Construction materials from lahar could be a factor in Porac supermarket collapse —geologist Rodolfo

Sands from lahar or mudflow are not safe for construction use, according to a geologist on Thursday.

In Cedric Castillo's report on GMA News TV's State of the Nation with Jessica Soho, geologist Kelvin Rodolfo said the collapse of Chuzon Supermarket in Porac after a magnitude 6.1 earthquake hit Luzon could possibly be attributed to poor construction materials.

He warned that lahar in construction materials would not make sturdy structures.

"'Yung lava na maraming bubble... kung gagamitin mo ito sa kongkreto, hindi matibay. Madaling madurog," Rodolfo said.

"If you have a pillar, kahit na maganda 'yung bakal mo, it's not enough," he added.

Five people were reported dead after the four-storey supermarket collapsed. The owner's camp denied irregularities in the construction of the building but investigations are ongoing.

Lahar and local economy

To recall, the eruption of Mt. Pinatubo in 1991 caused lahar to bury some areas in Pampanga.

Over the years, the curse of lahar seemed to have been reversed. The local government of Porac earned an income of P16 million in 2018 from collecting taxes from sand and gravel quarrying in the area.

The raw lahar is processed to separate the sand from it. These sands are then mixed with commercial cement to make hollow blocks.

"'Yun po ang main, pinaka-income namin sa Porac. Dati po mostly sugar. Iba-iba, kamoteng kahoy, gulay 'yun lang. Kaya halos walang income 'yung bayan ng Porac dati," Porac Mayor Condralito Dela Cruz said.

The local government said these materials with components of lahar are reliable and were used in most of the residential and government infrastructures in town.

Municipal Engineer Glenn Lansangan said their post-quake inspection in government infrastructures showed little damages.

"Wall cracks, 'yun lang naman ang ano natin regarding sa integrity ng mga structure natin, 'yun lang kino-consider natin. So far naman sa mga structure, wala naman tayong naging problema. Okay pa naman, safe gamitin," Lansangan said.

He added that using sands from lahar for construction is approved by the standards of the Department of Public Works and Highways (DPWH) and the Department of Trade and Industry (DTI).

Standards

According to the DPWH Bureau of Research and Standards, sands from lahar are being used in public infrastructures.

The agency's standard specifications book requires no specific type of sand; it only indicates "natural sand."

"Dun sa specification natin, wala namang sinasabi kung anong klaseng sand 'yan. Kapag tinest natin at nakapasa siya doon sa testing requirement result, pinapagamit natin 'yan sa mga construction project," DPWH director Reynaldo Tagudando said.

"Hindi lang 'yung sand ang tine-test natin. Kung gagamitin 'yan para sa concrete mix, 'yung semento tine-test din natin 'yan saka 'yung aggregates," he added. —LDF, GMA News