Hundreds of feet below one of the world’s most famous cities, a different breed of men dig and blast their way through solid rock. These urban miners create the tunnels that ensure the survival of the city above. Meet Walking Boss Morgan Curran and the Sandhogs of Local 147. Under great pressure, these men work to complete the Croton Filtration Plant, a facility that will help ensure the safety of the city’s water supply. In one tunnel they use the “Mole”, an enormous tunnel-boring machine that relentlessly eats away at the rock. In the other tunnel, they’re using large quantities of dynamite to blast their way through the earth. When a void develops along one of the tunnel walls, the hogs race to put up ring steel to prevent a cave in. And while the Brooklyn Bridge celebrates its 125th anniversary, the Sandhogs continue to toil below, preparing and detonating their next blast.