An international company is asking for a 100-year extension to continue mining operations along the San Joaquin River. If approved, crews with CEMEX would blast hard rock and drill a 600-foot-deep pit at one of the two sites for the Rockfield Project located on Friant Road north of Willow Avenue. According to the Draft Environmental Impact Report (DEIR) for the project, the output would increase to 3 metric tons in about 10 years, causing production in the area to double. The changes are sparking some concern among community members and environmental advocates in Fresno County.