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Tailings Behavior & Characteristics

Initial Assessment – 1997 to 1999

Criteria Ramu DSTP site
Steep slopes >12% so that tailings flow by gravity into deeper water Very good – slope of DSTP more than 200
Stable near-shore slopes Good
Deep ocean basin for tailings disposition Very good – detailed ocean profiling indicates that most tailings will deposit in Vitiaz Basin at depths between 1.0km – 1.6km deep
Natural sedimentation in DSTP location Excellent – High rainfall in PNG deposits 80 million tonnes annually of natural erosion/sedimentation into the Vitiaz Basin, meaning Ramu will contribute less than 6% of the total sedimentation load. High sedimentation also ensures distribution and dilution of the tailings deposits on the seabed will be relatively rapid over life of mine and eventual burial following mine closure.
Permanent density gradient to trap tailings below deepest mixing layer of 120m Excellent – Ramu DSTP outfall to extend to 150m, well below density gradient
No strong currents near sea-bed Good – Peak sea-bed currents measured less than 0.2 m/sec
No upwelling current Excellent – Upwelling currents do not occur below 100m depth. Ramu outfall at 150m.

Scientific Studies

Deep Sea Tailings Placement – Main Features

Tailings Placement

Natural Erosion

Natural Erosion
Ramu cobalt Mine

Challenges of Tailings Dams in Pacific Rim

Typical Tailings Dam

Typical Tailings Dam

DSTP Safeguards and Ongoing Monitoring

Ramu DSTP Benchmarking

Significant Advantages of Deep Sea Tailings Placement

Deep Sea Tailings Placements Around the World

Deep Sea Tailings Placements Around the World