like the title says digging holes around your base should result in making a pile of dirt at your feet, filling said hole would require the same amount of dirt, this also would go into the indoor lighting crop thread (http://smf.cataclysmdda.com/index.php?topic=6337.0) it would also discourage people from digging hundreds of holes to increase their construction skill.
I didn’t realize excessive hole-digging was a problem. ???
IIRC mounds of dirt are a terrain rather than a furniture, thus creating them might cause more problems than it solves if you’re on non-diggable terrain (say, digging a ditch outside the hospital entrance).
Having to manage and dump the dirt sounds like a lot of trouble to dig a simple hole. Especially once you consider that building is already so inferior to making vehicles.
You know, you are free not to use every single exploit you stumble across. Perhaps adding the same skill cap to constructions could help to resolve the problem.