If a laydown yard is not maintained or if the sub-grade (ground under the rock) gets soft, it will cause failure of the top surface. The top surface is only as good as the sub-grade unless it is thick enough to bridge over a soft sub-grade.
Preventative maintenance starts with a small puddle and doing something about it. As a truck or forklift travel across a puddle it will track the muddy material from it and take it elsewhere. The small puddle will eventually become a big puddle. It’s like what elephants do to water holes. As the water dries out the elephants will woller around in the mud and it will stick to their bodies, and then they carry the mud away. Each time that happens the waterhole becomes bigger and bigger.