MSHA - Code of Federal Regulations - 30 CFR 77.1608
30 CFR § 77.1608
(a) Dumping locations and haulage roads shall be kept reasonably free
of water, debris, and spillage.
(b) Where the ground at a dumping place may fail to support the
weight of a loaded dump truck, trucks shall be dumped a safe distance back
from the edge of the bank.
(c) Adequate protection shall be provided at dumping locations where
persons may be endangered by falling material.
(d) Grizzlies, grates, and other sizing devices at dump and transfer
points shall be anchored securely in place.
(e) If truck spotters are used, they shall be well in the clear while
trucks are backing into dumping position and dumping; lights shall be used at
night to direct trucks.