Unforunately, these things are not that common in Papua New Guinea. Companies typically dump waste into the river. Harmony Gold (whose recently spun a disaster into a media success story with the trapped miners in South Africa) claims that the Hidden Valley project will be the first. Though, this claim will depend on the dam making it into full production. The Ok Tedi dam, of course, was destroyed by an earthquake prior to completion and it was never replaced. And yes, Papua New Guinea does have regulations about these sort of things.