Grass looks greener after biosolids trial

By Gus McCubbing

SO FAR, so good – that is the verdict from the first review of a biosolids application trial at Fosterville Gold Mine (FGM), north-west of Heathcote, which was completed last week.

The two-year trial is a joint initiative between FGM and Coliban Water, and is designed to assess whether the application of biosolids will facilitate the growth of pasture and plants on rehabilitated mine land.

Biosolids are created when wastewater receives biological treatment and the pollutants in the wastewater are removed by converting them into a fine, fluffy mass formed by the aggregation of bugs and other fine suspended particles.

Coliban Water general manager (water quality and performance and regulation) David Sheehan said the reuse of biosolids is one way of turning a by-product from the wastewater treatment process into a valuable resource for the local region.

‘‘We recognise the environmental value in reusing resources. Biosolids contain nitrogen, trace metals and phosphorus, which are all beneficial for soil conditioning,’’ he said.

‘‘We’ve just completed our first review of the four-hectare trial site after the seeds were spread in late autumn. There is plenty of green popping up, so things are looking good so far.

‘‘It benefits FGM as they have free biosolids to help rehabilitate the land, and it benefits Coliban Water by having a secondary use for the treated biosolids. The pasture growth also helps to reduce dust in the mine vicinity.’’

FGM senior environmental adviser Joseph Hughes said the trial area was originally used for flotation mine tailings before the land was capped with oxidised waste rock.

‘‘Now it’s been planted out with native species like rough spear grass, burra weeping grass and salt bush. We opted for native pasture following input from community representatives prior to the trial,’’ he said.

‘‘There’s so many factors to consider in a trial such as this – the landscape, soil quality and potential rainfall. Eventually, a large portion of the affected land will need to be rehabilitated and the biosolids are obviously helping a lot.’’

In 2014 a small scale biosolids application trial was carried out, with moderate success.

‘‘The final land use plan for the entire mine site is to use both pasture and a box-ironbark native forest. There is potential to use biosolids more widely in rehabilitated areas of the mine site in the future,’’ Mr Hughes said.

An environmental improvement plan for the trial was developed in consultation with the Environmental Protection Authority and a range of stakeholders.