TRANSFORMING FALL CREEK: DigIndy tunnel supports Mid-North aspirations

Rain garden at the Children's Museum of Indianapolis. Photo by Doug Day.

by Doug Day

Destination Fall Creek (DFC) began in 2011 as part of a working plan to implement the Mid-North Quality of Life Plan. Leigh Riley Evans, CEO of the Mapleton-Fall Creek Development Corporation (MFCDC), said, “There are and have been some amazing things happening in this transit sweet spot running along Fall Creek. Participating in the DFC transformation has been a labor of love, and I’ve learned to never underestimate the power of partnerships.”

Additional partners in the initiative include Reconnecting to Our Waterways, the City of Indianapolis Department of Public Works (DPW), Citizens Energy Group (CEG), Central Indiana Community Foundation (CICF), and Mapleton-Fall Creek Neighborhood Association.

The biggest challenge to transforming Fall Creek is the combined sewer overflow (CSO) problem in Indianapolis. When the city’s first sewers were built in 1873, the 10-mile system dumped its contents into the White River. While not optimal, it was an improvement over open sewage running in gutters along streets and alleys. Twenty years later, a more comprehensive combined system was constructed but without treatment plants; that wouldn’t happen until 1925. Pipes simply carried the sewage to the closest waterway.


When the county’s suburbs were built, they used separated storm and sanitary sewers. Storm sewers collect and discharge rainwater to area waterways; separate sanitary sewers carry wastewater, or sewage, to sewage treatment plants. In the urban center of Indianapolis, the nearly 125-year-old system combines both stormwater and sewage during rain events of as little as one-quarter of an inch. The undersized system overflows about 60 times per year, dumping hundreds of millions of gallons of sewage into area waterways. Fall Creek has 22 of these CSO outlets, the largest of which is 12 feet in diameter.

In the urban center of Indianapolis, the nearly 125-year-old system overflows about 60 times per year, dumping hundreds of millions of gallons of sewage into area waterways. Read more.

Prior to 2006, approximately 7.8 billion gallons of overflows occurred each year. The United States Environmental Protection Agency (EPA) filed suit against the City of Indianapolis for these violations of the Clean Water Act. In 2006, the U.S. Department of Justice approved a consent decree between the City and EPA; the parties modified it in 2009. The modification permitted the construction of a 25-mile-long deep rock tunnel connector 250 feet underground, bored into the bedrock below the City. The 250-million-gallon storage tunnel will collect CSO to prevent it from discharging into waterways. Once the rain has passed, the combined overflow will be pumped to sewage treatment plants that will discharge clean water back to area rivers and streams.

An additional decree between the City and EPA in 2010 further reduced the total annual discharge and cut costs by approximately $444 million. When CEG took over wastewater and water operations from the City of Indianapolis in 2011, it also assumed responsibility for constructing the nearly $2 billion DigIndy Tunnel System, which had been expanded to a 28-mile network of five 18-foot-wide concrete tunnels. Once fully operational, DigIndy will prevent about 97 percent of CSO now flowing into waterways. The Fall Creek Tunnel must be completed no later than 2025.

“This tunnel system is the largest public works project in our city’s history,” said Jeffrey Harrison, CEG president and CEO. “Consequently, it impacts a significant part of our city, both underground and now aboveground. Our team is working efficiently to ensure we remain on schedule so that any disruptions to our neighborhoods are marginal.”


Map of detours beginning January 2, 2018. CLICK TO ENLARGE.

According to Laura O’Brien, CEG’s corporate communications coordinator, upcoming DigIndy tunnel work will require closing Meridian Street at 28th Street. (see map.) From January 2 until late October, 2018, 28th Street east of Illinois to Pennsylvania will be closed so that two large sewers (325 feet of 36-inch pipe and 560 feet of 60-inch pipe) can be installed. They will eventually capture and divert combined sewer overflows to the Fall Creek Tunnel.

CEG is coordinating with IndyGo’s Red Line construction that is slated to begin in March, 2018. DPW is also in the mix since the Central Ave. bridge over Fall Creek will reopen next summer but the College Ave. bridge will be closed for repaving. (see map and timeline.)

Even with the completion of DigIndy, Indianapolis will still experience rain so heavy an average two days per year that this new system will overflow and a mixture of stormwater and sewage will enter Fall Creek. To entirely eliminate this overflow, better management of rainwater runoff with green infrastructure is required. In particular, structures with big roofs and large parking lots need rain gardens like the one installed on Fall Creek across from the Julia Carson Center. In 2014, the City installed its first bioretention cell on the creek side between Broadway Street and College Avenue. It uses a natural system of stone, plants, and soil to filter pollutants before runoff is released into Fall Creek.

Graphic courtesy of CEG. CLICK TO ENLARGE.

While efforts like DigIndy and green infrastructure projects will dramatically reduce the number of days sewage overflows into Fall Creek, the goal is to completely eliminate the problem. Significant progress has been made. To fulfill the Destination Fall Creek aspiration to fully use Fall Creek for wading, swimming, kayaking, and canoeing, there is still a lot of work to do.

Doug Day is the “champion” of Destination Fall Creek, an initiative to “transform Fall Creek into a recreational, residential, and commercial destination with access to art, nature, and beauty for every citizen, every day.

  A version of this article ran in the October/November 2017 issue of the magazine.