Fed up with a city council that is intent on downplaying concerns about weak financing for a deep-bore tunnel, a group of city leaders is planning a referendum that, if filed, would suspend the city’s contract to build the tunnel until it reaches a public vote.

“If they want to have a tunnel, they need to guarantee that the tunnel is paid for—and paid for responsibly,” says Brady Montz, chair of the local affiliate of the Sierra Club, and one of the of people exploring a referendum campaign.

At issue is a draft ordinance before the city council that will give the state permission to dig the world’s widest deep-bore tunnel under downtown Seattle. Qualifying for the ballot—putting the ordinance to an up or down vote by the city electorate—would require the signatures of over 16,000 registered voters. If voters were to reject language adopted by the city council, the tunnel contract would have to be revised—possibly killing the project.

“The more responsive the city council is to the wishes of the voters,” Montz says, “the less likely that voters are going to file a referendum.”

Indeed, simply threatening a referendum could make the council more inclined to include provisions protecting Seattle taxpayers "because they know that eventually they are going be accountable to the voters," says Real Change director Tim Harris, another person involved in exploring a referendum. If the council wants the tunnel to proceed, the language must be popular enough survive a referendum challenge.

A city council consultant said on Monday that there was a 40 percent likelihood of cost overruns on the $1.96 billion portion of the project to build the tunnel itself (the full estimate to replace the Alaskan Way Viaduct is $4.2 billion). Preliminary plans from the state have tenuous funding and raise serious questions about whether officials are prepared for the risk. According to a law passed last year by the legislature, the state won’t pay overruns on the megaproject and Seattle property owners must bear any costs over the state’s estimates. The project cannot proceed without Seattle approving the contract to begin digging.

But Harris believes that the council has been dismissing valid concerns: “I think this is a classic example of the city council being locked into a course of action, ignoring the concerns about the cost overruns that have been raised.” Council members Richard Conlin, Sally Bagshaw, and Tom Rasmussen have refused to debate the issue in public.

Harris adds that the 18 organizations which recently signed on to a letter urging the council to address the cost problems “are the bones of the coalition that would support that referendum.” The groups involved have racked up several electoral success in recent years, particularly the Sierra Club, which worked to defeat viaduct and tunnel measures in 2007, defeat a highway funding package later that same year, and win two seats at city hall.

Montz notes, "When people want a referendum, resources can usually be found."

Whether the group actually files the referendum will depend on the final language passed by the council within the next two months, says Montz. For example, adopting a provision being pushed by Mayor Mike McGinn—which would require the state to amend the financing before the project can begin—could stave off a ballot challenge. So could measures that allow the city to void the contract if information shows the project is unfeasible. The state has yet to complete an environmental impact study, obtain bids for the project, or secure funding from tolling bonds of the Port of Seattle.

Once a referendum is filed on an ordinance passed by the city council, the ordinance is suspended while petitioners gather signatures for 30 days. Sponsors need 16,502 signatures to make the ballot, and voters can then approve or reject the measure.

However, the referendum could encounter complications if the council attempts to classify the bill as an emergency measure, which prevents a referendum from suspending it. But such an emergency would have to be “approved by the Mayor,” according on portion of the city charter, which seems unlikely given that McGinn’s position seems to jibe with referendum proponents.