How Does Geotechnical Engineering Keep Indonesia’s Largest Mines Safe?

When looking at massive mines with towering slopes and grand infrastructures, have you ever wondered, “How do they all stand safely?”

The answer lies in geotechnical engineering.

Below are some of Indonesia’s major mines that rely on geotechnical expertise as the backbone of their operations:

1. PT Freeport Indonesia (Grasberg, Papua)

Grasberg is the world’s second-largest gold and copper mine, located in high mountainous terrain with hard rock formations and extreme weather conditions. Its geotechnical challenges include:

• Designing open pit slope stability for hundreds of meters high slopes with varying rock strengths.
• Real-time slope monitoring using radar and slope stability radar (SSR) to detect even the slightest ground movement, ensuring the safety of workers and heavy equipment below.
• Reinforcement of structures in supporting facility areas within the mining complex.

2. PT Agincourt Resources (Martabe, North Sumatra)

The Martabe gold mine is situated in an area with steep slopes, sedimentary rocks, and tropical residual soils, requiring comprehensive geotechnical approaches such as:

• Conducting soil and rock investigations before constructing waste dumps, pit walls, and supporting facilities.
• Designing a tailings storage facility (TSF) that is safe and stable on low bearing capacity soils through ground improvement methods and deformation monitoring.
• Implementing drainage systems and slope reinforcements to prevent landslides during heavy rainfall.

3. MSM & TTN (North Minahasa, North Sulawesi)

The gold mines operated by PT Meares Soputan Mining (MSM) and PT Tambang Tondano Nusajaya (TTN) are located in mountainous regions with volcanic rocks of varying degrees of weathering. Their geotechnical challenges include:

• Designing pit slopes that remain stable in both strong and weathered rocks to ensure slope safety during mining.
• Conducting stability analysis for waste dump and disposal area slopes to safely accommodate waste materials.
• Ground improvement for supporting facilities such as crushers, conveyors, and access roads built over soils with inconsistent strength.

4. Amman Mineral (Batu Hijau, West Nusa Tenggara)

Batu Hijau in West Sumbawa is one of Indonesia’s largest copper and gold mines, with challenging geotechnical conditions:

• Designing open pit slopes on hard and fractured rocks, requiring advanced geotechnical software for slope stability analysis to achieve optimum safety factors.
• Ground and foundation stabilization for major facilities such as the crusher plant, concentrator plant, and concentrate export port.
• Surface water management and slope drainage systems to prevent erosion or slope failure during the rainy season.

Sources:

https://www.ptfi.co.id/id/tambang  
https://agincourtresources.com/id/profil-tambang-martabe   
https://archiindonesia.com/operation/  
https://www.amman.co.id/id/operasi/batu-hijau