Bellvue mine cleanup starts
A team effort to clean up the Bellvue historic coal mine opens the way to treating many other abandoned sites around New Zealand, says Dave Trumm from CRL Energy.
Five large (30m3), plastic tanks full of mussel shells, that host micro-organisms have been installed to intercept acidic drainage from the former underground mine into Nine Mile Creek, north of Greymouth.
“Throughout the project, we compiled plans, costs, consents, safety and design documents, stakeholder input, and developed justifications for the treatment process knowing we would be developing a template to clean up similar abandoned mine sites,” says Trumm.
This work follows on from pioneering research started by Dr Paul Weber (O’Kane Consultants) into the use of waste mussel shells for the treatment of acid mine drainage impacted waters and has involved student projects from the University of Canterbury, University of Otago and University of Windsor (Canada).
The passive treatment system will clean ~3 kilometres of water downstream from mine workings, and take out 65-70 percent of the water’s acidity load.
"We expect to learn along the way. We have run smaller versions of these containerised treatment systems, but, at this scale our system is a prototype, and all going well we will be able to present the results from this project over the next couple of years to assist with future clean up projects. We are also teamed up with chemists and ecologists (Prof. Jon Harding, Prof. Jenny Webster-Brown and students from University of Canterbury) and they will measure recovery of the stream chemistry and aquatic ecosystem. We also work with rehabilitation specialists (Dr Robyn Simcock from Landcare Research) who will complete surface rehabilitation studies at the site."
The mussel shells, obtained from Havelock from the local shellfish industry, provide a substrate for sulphate reducing bacteria that remove metals from solution and also produce alkalinity. The shells are an added bonus for the alkalinity they also provide.
Trumm says they will turn the tap on before Christmas 2017, "We currently have the tanks full and are letting the sulphate reducing bacteria build up in the system before we flick the switch."
Bellevue is a landmark project for full treatment, he says. “It has the second most acidic mine drainage we have encountered outside of operating mines where water is treated prior to discharge. So if we can fix this site we have taken a major step toward rehabilitation of other AMD legacy sites."
“There were so many people involved in the project, I want to thank them all,” says Trumm.
As well as those already mentioned, CRL Energy’s James Pope and Paul Weber collaborated on system design, The Coal Association of NZ provided cash co-funding that enabled this project, Tai Poutini Polytech provided in-kind labour and equipment, West Coast Regional Council, the Department of Conservation, and Solid Energy provided substantial in-kind support. The overarching project (Mine Environment Life Cycle) is funded by MBIE. GH Foster Contracting was commissioned to do much of the construction work, which proceeded efficiently and professionally.