To protect the natural resources in the city and assure that their utilization is not prejudiced by the intrusion of incompatible uses;

To indicate clearly to all interested parties the portions of the city that have been designated for rock, sand and gravel extraction and processing subject to compliance with the standards of this chapter;

To protect properties and uses not in the Q district from nuisances incidental to extraction, processing and hauling rock, sand and gravel;

To ensure that general reuse plans for sites used for rock, sand and gravel extraction and processing are maintained and effectuated.

Mining, quarrying, excavating, extracting, harvesting, sorting, crushing, reducing, washing, refining or other processing of rock, sand, gravel, stone, earth or other mineral, subject to the conditions prescribed in Sections 18.52.050 through 18.52.100 of this chapter.

Watchmen's living quarters when incidental to and on the same site as a conditional use.

Airports and heliports.

Agricultural processing plants.

Asphalt and asphalt products manufacture.

Automobile and motorcycle racing stadiums and drag strips.

Cement and concrete products manufacture, including concrete mixing and batching.

Commercial and private recreation facilities.

Drive-in theaters.

Dwellings accessory to an agricultural use.

Firearm sales at a rifle or pistol range.

Garbage and refuse incineration.

Gas and oil wells, exportation, production, and related facilities.

Golf courses and golf driving ranges.

Public utility and public service facilities including pumping stations, power transmission stations, power distribution stations, equipment buildings, service yards, drainageways and structures, water reservoirs, percolation basins, well fields, and storage tanks. These facilities must be found by the planning commission to be necessary for the public health, safety, or welfare.

Riding academies and stables.

Rifle and pistol ranges.

Sanitary fill operations.

Accessory structures and uses located in the same site as a conditional use, and the following accessory structures and uses located on the same site as a permitted use or a conditional use that has been granted a use permit:

Location and extent of all extraction areas, together with typical cross sections and proposed sequence and phases of operation in each area;

Location of fences and buffers, grading and planting plan for all buffer strips, and proposed sequence and dates for installation of landscaping;

General location and configuration of storage areas for topsoil, other overburden, silt, extracted material, and waste;

Location and design of all processing facilities, including outline specifications for equipment to be used, sufficiently detailed to indicate compliance with the required conditions;

Description of all harvesting procedures including outline description of equipment to be used sufficiently detailed to indicate compliance with the required conditions;

Location, width and surfacing of all roads and parking and loading areas that will be maintained for three months or longer;

Proposed hours of operation;

Proposed haul routes within the city;

Additional data necessary to evaluate the proposal.

The permit holder shall be notified of the proposed restrictions.

A public hearing shall be held in accord with Section 18.12.040 of this title.

The planning commission shall find that restrictions to be imposed are necessary to protect the public health, safety and welfare.

A reasonable time period shall be allowed prior to the effective date of new restrictions necessitating amortization of existing investment.

A reasonable termination date shall be set for uses for which no expiration date was specified in the preexisting use permit.

Landscaped buffers planted and maintained as prescribed in Section 18.84.260 of this title shall be provided adjoining the boundary of a Q district. Where the Q district adjoins or is across the street from an R, O, C-N, C-C, C-R or PUD district, the buffer shall have an average depth of 200 feet and a minimum depth of 150 feet. Where the Q district adjoins or is across a street from a C-S or an I district, the buffer shall have a minimum depth of 50 feet. Where the Q district adjoins an A or an S district, a strip having an average depth of 200 feet and a minimum depth of 150 feet shall be held for use as a buffer, but need not be improved until the zoning map is amended to reclassify the property adjoining or across the street, at which time the buffer shall be improved as required by this section. The depth of a buffer adjoining or across the street from a P district shall be determined by the commission. Where the Q district adjoins a freeway, railroad, arroyo or flood-control channel, the minimum depth of the buffer shall be 50 feet. Buffers shall be improved and planted sufficiently in advance of nearby extraction operations to allow the trees and other plant materials to attain sufficient height and mass to provide effective buffering.

Final cuts in any pit or quarry shall not exceed the normal angle of repose of the excavated materials, and shall not exceed one foot horizontal to one foot vertical.

Temporary cut slopes steeper than one foot horizontal to one foot vertical shall be no closer to a property line than 25 feet plus the vertical depth of the cut, shall be no closer to a public street right-of-way than 50 feet plus the vertical depth of the cut, and shall be no closer to a stream or channel than 100 feet plus the vertical depth of the cut.

The excavation of a pit or quarry shall be conducted in such a manner as to prevent accumulation of polluted water or natural seepage to the maximum extent possible, but not precluding the use of pits for recharge purposes.

Dikes and other barriers and drainage structures shall be provided where necessary to prevent silting of drainage channels or storm drains in the area surrounding the excavation.

Where required by the commission, final cut slopes shall be treated to prevent erosion, topsoil shall be replaced on such slopes to support vegetation and suitable groundcover shall be planted and maintained for a period sufficient to provide vegetation of a density and groundholding capacity that will prevent erosion.

Material used for refilling a pit or quarry, including overburden removed from elsewhere on the site, shall be of a quality determined suitable to prevent contamination of the groundwater either during operations or upon completion or termination of operations.

Quarry or pit excavations that penetrate near or into a water-bearing stratum shall be conducted in such a manner that such stratum will not be subject to pollution or contamination either during operations or subsequent to termination. The commission may prescribe the maximum depth of a pit or quarry in relation to the depth of any aquifer described and defined in publications of the state Department of Water Resources.

Fencing shall be provided and maintained surrounding all areas being excavated to prevent unauthorized access in accord with the requirements and specifications of the public works department. Such fencing shall be located no closer than 10 feet from the top edge of a proposed cut slope.

All reasonable control measures shall be employed to reduce dust in the processing and transportation operations. Haulage roads shall be paved, oiled or watered, and shall be maintained in a dust-free condition. Access roads shall have pavement at least 24 feet wide and shall extend from the public street to the permanent public scale but not less than 500 feet.

Vehicles hauling excavated material shall be loaded in such a manner as to prevent spilling the material while in transit. The commission may designate which public streets may be used in hauling excavated material, and may prohibit the use of any other street.

No explosives shall be used except as expressly permitted by the commission.

Adequate provision shall be made for protection of pits and quarries from overflow from adjacent streams by the construction of levees and other devices to prevent flooding. No obstruction shall be placed in any stream unless authorized by the Alameda County Flood Control and Water Conservation District.

Except during emergencies, or when equipment repairs must be made, all extractive or processing operations shall be conducted only during the hours approved by the commission.