CEMEX Clayton Quarry Reclamation Plan Amendment


SCH Number
Lead Agency
Contra Costa County
Document Title
CEMEX Clayton Quarry Reclamation Plan Amendment
Document Type
NOP - Notice of Preparation
Project Applicant
Compass Land Group
Present Land Use

Document Description
The applicant is requesting approval of two land use permits (County File #’s LP15-2030 and 2031) for the purposes of amending it reclamation plan and corresponding operations, which includes the following components: • Reclamation over an anticipated period of 50 years to a post-mining land use of open space; • Reduction of the surface mining disturbance footprint that leaves the east rim of the quarry intact, providing a visual buffer between the quarry and viewsheds to the east; • Permanent overburden fill areas; • Final grading contours reflecting a maximum depth of excavation at elevation 110 feet mean sea level with finish slope angles that achieve adequate factors of safety; • A final drainage plan that provides for the quarry pit to slowly fill with stormwater following reclamation to form a quarry lake with a controlled outflow that conveys stormwater to natural drainage courses and human-made drainage facilities; • Revegetation of the quarry east rim, overburden fill areas, and processing plant site to a combination of chaparral and grassland habitats that feature California native seed mixes; • Elimination of requirements to backfill, grade, and compact the quarry floor and benches, given that the planned open space end use will provide for a future quarry lake; • Clarification of pre-1976 (pre–California Surface Mining and Reclamation Act (SMARA)) disturbance areas, including any areas disturbed outside the boundaries of the 1983 Reclamation Plan; and • Achievement of current State reclamation standards during reclamation. In addition, and in response to stakeholder input, CEMEX has incorporated into the Revised Reclamation Plan a new screening berm (between the existing processing plant site and residential communities to the north) and an alternate driveway for accessing the site farther north along Mitchell Canyon Road.

Contact Information
Francisco Avila
Contra Costa County, Department of Conservation and Development
30 Muir Road
Martinez, CA 94553

Phone : (925) 674-7801


37°55'15.9"N 121°56'46.53"W
Contra Costa
Cross Streets
Mitchell Canyon Road and Diablo Downs Road
Total Acres
Parcel #
112-020-007, 112-020-013 and 112-010-016
State Highways
Pine Hollow Middle, Mt. Diablo Elementary, Highlands Elementary
Mitchell Canyon Creek
Other Location Info
515 Mitchell Canyon Road, Clayton, CA 94517

Notice of Completion

Review Period Start
Review Period End
Development Type
Mining (Amendment to reclamation plan of existing quarry operation.)(Diabase Mineral)
Local Action
Use Permit
Project Issues
Aesthetic/Visual Air Quality Biological Resources Drainage/Absorption Geologic/Seismic Greenhouse Gas Emissions Minerals Noise Soil Erosion/Compaction/Grading Tribal Cultural Resources Vegetation Water Quality Land Use
Reviewing Agencies
California Air Resources Board California Department of Fish and Wildlife, Bay Delta Region 3 California Department of Parks and Recreation California Department of Resources Recycling and Recovery California Department of Water Resources California Governor's Office of Emergency Services California Natural Resources Agency California Regional Water Quality Control Board, San Francisco Bay Region 2 California State Lands Commission Department of Toxic Substances Control Office of Historic Preservation State Water Resources Control Board, Division of Water Quality California Native American Heritage Commission California Department of Conservation California Department of Transportation, District 4


Environmental Document
_2020020323 Memo   PDF 6241 K CEMEX Clayton Quarry NOP_Final web version   PDF 10454 K Comment Period Extension Request   PDF 48 K LP15-2030 31 NOP   PDF 6135 K
Clayton Quarry CEQA notice of completion   PDF 314 K
State Comments
2020020323_CDFW Comment   PDF 2245 K 2020020323_Conservation Comment   PDF 491 K 2020020323_NAHC_NOP CEMEX Clayton Quarry Reclamation Plan Amendment Project 2-18-2020   PDF 267 K

Disclaimer: The Governor’s Office of Planning and Research (OPR) accepts no responsibility for the content or accessibility of these documents. To obtain an attachment in a different format, please contact the lead agency at the contact information listed above. You may also contact the OPR via email at state.clearinghouse@opr.ca.gov or via phone at (916) 445-0613. For more information, please visit OPR’s Accessibility Site.

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