DENR bureau warns mine wastes spill threaten 2 Marinduque towns

As the province continued to experience erratic but heavy monsoon rains, flash floods threatened to inundate the towns of Boac and Mogpog, not just from a leaky Marinduque Copper Mining Corp. (Marcopper) dam but also from a siltation dam “in imminent danger of collapsing” and an abandoned open pit filled with millions of cubic meters of water and mine wastes.

This assessment was contained in a report of the Mines and Geosciences Bureau (MGB) of the Department of Environment and Natural Resources (DENR), a copy of which was obtained by the Inquirer.

According to engineer Mario Alban of the MGB-DENR for Mimaropa (Mindoro, Marinduque, Romblon and Palawan provinces), the report on the latest monitoring activity conducted from Oct. 13 to 14, showed a “progressive erosion of highly erodible materials” at the slope of Marcopper’s Maguila-guila siltation dam that may cause eventual flooding along the Mogpog River.

The report said erosion had significantly altered the steep slope of the Maguila-guila waste dam, causing a rapid increase in the rate of siltation along its stream channels.

It also said that continuous erosion and movement of earth materials downstream of the Maguila-guila creek toward the Mogpog River would further aggravate the siltation problem in the lowlands which may result in eventual flooding.

The inspection also disclosed that the Maguila-guila siltation dam’s catchment reservoir is now heavily silted by bed-load materials. This heavy siltation of the dam may contribute to its imminent collapse, the report said.

Seasonal rains in 1993 caused intense flooding and the then newly built dam collapsed altogether.

The Maguila-guila dam is among the dams of Marcopper identified as in “imminent danger of collapsing” by the United States Geological Services as early as 1996.

Primarily an agricultural town, Mogpog (population: 31,330) is situated on the northwestern part of Marinduque. It is adjacent to the town of Sta. Cruz where the Marcopper mine site is located.

Almost half of its land is planted with coconut trees. Only 12 percent are irrigated and rain-fed rice lands.

If a flash flood occurs, 15 riverside villages and the low-lying villages in the town proper will be inundated, and will affect almost 50 percent of the town’s population.

Tapian Pit

In the same field inspection conducted in October, the MGB monitored that the water level of the Tapian Pit was at 314.57 meters, less than 6 m short of the rim but 4 m more from a discharge tunnel situated at 310 m.

The Tapian Pit is a 130-hectare wide and 320-m deep hole that was created in the process of mining copper near the summit of Mount Tapian.

“Should the pit burst or collapse, an estimated 20 million cubic meters of tailings and another 8 million cubic meters of water will cascade down the Boac River that will spell disaster for the province’s capital town,” the report said.

On March 24, 1996, a plug in a drainage tunnel at the Taipan Pit failed, causing the release of about 1.5 million cubic meters of toxic mine tailings into the Makulapnit and Boac Rivers.

At least 36 persons died from heavy metal contamination caused by the mine wastes, the Marinduque Council for Environment Concerns (Macec) said.

The spill, which also left the Boac River virtually dead, is considered the country’s worst industrial pollution disaster. It also affected the Calancan Bay, Mogpog River and surrounding communities.

Marcopper ceased operations soon after. Placer Dome, the Canadian mining firm that managed Marcopper, left the Philippines without compensating the victims of the spill. Company officials were later charged with violating the Water Code, National Pollution Control decree and reckless imprudence resulting in damage to property.

Miguel Magalang, Macec executive director of the Marinduque Council for Environmental Concerns (Macec), earlier warned that a repeat of the 1996 mine spill would be a major catastrophe with devastating effect on crops and lives in almost 50 percent of Boac’s 54,000 population.