Kanmantoo Copper Mine Site Rehabilitation Project

Project Overview

Erizon was approached by Hillgrove Resources in May 2018 to provide an effective revegetation strategy 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 into the site conditions from Hillgrove Resources’ environmental specialists. During the onsite consultation, comprehensive soil samples were taken from locations around the site, and laboratory analysis showed that the soil pH levels were moderately alkaline with low levels of calcium, elevated levels of potassium and magnesium, and some areas also high in sodium.

The findings confirmed that the lack of onsite vegetation was likely due to the poor structure of the soil profile Based on these findings, Erizon designed the following hydromulching and amelioration program as a remediation strategy:

• 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

Solution

The foundation of the recommended solution consisted of EnviroPro – a Hydromulching HGM designed to be combined with water and used as a carrier for seeds, fertilisers, binders, 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. Because these fibres are hygroscopic, they delivered up to 50% more water holding capacity, creating a moisture reservoir for seeds, and providing a protective erosion control cover. This allowed the soil to maintain an optimal temperature and subsequently promoted accelerated germination.

Meanwhile, the custom amelioration formula consisted of Nitrogen, Phosphorus, Potassium (NPK) controlled Troforte Fertiliser, and Calcium. These added supplements ensured that enough nutrients were available to facilitate long-term crop establishment while providing erosion and dust control on the applied areas.

The seeds used were those harvested by Hillgrove Resources onsite to ensure a local, native solution was provided.

Scope

Erizon undertook hydromulching, rehabilitation, and batter stabilisation at the Kanmantoo Copper Mine over a span of 10 days.

The project was undertaken in a two-part application process across the 40 hectare project area. The first pass contained native seeds, custom fertilisers, 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 HydroRigs were the most effective and viable piece of equipment for application on this site. These trucks hydraulically applied the hydromulching blanket solution onto the contours of the substrate batters quickly and easily.

Challenges

Erizon recognised and addressed the following issues throughout the duration of the project:

At the time of the project, Kanmantoo was still an operational mine site where heavy vehicles were regularly used. Erizon’s team was required to align internal company safety measures with those of the mine.

The environmental conditions also 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 clear skies to begin and complete work efficiently.

Results

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 collaborating with Erizon throughout the execution of the project.

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