Drainage system key to solving floods

CEBU, Philippines - Unless the inadequacy of the drainage system in the city’s lowlands is resolved, the problem of flooding will remain whatever mitigation is put in place in the mountains, said Genvi Developer Corp., developer of Monterrazas de Cebu.

Genvi said that they did not cause the heavy flooding in Guadalupe and Tisa last July 20, rather it was caused by the excessive rainfall or above normal rain intensity experienced that day.

“What we caused is a little runoff and a little silt which are the consequence of development,” said Genvi managing director Dindo Perez.

“For us to be blamed for what happened, it’s painful. Because we know we worked hard, had sleepless nights,” he added.

Genvi officials said that their mitigation measures are in place which will be further improved as they go on with the development.

Currently, there are 13 permanent detention ponds in place to control the runoff that was caused by the development, particularly the hauling for the road development.

The detention ponds were designed based on a 25-year recurrence interval while in a subdivision like what they are developing, they are only required to base their design on a 10-year recurrence interval.

“Meaning, these detention ponds are designed to capture additional water over a 25-year period. There might be inaccuracy with the data now due to the climate change,” Perez said.

“We have gone beyond what is required of us,” he added.

Genvi insists that the heavy flooding was due to the monsoon traps and it was expected to flood which happened basically in major areas in the city.

Project director Aristotle Agbisit said that their detention ponds temporarily traps and regulates the flow of the runoff that was caused by the removal of the surface due to road construction.

But he said they cannot control the pre-development runoff, which is the natural volume of water that flows even before they started the development.

Agbisit said that they constructed the detention ponds even before they started the major development in the area.

Major works were stopped days before Mayor Michael Rama issued the Cease and Desist Order because Perez said they committed to address the flooding problem. Agbisit said the underground electrical works and paving works and the construction of the drainage system continues.

Genvi plans to construct a diversion canal that will divert at least 40 percent of the runoff to another area so only 60 percent will have to go to the Guadalupe area.

They plan to also construct a parallel drainage pipe from the Genvi property to the Grand Legacy Subdivision to complement the existing drainage constructed by Genvi.

But the problem is Grand Legacy’s drainage system is also not connected to any drainage system beyond its property so the water still finds its way out to houses.

Perez said the city government and all agencies concerned must do something with the drainage system in the urban area because it is aggravating the problem.

“Then they want us to defray the cost which is already tantamount to admitting that it is indeed our mistake,” Perez said.

“This incident is costing the company money that should have not been spent. Our permits were assessed and granted on the presumption that the city can accommodate us,” Perez said.

“You cannot just let the developer invest and say oh, we were wrong. It would have been okay if they denied us from the beginning,” he said.

Perez said the Monterrazas was presented seven times to the previous administration.

Genvi officials also said that there was no basis to the notice of violation issued by the Environmental Management Bureau which they are set to clarify with the agency during the schedule technical conference. (FREEMAN)