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FROM COALMINE TO FARMLAND

When the mineral reserve has been completely mined out, and there’s nothing but a big hole in the ground, there is still the responsibility to rehabilitate the land to bring it back to a useable form.

But the Bloomfield Group are well ahead of the rehab game with their Rix’s Creek coal mine, near Singleton in New South Wales. The family-owned Bloomfield Group has been operating in the Hunter Valley for more than 77 years, laying claim to a long history of operating in an environmentally sensitive manner through all phases of operation, from exploration through to rehab.

Only 100 metres from the New England Highway, the Rix’s Creek Coal Mine is one of the most visible in the Hunter Valley, with a production level of 1.5 million tonnes transported to the port of Newcastle each year. The mine is due for drafting of a new Environmental Impact Statement for extension of the mine life from 2016 for 21 years, but the environmental standards in place at the mine should ensure that approval is no problem.

Rix’s Creek senior environmental manager John Hindmarsh is in the process of restoring land on the mine site for agricultural use as a cattle grazing property. Hindmarsh has said the original rehab goal was to bring the land capability back to an equivalent or higher capacity than the pre-mining landscape. Top soils from the original mine development were retained in the original rehab plans to use for top dressing, however due to the degraded state of the land prior to mining, some soil from the site was deemed unsuitable for that purpose. “Because nature put them there I’ve stripped those top soils and tried to use them with some ameliorants applied to them to try and improve the soil structures and fertility,” he said. “We use biosolids in our rehabilitation mix as well as some chemical fertiliser when we plant the seed.”

Rix’s Creek environment officer Jason Desmond said the rehab process is a staged approach which begins with prestripping topsoils from land to be mined, and taking them back to rehabbed areas. “Not all mines are the same, but for ourselves we are restricted by a dump height,” he said. “We play around with the dump height to make it as natural as possible with the surrounding landscape, so that’s based on bringing waste rock out of the mine, trucking it out to somewhere near our final design height, and then try to marry it in with the existing mine land so it looks as natural as possible.

“As we continue to strip out the mine, we pre-strip the topsoil and take it back to the rehab area with dozers and trucks, and then play around with it with a rehab tractor.”

After the topsoil is brought across, and spread out, the rehab crew adds biosolids to the topsoil, essentially leftovers from waste treatment works. “It’s a very wet product, about 70 per cent moisture, 30 per cent solids, and it has really high levels of nitrogen, phosphorous, which really gives our pasture species a kick on,” Desmond said. “We spread out the biosolids after landscaping the topsoil with dozers, and then we rip it in to incorporate it and enrich the topsoil, then in the final process we put seed on top and wait until the rain comes.” Desmond said the rehabbed lands were intended to be a higher quality of grazing land than unmined lands adjacent to the mine, also incorporating diversity to encourage movement of non-agricultural species.

“We’re going to start doing trials so we can get cattle on and prove that it’s able to hold up, which we think it will,” Desmond said. “We also have native tree species which are endemic in the area, as well as habitat corridors and windbreaks, so when we do put cattle down they can find protection and shelter, and so that other species can move in and out of those corridors.

“We also have 60 hectares of forestry plantation which was planted ten years ago as an experiment to see if mines can engage in forestry.” Organiser for the Tom Farrell Institute’s Mined Lands Rehabilitation Conference, Nigel Stace, viewed the rehabilitated lands recently at a tour during the Hunter Valley Coal Festival in April.

“We were taken to a very large field and shown how luxurious the grass was growing, and there was opportunity for discussion about technical aspects of the rehab,” he said. “We were also shown the various phases of the rehab, how the land is built up, bringing in the soil and plants, it’s a multi-stage process.”

Stace expressed that rehab can have a very positive impact on the public and community view of mining operations, as well as the business of mining.

“I think mine rehabilitation should be seen as part of the mining core business. If it’s seen as core business and is done visibly well to society, then so much more social capital can flow to mining operations,” he said. In his hands-on role with the day-today operations of the mine rehab crew, Desmond said he finds the rehab work extremely rewarding.

“It’s like with a gardener at home, if you you’re passionate about it you can’t leave it alone.

“I like saying to people they can come and enjoy and view the land, that it is of a high enough standard,” he said. “I’m probably am heavily critical of my own rehab, what gets done, and I like to get people to spent longer to do a better jobI’d rather people go back through and have it set up properly so in the future, if and when, it can be used.

Desmond said the MD, John Richards, has a standing challenge for the rehabilitation crew which ensures the quality of their work.

“John Richards, he’s put the standard out to us that we have to have the rehab good enough that at end of life of the mine, he should be able to ride a quad bike through the land and chase cattle,” he said. “And that is a fairly high standard if you’ve seen some of the rock material that goes in there.”