The Metropolitan St. Louis Sewer District has agreed to spend $4.7 billion to make extensive improvements in its sewer systems and treatment plants over the next 23 years as part of a settlement with the federal government, the State of Missouri, and the Missouri Coalition of the Environment Foundation.

In the settlement announced August 5, MSD will be required to install a variety of pollution controls, including building three large storage tunnels ranging from approximately two miles to nine miles in length, and to expand capacity at two treatment plants.

MSD says it has already spent $2.3 billion over the past two decades to eliminate more than 300 sewer overflows. These controls, plus the new controls under the consent decree, will result in the reduction of almost 13 billion gallons per year of overflows into nearby streams and rivers, the Justice Dept. says.

The consent decree also stipulates that MSD invest at least $100 million in a large-scale green infrastructure program, focused in environment justice communities in St. Louis.

The settlement resolves litigation brought by the United States in a lawsuit filed in June 2007 alleging that on at least 7,000 occasions between 2001 and 2005, failures in MSD’s sewer system resulted in overflows of raw sewage into residential homes, yards, public parks, streets and playground areas. It is the latest in a series of settlements that are part of an EPA initiative to reduce raw sewage and contaminated stormwater out of the waters of the United States.

EPA Regional Administrator Karl Brooks said, “This agreement will bring jobs and long-term economic investments while significantly improving the environment for future generations.”

In a statement, MSD said, “There has never been any question about the need for continued work to upgrade and modernize the nation’s fourth largest sewer system. Rather, the true question is how quickly this work is completed, which is the driver behind continued increases in monthly sewer bills.”

The settlement is subject to a 30-day public comment period and court approval.