CHARACTERIZATION OF IRON-ORE MINE WASTE ROCK PILES TO ASSESS POTENTIAL FOR USE IN SALTON SEA ROCK-FILL BARRIERS

摘要

The California Department of Water Resources (DWR) is currently preparing a Programmatic Environmental Impact Report (PEIR) for environmental restoration of the Salton Sea in California. The PEIR will consider a number of alternatives that could require up to 80 million cubic yards of large quarried rock (up to 4 feet in diameter) for in-sea construction. One of the possible rock sources is a former iron-ore mine with large on-site stockpiles of waste rock. The waste rock was placed in terraced piles by end-dump trucks, and the resulting piles fill whole valleys to 330 feet in depth. An exploration program designed to characterize the particle size, geologic origin, and durability of the waste rock and to verify the available quantity of rock was implemented by DWR and CH2M HILL. The program included use of geophysical resistivity profiling, deep core-hole drilling, and generation of continuous down-hole borehole-wall video images using a Borehole Optical Televiewer Probe (OPTV). The combination of these investigative tools coupled with probability-based surface feature visual observation techniques resulted in characterization of the approximately 60 million cubic yards of waste rock in the two primary piles at the mine.