Two men have been rescued alive from a tunnel in Nepal after it was buried by a massive flash flood, in a complex operation described as "layer upon layer of miracles." The survivors, identified as Sanjaya Shah and Kabir Maharjan, were found on Friday after being trapped in the Trishuli 3A Hydropower Station tunnel.

The rescue followed a devastating flash flood on the Nepal-Tibet border last week, which has claimed over 1,300 lives and rendered the landscape almost unrecognizable. The floodwaters inundated several hydropower stations, including the one where the men were working.

Arnold Dix, a tunnelling expert advising Nepal's hydropower authorities, detailed the immense challenges faced by rescuers. The first hurdle was locating the tunnel entrance, which had been completely buried by an avalanche of debris. "I've never known a rescue operation where you had to look for an entrance of a tunnel that was previously up the hill, that was now underground," Dix stated.

Dix and his team utilized a combination of engineering techniques, old topographic maps, post-disaster satellite imagery, helicopter footage, and surface clues like power poles to pinpoint the tunnel's likely location. Once found, the next critical step was locating the trapped survivors within the debris-filled tunnel.

Rescuers had to clear a path through mud and rocks, some larger than cars. Explosives were used with extreme caution, a risky measure in such a confined space. The Nepalese army was credited with precise execution of these blasts to avoid destabilizing the tunnel structure. Concurrently, the team discovered the tunnel was filled with water.

To address the water ingress, Nepalese rescuers dug trenches from the tunnel to the nearby river, employing excavators and pumping machines to drain the floodwaters. This drainage was crucial before further excavation could proceed safely.

Finally, a narrow passageway, only about a meter wide, was dug through the debris at the tunnel's crown. This method utilized the original tunnel's roof for support and minimized the risk of further flooding. In the early hours of Friday, faint calls from the survivors were heard, leading to their eventual extraction.

Despite this success, Dix indicated that the work is far from over, with dozens more people potentially still trapped inside other affected tunnels. The ongoing rescue efforts are now focusing on reaching what Dix termed the "Goldilocks zone" within the remaining blocked sections.