Mark West Quarry in the hills between Santa Rosa and Calistoga is asking Sonoma County supervisors for permission to expand to a neighboring property, but owners say it will not represent a major increase in the volume of rock being mined.
The century-old quarry already has permission to annually mine up to 500,000 cubic yards, or about 750,000 tons, of hard rock known as aggregate, highly prized as the base for roads, building foundations and other construction projects. The quarry had been digging steadily northward on the 87-acre property until it began to hit an unexpected patch of volcanic rock that is not useful for gravel and other rock products.
The proposed expansion, on a 33-acre site to the west, will allow the Porter Creek Road quarry to follow the harder rock that it has been mining since 1910, said county planner Sigrid Swedenborg.
"They want to move west so they can stay in the same strata," she said.
The maximum volume of rock coming out of the quarry will not change under the proposal, which will come before the supervisors on Tuesday, Nov. 5, she said. The owner, BoDean Co. of Santa Rosa, is asking the board of supervisors to rezone the new property for mining and grant a 20-year use permit to dig there.
Some neighbors are crying foul, raising concerns about noise, views and a likely increase in truck traffic on the narrow and winding roads on the mountain.
"The county really hasn't looked at the impact on everyone here in our forest and our neighborhood," said Janet Angell, operator of the nearby Petrified Forest, a private tourist attraction that features well-preserved redwoods and other fossilized trees that are more than 3 million years old.
When the matter came before the county planning commission in September, Angell complained that the removal of the trees on the new site would damage wildlife and scenic views and would harm the rural character of the area, which is protected by a county plan for the Franz Valley area.
The consultants preparing the environmental impact report on the project, however, said they found no inconsistency with the Franz Valley plan.
Angell and other residents also raised alarms about the portions of the environmental impact report dealing with traffic, showing that the quarry might add between 37 and 59 trips per day by heavy gravel trucks headed west toward Highway 101 on Porter Creek Road or east toward Calistoga on Petrified Forest Road.
"The imposition of expansion will only intensify a very dangerous situation," wrote neighbor Anita Salas in objecting to the plan.
But Swedenborg said the report's figures are misleading, since they are compared just with truck traffic in recent years, which has been depressed because of the economic downturn. The figures in the report reflect traffic much like it was before the downturn and is consistent with the maximum amount of rock the quarry is already permitted to ship out.
The report outlines a series of measures, including widening portions of the Porter Creek/Mark West Springs Road toward Santa Rosa and adjusting the intersections in Santa Rosa and Calistoga that could ease the traffic congestion. Widening the road into Santa Rosa alone, however, could cost more than $30 million, and the report calls on the quarry to pick up roughly a quarter of the cost of eventual widening the road.