K-Pit is the largest and wettest of the pits to have been mined by Cliffs Asia Pacific at the Koolyanobbing Iron Ore Mine. Most of the ore comprised specular hematite and vuggy goethite, which have a high porosity and permeability. The pit was located along several faults, which enhanced groundwater inflows.
To enable dewatering during the final stages of mining, Rockwater was contracted to design and supervise the drilling of three, 125 m-deep production bores in the pit floor.
Owing to instability of the ore, it was necessary to drill the holes using a combination of dual-rotary, mud-rotary and ODEX techniques. Air-lift yields of up to 60 L/s were produced during drilling and the bores were test-pumped at 50 L/s with minimal drawdown.
Rockwater has performed similar dewatering investigations at other iron-ore deposits in the central Yilgarn Craton, including Windarling, Deception, Mt Jackson, Carina and Parker Range.
We continue to perform a dominant role in supplying hydrogeological advice to iron-ore projects in the central Yilgarn region.
