Kanlaon lahar dredging urgent in Negros town
BACOLOD CITY—Huge volumes of volcanic debris from Mt. Kanlaon washed down the waterways in La Castellana town in Negros Occidental on Friday, triggering floods and evacuation of residents.
Heavy rain spawned by Severe Tropical Storm “Opong” (international name: Bualoi) washed down volcanic debris consisting of stones and sand that was about half a meter thick into the highway in Sitio Tamburong, Barangay Biak na Bato in La Castellana, making it temporarily impassable early Friday morning, Mayor Añejo Nicor said.
The flood left a truck stranded at the highway but the road was made passable by mid-morning after clearing operation was conducted, he said.
Ibid Creek in Barangay Biak na Bato, which was still being cleared of lahar sediment caused by the previous volcanic eruption and rains, overflowed again between Thursday and Friday, he said.
As of 4 p.m. on Friday, 81 families composed of 254 individuals were affected by flooding in Sitio Tamburong in Biak na Bato, said Remuel Lajo, head of the La Castellana Incident Management Team.
DENR permit
Friday’s floods in La Castellana occurred just as the Mt. Kanlaon Natural Park (MKNP) Protected Area Management Board endorsed to Environment Secretary Raphael Lotilla the request of Gov. Eugenio Jose Lacson to authorize him to issue a special permit that would allow private firms to clear the lahar sediments from Ibid Creek.
The province and La Castellana had been clearing the creek of tons of lahar deposits but it could not do it fast enough to avert floods, which had occurred during heavy rains in August and early this month.
The removed lahar sediments could not be taken out from the area since Ibid Creek is located within the MKNP where extraction of materials is prohibited.
Allowing private contractors to dredge and remove the lahar, which the provincial government was offering to them for commercial use as construction materials, will require the approval of Department of Environment and Natural Resources.
How much to remove
While the initial estimate of the lahar sediments to be cleared from Ibid Creek was 25,000 cubic meters (about 8,800 tons), the Department of Public Works and Highways (DPWH) said the volume could be about 100,000 cubic meters (about 35,300 tons), Lacson added.
Lacson said they have requested a study to determine the exact amount of lahar sediments in the creek, including an assessment of the area upstream. He stressed that the appropriate agency should be the one to determine the final volume.
The governor also asked the DPWH to redesign the Tamburong Bridge in Biak-na-Bato, saying the bridge’s current box culvert design is not ideal for the flow of volcanic sediments.
