MARTINEZ -- A public hearing on a propane-and-butane recovery project at the Phillips 66 refinery in Rodeo has been continued for the third time by the Contra Costa County Board of Supervisors, to June 3.

The hearing on appeals of the Contra Costa Planning Commission's Nov. 19 approval of the project and on its final environmental impact report started Jan. 21.

The environmental organization Communities for a Better Environment and the law firm Shute, Mihaly & Weinberger on behalf of the Rodeo Citizens Association filed the appeal, arguing that the environmental report does not adequately study the project's potential impacts and that it overstates the baseline amounts of propane and butane produced at the refinery.

The appellants also warned that Phillips plans to process more and dirtier oil.

Phillips 66 has characterized many of the objections as speculative and based on incorrect assumptions, arguing the project would reduce emissions of the pollutant sulfur dioxide.

Phillips 66 wants to install new equipment to recover propane and butane instead of using it as fuel in its boilers or flaring off excesses. The refinery has said it does not need to refine heavier crudes to make the project work. Regardless, there are no restrictions on the kinds of crude the refinery can process now or in the future.

The supervisors originally continued the Jan. 21 hearing to April 1 to give the county staff and the refinery more time to address questions raised by the public as well as by several public agencies, including the Bay Area Air Quality Management District and the city of Martinez.

Concerns included cumulative effects of the Phillips 66 project combined with other petroleum-related projects in the region, as well as perceived dangers of storing and transporting hydrocarbons in populated areas. Phillips has argued that its propane and butane recovery project stands alone.

The supervisors postponed the April 1 meeting to May 13, again to give county staff and the refinery more time to respond to the questions. Tuesday's postponement to June 3 is to allow county staff additional time.

Contact Tom Lochner at 510-262-2760. Follow him at Twitter.com/tomlochner.