Tuesday, March 01, 2011

Dam still stable but needs desilting

Dam still stable but needs desilting
By Candeze R. Mongaya
Cebu Daily News
March 1, 2011

The Buhisan Dam is stable enough to last for another 100 years, water district officials said.

But the dam is heavily silted and needs to have six million cubic meters removed to enlarge its capacity to hold rainwater and runoff from the watershed of Cebu City’s mountains.

Metro Cebu Water District (MCWD) general manager engineer Armando Paredes said initial drilling showed that the dam’s rock formation remains intact.

“Our problem is how to dispose of the silt because there’s no enough area,” Paredes said.

The 100th anniversary of the completion of the Buhisan Dam will be commemorated on Feb. 11, 2012.

The Buhisan Dam has a 60-hectare pond area that produces 5,000 to 10,000 cubic meters of water per day.

The Buhisan Dam supplies about 5 percent of the water supply of MCWD.

The water district relies mostly on groundwater pumped from the aquifer to service households and commercial-industrial customers in its franchise area.

Paredes said they plan to tap the private sector to help with the desilting.

The MCWD conducts gradual disilting every summer when the pond has a low water level, said Paredes.

The silt is gradually released downstream.

Paredes also acknowledged the efforts of non-government organizations involved in preserving the Buhisan Watershed Forest where a healthy tree cover is important.

“Buhisan is very well reforested,” Paredes said.

MCWD assistant general manager Ernie Delco said while disilting “is important, it’s not very urgent.”

Aside from the MCWD, other stakeholders involved in efforts to rehabilitate the Buhisan Watershed Forest Cover are the Cebu City government, Department of Environment and Natural Resources (DENR), the Philippine Business for Social Progress and Cebu Uniting for Sustainable Water.

Paredes said they hired a technical team to study the stability of the nearly century-old dam.

Results of the study will be released next month or May.

The MCWD will also develop an operations manual as a guide about the dam’s functions.

The study also included scenarios on the risks of possible landslides.

But Paredes said “minor” erosion would create little effect on the dam’s stability.

He said the dam’s rock foundation is still solid, based on the drilling done by the researchers.