by yvonnedroms » Nov 14, 2010 9:16 pm
From Spéléo Secours:
On Thursday, Nov 11, the first teams in had to check the reinstallation of the phones and to make sure that Sump 1 was emptied. The team was kept to a minimum so as not to unnecessarily raise the level of CO2 between the two sumps. In the meantime, the divers got their gear ready for diving through Sump 2 in order to do a reconnaissance beyond, whether underwater or in air-filled passage. If the latter were the case, they took along the necessary instruments to verify whether the air they would encounter beyond the sump is breathable or not. The 2 divers and 8 sherpas entered the cave around 2 pm. Once at the bottom, the first diver entered into the sump and after only 12 feet, at -3 feet of depth, he was stopped by a sand plug with only 6 to 8 inches of water at the ceiling. Three times, the two divers tried unsuccessfully to pass through the sump. Around 4 pm, the surface is called with the news. Right away, technical solutions to this new setback are discussed, with the supposition that this sump could be similar to Sump 1. The divers and support team return to the surface.
On Friday, Nov 12, everyone is looking for new ideas. One of them is a bit ambitious. It’s necessary to pump out Sump 2, but since it’s not possible to get through it, there is no way to pump it out downstream. Therefore, the choices are to pump out the water to the outside, or to store it underground. In the end, the best idea is to build a dam capable of holding back a large quantity of water. It needs to be able to hold back the active stream’s water (2 liters/second) and in addition, to hold the water that will be pumped out of Sump 2. The idea is not to empty out the sump, unless it happens to be very short. It’s mainly to evaluate its dimension and how it reacts. The floor of the sump, being filled with very compacted sediment, could also be dug in order to increase the height of the passage.
Once this idea was adopted, the pump and accessories capable of pumping water up to the dam had to be procured. Then it was necessary to figure out the best location for the dam, and to calculate its capacity. The equipment was bought. The dam was positioned upstream in the main stream. Taking into account its height, just over 2 feet, the capacity was about 20 cubic meters (5300 gallons). Four-inch steel rods were used as the support structure, anchored in the opposing walls. Bags filled with sand and cobbles were positioned against this metal barrier. As in any dam, the bottom was built thicker than the top, and an overflow incorporated. Then the pump was installed, as well as the hose 180 feet upstream to the dam. By end of the afternoon, the set up was ready. The divers returned to the bottom, and started the pump. Two other people were at the dam to oversee the operation. One team was at Sump 1 to keep an eye on its level. Once all was set, the operation started in this order:
1. Sump 1 is fully emptied.
2. The dam is sealed.
3. Sump 2 is pumped into the dam.
After some electrical snafus due to the ambiant humidity, the complex system functioned. After about 1.5 hours of pumping, the level of Sump 2 was lowered by about 4 feet. The divers, helped by two cavers, dug in the entrance of the sump. Since the sump’s level went down quite a bit, it was thought that it is reletively short. The divers tried again to get through. This time, they got an additional 3 feet. But the distance between the ceiling and the floor is still only about 4 inches.
That evening, the entire team, quite tired, left the cave. Even though the sum seems to block the efforts for now, a fissure found a bit before and on the left of the sump was found. The objective for the next few days will most likely be in this direction.
-Yvonne
(P.S. There is no Sunday morning update for what was achieved on Saturday.)