensor in conduit would help make it less sensitive. This will help a little but typically putting it in conduit is to fix the wand from picking up interference from ground water.