JAKARTA ~ A plan to use concrete balls to stem the disastrous ooze from a “mud volcano” in East Java province may be revised after they slid deeper than expected, a spokesman said.
The balls slid about one kilometer into the crater, roughly twice the depth anticipated, and many more than planned may be required to staunch the mudflow, said the operation’s spokesman, Rudi Novrianto.
“Based on our monitoring of Monday’s operations, we may later decide to add to the number of ball chains, but the decision will only be made once the initial target of 374 chains have been dropped into the mud hole,” he said.
Each chain comprises four concrete spheres weighing 400-500 kilograms. Five chains were dropped into the crater up to Monday.
The audacious but experimental plan aims to slow the toxic mudflow – which has submerged entire villages in East Java – by about 50-70 percent.
Basuki Hadimuljono, head of the team trying to plug the steaming crater, was quoted by local media as saying that the number of chains required may rise to 1,000 from the initial estimate of 374.
Several geologists, including Edi Sunardi from the University of Pajajaran, have said the scheme will likely fail.
“We are looking at a plane, and you cannot plug such a plane with concrete balls,” Sunardi has said, adding that the balls might even resurface.
But Andang Bachtiar, a private-sector geologist, said the plan still appeared capable of cutting the volume of mud reaching the surface.
He said it was a complex matter whether more balls than planned would be needed at a lower depth.
“If the section at that depth is actually larger than the section at a depth of 500 meters, then more balls may be needed. Basically, it would depend on a lot of factors,” he said.
Ari Setiadi, one of the technical experts working at the crater, said it was not necessarily a bad development that the balls had slid deeper than expected.
“What is important is that they fall below the threshold safety level of 100 meters,” he said.
Setiadi said the impact of the operation was being monitored carefully, adding: “So far, so good.”
Novrianto said ongoing site repairs and the partial collapse of a dyke holding back the mudflow had delayed the resumption of the operation on Tuesday.
He added that the wind kept changing the direction of toxic fumes rising from the crater. They are sometimes blown towards workers, hindering the effort to slow the flow.
Exploratory drilling in May last year by local gas company PT Lapindo Brantas pierced an underground chamber of hydrogen sulphide, forcing hot mud to the surface in Sidoarjo.
The sea of mud has inundated hundreds of hectares of land and made 15,000 people homeless. It is also threatening to swamp a key railway, which is to be rerouted away from the danger zone.
Experts are unsure how long the crater will spew mud if left unchecked.