An automatic pump system that was supposed to drain large amounts of water from Colorado’s state-of-the-art Central 70 highway corridor failed Sunday night, trapping dozens of drivers in their cars during a flash flood.

Denver firefighters rescued 29 people, 11 of whom were stranded along the reworked two-mile stretch of highway. No one was injured.

When engineers noticed that water was rising at Brighton Boulevard and York Street off Interstate 70, they did some troubleshooting and managed to activate the pumps manually.

“After the pumps turned on, the area was drained in a short period of time indicating that the pumps, once manually started, were working as intended and the error was corrected,” Kiewit Construction, the company that is reworking the highway, said in a statement. 

WATCH: 29 rescued from vehicles after heavy rain causes street flooding in Denver

The Colorado Department of Transportation said it expects Kiewit to adhere to the terms of its $1.2 billion contract, “including ensuring full functionality of the drainage system.” 

Water was just starting to rise when 9-year-old Isaac Jacobs and his best friend, Liam Melka, 10, joined a growing crowd straining to peer over the rail down to the highway below.

“Kids were screaming and people were on the roofs of their cars. I felt bad,” said Isaac.

“Cars were broken down and people couldn’t move,” said Denver fire spokesman JD Chism.

Though no one was injured, this was a near-disaster that Denver City Councilwoman Candi CdeBaca predicted long before the Central 70 Project was approved. She still lives in her grandmother’s Elyria-Swanson home and the I-70 expansion is partly why she got into politics.

Her “Ditch the Ditch” crusade resulted in three lawsuits brought by the environmental advocacy group Earthfirst to halt the I-70 expansion. Two of the suits were dismissed, but one, against the state, resulted in a settlement with a provision for a community health study. 

At the time, she warned city and state officials that building two miles of highway below grade could be a death trap for travelers.

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“We told them there is no way that this is not going to flood. There is no way that this is not going to exacerbate pollution, and there is no way this (is) not going to be a hazard if there is a fire or severe ice or severe snow,” said CdeBaca.

She worried that the tractor-trailers that roar over the busy highway on their routes in and out of the mountains are a hazmat spill waiting to happen.

“What if they overturn in the tunnel?” she said.

Large fans hang from the ceiling of one of the overpasses in case there is a poisonous spill or fire, said Kiewit Construction spokesperson Matt Sanman.

CDOT spokesperson Stacia Sellers said the project is on budget. She said traffic started moving westbound in May 2021 and after the old viaduct was removed, vehicles started traveling eastbound last month. 

Construction started in August 2018 to ease I-70 congestion and to replace Brighton Boulevard’s 55-year-old viaduct. It runs two miles east to west from Brighton Boulevard to Colorado Boulevard. The stretch includes an elementary school, a shopping center, a handful of small businesses and thousands of bungalow-style homes in the Globeville and Elyria-Swansea neighborhoods.

Though all of it is below grade, 900 feet of the project is actually a series of overpasses — one that will soon have a grassy park roof with soccer fields and playgrounds. It’s scheduled to be complete by December and is Colorado’s largest and most expensive infrastructure project.

Heavy rain causes street flooding in Denver

The National Weather Service reported that the Globeville and Elyria-Swansea neighborhoods on Sunday received 1.42 inches of rain and also experienced some hail.

CdeBaca said it’s ironic that a storm roared over the Central 70 Project while the asphalt is still gleaming. Sunday night’s storm, she said, was a wake-up call.

“We fought for years and for this to happen in literally the first year of it being open in a 50-year flood event?” said CdeBaca. “Everyone should be outraged as we were when we were fighting it.”

Isaac Jacobs’ dad, Jeremy, is not upset with the noise and the pollution coming from the highway next door. He wants people to know that Kiewit Construction has been honest and attentive to the neighborhood’s needs, stressing that “this was just a bad storm.”

On Sunday, Isaac and Liam watched firefighters tread water with children on their shoulders. But once the two got home, they had a life of their own to save.

They saw a drenched white poodle with a red collar lost and running scared in the backyard. They dried him off, fed him and named him “Ozzy.” They’re hoping that the owner will realize that the dog survived the I-70 flood of 2022 — and that the pet will be reunited with its owner.