Tiwi town council approves geothermal waste injection project

TIWI, Albay — After two years of protests from some 2,000 residents of Barangay Biyong here, the local town council has finally issued a resolution allowing the National Power Corporation (Napocor) and the Philippine Geothermal Inc. (PGI) to put up a geothermal waste injection project at Naglabong 26 on Wednesday.

Power experts say that the Subsurface Geothermal Residue Injection Project (SGRIP) will provide socio-economic benefits to the local community and increase the value of geothermal power plants here before the government sells them to private investors.

Tiwi geothermal plants, built with a capacity of 330 megawatts, have been generating less power because of its aging equipment. The facilities are undergoing rehabilitation until December this year.

Abet Buban, PGI environmental specialist, said once the Naglabong 26 injection plant is fully operational, it will pump approximately 3,000 cubic meters of residues and sludge to a deep underground chamber that is 200 feet in diameter and 500 feet high.

Buban said injecting residues underground has been the normal waste disposal practice of geothermal plants worldwide and is considered safe compared to other means.

He also debunked fears of some locals that the injected waste might rise again to the surface and contaminate ground water in the area.

"Once underground, the chemicals will stick to spaces and cracks in between rocks as the water dissipates due to undergound temperature and pressure," Buban said. "There is also no danger of contamination because the water table at Barangay Biyong is located about 130 feet deep. The geothermal waste will be isolated at depths between 3,150 to 4,250 feet."

He explained that the Naglagbong-26 site was chosen because it has a drilled deep of more than 5,000 feet and the layers of clay-altered rocks underneath can effectively seal the waste chamber.

The facility, Buban added, will likewise be fitted with high-tech equipment so it can withstand any emergency that may arise.

Its features will include a waste material sorter, crusher, ball mill, hyro-cyclone, dewatering unit, slurry/viscosifier unit and pressured injection well.