My coal stove is in my basement so I keep several metal ash cans outside above my bilco doors. Every day I empty the ash in the cans and when they are all full (usually 7-10 days) I put them in my truck and dump the ash at a friends. He has an alley that is nothing but potholes. The ash makes a great filler. Also by leaving the ash outside in the cans everyday moisture eliminates the dust.
Once his alley is complete I plan on just dumping in areas that are posted looking for clean fill.
Hope this helps.