Sonoma County supervisors today are set to consider a proposal to expand the Stony Point Rock Quarry west of Cotati.
The business, just south of Highway 116 on Stony Point Road, is owned by members of the Soiland family, who own several other rock and landscaping supply sites in the county.
They are seeking to expand the existing 73-acre quarry footprint by about 14 acres and deepen the current pit by 40 feet, to 80 feet above sea level.
Annual mining levels could rise from a current upper limit of about 397,000 tons, based on a rolling five-year average, to a fixed limit of 480,000 tons.
Including the import of other materials, total annual sales from the site would be limited to 600,000 tons. The current level is about 380,000 tons.
A quarry has existed on the site for more than 90 years, and the proposal has drawn little opposition, with concerns about noise and groundwater impacts mostly advanced by a few neighbors.
A county environmental study found all impacts linked to the expansion to be less than significant.
County planners have also included in the proposed 20-year permit a list of 65 operating conditions, including measures to limit noise, traffic and other environmental impacts.
The proposal also includes a reclamation plan that would return the 120-acre property to grazing land and wildlife habitat once mining operations have ceased.
The hearing before the Board of Supervisors is set to begin at 2:10 p.m.