New Delhi, Nov 26 : National Disaster Management Authority (NDMA) on Sunday said that work is on to retrieve broken parts of the auger machine while manual and vertical drilling have also started to rescue the 41 trapped workers in Uttarakhand's Silkyara tunnel. The rescue operation is going on for last 14 days to bring out the 41 workers trapped in Silkyara tunnel in Uttarakhand's Uttarkashi. NDMA Member Lt Gen (retd) Syed Ata Hasnain told reporters here that all efforts are going on to rescue the workers. He said that vertical drilling which is considered as the second best option and has been started around noon and 15 meters of drilling has already been completed. He said that after 86 meters of vertical drilling, the crust of the tunnel will have to be broken to bring out the trapped workers. Hasnain said that as many as six plans are being executed to rescue the workers but the best option so far is horizontal drilling under which 47 meters of drilling have been completed. On November 12, an under-construction tunnel collapsed in Uttarakhand's Uttarkashi leaving 41 workers trapped. /IANS