Land subsidence prompts calls for audits

Irawaty Wardany, The Jakarta Post, Jakarta | Thu, 04/29/2010 11:13 AM

Experts warned building managers to beware of cracks and lopsided structures in buildings in areas greatly affected by land subsidence as this could indicate the need of further reinforcement.

They also called for audits into the construction work.

“If cracks are found, the structures must injected with epoxy,” Puguh Winanto, a technical structure expert at the Assessment and Application of Technology Agency (BPPT), said.

Puguh said cracks of widths between 0.2 millimeter and 0.4 millimeter were especially concerning.

A study recently found that massive development in the capital has caused Jakarta to sink up to 10 centimeters per year due to extensive ground water extraction and pressure from high-rise buildings in the city.

The highest rate of subsidence was recorded in coastal areas in North Jakarta including Muara Kapuk and Ancol, where extensive development had increased pressure on the relatively young and porous soil beneath.

As for lopsided buildings, Puguh said the BPPT had not ascertained the degree of tilt that could be considered dangerous as there were no studies on the matter.

“A direct effect might be an uncomfortable sensation inside the building,” he said.

However, Puguh underlined that subsidence would not contribute significantly to damage to buildings.

“If the piling are embedded in hard and solid rock, then subsidence would have no relatively significant impact,” he said.

As long as the piles, floor and girder of the main building were not cracked, the building was relatively safe, Puguh said.

A former member of high-rise buildings investigation division at the BPPT, Mulyo Haris Pradono, also said that high-rise buildings were normally built on pilings implanted in solid rock up to 30 meters beneath the ground.

“So they are strong enough to support the buildings and will not be affected by subsidence,” he told The Jakarta Post.

BPPT’s head of disaster mitigation technology, Sutopo Purwo Nugroho, said the agency had the technology and human resources to audit the structural integrity of high-rise buildings.

Unfortunately, he said, no building managers or even the city administration, were interested in using the technology.

“We have sent proposals to the city administration and some building owners but none of them responded,” he said.

He said he assumed it might be because of the prohibitively high cost of the audit.

“An audit can cost up to Rp 200 million [US$22,000],” he said.

He said an audit was a one-time evaluation and only needed to be repeated following a strong earthquake.

As long as the piles, floor and girder of the main building were not cracked, the building was relatively safe.

Related Article:

Jakarta sinking as fast as 10cm per year

All buildings to self-audit energy efficiency: New law

The Jakarta Post, Jakarta

With an aim of securing energy supplies, the government is drafting a regulation on energy conservation that is expected to push commercial and industrial building management to start saving energy voluntarily, an official said.

The head of the energy conservation sub-directorate at the Energy and Mineral Resources Ministry, Indarti, said Tuesday the draft mandated an energy manager to audit total energy usage for all buildings and report it to the ministry every six months.

"An energy manager must know total energy waste for the building. The ministry will scrutinize it and give recommendations so buildings and plants can save energy without decreasing productivity."

The recommendations will vary with buildings' energy infrastructure in terms of cost implications, she added.

Indarti said the ministry wouldn't require reports from buildings that used only a small amount of energy.

The draft is expected to be completed next year, she said.

At present, energy audit responsibilities fall wholly on government. So far this year the ministry has examined energy usage at 68 buildings and 132 plants. Next year, when the energy audit budget drops to Rp 4 billion (US$431,732) from a current Rp 22 billion, it will examine only 16 buildings and 28 plants.

Tunggul Sirait of the Indonesian Electricity Society said the government would set up a national energy board to promote energy conservation. It will be chaired by President Susilo Bambang Yudhoyono and include representatives from industry and universities, as well as technological experts, he said.

The board is mandated by a 2007 national energy law -- Law 30 -- intended to provide a framework for conservation and renewable energy.

Conservation, according to managing director of electricity management company PT Schneider Indonesia Eddy Tjahja, was the most efficient way to ensure that energy would be there when needed.

"We can save by up to 35 percent of total energy consumption if we use electricity efficiently," he said.

Some industries, including textiles and hospitality, say they have been using special devices and monitoring their utility bills to help conserve energy since electricity costs went up in 2006. (adt)