CLIENT: BarCan (Barite Mud Services Inc.)
PROJECT: BarCan Tailings Pond Decanting Project
PROJECT TYPE: Brownfield
LOCATION: Newfoundland and Labrador, Canada
COMMODITY: Barite
SERVICE SCOPE: EPCM
BACKGROUND
The objective of the project was to expose historic tailings material that had been sub-aqueously deposited so that mechanised mining could reclaim this material for reprocessing. In order to achieve this, the level of the pond needed to be reduced by approximately 1m. This involved evacuating 564, 708 m3/h from the pond over a two-month period. The pond water naturally overflows into the watercourse to this process had to be accelerated.
Numerous methods were evaluated but were deemed to be either impractical or pose unacceptable risk to the operation. The output of extensive evaluation was using a siphoning system.
THE CHALLENGE
The project faced numerous limitations in terms of limited electrical power at that location, the fact that the dam wall structure is critical infrastructure and the downstream environment being very sensitive variations of water flows.
No electrical power was available for the operation of pumps, the pumping alternatives therefore involved either installing a new powerline to the site or using diesel pumps. Both options involved unfavourable capital or operational costs.
In order to prevent any adverse impacts to the dam wall structure, the system had to be completely independent of the dam wall so that its construction and operation would not affect its structural integrity.
The downstream watercourse was also sensitive to high water velocities which could cause erosion so a suitable method to dissipate the water energy was required.
THE SOLUTION
Following numerous trade-offs and field experiments, a siphoning system was arrived at. This system involved installing 4 pipelines that draw water from behind a protective silt curtain. The pipelines then run over the top of the wall and down into the valley below.
The system operates by making use of the natural difference in elevation between the dam water level and the pipe discharge point below. The 5 m of driving head provides sufficient driving force to flow 1144 m3/h out of the dam.
ACHIEVEMENTS/HIGHLIGHTS
No power source needed to operate the system.
No impacts to dam wall structure.
Mitigation of erosion to downstream watercourse.
Environmentally friendly operation that runs on its own without the need for external energy input.
