A giant tunnel boring machine that has been digging a new 10-foot water tunnel in Montgomery County has broken down and could be out of service for up to three months, officials from the Washington Suburban Sanitary Commission said Thursday.

WSSC spokesman I.J. Hudson said the utility does not know how long the machine breakdown will delay the project, which is scheduled to be completed in 2013. Other work on the $168-million project, which began in summer 2009, is continuing, he said.

The machine named “Miss Colleen” came to a halt Feb. 28 as it chewed through underground rock just north of the Capital Beltway, between an access shaft near Connecticut Avenue and another shaft near Interstate 270 at Tuckerman Lane, the WSSC said. Workers took the machine apart in the tunnel, lifted it out in pieces and took the broken parts back to the manufacturer, the Robbins Company, in Ohio, where they will be repaired, Hudson said.

The 5.3-mile Bi-County Water Tunnel will run between I-270 near Tuckerman and the Church of Jesus Christ of Latter-day Saints’ Washington D.C. Temple. It will contain an 84-inch water main and will run 90 to 200 feet below ground, depending on topography. By connecting two existing 96-inch mains, the new pipe will help meet increasing demands for water in Prince George’s and Montgomery counties, the WSSC said. It also will increase reserves of clean water in case of an emergency.