Planning, and operation of ventilation system in surge tunnels of lower Subansiri hydroelectric project (8 × 250 MW)

Ventilation Management and its Efficiency is the most vital aspect for the Construction of Underground Tunnels and Caverns. Ventilation in a Long Tunnel forms the most vital coercion not only for Operating Machines but also for creating an apposite work environment for the workforce. Firstly, compromising the Ventilation system of Tunnelling can be appalling and can produce Chronic Fatigue stress in the workforce. It will eventually lead to Low Productivity and a Significant rise in Operational and Overheads costs of the project. Secondly, the Machinery operating inside the tunnel is based on Internal Combustion and the Combustion of a fuel occurs in presence of Oxidizing agent (usually fresh air) and is accompanied by the generation of Heat and Noxious fumes and gases as the by-product. In both cases, Fresh air is required by Forcing Ventilation directly to the Work fronts and followed by Exhaust Ventilation, sucking consumed and Loaded air out of the tunnel. In this scenario, this paper emphasizes the practical approach adopted during the Planning, and Operation of the Ventilation system in the Surge Tunnels of the Lower Subansiri Hydroelectric Project (8 x 250 MW). The methodology adopted for tunnelling in Surge Tunnel is by Mechanical means (Drill & Blast, TBMs are not feasible). Excavation in Surge Tunnel can only be carried out either by Road Header or a combination of Drum Cutters, Rock Breakers, Wheel Cutters etc. The accurate design of this Ventilation system in the Surge Tunnel involves many complex formulas and calculations based on certain assumptions. It involves a combination of both Forced and Exhaust Ventilation and eliminates the demerits of both (Forced and Exhaust Ventilation). Additionally, this paper converges on different Dust Suppression Techniques adopted during Excavation and Shotcreting works. The efficacy of the ventilation system deployed in the Surge Tunnels of the Lower Subansiri Hydroelectric Project (8 x 250 MW) wields an immense effect on how effectively the tunneling operations progresses.