Santa Rosa acted properly in letting an asphalt plant add three new 82-foot-high silos without a full environmental review, a judge has tentatively ruled.

The city's decision to exempt the BoDean company from performing an environmental impact report for its project was justified because the upgrades will not increase the plant's production capacity, merely its storage capacity, Judge Elliot Daum wrote in his tentative ruling released Thursday.

"Adding some storage space to a facility that already exists and which already has both the physical ability and permitted allowance to produce more than the silos can hold, logically and reasonably could fall within the scope of an alteration of 'existing facilities,'" Daum wrote.

State environmental law exempts certain projects from full environmental review if they involve "negligible or no expansion of use" or the "replacement or reconstruction of existing structures and facilities."

The city cited both exemptions when in 2012 it granted BoDean a permit to install the three silos, each of which can hold 280 tons of hot asphalt, and related conveyor belts and other machinery.

The company said the $1.5 million project would help it save money and energy and reduce emissions and other impacts to the neighbors by allowing it make larger batches of asphalt, thereby reducing how often the plant had to be turned on and off.

But neighbors called the upgrades an expansion of operations that would allow the plant to produce and deliver more asphalt, thereby likely increasing the odors, dust and traffic they contend with today.

They also argued an exemption shouldn't be granted because the West End plant operated in the "unusual circumstance" of being an industrial operation in an area that wouldn't normally permit such a use.

The judge found that the city was right to grant the first exemption in cases of "negligible or no expansion of use." But he was less swayed by the second exemption, ruling that the new silos weren't a "replacement or reconstruction of existing structures and facilities" because the old silo will remain in place.

On Friday morning, Rachel Mansfield-Howlett, the attorney for the group called Citizens for Safe Neighborhoods, argued that the city relied on both exemptions in granting the permit. But Daum said he was "confused" by that claim.

Assistant City Attorney Molly Dillon said she believed both exemptions apply, but only one is necessary under the California Environmental Quality Act. She said the city "did a very full and complete job" in reviewing the project before granting the exemption.

Daum said he would consider the matter further and issue a ruling at a later date.

(You can reach Staff Writer Kevin McCallum at 521-5207 or On Twitter @citybeater.)