Photograph of sandhobs 80 feet beneath the ground--near Van Cortlandt Park in the Bronx--by Brent Stirton/History Channel Tonight, the History Channel will air the first episode of Sandhogs (10 p.m.), its 11-episode series about the workers behind moving the city's big infrastructure projects, like Water Tunnel Number 3 and the 7 Subway Line Extension, along. (Last month, we got a sneak look at some images from the show.) In this episode, viewers get to......