UPDATE 2-Judge tells Chevron to stop Calif. refinery work

(Updates with Chevron comments, paragraphs 4-6, 8-9)

By Erwin Seba

HOUSTON, July 2 (Reuters) - A California state judge ordered Chevron Corp (CVX.N) to halt a $1 billion project aimed at expanding the types of crude oils its San Francisco Bay-area refinery in Richmond, California, can process, according to court documents released on Thursday.

Contra Costa County Superior Court Judge Barbara Zuniga sided with California environmental activists that the environmental impact report filed to obtain construction permits for a new hydrogen plant failed to depict how pollution from the refinery would be changed by the project and provide a greenhouse gas mitigation plan as required by California law.

"It's a complete victory," said Will Rostov, attorney for Earthjustice, which represented California community groups opposing the project.

A Chevron spokesman said the company would begin demobilizing the project and was laying off workers as it weighs its next move in consultation with the City of Richmond, California, which issued the permits.

"Chevron is disappointed with the court's ruling," said company spokesman Brent Tippen. "Chevron believes the project was properly analyzed and permitted."

One hundred workers out of the 1,000 employed on the project have been laid off and more will be let go in the coming weeks, Tippen said.

Zuniga's order provides a 60-day period for Chevron to demobilize the project, but that work cannot include any new construction, according to the order.