Normandy Golden Grove – Scuddles Mine – Up-Cast Ventilation Shaft – WA,1992-1993
The 350-meter deep Northern Up-Cast Shaft of this mine was raise bored to 4.1 meters diameter and, at time of completion, registered 1536 liters per minute of water ingress. Apart from excessive pumping costs, this large volume in the shaft decreased fan efficiency and caused problems with water spray onto surface electrical power stations and surrounding vegetation. It was critical to eliminate airborne water in the shaft that would become entrained in the up-cast airflow.
Geological investigations suggested that water was entering the shaft in two zones (145 meter and 179 meter depths) and that it was unlikely that water inflows would be encountered at depths greater than 200 meters. SCEM66 was applied from a 2 deck stage suspended from an air winch capable of descending to a 200 meter depth. Shaft inspection revealed water ingress was from both vertical and horizontal cracks and fissures.
Water sealing by drilling and injecting was systematically carried out from the 114 meter level downward. Within one week all the airborne water was eliminated and measurement in the shaft at the 200 meter depth showed residual water make of 75 liters per minute. Additional measurements at a V-notch weir at the base of the shaft indicated water make of 335 liters per minute, indicating that leakage was occurring below the 200 meter depth.
Some six weeks later, readings at the bottom of the shaft indicated water ingress had increased to 970 liters per minute. In December 1992, Sovereign remobilized and inspected the entire shaft. The inspection revealed that the raise boring had intersected an HQ diamond drill hole at the 273 meter depth. The drill hole was discharging more than 600 liters per minute at the time of the inspection. The inspection also revealed that the water table around the shaft had recovered after the first application of SCEM66 and the water table was now at a shallower level situated above where grouting had previously occurred.
In June 1993, the top 130 meters of the shaft were lined with reinforced concrete. At that time, the diamond drill hole and other previously untreated water ingress zones were sealed with SCEM66. Total shaft water make was reduced to less than 120 liters per minute.
