26 January 2011
Attabad – draining operations
Posted by Dave Petley
Over the last week there has been a temporary dam in place blocking the spillway at Attabad to allow the Frontier Works Organisation to undertake excavations on the spillway. It is unclear as to the intention of these operations – i.e. whether these are to deepen the spillway, to widen it, and/or to reinforce it. However, the Pamir Times reports that the temporary dam was removed today and that the water level is now reducing at a rate of about 7 inches (18 cm) per hour. Flow through the spillway is reported to be 22,000 cubic feet per second – i.e. about 600 cubic metres per second.
Can anyone provide any more information?
It is easy to be an arm chair advisor, but I wonder whether horizontal directional drilling of the type used for utility service installations might be a solution here. The aim would be to try and induce a controlled piping failure of the barrier.
Tricky, I know, but I think that with some thought the risks could managed and the piping failure staged. The risk to operators might be low if the operation is carefully planned with escape routes but there would be a significant risk of the equipment being damaged or lost.
This kind of equipment is lightweight (<10 tonnes) and readily transportable. Drilling a 150mm (6") pilot hole starting from below the dam wall then a few hundred metres through the barrier into the lake bed is the type of thing this equipment can do in soil or rock.
Do you know if it has ever been attempted?