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Monitoring of water quality along the Katak River, the area around the Tujuh Bukit Gold Mine in Banyuwangi, East Java, Indonesia. [Photo: M. Afan Arisandi/BSI]
Water conservation is an important component in sustainable mining. Management and use of water, also monitoring of water quality at Merdeka’s operations and projects are carried out in compliance with applicable regulations, taking into account global environmental threats, environmental conditions, and surrounding communities.

Through consultation with various stakeholders, we responsibly use water efficiently in each of our mining operations and projects through rainwater collection, water recycling and prevention of water pollution. Especially considering that the Tujuh Bukit Gold Mine (Banyuwangi, East Java) and the Wetar Copper Mine (Wetar Island, Southwest Maluku) are in areas that are considered a top priority in the water-related climate resilience study conducted by the Ministry of National Development Planning/National Development Planning Agency. with Low Carbon Development Indonesia. This top priority status requires the Tujuh Bukit Gold Mine and Wetar Copper Mine to conduct a water balance study, so that there is no shortage of water for mining operations, the environment, and the community.

Dam water reservoir at the Tujuh Bukit Gold Mine. [FOTO: M. AFAN ARISANDI/BSI]
In 2021, the Tujuh Bukit Gold Mine and Wetar Copper Mine successfully maintain a closed process water system. In both mining operations, any release of water due to certain conditions—such as heavy rainfall—is carried out with a minimum amount, according to government standards. Meanwhile, at the Wetar Copper Mine, the addition of process water does not exceed 18,000 m3 per month.

Water management target at the Tujuh Bukit Gold Mine is to maintain the closed water process and utilize rainwater for other activities, and avoid taking water from sources outside of it.

For operational needs—such as processing ore, spraying road dust, and washing heavy equipment and light vehicles—the Tujuh Bukit Gold Mine only uses water from rainwater collection ponds; do not use water from rivers or other bodies of water. Meanwhile, for domestic needs—such as office facilities and employee accommodation—the Tujuh Bukit Gold Mine utilizes groundwater from several drilled wells that already have a Groundwater Extraction Permit.

The rainwater collection pond at the Tujuh Bukit Gold Mine is very effective due to the high rainfall at the mine site (2,500 mm/year). Excess water is channeled into three rivers through three points of compliance, by first being collected in a control pond for monitoring and monitoring minus the sediment in it. At one point of compliance receiving water from multiple pools, the water is treated in a Detox Plant or detox plant to be removed of all potential contaminants. All of these compliance points have been regulated and obtained permission from the government, and are monitored regularly.

In 2021, the use of water at the Tujuh Bukit Gold Mine for operational needs decreased by 13.5% compared to 2020, due to the leaching irrigation process 2020. On the other hand, the water intensity in 2021 increased by 9.7% to 10.8 m3/oz gold, compared to the previous year (9.9 m3/oz gold), due to lower ore quality. Meanwhile, the use of domestic water in office facilities and employee accommodation, which comes from groundwater wells, increased by 20.3%—from 24.6 ML in 2020 to 29.6 ML in 2021, in line with the increase in the number of employees and contractors.

Tujuh Bukit Gold Mine recycles domestic wastewater in water treatment facilities domestic waste, the proceeds of which are used for sprinkling non-mining road dust. The Tujuh Bukit Gold Mine also operates a cyanide solution treatment suite at the leaching facility. In 2021, water recycling for mineral ore leaching was 30.4% greater than in 2020, due to an increase in the volume of ore processed.

The Wetar Copper Mine operates a closed solution circuit at its leach facility to extract copper minerals from ore. The required water is pumped from the Lurang River (and the volume is reported monthly).

Water consumption in 2021 is relatively the same compared to 2020. However, the intensity of water consumption in 2021 will decrease to 7.69 m3/ton copper, 71.4% lower than 26.87 m3/ton copper in 2020. The decrease in water intensity is due to the quality of the ore processed. in 2021 even better.

The Wetar Copper Mine plans to increase its water storage capacity by converting the Kali Kuning pit into a holding pond covered with waterproof material. This project was approved by the government in July 2021 and succeeded in increasing the mass capacity of the water balance. The plan to add water treatment facilities and increase water neutralizer facilities will continue to be implemented from 2021 to 2022.

If the discharge of surface water is forced to be carried out from a closed-circuit process water system, the water will be treated at a water neutralizing facility until it meets government quality standards. Before being released into nature, the water is collected in a pond to be checked so that it does not exceed the quality standard at the point of compliance.

All surface water flows into the sediment pool. In each main pond to compliance points, with regular measurement and monitoring carried out according to the AMDAL.

The Wetar Copper Mine also monitors water quality in rivers within the mine boundaries and in seawater near river mouths. The Wetar Copper Mine AMDAL has identified a natural mineralization process occurring along the Kali Kuning and Wetuk Rivers—the pH in both rivers is naturally lower than the threshold set by the government. Monitoring of rivers and coastal areas is carried out on a quarterly basis by a third party; and the results are reported to the government on a quarterly basis.

Sustainability Report

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