With fast cars, movie stars and lots of instances of the patriotically bizarre, it’s no wonder the Indianapolis 500 is known as “The Greatest Spectacle in Racing.”
Hundreds of thousands of people come to Speedway to experience the race in person every year, making the town’s population explode from about 14,000 to more than 350,000 overnight.
The surge of people is great for the local economy, but it strains the town’s resources, especially its ability to handle wastewater. And, if you live there, it will eventually cost you an extra $8 bucks a month.
Every beer, soda, hot dog or pork tenderloin sandwich consumed by visitors in town that day eventually makes its way to the Speedway Wastewater Treatment Plant.
According to Speedway Town Manager Grant Kleinhenz, the plant can handle the amount of physical flow of increased bathroom use during the race. The flow’s chemical content, though, is another story.
“People go to the race. They drink several beers, they drink several bottles of water, they have other beverages and they go to the bathroom a little bit more often,” Kleinhenz said. “Urine has a high concentration of certain chemicals. Ammonia is one of those, and that is a very difficult thing to deal with, particularly in volume.”
Ammonia is toxic to fish and other aquatic life in large concentrations. As a result, the chemical is one of several regulated pollutants in the state’s wastewater discharge permits.
For seven of the last 10 years, Speedway has reported exceeding the amount of pollutants, mainly ammonia, its state permit allows it to discharge in May due to the race.
The exceedances, as they are called, have gotten the town into some trouble with the Indiana Department of Environmental Management. In fact, handling the problem and overflow issues will cost the town $14 million in wastewater plant upgrades in coming years — hence the higher monthly bills.
So here’s the burning question. The 110th running of the Indianapolis 500 is happening May 24, so is the town ready to handle this year’s crowds?
Mirror Indy spoke to Kleinhenz and Speedway wastewater superintendent Brad Sloan about the town’s race day wastewater challenges and what they’re doing to prepare for the race.
How the plant prepares for race day
With events happening in the days leading up to the race, visitors usually start coming to town the Tuesday or Wednesday before race day.
“They go to our restaurants, and they go to our shops and use the restrooms there, so we start to have a build up,” Kleinhenz said. “Come Carb Day, we have an extra 10,000 to 15,000 people on our streets for our street event called Rockin’ on Main. Then on Saturday and Sunday, we have upwards of 350,000 extra people in town.”
Preparations for race day at the treatment plant begin a month before the race. The town makes several arrangements at its facilities to hold increased wastewater flows.
The Speedway Wastewater Treatment Plant is designed to handle an average of 7.5 million gallons of wastewater flow a day, but can handle up to 8.9 million gallons if needed, says Sloan.
Like many treatment plants, the plant uses microbes to break down waste so it can be released into the environment. Speedway’s plant, though, is the only one in the state that feeds those microbes using pure oxygen instead of just available air, which contains oxygen and other chemicals. That difference helps microbes grow faster and consume waste more efficiently.
The plant has a storage nitrification/denitrification reactor, which converts ammonia in the waste into nitrogen gas, which is safer for the environment in moderation. Too much nitrogen in waterways can cause an overgrowth of aquatic plants and algae. That can then suck up all the oxygen in the water in a small area.
“We flush those systems to make sure they’re really in peak operating position,” Kleinhenz said.
The town also worked with Merrell Bros., Inc., which handles waste from portable toilets at the IMS and has its facility next to the Speedway Wastewater Treatment Plant. The company helps ship the waste to Citizen Energy Group’s Belmont Advanced Wastewater Treatment Plant for the week.
“That’s a heavy concentration,” Sloan said. “We will monitor that, of course. We monitor them every day they’re running.”
The town also has plant operators working at the plant on race day and other maintenance workers on call in case something happens. Those workers are issued passes to get through the race day traffic.
“It’s definitely monitor, monitor, monitor,” Sloan said. “We have computers and stuff here that tells us what the flow is and everything else. Guys also go out, put an eye on things, too.”
Here’s the problem
Despite its preparations, the town has reported violating the amount of pollutants it’s allowed to release into the water the last seven out of 10 years due to the race.
The only exceptions were in 2016, the sold out 100th running; 2020, when the race was held in August without spectators due to COVID-19 concerns; and in 2021, when only about 135,000 spectators arrived to watch the race in person.
In the other years, the plant violated its permit due to the race and noted so in its monthly discharge report.
For example, last June the plant reported having a maximum weekly average for ammonium about three times the amount allowed by its permit. The monthly average was also 67% higher than allowed.
A comment added to the report said, “Sold out Indy 500 sent high concentrations to (wastewater treatment plant).”
Sloan says the crowd size and how much they drink often determines how much ammonia the plant will have to handle. The plant’s proximity to the Indianapolis Motor Speedway, about 1.3 miles, means the urine doesn’t have much time to dilute. The plant receives it as the most concentrated ammonia peoples’ bodies can make.
A deal with the state
In August 2025, IDEM sent Speedway a notice for violating its discharge permit between 2022 and 2025.
The agency cited violations in the amount of multiple regulated pollutants discharged into the water, including ammonia.
Agency inspectors singled out “inadequate maintenance and operation” of the plant during the Indianapolis 500 as one of the town’s permit violations.
Kleinhenz disagrees with IDEM’s assessment.
“I’m not saying we didn’t have issues. We did have a couple of issues. We did not feel those issues were as terrible as the words made it seem,” Kleinhenz said. “We do take those things seriously, and we fight to make sure we’re treating our wastewater properly, appropriately, ethically, environmentally consciously and doing it affordably. And I’m not going to apologize for doing that.”
Speedway signed an agreed order, essentially a settlement, with IDEM. The town agreed to develop a plan to control its pollutants or potentially pay thousands of dollars for each violation and each day it took to report it.
The plan, which was approved by IDEM, included a $14 million expansion and modernization of its wastewater treatment plant that will begin construction in June after the race.
Kleinhenz said no state grants were available. The cost of the plant will be paid through a sewer fee rate increase of about $8 for the next 20 years.
Some might wonder why Speedway continues to operate its own plant despite the many challenges it presents to the town.
For Kleinhenz, the answer is simple. Not only is operating its own plant about $20 per month cheaper for Speedway residents than a contract with Citizens Energy Group would be, it also helps maintain the town’s independence.
“We want to maintain our identity as our own unique municipality,” he said. “We love Indianapolis, but we want to be our own thing.”
Mirror Indy, a nonprofit newsroom, is funded through grants and donations from individuals, foundations and organizations.
Mirror Indy reporter Enrique Saenz covers west Indianapolis. Contact him at 317-983-4203 or enrique.saenz@mirrorindy.org. Follow him on Bluesky at @enriquesaenz.bsky.social.
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