A new sewer line that started operating this week eventually will replace one that breaks frequently, Lexington officials announced Tuesday.

The North Elkhorn Force Main will carry sewage from east of the city to the Town Branch treatment plant west of downtown.

The new line cost $13 million. A new pump station, near Winchester Road and Interstate 75, cost $4 million.

The old pump station was one of the city's worst offenders for sewer overflows. During wet weather — after a heavy rain or snow melt — untreated sewage often flowed into Bryan Station Creek, a tributary of North Elkhorn Creek.

Replacement of the sewer line and pump station were required under the city's consent decree with the U.S. Environmental Protection Agency. That agreement was reached in settlement of a lawsuit the EPA filed, charging that the city was violating the Clean Water Act.

Mayor Jim Newberry said the new pump station and sewer line represent "enormous steps toward stopping sewage from polluting Lexington creeks."

For now, 75 percent of the sewage that passes through the pump station goes to the Town Branch treatment plant. The rest flows through the old line to the West Hickman treatment plant in Jessamine County.

The old sewer line won't be put out of service until five smaller pump stations are eliminated in 2010, said Charles Martin, director of the city's Division of Water Quality.

The line has ruptured numerous times during the last dozen years, including twice in August.