Copper residue shows in river water

SAN PEDRO CITY—The sight of bluish green water flowing through the Boac River in Marinduque province has raised suspicions of a high level of acid seeping from mine wastes left in the defunct Marcopper mining site.

The Environmental Management Bureau (EMB) in Mimaropa (Mindoro, Marinduque, Romblon, Palawan) region said it will test the river’s water quality this month, after the Boac town government, through its municipal planning and development office, called its attention to what was reported as an “acid mine drain” or outflow of acidic water from metal mines.

Buena Rioflorido, of the EMB Mimaropa, said the EMB conducts quarterly water quality tests, but samples are taken only along the 10-kilometer stretch downstream of the 27-km Boac River.

Acid mine drain

Rioflorido cited concerns over EMB employees’ safety in going to the headwaters, which is a four-hour hike to Barangay Hinapulan. The area is inaccessible to vehicles.

In a telephone interview, Luna Manrique, Boac planning officer, said town officials and residents noticed the water’s distinct color when they visited the headwaters on Aug. 17. The same condition of the water had been seen during visits by town officials in July 2013 and March 2015, he said.

Manrique said he believed the acid mine drain came from tailings piled at the Bol River dam, one of three dams of Marcopper Mining Corp. The other two are the Makulapnit and Maguila-guila dams.

Worst mining disaster

In 1996, one of Marcopper’s drainage tunnels gave way and unleashed about 200 million tons of mine tailings into the Boac River system. The spill, tagged as the worst mining disaster in the Philippines, forced the company to shut down as Marcopper and its parent company, Placer Dome, faced a string of class suits from the Philippine government.

Manrique said residents feared that the water could be highly acidic that they could no longer fish or bring their carabaos to drink water from the Boac River.

‘Natural occurrence’

But Roland de Jesus, regional director of the Mines and Geosciences Bureau, described an acid mine drain as a “natural occurrence,” especially in areas with large deposits of copper.

Copper ore, when submerged in water, becomes acidic giving off the bluish green color, he said.

“The [acid level] normalizes as the water flows downstream into the populated villages. It is diluted by freshwater from different tributaries, making it available for domestic use,” De Jesus said.

Site still intact

Even after the mining operations were shut down, the 100-hectare Marcopper mining site, complete with an airstrip, a hospital and housing facilities, has remained intact.

The compound is highly secured that even government agencies are barred from entering the site.

De Jesus said Marcopper, which operated in the 1970s, had not submitted a closure plan since its permit was granted before the enactment of the Philippine Mining Act of 1995 (Republic Act No. 7942).

Under RA 7942, mining companies are required to come up with a final mine rehabilitation and decommissioning plan and set aside funds for the rehabilitation of their host communities.