In a ruling dated Dec. 6, 2017, the Tenggarong District Court in East Kalimantan found PT Indominco Mandiri -- a subsidiary of coal producer Indo Tambangraya Megah (ITM) that is controlled by Banpu Group Thailand -- guilty of illegally dumping two types of waste, fly ash and bottom ash, which were produced at the firm's coal power plant.

Fly ash is a powdery material made by burning ground coal, while bottom ash is formed at the bottom of a coal furnace.

The Environment and Forestry Ministry has categorized fly ash and bottom ash as hazardous toxic waste. If not managed, the two can pollute waterways, ground water, drinking water and the air.

Indominco had a temporary waste disposal site for fly ash and bottom ash produced by its power plant in Santan subdistrict, Kutai Kartanegara regency, according to the ruling. But due to overcapacity, the company dumped the waste at an illegal open dump inside the firm's power plant area, the court found.

Indominco did not increase the capacity of the temporary waste disposal site and the amount of machines to produce paving blocks, which use coal waste as a material, even though the amount of waste generated from its mining activity and power plant had increased, the court found.

In a statement released on Thursday, NGO Mining Advocacy Network (Jatam) criticized the ruling for not sentencing the directors of Indominco to jail.

Articles 60, 104 and 116 of the 2009 Environment Protection and Management Law state that a person who illegally dumps waste faces two years in jail and a maximum fine of Rp 3 billion.

Jatam national coordinator Merah Johansyah said the court should have revoked Indominco's mining business permit.

The open dump had caused several environmental problems in the surrounding area, according to locals quoted in Jatam's statement. "We’ve had of enough of pollution in the Santan River. Please don't add to our problems by polluting the air and the ground water as well," said Romiansyah, a Santan resident. (evi)