INCIDENTS

Marinduque (Marcopper Mine) - Tailings Dam Failure, Phillipines, March 1996

BACKGROUND

On 24 March 1996, mine tailings of the Marcopper Mining Corporation (Marcopper) began escaping from the Tapian Pit through the plugged rainwater drainage tunnel into the Makulapnit and Boac Rivers on Marinduque Island in the Philippines. While reports vary, between two and three million cubic meters of mine tailings were estimated to have been released into the 26 km Makulapnit and Boac River systems over the following 4-5 days at a discharge rate of between five and ten cubic meters per second.

Marcopper, a joint venture of Placer Dome (40%) and the Philippine Government, started its mining operations at the Mt. Tapian ore deposit on Marinduque Island, Philippines, in 1969. Copper concentrate, containing gold and silver, was produced from the deposit. The milling or processing method followed the conventional crushing, grinding, flotation mill, filtering and thickening to produce copper concentrate and tailings residues. The process did not utilise any cyanide or mercury.

Type of Incident

• Loss of tailings from storage pit through old drainage tunnel

• Release of 2-3 million m³ of mine tailings (no cyanide or mercury)

IMPACTS

• Evacuation of 1200 residents.

• Seriously affected approximately 700 families from 5 villages by loss of most river crossings, loss of road connections

• Inundation of between 6 and 10 hectares of cropland used for banana and other agricultural purposes.

• Deposition of tailings in the upper sections of the Makulapnit and Boac Rivers

• Loss of aquatic life, productivity and beneficial use of the rivers for domestic and agricultural purposes.

• Cleanup costs = US$80 million

LINKS:

• Relief Co-ordination Branch. Joint UNEP/DHA Environment Unit. The Marinduque Island Mine Disaster, Philippines

• Marcopper Web Site - The Glorious 80's to The Disasterous 90's

• The Ugly Canadian: The Philippines, Marcopper

• Technical Issues - Tailings

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