TABUK CITY, Kalinga – The Department of Public works and Highways – Lower Kalinga District Engineering office (DPWH-LKDEO) belied serious allegations in the implementation of multi-billion rock netting projects in the different parts of the province, saying that such interventions are part of the slope protection and bio-engineering measures to address the slope stability in the area.
In a comprehensive report, the DPWH_LKDEO stated that major roads in the Cordillera have been consistently closed during the occurrence of heavy rains and that situations prevented the smooth delivery of agricultural crops from the farmers to the market, transportation of materials and people, thus causing the decline in the region’s agricultural output and contribution to the national growth and development due to impassable road networks that resulted in economic losses.
Based on the 2007 study conducted by the Japan International Cooperation Agency (JICA), losses induced by road closure disasters in the country were estimated to be around P2.6 billion or $52 million annually. The number of road closure disasters is 2,708 road closures per year while the Cordillera alone experiences 981 rod closures annually contributing to about P1.1 billion or 45 percent of the total annual losses due to road closures based on 2004 and 2005 DPWH data.
The DPWH admitted that the road network is a weakness in the region and many main roads are cut off by damages from natural disasters. It implies that steady improvement is necessary in the network of main roads as basic infrastructure.
Further, several steps were proposed to mitigate further slope failure and reduce landslide risk in the region. However, landslide triggers increase with high seismic activity and excessive rainfall both of which weaken the slope stability.
The report added that slope disasters on the country’s highways were reduced by adverse natural conditions such as fragile geology and heavy rainfall and inappropriate selection of slope counter measures, poor maintenance of road drainage systems and defective construction.
The DPWH, together with the JICA, classified the road slope disasters on the country’s highways into seven categories such as soil collapse, rock slope collapse, landslide, road slip, debris flow, river erosion and coastal erosion taking into consideration the failure mechanism and countermeasure option for each disaster type.
The landslide inventory report stipulated that the DPWH-LKDEO had 293 records of soil slope collapse, 286 occurrences of rock slope collapse, 4 instances of landslides, 41 records of road slips, 11 debris flows and 1 river erosion and having no coastal erosion from 2014-208.
It was also noted that the aforesaid road cut slope sections have a moderate to high landslide susceptibility based on the two landslide hazard maps of the Cordillera from the agency and the Mines and Geosciences Bureau (MGB).
The DPWH-KDEO pointed out that various countermeasures for road slope protection on national highways had been implemented for the construction of new roads and the rehabilitation of existing ones.
On soil slope collapse, the interventions that were undertaken were cutting, surface drainage channels, retaining walls and vegetation while on rock slope collapse, the projects that had been undertaken were rock fall netting, catch wall, catch fence, mortar shotcrete and rock shed.
For landslides, the implemented projects include retaining walls and vegetation while, for road slips, surface drainage channels, retaining walls and reinforced soil embankment were completed and will be implemented.
Sabo dams had been put in place to address debris flow while for river erosions, revetments and groins were implemented.
On coastal erosion, the projects that were done were concrete retaining wall, grouted rip rap and wave absorbing works.
The DPWH-KDEO claimed that the proposed rock netting sites in four major road sections in the province were programmed to mitigate the effects of slope collapse since the said sites have histories of past road slope disasters classified as rock slope collapse.
Earlier, concerned elected officials and residents petitioned public works Secretary Manuel Bunoan to initiate the immediate stoppage and investigation of the ongoing rock netting projects in Kalinga.
The petition stated that the rock netting projects that were completed in the province were not economically and environmentally sound considering that the government would spend about P100 million for a certain section consisting of more or less 100 meters only.
The said projects will also affect the growth of Kalinga’s endemic trees and plants.
On the other hand, representatives from the Department of Environment and Natural Resources (DENR) explained that the materials used for the rock netting project are environmentally friendly as the same is used for bio-engineering interventions that refutes the alleged baseless allegations of the petitioners.
