DigIndy tunnel keeps 55M gallons of sewage out of waterways

INDIANAPOLIS (AP) — In year’s past, the heavy rainfall that pummeled Indianapolis recently would have swamped the city’s sewer system and created a sticky, foul, disgusting situation.

Not this year.

In the first real test of the city’s newly opened DigIndy tunnel, Citizens Energy estimates the system prevented more than 55 million gallons of sewage last week from flowing into the White River and Eagle Creek.

That’s enough sewage diverted to fill 83 Olympic swimming pools. Or roughly 416,568,047 regular-sized water bottles.

“We couldn’t be more pleased with how the (tunnel system) performed over the last week,” said Jeff Willman, Citizens Energy vice president of water operations, “capturing nearly 55 million gallons of sewage that previously would have entered our waterways.”

The first 11 miles of the DigIndy tunnel, known as the Deep Rock Tunnel Connector and the Eagle Creek Deep Tunnel, opened Dec. 29.

Since coming online two months ago, this section has kept more than 74 million gallons of sewage — which could fill as many as 560 million water bottles — from polluting area waterways. It is expected to prevent more than 1 billion gallons from entering the river on an annual basis.

Measuring 18-feet wide and 250-feet deep, this project is part of a federal consent decree with the U.S. Environmental Project Agency, the Department of Justice and Indiana’s Department of Environmental Management.

The goal: to clean up the city’s waterways from the billions of gallons of sewage and storm water overflowing into them every year.

“Wastewater that leaves your house will usually go to treatment plants,” said John Trypus, director for Citizens’ underground engineering and construction team. “That is unless we get some rain.”

Indianapolis and the greater central region got plenty of it recently.

During the week of Feb. 19, Indianapolis saw approximately 4 inches of rain, according to the National Weather Service. The 1.7 inches of rain that fell on February 24 alone tied the record rainfall amount for the day, the Service’s data shows.

All it takes in Indianapolis is a quarter inch of rain to send waste out of one or more of the city’s 134 overflow points, or outfalls, into the river.

“It’s not just during abnormally heavy rain events that this segment of the system will make a great impact,” Willman said. “Even during rain events of as little as one quarter of an inch, which are much more common, thousands of gallons of sewage will be prevented from entering the White River and Eagle Creek.”

Now, four of the more than 100 outfalls — two of which are the biggest across the entire system — dump their waste into the tunnel’s open section instead.

This segment then pumps the sewage to the previously expanded Southport Advanced Wastewater Treatment Plant to clean and treat the water. Citizens officials have said the aim is to not have wastewater held in the tunnel for more than three days before being treated.

For those outfalls not yet captured by the tunnel system, Citizens estimates that roughly 400 million gallons of sewage entered the city’s waterways during the week of heavy rainfall. Residents should rest assured: That water is still treated before it returns to their homes.

That said, the waste can still be detrimental for plants and wildlife in and along the waterways, as well as render them useless for recreation.

“Anyone who’s looked at the pollution to the White River system cannot deny the significant and deleterious effects that combine sewer overflows have,” said Jill Hoffmann, executive director of the White River Alliance.

She added that the scale of the sewer overflow threat is like “no other single pollution source,” calling it “the proverbial 800-pound gorilla in the realm of urban water quality.”

Which is why Hoffmann said she is thrilled that the DigIndy tunnel system is open and working well to reduce the raw sewage reaching Indianapolis waterways.

“I personally cannot wait,” she said, “to see and sample the river once the full tunnel system is complete.”

Planning for the project began as early as 2006, while construction didn’t kick off until 2013.

When all is said and done, and the entire project comes to a close, only one or two overflows should happen each year in extreme events, releasing 220 million gallons of the contaminated water. That is an almost 99 percent reduction, according to Citizens spokeswoman Laura O’Brien, and surpasses the 95 percent reduction goal.

The tunnel, with a $2 billion price tag, will be 28 miles long in total and is set for completion in 2025 when the Fall Creek and Pleasant Run tunnels open. Two other sections of the network — the White River and Lower Pogue’s Run tunnels — are expected to come online in 2021.

“(This week) demonstrates that the system is performing as designed,” O’Brien said. “It is also important because it is a preview of how large of an impact the overall system will have when completed in 2025, where we anticipate capturing up to 6 billion gallons of combined sewage annually.”