Kanmantoo Copper Mine

Hillgrove Resources previously attempted to rehabilitate a section of batters within their Kanmantoo Copper Mine site, however, failed to deliver sufficient vegetation growth. The methodology consisted of a hydroseeding solution combined with a dust suppression binder. As a result of utilising the binder, a sealed crust was formed on the substrate causing limited access of water and air to permeate through the surface, affecting the germination of vegetation.

Erizon was approached by Hillgrove Resources in May of 2018, to provide an effective revegetation strategy solution for early rehabilitation and soil stabilisation of their Kanmantoo Copper Mine site. The client was seeking to minimise dust and stabilise soil on batters around their site and tailings dam, due to recent extreme weather blowing gusts above 90km/hr.

Erizon took the time to understand the logistical challenges due to previous failed attempts and gained great insight from the Hillgrove Resources, environmental specialists to further their knowledge of the site and environmental conditions. During an onsite consultation, comprehensive soil samples were taken from locations around the site, which showed that soil pH levels were in-between alkaline to moderately alkaline with major imbalances of low levels of calcium, elevated levels of potassium and magnesium with some areas also high in sodium.

The basis of these findings suggested that that the soil profile consisted of a poor structure, underpinning the rationale behind the lack of vegetation on site. In response to these results, Erizon designed the following hydromulching and ameliorate program as a remediation strategy to underpin successful root growth and development for optimal vegetation coverage:

• EnviroPro- Hydromulching HGM (Hydraulic Growth Medium)
• A blend of native seed provided by the client
• Application of slow-release Enviro Calcium
• A custom Troforte Fertiliser
• Application of a binder

The foundation of the recommended solution comprised of EnviroPro - a Hydromulching HGM, designed to be combined with water used as a carrier for seed, fertiliser, binder, cellulosic mulch, and trafficking dye.

This combination provided benefits of biologically active soil conditioners and a blend of organic mulch fibres, binders, and soil stabilisers. These fibres are hydroscopic, therefore delivering up to 50% more water holding capacity by creating a protective erosion control cover and moisture reservoir to the seeds; providing the ability for the soil to maintain an optimal temperature, subsequently promoting accelerated germination.

The basis of the custom amelioration formula consisted of Nitrogen, Phosphorus, Potassium (NPK) controlled Troforte Fertiliser and Calcium. These added supplements would ensure that enough nutrients were available to facilitate long-term tactile cover crop establishment while resulting in erosion and dust control on the applied areas.

Erizon was notified early on during consultations with the Hillgrove Resources that they would be requesting to utilise their own onsite harvested native seeds within the tailored solution.

Erizon undertook hydromulching, rehabilitation, and batter stabilisation on-site at the Kanmantoo Copper Mine, over one continuous site visit, spanning a total of 10 days. The project involved delivering a high-quality solution underpinned by expert personnel and specialist equipment.

The project was undertaken in a two-part application process rendering across the 40-hectare project area twice. The first pass contained native onsite seed, custom fertiliser, and mulch to ensure favourable seed to soil contact. The second pass consisted of the mulch and binders, designed to provide a protective moisture shield for the seed.

Erizon’s purpose-built, mine specific HydroTucks were the most effective and viable application equipment for vegetating vast expanses of land quickly and easily, such as batters found on-site. These trucks allowed for the essential seed to soil contact, by hydraulically applying the hydromulching blanket solution onto the contours of the substrate batters.

Erizon recognised, and address problems throughout the duration of the project with the following issues attended to promptly and efficiently:

Given the time of the project, Kanmantoo was still an operational mine site with the regular use of the heavy vehicle interaction; therefore Erizon’s team were enforced to align with internal company safety measures with those of the mine.

The environmental conditions proved to be a challenge for the team with wet weather battering South Australia for an extended period before the commencement of work. The team did, however, receive a small window of three days of clear skies to begin and complete works effectively.

Hillgrove Resources was extremely pleased with Erizon’s efforts, professionalism and execution of the services provided. Communication and experience played a vital role in the success of this project, with environmental specialists working in collaboration with Erizon throughout the entirety of the program.

Feedback from the client suggested that the mulch approach assisted in the germination of the seed, by helping draw in moisture and suppressing weed growth. Given the limited rainfall in the region, the mulch also provided addition dust suppression and protection of the topsoil and seed from wind erosion.