Nickel Waste in Weda Bay Reclamation

WHITE smoke billowed instantly when black, gravel-like material dumped from a truck hit seawater. Since 2022, coastal reclamation in Weda Bay, Central Halmahera Regency, North Maluku, has continued unabated when Tempo visited the site inside Indonesia Weda Bay Industrial Park (IWIP) in Lelilef Sawai village, Weda tengah subdistrict, on Wednesday, August 27, 2025. Dozens of excavators and dump trucks were busy piling and leveling the material to extend Cekel Airport owned by IWIP.

According to information obtained by Tempo, the reclamation material was slag, a solid waste left from nickel processing. Several workers said the slag came directly from the smelters inside the 5,000-hectare industrial zone. Tempo reviewed video footage showing the material being transported from the smelter to the reclamation site. Slag is poured out of furnaces into cooling ponds, then hauled into trucks by cranes. “The truck will then take it to the reclamation location,” said a truck driver at IWIP.

Julfikar Sangaji, coordinator of the North Maluku Mining Advocacy Network (Jatam), said the airport expansion—with a 2,500-meter runway—relied on slag as the main reclamation material. The reclaimed area covered 30 hectares. Based on Jatam’s mapping analysis, Julfikar added, the reclamation buried coral reefs and seagrass beds. “Even though slag was removed from the category of hazardous and toxic waste (B3), its heavy-metal content can still disrupt marine ecosystems,” he said in Ternate, North Maluku, on Sunday, August 242025.

Concerns about heavy-metal contamination in Weda Bay were confirmed by research from the Indonesian Forum for the Environment (Walhi) of North Maluku in 2023. Walhi tested seawater samples from six points around the reclamation area. Laboratory results showed the water’s potential of hydrogen (pH) had dropped to 6.6, making it acidic. In fact the Environment Minister Decree No. 51/2004 on Seawater Quality Standards regulates seawater pH to remain between 7 and 8.5.

The study also found ammonia levels reaching 0.4 milligrams per liter (mg/l), exceeding the Environment Ministry’s limit of 0.3 mg/l. Nickel was detected at 0.10 mg/l—double the safe threshold of 0.05 mg/l. Mercury levels hit 0.001 mg/l, above the safety standard set by the United States Environmental Protection Agency (EPA).

In May 2025, the Nexus3 Foundation and Tadulako University in Palu released another study on environmental conditions and human health around Weda Bay, one of Indonesia’s nickel industry hubs. Fieldwork conducted in July 2024 found fish caught near Weda Bay contained arsenic and mercury at various concentrations exceeding safe limits.

Blood tests on local residents showed 47 percent of respondents had mercury levels above the safe threshold of 9 micrograms per liter (µg/l), while 32 percent had arsenic above the safe limit of 12 µg/l. A total of 46 people took part in the study. The research also measured heavy-metal concentrations in the blood of IWIP workers. It found that the levels in local residents were higher than those in company employees.

“This research is a serious warning about the long-term threat of heavy-metal exposure to both public health and environmental sustainability,” said Darmawati Darwis, a lecturer at Tadulako University’s Faculty of Mathematics and Natural Sciences, during a press conference on May 26, 2025. “The findings underscore the need for routine environmental and health monitoring, along with law enforcement against polluting industries. We urge data transparency and collaboration across sectors to protect communities and ecosystems.”

The same study tested 16 randomly collected fish samples from Weda Bay. All contained mercury and arsenic in their flesh. Mercury concentrations ranged from 0.02 to 0.28 milligrams per kilogram (mg/kg), with the highest found in barracudas. Arsenic concentrations ranged from 0.43 to 3.03 mg/kg, peaking in sorihi fish (Rastrelliger sp.) caught near Gemaf at 3.03 mg/kg. “The World Health Organization’s tolerable limits are 2 mg/kg for arsenic and 0.5 mg/kg for mercury,” Yuyun Ismawati, Nexus3 founder and senior advisor, told Tempo on June 1, 2025.

Yuyun said her team’s research recommended reviewing nickel industry permits. The Environment Ministry, she added, must evaluate compliance with environmental standards, including emissions limits, waste management, and ecological impacts.

Deputy for Waste, Hazardous and Toxic Materials Management at the Ministry of Environment, Ade Palguna Ruteka. menlhk.go.id

Ade Palguna Ruteka, Deputy for Waste, Hazardous Waste, and Toxic Substances Management at the Environment Ministry, said slag was removed from the hazardous waste category because toxic characteristic leaching procedure (TCLP) on the material fell below danger thresholds. He added slag had proven useful as raw material for bricks, paving blocks, and concrete. “The product quality and environmental parameters also met requirements,” Ade wrote in a statement to Tempo on Tuesday, September 16.

Ade explained that licensing procedures for using slag in reclamation are set under Environment Minister Regulation No. 19/2021 on Non-Hazardous Waste Management. Companies must prepare a technical detail document (DRT) outlining waste management plans, work procedures and designs, and environmental standards. “Once prepared, the DRT must be integrated with environmental approvals.”

To ensure slag does not pollute the marine ecosystem, Ade said his office would test seawater and marine life quality in line with regulations. “For example, testing heavy-metal levels in seawater and marine organisms, then comparing them with applicable standards,” he said.

IWIP management emphasized that its use of slag was backed by official documents, including DRT and laboratory tests such as TCLP, to ensure hazardous elements stayed below safety thresholds. “IWIP also implements additional controls, including periodic TCLP and chemical characterization tests, stabilization and solidification in metallurgy processes, and regular monitoring of seawater and marine biota through KAN accredited laboratories,” IWIP stated in a written response on Thursday, September 25.

The company said it had been reusing slag since 2022. Currently, the firm focuses on slag utilization in the construction sector, such as for concrete mixes, bricks, and paving blocks. “So slag is not only a byproduct of nickel processing but also carries added value while reducing environmental risks.”

IWIP reported its slag-based brick production capacity reached 120,000 units per week, all used for construction within the industrial complex. This, the company argued, improved material quality, reduced reliance on natural resources, and aligned with circular economy principles.