Sand can’t be compacted, worst for reclamation
This refers to the news item “Quake drills all for naught if land reclamation continues, says expert” (News, 2/28/16). The report included a rebuttal by Joselito Gonzales, Philippine Reclamation Authority (PRA) assistant general manager for reclamation and regulation, of a scientific presentation I made regarding the dangers of reclamation.
This is a case of “I say, he (Gonzales) says.” Whose statements can be trusted?
My credentials on the issue include a doctorate in marine geology and numerous peer-reviewed articles on that discipline (published in international journals); numerous years of research and teaching marine geology and sedimentology (which includes all the many facets of sand and its properties); numerous studies regarding natural hazards in the Philippines; and membership in the National Academy of Science and Technology conferred by years of respected science.
Gonzales’ qualifications? He may be an excellent lawyer. But can he claim expertise in geology, engineering, hazard mitigation? For that matter, no one in the PRA board can claim much expertise in the science and engineering of reclamation, except perhaps Floro C. Urcia; the expertise he claims consists of eight days of trainings and seminars.
Gonzales admitted he spoke for the Manila Goldcoast Development Corp. I have critiqued that absurd project in a lengthy, profusely documented article published in 2014 in Philippine Science Letters: “On the geological hazards that threaten existing and proposed reclamations of Manila Bay.” In that article, I invited reclamation proponents to make their rebuttal and commentary. No one did.
Gonzales stated that sand can be used for reclamation “if properly compacted.” Sand cannot be compacted; and saturated with water, it is absolutely the worst material for reclamation, in terms of its ease of liquefaction.
Gonzales claimed that sand used in reclamation can be treated and made impervious to liquefaction. This might be true for materials near the surface, but the sediments underlying Metro Manila’s nearshore areas, coastal Central Luzon and Laguna de Bay include sand layers hundreds of feet deep, which can liquefy and cannot be treated.
Yes, as Gonzales pointed out, the Laguna Lake Development Authority and the Department of Public Works and Highways are in charge of the Laguna Lakeshore Expressway Dike.
But the DPWH record on dike building does not inspire much confidence. In the 1980s, it built flimsy lahar dikes at Mayon Volcano despite my scientific objections. The building of these dikes, designed to contain water floods and not lahar, continued until Supertyphoon “Reming” breached them all in 2006, killing 1,266 people who had sought safety behind them.
In the 1990s, the DPWH’s lahar-dike builders repeated the mistakes on a much larger scale at Pinatubo despite scientists’ objections. The dikes were all quickly breached. In October 1995, Tropical Storm “Mameng” triggered lahar overflows that breached the Gugu dike and totally destroyed Barangay Cabalantian in Bacolor, Pampanga, killing many people.
Since the early 2000s up to the present, the DPWH has built numerous, costly, ineffective flood-control structures in Central Luzon and Camanava (Caloocan, Malabon, Navotas and Valenzuela) area. The objections of academician Fernando Siringan, director of the Marine Science Institute at UP Diliman, have made no difference. And year after year, more money is being spent on cosmetic repairs.
—KELVIN S. RODOLFO, professor emeritus of earth and environmental sciences, University of Illinois at Chicago; senior research fellow, Manila Observatory; corresponding member, National Academy of Science and Technology
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