CEMEX Clayton Quarry
Project Overview
Project Location
The project site is located at 515 Mitchell Canyon Road, on the east side of Mount Zion, approximately one-half mile south of the city of Clayton in an unincorporated portion of the County. Surface mining disturbances are planned on approximately 190 acres within a 335-acre property.
Project Description
The applicant, CEMEX, is requesting approval of a revised Reclamation Plan which includes the following components:
- Reclamation over an anticipated period of 47 years to a post-mining land use of open space;
- Reduction of the surface mining disturbance footprint relative to the existing reclamation plan that leaves the east rim of the quarry intact, providing visual buffer between the quarry and view sheds to the east;
- Permanent overburden fill areas;
- Final grading contours reflecting a maximum depth of excavation at elevation 110 feet above mean sea level (msl) 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 man-made drainage facilities;
- Removal of facilities, structures and equipment associated with mining;
- 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 would provide for a future quarry lake;
- Clarification of pre-Surface Mining and Reclamation Act (SMARA) (1976) disturbance areas, including any areas disturbed outside the boundaries of the approved reclamation plan;
- Removal of 79 out of 123 existing trees, to be replaced with 400 foothill pine trees that would form a tree screen along the quarry east rim;
- Compliance with current State reclamation standards to be achieved during reclamation; and
- An exception request to Division 914 of the Contra Costa Code of Ordinances (Offsite Collect and Convey requirement).
In addition, and in response to stakeholder input, CEMX has incorporated into the project a new screening berm (between the existing processing plant site and residential communities to the north).
County File #’s CDLP15-02030 and 31
Current Project Status
The Final Environmental Impact Report (FEIR) was posted on August 23, 2022.
View the FEIR (PDF)
There is an anticipated public hearing at the County Planning Commission on September 28, 2022. Agendas and staff reports are available prior to the meeting on the County Planning Commission website.
Project Milestones
February 18, 2021
The Draft Environmental Impact Report (DEIR) is available for public comment was published on February 18, 2021.
The comment period for the DEIR extends from February 18, 2022, to April 4, 2022.
View Notice of Availability (PDF)
March 16, 2020
The Zoning Administrator took comments on the Notice of Preparation.
February 14, 2020
The Notice of Preparation (NOP) was posted on February 14, 2020.
View Notice of Preparation (PDF)
Draft EIR (Environmental Impact Report)
Final Environmental Impact Report (FEIR)
Public Notices
Draft Environmental Impact Report (DEIR)
- Clayton Quarry DEIR Cover (PDF)
- Clayton Quarry DEIR Table of Contents (PDF)
- Clayton Quarry DEIR Executive Summary (PDF)
- Clayton Quarry DEIR 01 Introduction(PDF)
- Clayton Quarry DEIR 02 Project Description (PDF)
- Clayton Quarry DEIR 03 Terminology Approach and Assumptions (PDF)
- Clayton Quarry DEIR 04 Environmental Analysis (PDF)
- Clayton Quarry DEIR 04.1 Aesthetics and Visual Resources (PDF)
- Clayton Quarry DEIR 04.2 Air Quality (PDF)
- Clayton Quarry DEIR 04.3 Biological Resources (PDF)
- Clayton Quarry DEIR 04.4 Geology and Soils (PDF)
- Clayton Quarry DEIR 04.5 Greenhouse Gas Emissions (PDF)
- Clayton Quarry DEIR 04.6 Hydrology and Water Quality (PDF)
- Clayton Quarry DEIR 04.7 Land Use and Planning (PDF)
- Clayton Quarry DEIR 04.8 Noise (PDF)
- Clayton Quarry DEIR 05 Cumulative Impacts (PDF)
- Clayton Quarry DEIR 06 Alternatives (PDF)
- Clayton Quarry DEIR 07 Other CEQA (PDF
- Clayton Quarry DEIR 08 List of Preparers (PDF)
- Clayton Quarry DEIR 09 References and Resources (PDF
- Clayton Quarry DEIR 10 Acronyms and Glossary (PDF
DEIR Appendices
- Clayton Quarry DEIR Appendices Cover (PDF)
- Clayton Quarry DEIR Appendices Table of Contents (PDF)
- Clayton Quarry DEIR Append. A-1 Notice of Preparation (PDF)
- Clayton Quarry DEIR Append. A-2 Comments on the Notice of Preparation (PDF)
- Clayton Quarry DEIR Append. A-3 Scoping Meeting Comments (PDF
- Clayton Quarry DEIR Append. A-4 Initial Study (PDF)
- Clayton Quarry DEIR Append. A-5 NOC of the Notice of Preparation (PDF)
- Clayton Quarry DEIR Append. A-6 NOP Distribution List (PDF)
- Clayton Quarry DEIR Append. B-1 Proposed Reclamation Amendment (PDF)
- Clayton Quarry DEIR Append. B-2 Revegetation Plan (PDF)
- Clayton Quarry DEIR Append. C Visual Simulations (PDF)
- Clayton Quarry DEIR Append. D-1 Air and Greenhouse Gas Emissions Study (PDF)
- Clayton Quarry DEIR Append. D-2 Public Health Risk Assessment of Site Reclamation (PDF)
- Clayton Quarry DEIR Append. D-3 1983 Reclamation Plan Backfill Emissions (PDF)
- Clayton Quarry DEIR Append. E-1 Biological Resources Assessment (PDF)
- Clayton Quarry DEIR Append. E-2 Arborist Report (PDF)
- Clayton Quarry DEIR Append. E-3 Clean Water Act Jurisdictional Delineation (PDF)
- Clayton Quarry DEIR Append. F Geotechnical Evaluations for Revised Reclamation Plan (PDF)
- Clayton Quarry DEIR Append. G-1 Hydrology and Water Quality Evaluation Report (PDF)
- Clayton Quarry DEIR Append. G-2 Drainage Plan (PDF)
- Clayton Quarry DEIR Append. G-3 Adaptive Management Program (PDF)
- Clayton Quarry DEIR Append. G-4 Quarry Lake Water Quality Analysis (PDF)
- Clayton Quarry DEIR Append. G-5 DA71A Drainage Area Runoff Estimates (PDF)
- Clayton Quarry DEIR Append. G-6 Quarry Road Runoff Management (PDF)
- Clayton Quarry DEIR Append. H Clayton Quarry Draft MMRP (PDF)
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Francisco Avila
Principal PlannerPhone: 925-655-2866
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Current Planning
Physical Address
30 Muir Road
Martinez, CA 94553
Phone: 925-655-2705