EVERETT — The city has filed a lawsuit against Kimberly-Clark Corp. over the company’s failure to cover its former waterfront pulp-mill site with topsoil.

When the company shut down the mill in 2012 and received a permit to demolish buildings on the site, it was with the stipulation that the rubble be covered with topsoil and that grass be planted to contain pollution on the site, the city says.

The company has complained that the requirement would make it harder to sell the property. Kimberly-Clark proposed another plan for the property that would not require it to cover the debris, but the city rejected it.

Everett instead extended the cleanup deadline to April 15, and extended it again to June 15.

But the Dallas-based corporation has maintained it is not legally required to cover the site and that doing so would actually increase the amount of dust in the air while making it harder to sell the land to another company — which would then have to remove the topsoil before developing it.

The city’s deadline passed with no progress, and then on July 9, the City Council authorized a lawsuit over the company’s failure to comply. The suit was filed Monday in Snohomish County Superior Court.

In an emailed statement, Kimberly-Clark said it will fight the lawsuit and “believes it has acted appropriately and complied with all permit requirements in its efforts to safely demolish and remediate the site so it can be effectively marketed and redeveloped in order to bring jobs back to Everett.”

The waterfront site was first developed more than a century ago and was primarily used for paper and pulp manufacturing from 1931 until the mill closed in 2012.

In October 2013, Kimberly-Clark announced it had reached a tentative deal to sell the 66 acres of industrial waterfront to Saltchuk. The Seattle-based company was interested in the land as a new home for its subsidiary, Foss Maritime Co., which operates a shipyard and maintains a fleet of tugs, barges and other specialty vessels.

But that deal fell through in April 2014.

Further geological inspection by Saltchuk found that the pilings of the former mill buildings, which are connected across much of the site, are more vulnerable to seismic activity. The two companies couldn’t agree how to split the cost of stabilizing the site and getting it ready for redevelopment.

City leaders, including Mayor Ray Stephanson, had hoped the prime industrial property could be used for another industrial or maritime purpose.

City spokeswoman Meghan Pembroke would not comment on the suit or the nature of any previous negotiations between Everett and the company.

“We have had discussions with Kimberly-Clark, but we weren’t able to reach a resolution,” she said.

In the lawsuit, the city also accuses the company of failing to comply with the state’s Shoreline Management Act by putting concrete debris within 200 feet of the East Waterway.

Soil on the former mill site is contaminated with arsenic, lead, cadmium and other toxic materials, and the city is concerned that airborne dust might affect a nearby residential neighborhood.

The state Department of Ecology has been working on a long-term site cleanup plan, which could be ready by the spring of 2015.

The Ecology Department has tried to stay out of the conflict between the city and the company, however.

“As long as Kimberly-Clark is ready to respond to any dust, the Department of Ecology doesn’t have a position on what the ground cover should be,” Andy Kallus, the department’s site manager, said earlier this summer.

The city is seeking a judicial order to compel Kimberly-Clark to comply with the law and cover the site as soon as possible.

Dan Catchpole contributed to this report. Chris Winters: 425-374-4165 or cwinters@heraldnet.com. Twitter: @Chris_At_Herald.