OLYMPIA, Wash. (AP) — A judge has ruled that contractors who built Seattle’s new Highway 99 tunnel may continue to sue the state for $500 million in cost overruns, despite losing steel-pipe fragments and boulders that are crucial evidence.

The Seattle Times reports that Thurston County Superior Court Judge Carol Murphy also ruled Thursday that jurors in the possible trial this October will receive “adverse instructions,” and Seattle Tunnel Partners (STP) could be limited in calling expert witnesses.

But she stopped short of tossing out the case entirely, as the state’s lawyer requested.

Murphy ruled this spring that STP committed “spoliation,” the legal term for losing or destroying evidence.

The steel, boulders and a deputy project manager’s missing journal are relevant to the core argument pressed by STP: That an 8-inch-diameter steel pipe, buried by Washington state in 2002 for groundwater testing, caused the giant tunnel boring machine Bertha to stall next to the city’s waterfront in December 2013.

The state says it isn’t responsible for Bertha’s breakdown and cost overruns.

The total claims by STP, to cover repairs to the 4 million-pound drill and more than two years of delays, exceed $500 million.