Mines produce waste, a lot of it. Some companies construct tailings dumps, some tailings dams and others just dump it in rivers or the sea, whatever method they use, mining leaves behind a legacy of waste that lasts forever. Burst dams, pollution, filled rivers and devastated ecosystems are regular consequences of modern mining where recovery rates can be as little as 5-10 grams of gold per tonne of rock and ore mined.
Submarine Tailings Disposal [from STD Toolkit - Mining Watch Canada]
Submarine Tailings Disposal is dumping mine tailings into the sea through a submerged pipe. In the Western Pacific region, mining companies argue that Submarine Tailings Disposal (STD) is the best solution for tailings disposal. They say that storing tailings on the land in this region is risky—because the Western Pacific experiences earthquakes; has many moun- tainous islands with no place for on-land storage; is an area where land is urgently needed for agriculture; and has high rainfall, making tailings dams vulnerable to collapse. In modern STD systems, mining companies claim that the goal is to deposit tailings into deep waters of the sea where there is little oxygen. They say that therefore tailings will be less likely to oxidize and leach out toxic metals. Mining companies also argue that marine life at these depths is not so abundant and it is not important to the human food chain.
By pumping their tailings into the sea, mining companies remove unsightly tailings on land. They “solve” the problems of maintaining tailings impoundments and dams, and managing acid mine drainage and metal leaching from tailings impoundments, sometimes “in perpetuity” (forever). And in case of a dam failure, mining companies avoid the risks of social rage and of expensive clean up.
Unlike on land, if something goes wrong with an STD system, there is little the company, or anyone else, can do. The public may not even discover a problem, because it is out of sight under the sea. Even if a problem becomes known, it is harder to hold a company legally and financially responsible.
STD is also a relatively cheap mine-waste solution. Placer Dome’s Dick Zandee wrote in a 1985 article about their surface disposal system into Calancan Bay in the Philippines that, “operation of the current sea-disposal system costs less than half as much as the operation of the tailings-pond system.” For the Kitsault mine in Canada, which was given a special site-specific exemption in 1979 to operate an STD system, it was estimated that STD would save the company $25 million dollars per year in tailings disposal costs relative to the cost of land-disposal. The U.S. Department of the Interior concluded that, on average, STD use resulted in a 17% reduction in capital costs and a 1.6% increase in operating costs.
In discussions with local communities and governments, mining companies and their consultants make claims about the environmental acceptability of STD and they claim STD, or Deep Sea Tailing Placement “is proven technology.” But there are known risks related to STD that mining companies and their consultants either do not discuss with local communities or tend to minimize their severity by speaking of “mitigating measures” that can be taken or good “monitoring systems” that will warn people when a problem does occur. Especially during the pre-permitting phase, there is not enough transparency about the risks associated with STD.
