Headquarters set up

Sichuan Governor Yin Li and Huang Yuzhi, vice-minister of emergency management and head of the National Coal Mine Safety Administration, went to the mine immediately to oversee search-and-rescue operations, according to Hu Xiaohua, an official in the Yibin municipal government information office.

Fifteen teams comprising 225 people attended the disaster scene, while an emergency rescue headquarters was set up at the site.

Hu said many senior experts in ventilation, drainage, hydrology and geology from the National Mine Rescue Center, the Xi'an Branch of the China Coal Group and the Chongqing Coal Research Institute were invited to the site to direct operations.

Less than two hours after the accident, the first pumps were on their way to Gongxian from the Sichuan Provincial Coal Mine Emergency Drainage Station.

At 11:30 pm on Dec 14, officials from the drainage station decided to use underground pumps at the scene to drain 550 cubic meters of water per hour. Soon afterward, two huge pumps were sent to the site.

In case the pumps failed as they operated continuously, two others were brought in from neighboring Chongqing municipality and put on standby, Hu said.

Rescuers had to walk underground for about two hours to get to the affected area.

Using a map of the tunnel network, experts were able to work out the approximate location of the 13 trapped workers－an elevated platform in a tunnel.

As the platform was relatively high, the concentration of gas there was low, so the experts thought those who were trapped had a good chance of surviving.

However, floodwater had been pouring into the mine. At the peak of the flooding, the water level rose at a rate of 1.45 meters per hour, posing a considerable threat to the miners.

Six different types of submersible pumps started to pump water out simultaneously, and compressed air was provided for the miners.

Hou Jianming, head of the emergency command center at the Sichuan Provincial Department of Emergency Management, described the drainage operations in the mine as a race against time.

"With each 1-meter drop in the water level, our hopes that the trapped miners would survive their ordeal rose," he said.

At 11:29 am on Dec 15, pumps draining 220 cubic meters of water an hour, along with a number of smaller ones, were put into operation.

Wang Xiong, an engineer with the Sichuan Provincial Coal Mine Emergency Drainage Station, said: "Everything proceeded according to the rescue plan. But after several hours of water being pumped out, the level of the water underground rose, instead of falling, as a result of the continuous flooding."

The rescue headquarters issued an order for the drainage rate to be stepped up to enable the rescuers to reach the area where the miners were trapped.

Wang Xiong said that using a pump that could drain 550 cubic meters of water an hour meant there was real hope of saving the workers, but installing the equipment was demanding work.

Such a pump weighs about 12 metric tons and comes with 30-meter-long pipelines that weigh more than 120 kilograms.

"More than 400 meters of pipelines needed to be laid, all of which involved intensive manpower. Rescuers sweated heavily underground as they worked, and it was extremely difficult to install the pumps and lay pipelines," Wang said.