READING, Pa. -

An aging sewer main has done it again.

For the second time in three years, crews are working around the clock to repair a broken main and stop the flow of raw sewage into the Schuylkill River.

The 42-inch sewer main ruptured in southwest Reading on Monday.

Workers were then forced to open an emergency gate, allowing raw sewage to be dumped into the Schuylkill River, said Carl Geffken, the city's managing director. Otherwise, Geffken said, the sewage would have backed up into residents' homes. 

"As required, from what I understand by the commonwealth, that a gate, and in this case a gate into the Schuylkill River for the city of Reading, is required in case of an emergency, and this was an emergency," said Geffken.

The break is located just 50 feet from the Schuylkill, on the west bank under the West Shore Bypass near Brentwood Drive.

The piping runs from the 6th and Canal streets area, onto the river, down the west shore to the city's main waste water treatment plant on Fritz's Island.

Charlie Jones, the city's public works director, said workers are still trying to pinpoint an exact cause of the break, but they have some ideas.

"It is a very wet month of August," said Jones. "More rain in just about any month in history. And then we had the earthquake last week, followed by a hurricane, softening the ground, perhaps weakening the area around the pipe."

Jones said the ruptured pipe is 60-years-old, so the city is going to build a new $15 million sewage pipeline.

Construction is expected to be completed by March 2012.

City officials said they expect to receive a fine from the Pennsylvania Department of Environmental Protection because of the rupture.

Meantime, other municipalities that use the Schuylkill has a source of drinking water were notified about the break on Monday.

Jason Bobst, Pottstown borough manager, said it's a huge concern for the borough, which has added chlorine to the water as a precaution.

So far, Bobst said the water is safe to drink.

If the water becomes unsafe, Bobst said the borough will shut down its water intake from the Schuylkill River and runoff of water in their plant.