GEOLOGISTS from the Mines and Geosciences Bureau (MGB) and Department of Public Works and Highways (DPWH) said developments on Shrine Hills, including one that involved the diversion of a waterway, and the excavation done for road widening were among key contributing factors of the landslide along the Diversion Road, in Davao City.
This, aside from the fact that the affected slope bore debris from an old landslide and thus has been unstable long before.
MGB Geosciences Division Officer-in-Charge Beverly Mae Brebante during the City Council session Tuesday, October 10, said based on the ocular inspection done on September 30, they have already noted cracks within the Seventh Day Adventist Retreat House and adjacent properties.
"The vertical displacement of the stability was noted and the cause of the mass movement is attributed to the weakening of the slope material and the tapping of the base slopes. Road widening may have weakened the stability that triggered the mass movement on the area. Also it was added that a spring was observed at the base slope and according to interviews, the presence of spring may have contributed to weakening of the slope due to the saturation of the soil and this spring was already present prior to the road activities,” Brebante said.
Brebante said she furnished a copy of the report to the DPWH and also to the Davao City Risk Reduction and Management Office (CRRMO).
Thea Shaira Mae V. Peguit, Geologist II of DPWH, clarified that while the excavation for the road widening may have been a factor, it is the developments on the top of the slope which led to the landslide.
“The primary reason of the landslide was because of the development incurred outside our project, which is above the slope,” Pequit said.
She said that tracing the history of the area where the landslide has occurred will show that there have been landslides before in the same area as shown by some debris. But structures were still built on the slopes, like the Seventh Day Adventist property and other private properties.
“Because it is standing on landslide debris, that particular area is already weak and made of unconsolidated materials. Aside from that, the development there is a diversion of a waterway, which I believe does not have any government permit and that diversion of waterway have caused additional weight,” Pequit said.
Pequit added that they did not coordinate with the MGB prior to the project since they have known that the area is already landslide prone.
She said they are already preparing for the mitigation measures the MGB suggested in their September 30, 2017 ocular but the landslide happened.
DPWH Spokesperson Dean Ortiz said they intend to conduct lowering of the slope through riprapping of the area and to prevent erosion, they intend to install coconut nets.
DPWH Engineer Michael Dela Vega committed that they will finish the road clearing operations within five days.
Meanwhile, a representative of the radio station compound now teetering on the brink of the landslide area has refused to the issue any comment yet on the possible charges and demolition of their establishment.
A staff of Hope Radio told Sun.Star Davao yesterday said that their management will issue their official statement once the clearing operations will be done.
The radio station is one of two establishments which had been issued with notice of violation by the City Engineer's Office (CEO) for not getting a building permit prior to building of structures in the area.
Aside from the Hope Radio, CEO also issued a notice of violation to the owner of the residential house in the area.
The City Planning and Development Office (CPDO) also said that they are planning to file charges to violators of the zoning ordinance.