In February, Colorado Department of Transportation executive director Shailen Bhatt dared opponents of his department’s plan to widen I-70 “to sue us.” On Sunday, a group led by RiNo developer Kyle Zeppelin took Bhatt up on his offer—well, sorta.

Zeppelin and a group of community activists filed a lawsuit against the Federal Highway Administration (FHWA), which performed a necessary environmental impact study (EIS) on the I-70 expansion before granting approval for the project in January. Plaintiffs allege that the study violates the National Environmental Policy Act (NEPA) because it didn’t examine CDOT’s entire plan.

“We are standing up to CDOT,” Zeppelin said Monday morning during a press conference outside of the federal courthouse in downtown Denver. “We’re looking for solutions for the 20th century and not the 1960s.”

CDOT wants to spend $1.2 billion to expand I-70 between Chambers Road and I-25 in Northeast Denver. Opponents claim that the project will cut huge sections out of the Globeville and Elyria-Swansea neighborhoods, polluting the area even more, and displacing the minority communities who call the area home. (In April, federal investigators concluded that the project would lead to an exodus of Latinos from Elyria-Swansea, but said the state didn’t have any better options.)

The main issue of this lawsuit revolves around the plan to embed a portion of I-70, between Colorado and Brighton boulevards, about 40 feet into the earth. An underground road, of course, could be subject to flooding. So the city of Denver has agreed to construct a drainage structure, called the Platte to Park Hill Stormwater System, as a safeguard.

The problem (at least in terms of this lawsuit) is that the Platte to Park Hill project was not accounted for in the FHWA’s EIS. According to the plaintiffs’ complaint, this is especially concerning because the lowered section of the highway would sit on a superfund site and the project itself would disturb 35 known hazardous materials sites.

In a statement released on Monday, the Central 70 project director Anthony DeVito said that CDOT believes the EIS will stand up to the legal test. “CDOT is confident that our unprecedented community outreach process and our thorough technical analysis meet and exceed the standards set by the National Environmental Policy Act,” DeVito said.

Melissa Hailey, an attorney at the Denver firm of Keating Wagner Polidori Free representing the Zeppelin crew, says the next step will be filing for an injunction within the next 30 days, which could halt construction until the FHWA restarts its EIS—or, you know, just gives up. The latter, you can be sure, is not likely.

(Read 5280‘s special report on Denver’s Globeville neighborhood)