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4 Environmental Analysis 4.12 Mineral Resources 4.12 MINERAL RESOURCES This section evaluates the issues related to mineral resources that have been identified in the Griffith Energy Storage Project (Project) area. It considers the physical setting and regulatory context while evaluating the criteria for potential impacts and their significance. The methods used to evaluate these impacts are explained below, and the results of the impact assessment are presented. The County did not receive scoping comments related to mineral resources. 4.12.1 Existing Conditions The existing conditions considered for this Project site include the geology and natural setting and, in this context, the potential for impacts mineral resources is evaluated. 4.12.1.1 Geologic Environment The geology of the regional environment is described in greater detail in Section 4.7, Geology, Soils, and Paleontological Resources. The Project site is located in foothills on the northeastern flank of the Diablo Range, which divides the San Francisco Bay Area from the Central Valley of California. The Diablo Range is part of the Coast Ranges geomorphic province, and the Project site is along its boundary with the adjacent Great Valley geomorphic province to the east. The Diablo Range includes a variety of rocks with ages ranging from the Quaternary to the Jurassic period. In the vicinity of the Project site, the rocks are almost exclusively sedimentary. East of the Project site, on the floor of the Great Valley, the underlying materials are primarily the youngest alluvial sediments, Quaternary age, unconsolidated to semi-consolidated,and mostly non-marine(Q).The Project site sits on older materials (QPc), Pliocene to Pleistocene in age, slightly more consolidated than the younger materials, and deposited into both non-marine and marine environments. 4.12.1.2 Mineral Resources Potential The Mineral Resources Data System is an online database with mine information administered by the U.S. Geological Survey (USGS). This system maintains data on metallic and nonmetallic mineral resources, including deposit name, location, commodity, deposit description, production status, and references. The online database was reviewed to confirm the presence or absence of existing surface mines, closed mines, occurrences/prospects, and unknown/undefined mineral resources in the vicinity of the Project (USGS 2022). No mineral resources or operations are located within the Project site boundary. Within the Midway Quadrangle (USGS 1:24,000 Topographic Map Series), a total of 21 locations are identified by the Mineral Resources Data System, but none are listed as active. Seven were identified as a past producer, six were considered a prospect, six were identified as an occurrence, and two were of an unknown status. Ten locations were associated with manganese as the commodity, while three were associated with clay, three were sand and gravel, and two were gemstone commodities. Quartz, silica, sulfur, and crushed stone were each identified at a single location. The closest location is approximately 3 miles to the west, off Patterson Road, in the middle of a wind energy facility. The other locations are all found at the southern end of the Midway Quadrangle, more than 6 miles to the south of the Project site. The State of California maintains a robust database on active and permitted mines as well as a separate database on oil and gas wells and injectors. Figure 4.12-1 shows the regional locations of this activity surrounding the Project site. Griffith Energy Storage Project 4.12-1 Tetra Tech/SCH 2022120675 Draft Environmental Impact Report August 2023