Selective Placement of Coal Stripmine Overburden in Montana. II. Initial Field Demonstration

摘要

A week-long selective overburden handling dragline operation was conducted at a strip mine near Colstrip, Mont. The objective of the demonstration was to hydrologically isolate a saline overburden zone during placement in the spoil piles. The saline zone had concentrations considered inimical to successful reclamation and was potentially dangerous to future water quality in the spoils aquifer. The zone was identified after review of chemical data for overburden samples collected from the intense 60-m-grid drilling pattern. The saline zone in the overburden was (1) handled in a normal manner; (2) segregated and buried; and (3) segregated, buried, and covered with a relatively impermeable 1.0-m thick clay cap. The method used to formulate this demonstration, the demonstration itself, and the monitoring and evaluation techniques are described in this report.