Loop Organics has partnered with energy company AGL Macquarie to supply a significant amount of organic material to rehabilitate AGL’s 850-hectare mine site.
The NSW Government requires all mining companies to rehabilitate closed mine sites to return the land to a condition that is as good, or better, than it was before.
Open cut mining and the associated infrastructure, such as tailings dams, roads and buildings, removes and disturbs topsoil. Above ground mining generally involves the stripping and stockpiling of topsoil so it can be replaced, but long-term storage can result in a decline in soil quality.
The staff of organic waste company Loop Organics have long term experience assisting the rehabilitation of mines in the Hunter Valley, NSW. The company does this through the use of biosolids, which provide increased nutrients and encourage better soil quality for effective plant growth.
Loop Organics was established by Lisa Rawlinson and Dominic Flanagan, who have more than 50 years of experience in the organic waste management sector between the two of them.
Dominic Flanagan, Loop Organics Environment Manager, says subsoil typically has limited value as plant growth media due to its poor structure, low levels of nutrients and organic matter and high salinity.
“Biosolids and other organics can be used to create the topsoil with properties suitable for the target vegetation,” he explains.
“We provide suitable biosolids to be used in mine rehabilitation, organise collection and transport to the site, manage the storage and application of biosolids with the mine site.”
In the Hunter Valley, energy company AGL Macquarie is rehabilitating around 850 hectares of old mine sites that once supplied coal to power stations. Ash is being placed into the mine voids to create a more natural landform. To return the land to grazing pastures, AGL needed to develop a biologically active soil with a sustainable carbon and nutrient cycle.
To do so required a significant amount of organic matter and compost to mix with the degraded soil, so AGL set up a tender process to select a company that would be able to supply these materials.
Matt Parkinson, Environment Advisor from AGL Macquarie, says the old mine site required around 1.4 million tonnes of organics in total to return the land to its former state of grazing pastures. Additionally, there are other areas which will also require another one million tonnes of organics for rehabilitation in the years ahead.
“We are required to meet the waste exemptions, which include conditions we must strictly adhere to. For pastures we want a lot of good nutrients in the soil to promote sustainable plant growth. For woodland areas, we want to provide ecological value for native species,” he explains.
“Some organic streams are high in these nutrients while others have liming properties, which is good for the soil structure as it helps to break down the clay.
“We selected Loop Organics after we were impressed by their credentials and chose them to provide us with a high-quality supply of organic compost. They have set up a composting facility and have been helping us for the last three years,” Matt says.
Loop Organics facility is able to process up to 50,000 tonnes of garden organics and biosolids to create specialised soil amendment products for rehabilitation purposes.
Matt says the organic material is vital to ensure AGL has the amount of topsoil it would require to complete site rehabilitation plans.
“Our relationship with Loop Organics is an important one, as they also provide us with expert rehabilitation advice in addition to the work they’re doing at the composting facility,” he says.
The company operates large scale biosolids management and reuse programs for Central Coast Council, Hunter Water and Coliban Water, reusing more than 100,000 tonnes of biosolids and food waste per year through land application programs.
The Hunter Valley facility, located in Ravensworth, is situated within a market with a large demand for organic products and along B-double transport routes.
The project was supported by the Environment Trust as part of the NSW EPA’s Waste Less, Recycle More initiative funded by the waste levy.
It uses an open windrow composting process to create products that meet EPA NSW requirements over a number of weeks.
CLOSING THE LOOP
Lisa Rawlinson, Loop Organics Director, says the company has experience with the land application of organic wastes since 1994, and provides many other organic services.
“We utilise biosolids as they are a valuable source of nitrogen, phosphorous, trace elements and moisture for mine rehabilitation and agricultural soils.
“They also help to create the correct mixture for composts using woody green waste and other high carbon-containing inputs,” she explains.
“In Sydney we also operate a liquid food waste soil injection program, using liquids from bakeries, poultry producers and food preparation and manufacturing facilities. These provide nutrients, organic matter and moisture to improve soil fertility.
Another service that Loop provides is sludge lagoon dewatering using a range of technologies, including centrifuges and geotextile bags. The dewatered materials can then be recycled by direct land application or composting.
“Our practical experience and technical understanding in reusing a wide range of organic wastes enables us to deliver proven and sustainable solutions for our clients,” Lisa says.
“We look forward to working with AGL Macquarie to help with the success of their rehabilitation program.”
Pictured: Dominic Flanagan and Lisa Rawlinson