Boston races against mother nature's icy clock

Subways and commuter trains are running again in Boston, but the city is racing against the clock, as plows and shovels chip away at nearly 6 feet of snow before Thursday's forecasted storm.

Boston's Mayor Marty Walsh said snow could end up in Boston Harbor, but because plows pick up oil and other contaminants along with the snow, dumping it there is considered a last resort, reports CBS News correspondent Jericka Duncan.

Hundreds of National Guard troops rolled in Tuesday night to help clear the record snow, which city officials say is becoming more dangerous.

"As the snow starts to melt the water has no place to go," Mayor Walsh said. "These roofs are getting heavier and heavier and heavier."

A piano store in the Boston suburb of Rockland was reduced to a woodpile after it buckled under 7-foot snow drifts.

"We have dozens of kids that come here for lessons every day, so it could have been really, really bad," Piano Mill owner Rob Norris said.

Every hour, Boston's Public Works Department is turning 400 tons of powder to water, with the help of snow melters. The city has already spent over $30 million on snow removal.

"There are just mountains and mountains of snow that we'll probably have around here until June," Ippolito Snow Services owner Frank Ippolito said. "We'll just be praying for warm weather."

But the threat of another several inches in Thursday's forecast on top of the more than 70 inches the city has already seen this winter doesn't bother everyone.

"This winter's definitely been a marathon, but you know, we're just gonna have to keep slugging it out," one Bostonian said.

Schools are back after missing eight days and an emergency parking ban remains in effect until Wednesday evening.