. "Among other things, we adopted definitions of three new terms in 30 CFR 701.5. ???Coal mine waste??? is defined as ???coal processing waste and underground development waste.??? ???Impounding structure??? is defined as ???a dam, embankment, or other structure used to impound water, slurry, or other liquid or semi-liquid material.??? ???Refuse pile??? is defined as ???a surface deposit of coal mine" . . . .