Clayton Quarry Reclamation Plan Amendment

3 Documents in Project


SCH Number
Lead Agency
Contra Costa County
Document Title
Clayton Quarry Reclamation Plan Amendment
Document Type
NOD - Notice of Determination
Document Description
The applicant is requesting approval of two land use permits (County File #’s LP15-2030 and 2031) for the purposes of amending its reclamation plan and corresponding operations, 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).

Contact Information

Francisco Avila
Agency Name
Contra Costa County
Job Title
Principal Planner
Contact Types
Lead/Public Agency


Contra Costa
Northern California, San Francisco Bay Area
Cross Streets
Mitchell Canyon Road and Diablo Downs Drive
Total Acres
Parcel #
122-020-007 and 122-020-013
Mitchell Creek
14, 23
Other Location Info
East side of Mount Zion

Notice of Determination

Approving Agency
Contra Costa County Planning Commission
Approving Agency Role
Lead Agency
Approved On
County Clerk
Contra Costa
Final Environmental Document Available at


(1) The project will have a significant impact on the environment
(2a) An Environmental Impact Report was prepared for this project pursuant to the provisions of CEQA
(2b) A Mitigated or a Negative Declaration was prepared for this project pursuant to the provisions of CEQA
(2c) An other document type was prepared for this project pursuant to the provisions of CEQA
(3) Mitigated measures were made a condition of the approval of the project
(4) A mitigation reporting or monitoring plan was adopted for this project
(5) A Statement of Overriding Considerations was adopted for this project
(6) Findings were made pursuant to the provisions of CEQA


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