CLIENT: Kestrel South
PROJECT: Dredging and De-watering
SCOPE OF WORK:
Two silt traps totaling approximately 40,000m3, upstream from a holding dam had become full of coal fines running down from the adjacent stockpile.
This was beginning to cause silt ingress to the holding dam. Removal was complicated because despite having access ramps, the traps were HDPE lined so could not be cleaned using earth-moving equipment.
CHALLENGES FACED:
Each trap began in a totally full (zero-water) condition. This meant that a hole had to be dug to fit the dredge in, which was then filled with water. It was then possible for the dredge to enlarge this to create enough room to manoeuvre, then ramp up to full production. Also, as there was no other suitable impoundment or location to move the material to, this necessitated the use of Geotubes.
ACHIEVEMENTS/OUTCOMES:
To utilise one of our VMI dredges fitted with Liner-Guard system to allow recovery of the material without damaging the liner. Due to long batters cranage would be difficult, so this was launched and retrieved using our super-tilt trailer and the access ramps. A Geotube farm was constructed in an area adjacent which allowed capture of the coal fines, while returning the water. Recovered material was dried, recovered and blended back into the stockpile. This methodology meant that it was possible to clean the traps and use the recovered material to help finance the works.