Erizon has worked alongside Rio Tinto to rehabilitate part of a highly productive coal mine into a thriving land of vegetation. Erizon environmental consultant Glenn Sullivan explains how.
Major mining companies generally have stringent selection criteria for the mining equipment, technology and services (METS) partners they engage to deliver a diverse range of projects.
When Rio Tinto decided to rehabilitate the Hail Creek coal mine in central Queensland, prior to selling its 82 per cent interest to Glencore in 2018, the job was thrust upon Erizon.
Using its environmental expertise, Erizon has turned a section of the site, which produced 9.4 million tonnes of saleable coal the previous year, into a land of vegetation fit for new purposes.
Erizon was selected for its extensive understanding of soil analysis and environmental conditioning, as well as its ability to quickly respond to large-scale requirements, according to Erizon environmental consultant Glenn Sullivan.
“The client wanted the job to be done as soon as possible, and we were there to deliver a solution within a short turnaround,” Sullivan, who had a leading role in the project, tells Australian Mining.
“Our in-house soil scientist and I were heavily involved in the planning, while a team of five that was trained by Erizon was in charge of the implementation.”
Erizon, which has more than 20 years’ experience rehabilitating mine sites, took just 12 days to execute the solution. The company transformed parts of the coal mine into areas where healthy vegetation could be grown in accordance with industry best practice.
The project covered 32.8 hectares of revegetation works for early rehabilitation and soil stabilisation, a term used to describe the restoration of weak and disturbed soil.
Erizon only used mine certified equipment on the project, including a 3D drone survey to map the area with high accuracy.
“By using 3D mapping and photogrammetry, which is the art of making measurements from photographs, it allows us to get a real understanding of the site,” Sullivan says.
“Though you do a site assessment, you can’t walk every metre of the ground, so we use modern technology to do that in a virtual form.
“When you take that photogrammetry survey of the area, you get an understanding of where the access points are and the range of parameters we’ve got from those access points to deliver our solutions.”
Erizon opted for a seed mixture of pasture grasses and native trees, which required amendments to help boost both the organic and microbial activity of the soil.
Sullivan says the amendment strategy played a big role in the successful result by providing optimal nutrients, growth and development of vegetation.
The team also hydraulically added a combination of water, seed and organic matter onto the surface substrate to ensure it achieved the maximum soil-to-seed contact.
Erizon incorporated hydromulching bonded fibre matrix (BFM), which provided extensive coverage and acted as a safeguard for the seed, helping it to retain moisture for faster germination and growth.
BFM also protects the soil and seed placement from erosion caused by wind and rain.
“We overcame the challenges that were presented by heavy rain events with the hydromulching mix,” Sullivan says.
“The mix was able to withstand the rainfall velocities and stabilise the soil, while waiting for the seeds to germinate and establish a biodiverse root system.”
Erizon delivered the solution using its mine compliant HydroTrucks, which had the ability to maintain and distribute an even application at a distance of 100 metres, covering more than 50,000 square metres of land a day.
Sullivan says Erizon’s mine compliant equipment sets the company apart from others in the marketplace.
“We also used drones to provide us with live imagery as the work was being conducted, giving us a bird’s view of the accuracy and uniform application of the product. And the implementation was very successful,” Sullivan says.
“We were able to stabilise the substrate and achieved a total ground cover while improving soil quality. We delivered the solution efficiently under high heat, high humidity conditions while prioritising personnel safety.
“Everyone was properly trained for the project and fit to execute the solution. We ensured there were adequate resources on site to help them manage their fatigue and stay hydrated.”
Under Erizon’s Vision Zero strategy, the company provides systems and operating procedures to support safe conduct.
Erizon is also equipped with the International Organisation for Standardisation (ISO) health, safety, environment and quality certification to conduct work on site.
The company established vegetation at the coal site after just two weeks of safe delivery of its activities.
Thanks to the superior erosion resistance delivered by the hydromulching solution, the site also withstood severe storms and 183.4 millimetres of rainfall in the area.
Erizon examined the area around four months later with drone monitoring, confirming that the project outcome was aligned with the agreed specifications.
“Rio Tinto was very pleased with the growth that had established in the stipulated timeframe. It was a big success,” Sullivan concludes.
This article also appears in the May edition of Australian Mining.