Fairfax hazardous-materials crews evacuated two homes and blocked off a street in the Mantua subdivision yesterday afternoon after a dark-blue liquid began bubbling out of a manhole. The substance was later determined to be a harmless dye dumped legally by a nearby T-shirt company.

The incident was nonetheless harrowing for residents of Mantua, where a 200,000-gallon petroleum leak discovered a decade ago devastated property values and led to a $100 million cleanup.

"It is a tad ironic that of all the places on the planet that this would happen, it would be on Tovito Road," the nexus of the earlier oil leak, said Fairfax Supervisor Gerald E. Connolly (D-Providence). Connolly headed the local civic association at the time. "Obviously, we're very relieved."

A few hours after yesterday's discovery, officials determined that the blue liquid came from Sundog Productions, a tie-dye T-shirt firm on Pickett Road nearby. The company has a permit to pour dye into the sewer system. Officials said a clog in the sewer line caused the dye to spew from the manhole and run down a hill into a small creek.

But before fire officials announced that the water-soluble dye was harmless, dozens of anxious homeowners gathered at the corner to watch the haz-mat crews. The scene was reminiscent of the 1990 discovery of oil leaking from the Pickett Road tank farm run by Texaco-owned Star Enterprises, which fouled sewers, creeks and yards in the Mantua and Stockbridge neighborhoods.

Texaco eventually agreed to purchase most of the homes on Tovito Drive and signed agreements guaranteeing the property values of at least 300 other homes in the area.

Staff writers William Branigin and Peter Pae contributed to this report.