For decades the Capitol Power Plant has burned coal as a means to power federal government buildings, dumping noxious chemicals into the city’s air. But after years of complaints from environmental activists and promises from congressional officials, the power plant is finally cleaning up its act.

Via the Hill’s Briefing Room blog, it looks like the Architect of the Capitol is at last set to begin renovations on the infamous tunnel that runs between the U.S. Capitol complex and the Capitol Power Plant. The work, which involves digging a big pit to access the tunnel about a block away from the Capitol South Metro station, will cause traffic around the intersection of North Carolina Avenue and First Street SE will be…