Six environmental groups sent letters to Mayor Ted Wheeler and Portland’s city commissioners on Friday, urging them to halt the expansion of a crude oil export terminal in Northwest Portland.

Portlanders are opposed to such an expansion, the letter states, and city officials should stand in its way by passing a moratorium, issuing stop work orders and convening hearings.

The expansion is being undertaken by Zenith Energy, a Houston-based petroleum terminals company. Zenith bought its Northwest Front Avenue facility in 2017, when it was a mostly mothballed asphalt and diesel transfer station.

In 2015, the terminal’s former owner applied for – and received – city permits to expand the facility for offloading rail cars. Construction is underway and expected to finish this month.

And despite concerns from environmentalists and commissioners, Portland leaders may be limited in their actions against Zenith. Building permits cannot be revoked unless a company is in violation of construction codes, which Zenith has not been found to be. It’s unclear if a city policy to ban expansions of fossil fuels infrastructure would apply to Zenith’s work since it was permitted before the ban was approved.

Since its purchase of the terminal, Zenith has singlehandedly created Oregon’s crude oil export market, The Oregonian/OregonLive reported this month.

Increasing numbers of freight trains hauling crude oil have been arriving at the facility from Canada, and unloading into Zenith’s storage tanks that can hold more than 1.5 million barrels of crude oil. The company contracts with Chevron, which owns a Willamette River dock across Front Avenue from Zenith, to pump the crude from storage tanks and onto vessels bound for foreign and domestic refineries.

Zenith’s business has worried environmentalists. The tar sands oil brought in from Canada is extremely flammable, carries heightened toxic inhalation hazards and can sink if spilled in water – causing extra damage to marine habitats.

Zenith also misled state environmental regulators last year to avoid conducting a mock cleanup of a major tar sands spill into the Willamette, The Oregonian/OregonLive reported last week. Regulators essentially shrugged when they discovered Zenith’s duplicity, the newsroom found.

[Read our investigation: Oregon exporter dodged crude oil spill preparedness drill]

Company executives have said Zenith never broke any state rules or laws and did not mislead regulators.

Recognizing the dangers in transporting millions of gallons of crude oil through the Columbia Gorge, along the Willamette River and through Portland neighborhoods, the environmental groups made several demands of the city:

Adopt an “immediate moratorium” on new fossil fuels infrastructure Issue a stop work order for the Zenith project and reassess safety at the site Hold a public hearing and call Zenith officials to testify about their work Put in place policies that make companies liable for damage caused in the event of a spill or explosion

The letter’s signatories: Mia Reback of Sustainable Energy and Economy Network, Khan Pham of OPAL Environmental Justice Oregon, Bob Sallinger of the Audubon Society of Portland, Nicholas Caleb of the Center for Sustainable Economy, Regna Merritt of Oregon Physicians for Social Responsibility, and 350PDX.

Marshall Runkel, chief of staff for Commissioner Chloe Eudaly, emailed Friday that Eudaly “supports doing whatever the city government can to do limit/eliminate the amount of fossil fuels that travel through and are stored in our city.”

Commissioner Jo Ann Hardesty issued a statement saying she shares the environmental groups’ concerns and finds that “crude oil transportation has no place in our city.”

“We’ve seen how fossil fuel industry activities endanger our communities, especially communities of color and low-income communities, and as a city we need to say that’s not acceptable," Hardesty said. “Our office is actively working to find solutions within the city and other jurisdictions.”

Representatives of Wheeler and the other commissioners did not immediately respond to requests for comment Friday.

-- Gordon R. Friedman

GFriedman@Oregonian.com