Monitoring for Safety and Efficiency in Open Pit Coal Mining

Author: Adhit Nugroho, Lidija Spiranec, Megan Hansen, Ruth Badley

Indonesia is among the world’s largest producers and exporters of coal with the majority of the country’s open pit mining sites located on the islands of Sumatra and Kalimantan. The coal mining industry accounts for around 3.5% of Indonesia’s GDP and is an important driver for economic development in the country’s remote areas.

PT- Pamapersada Nusantara (PAMA) is one of Indonesia’s major mining contractors. The company manages 16 coal mining operations on the islands. At their ABKL site, one of the site projects in East Kalimantan province, mining operations cover an area approximately 3000m wide. To help support safety and continuous operation, which is crucial to the regional and national economy, PAMA monitors their mines for slope movement with Leica Geosystems’ automated sensors and software.

The economic importance of Indonesia’s coal reserves  has grown since 2020 and global demand for the commodity continues to rise. The domestic market relies on coal for electricity generation and recent estimates predict annual consumption is set to increase from 111 to 125 million metric tons.

Investing to minimise risk

Measuring and monitoring the slope stability of mines has been a legal requirement in Indonesia since 2018 because of the significant impact mining disasters can have on workers’ safety, the environment, the financial sustainability of mining companies, and the wider economy.

As excavations get steeper, the greater the danger of rockfalls or pit collapse. Blasting, ground instability, weather conditions, and the angle of inclination can all affect pit wall stability. In the event of a disaster, the site would be evacuated and shut down until structural repairs allowed work to recommence.

PAMA, a long-standing Leica Geosystems’ customer, is committed to best practice monitoring procedures for safety and quality control on all its sites. As production at ABKL increased, Leica Geosystems’ automated monitoring solution was installed to aid risk management by providing advanced real-time slope deformation data for analysis by the engineering teams.

The right solution for the job

At large open pits like ABKL, the long-range capability of monitoring equipment is especially important. Due to the size of this mine and the accuracy specifications, the monitoring requirement called for a robust, precision instrument with long range measurement capability of up to 2500m.

With advice and training from Adhityo Nugroho, Senior Support & Monitoring Product Manager of PT Leica Geosystems, Indonesia, PAMA installed a Leica Nova TM50  total station. Designed with specific monitoring features, the TM50 offers automatic target recognition (ATR) up to 3000m, angular accuracy of 0.5”, advanced imaging for a complete visual record, the longest service interval, and automated data capture with GeoMoS Monitor.

Hendra Hutahean, ENG & CIS Director at PAMA explains, “We know that significant infrastructure projects, including dams and bridges across Indonesia and around the world rely on Leica Geosystems’ advanced monitoring systems. Our investment in these outstanding products gives our surveying and monitoring teams complete confidence that mining and excavation activities can progress safely and efficiently.”

Built for challenging conditions

The ABKL site is a typically demanding and harsh environment. An environmental ingress protection rating of IP65 guarantees Leica Geosystems’ monitoring total stations have the robustness required to overcome the challenges of continuous operation through dust and extreme weather.

“Durability and functionality in the field is vital to maintain efficiency and the Leica Monitoring System (TM50) is helping us meet our quality assurance goals – it is an essential part of our team, at work, round the clock, day in, day out, and proving its worth in the toughest conditions,” said Hendra Hutahean

The measurement data in GeoMoS is analysed in real-time, with a scheduled report automatically generated every 6 hours and distributed via the Telegram instant messaging platform to project managers. If thresholds for movement are reached at any time, a notification is sent out immediately and preventative actions are taken.

Reliably monitoring the possible movement of targets with each measurement requires the position and orientation of the TM50 total station to be monitored constantly as well. This is done by regularly measuring to stable reference prisms located behind the pit that areunaffected by mining activity.

PAMA also use Leica Geosystems’ instruments for surveying tasks in and around the mine, outside the areas covered by the automated system.

With ongoing support and training and following the success of the Leica TM50 at ABKL, PAMA installed its successor, the Leica Nova TM60 with ATRPlus at a second site. Additionally, they paired the TM60 with Leica GeoMoS Monitor and GeoMoS Analyzer software for automated data processing and analysis to facilitate existing workflows.

Correct action based on accurate data

By investing in an automated monitoring system from Leica Geosystems, PAMA has taken steps to minimise risks to safety and efficiency in open pit coal mining. With an advanced monitoring solution the geotechnical team and mine management can make informed and fast decisions based on accurate and reliable real-time deformation data. The monitoring of slope stability acts as an early warning system for any changes that exceed defined thresholds, whilst also allowing production to continue safely without unnecessary interruption.