Riprap ‘too high’, soil ‘too thick’

Posted on May 10, 2012

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THE riprap wall was built “too high”.

That was how an inspection team of the Mines and Geosciences Bureau of Central Visayas (MGB-7) described the 30-foot stone riprap on the banks of the Budlaan River that collapsed Tuesday night.

The team recommended the relocation of affected families living behind the Casa del Rio Subidivision.

They also noted “tension cracks” at the upper part of the wall, which could be vulnerable to a landslide.

The MGB said the retaining wall should be reinforced “using high-quality and first-rate materials” and that a cordon and warning signs should be put up immediately.

Senior Science Research Specialist and geologist Abraham R. Lucero Jr. said the area’s soil was originally quarternary alluvium, made of gradually deposited sand, clay and silt since it is located beside Budlaan River.

The subdivision developer later filled it with limestone soil which, he said was too thick.

He described the 20- to 30-foot high retaining wall as “too high.”

Lucero suggested that a benching type of riprap was better than a high wall.

Cracks in the riprap were noticed after the powerful Feb. 6 earthquake and repairs were made, said Jonji Gonzales, spokesman of Commonwealth Estate Inc. Casa del Rio was built in 2006 and the riprap wall was covered by a proper permit, h said.

He said one aspect that should looked into is the activities of residents who covered up the “weep holes” of the riprap wall, with plastic and tiles to prevent water from draining through them because they used the riprap as a wall of their houses.

The Cebu City Council asked city engineers and the Office of the Building Official to assess the soil in the site.

Councilor Nida Cabrera said barangay officials should report on any structures that have violated the three-meter easement zone provision under the law.

The councilor also called on the Environmental Management Bureau (EMB) to check on the integrity of the soil and to verify if the developer complied with the conditions of its Environmental Compliance Certificate (ECC). /Correspondents Jessa Chrisna Marie J. Agua and Tweeny M. Malinao

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