The Department of Environment and Natural Resources (DENR) yesterday assured the local government and residents of Marinduque that the mine structures and waste facilities of Marcopper Mining Corp. in Sta. Cruz, Marinduque have remained intact but vowed to keep a close watch on the inactive mine in the wake of a recent earthquake that hit the province.

“The results of an onsite investigation made by DENR experts showed that there were no manifestations of cracks in any of Marcopper’s structures nor were there seepages along the slopes and toe of its dams,” DENR Secretary Angelo T. Reyes said.

Before joining the President on her five-day official visit to China, Reyes sent a three-man team from the Mines and Geosciences Bureau (MGB) in Region 4-B (MIMAROPA) to the site following a request from Marinduque Representative Edmund O. Reyes and Governor Carmencita O. Reyes to look for any impact of the 5.2 magnitude earthquake that hit Southern Luzon on October 20. The epicenter of the earthquake was located offshore about 35 kilometers west of Boac, Marinduque, making the tremors most felt in the province.

“I have already instructed our men in the field to continue monitoring the site and for the company to institute measures to provide better access for monitoring activities,” Reyes added.

Reyes particularly ordered regular clearing of materials along spillways and toes of dams in order to facilitate the monitoring of seepages.

The investigation comes only two weeks after MGB 4-B declared the site intact in the aftermath of typhoon Milenyo that devastated parts of Luzon in September 28.

The team thoroughly checked on the various structures of the mine including the Maguila-guila Siltation Dam, Bol River Dam, San Antonio Pit, Tapian Pit, Lower Makulapnit Siltation Dam, Upper Makulapnit Water Reservoir, and Tunnel 310.

Based on investigation, the dams and water reservoir appeared stable and intact, showing no cracks, damages or structural deformations. The team also noted no sign of seepage.

Both the San Antonio and Tapian Pits indicated normal water levels. The walls of the two pits likewise appeared stable and unharmed by the earthquake.

Tunnel 310 was also found in stable condition with water flowing freely from the Tapian Pit toward the Bol River, and finally to the Boac River, preventing the build up of water that could dangerously affect the integrity of the pit.

The report, however, forwarded some recommendations to further ensure the safety of the mine, which has been inactive since the 1996 tailings spill.

The recommendations include: the construction of an additional dam at the upper portion of the Maguila-guila Dam to contain large volume of silt coming from the waste dump; and verification of geotechnical design and the slope stability analysis of the Upper Makulapnit Dam.

The report also stressed the need to implement previous recommendations made by DENR-MGB as well as the US Geological Survey study, which include the repair of the spillways; desiltation at the siltation pond and the Maguila-guila river; dewatering of the Tapian pit until water is maintained at elevation 305; declogging of Tunnel 310; and rehabilitation of the diversion canal at the East Tapian waste dump area.

8 November 2006