The Department of Justice, the Environmental Protection Agency (EPA) and the state of Indiana have reached an agreement with the city of Indianapolis on important modifications to a 2006 consent decree that will make Indianapolis’ sewer system more efficient, leading to major reductions in sewage contaminated water at a savings to the city of approximately $444 million.
Prior to 2006, the city of Indianapolis and its 800,000 residents experienced Combined Sewer Overflows (CSO’s) totaling approximately 7.8 billion gallons per year. Combined sewer systems, which have not been constructed for decades in the United States, carry both sanitary wastewater (domestic sewage from homes, as well as industrial and commercial wastewater), and storm water runoff (from rainfall or snowmelt) in a single system of pipes to a publicly owned treatment works.
A consent decree approved by a federal court in 2006 required the city to construct 31 CSO control measures, including a 24-million gallon capacity shallow interceptor sewer, to reduce the city’s overflows to approximately 642 million gallons per year. Those improvements were expected to cost approximately $1.73 billion over a 20-year period.
After the 2006 consent decree was approved, the city undertook additional engineering studies of its system and ultimately proposed a number of changes to its system to make it more efficient and to further reduce the numbers and volumes of overflows. The first change, which was approved in a 2009 amendment to the 2006 consent decree, eliminated the shallow interceptor in favor of a 54-million gallon, 25 mile long Deep Rock Tunnel Connector.
With the proposed changes, the city is now expected to reduce the amount of total annual discharge to about 414 million gallons, a significant improvement from the 642 million gallons that were expected under the original consent decree, and reduce the cost of the project by about $444 million.
The second set of changes to the system would be achieved through the amendment announced in December by Mayor Greg Ballard.
Mayor Greg Ballard detailed plans to save Indianapolis residents $740 million and provide cleaner waterways faster than originally planned. In addition to the savings, the improvements will divert ahead of schedule 3.5 billion gallons of sewage from polluting local waterways.
“Indianapolis was the first city in the nation to successfully renegotiate its agreement with the EPA. This announcement will save hundreds of millions of dollars for our residents, improve the environment and strengthen the city’s position as a great place to do business,” said Mayor Ballard.
The EPA, IDEM and the U.S. Department of Justice approved the plan on June 3, 2010. Final approval by the courts is required. The plan will modify 14 of the 32 Consent Decree control measures, provide new projects including pump stations, and change schedules and operational aspects to capture overflows earlier than initially planned.
The Consent Decree requires that, by 2025, the city capture and treat 97 percent of the sewage overflows in the Fall Creek watershed and 95 percent in the White River watershed in a typical year. By 2025, overflows will be allowed to occur during two storms per year on Fall Creek and four storms per year on White River and other waterways, in a typical year.