maybe u get smth from this : http://www.epa.state.il.us/water/per...

at pg 14 down, the number 800: mobe to demobe: Project duration mobe to demobe. From permit start to finish. this is about water. drilling on wetland.

I think it has somrthing to do with mobilization and demobilization, the costs of materiel, having it for a time period. The costs can very a lot, so you need to know when a rig or crane is available and for how long, cause of the cost of bringing it in.