Companies gearing up for tunnel contracts have set sights on Seattle, especially with the variety of opportunities afforded by Sound Transit. The latest, a portion of a $2.1 billion Northgate Link Extension project, has an apparent low bidder. And an apparently upset high bidder, too.

JCM Northlink LLC, a grouping of Jay Dee Contractors, Frank Collucio Construction Company and Michaels Corporation, easily outpaced the competition with a bid of $440 million, well below the engineer’s estimate of $594 million, to mine 3.4 miles of twin light rail tunnels between Husky Stadium at the University of Washington and the Northgate Mall area in Seattle.

But the fifth-place bidder—out of six—has pushed back against the process, saying Sound Transit’s eBid computer system didn’t send them a document relating to contract payment formula, a change about when payment of the final 5% of the contract would get doled out. Now Traylor Frontier-Kemper has filed an appeal for Sound Transit to reopen the bidding process.

Sound Transit hasn’t taken kindly to the TFK response, already rejecting earlier appeals to rebid. During media back-and-forth, Sound Transit says records show that even though there was a glitch—one that had happened before on other jobs—they show some TFK representatives actually opened the document.

TFK, with an initial fifth-best bid of $465 million, says the issue is about fairness and level playing fields. There’s been no talk that this small piece of information would have improved their bid by over $25 million.

Both JCM and TFK have tunneled for Sound Transit during the U-Link project.

If Sound Transit sticks to its plans and awards JCM the job, expect to see them launch two tunnel-boring machines from the Roosevelt Station site to excavate the tunnels to the University District Station. A third tunnel-boring machine will launch from the Maple Leaf Portal and bore two tunnels, one after the other, to the Roosevelt station.

The work will begin late in 2013 and last over four years.

Tim Newcomb is Engineering News-Record’s Pacific Northwest contributor. He has also written for TIME, Popular Mechanics, Popular Science and more. You can follow him on Twitter at @tdnewcomb or visit his website here.