Dewatering tunnel water management
Challenges
The tunnel boring machine pumps on the mining face were collecting a highly solids loaded water, causing an obstruction of the dewatering tunnel piping. This situation being very critical required a shutdown of operations every 2 weeks to scrub the piping.
In addition, the amount of solids to be generated on ground required the need of several trucks every week and the associated costs were a key issue for the company.
Finally, the space available for the water treatment facility on site was extremely limited given its urban character.
Outcomes
Disposal of sediments at source, keeping the discharge and dewatering lines clean.
A significant reduction in the amount of suspended solids pumped to the surface, from 150 000ppm to 200ppm.
Increase in the productive capacity of the tunnel boring machine by eliminating production shutdowns.
An 80% reduction of the volume of sludge evacuated from site weekly.
Sludge recovery to be used in dust control process on the cuttings transfer conveyor.
Increasing the dewatering pumps reliability by 400%.
Reduction of 60% in the volume of settling pond on ground.