Chapter 18.56


18.56.010    General.

18.56.020    Intent and purpose.

18.56.030    Definitions.

18.56.040    Permitted uses.

18.56.050    Permit – Required.

18.56.060    Permit – Application.

18.56.070    Plans, reports and data required to accompany permit application.

18.56.080    Permit processing.

18.56.090    Development standards.

18.56.100    Maintenance agreement(s).

18.56.110    Ridge preservation.

18.56.010 General.

A. The regulations in this chapter apply to all hillside development. Hillside development must also comply with all other applicable provisions of this title. Where this chapter conflicts with other provisions of this title, this chapter controls.

B. If land is zoned hillside planned development, but no hillside planned development permit is approved, no new use may be established. A single-family residential or agricultural building lawfully existing at the time of the establishment of hillside planned development zoning may be enlarged or structurally altered and a building may be constructed as permitted by this chapter.

C. To assist applicants in the early stages of project development, the community development department shall develop and maintain a general design guidelines document for the hillside planned development district. [Ord. 979 § 2 (Exh. A), 1990.]

18.56.020 Intent and purpose.

A. The city is fortunate to be situated between two significant natural resources: The Suisun Bay to the north and the dramatic foothills of Mount Diablo to the south.

B. These foothills to the south are a natural topographic feature, visible to residents and to many visitors traveling State Route 4 and the waters of the Suisun Bay.

C. While development to date has not substantially impinged upon these hills, the city recognizes the need to enact hillside development regulations that will ensure that any future development within these hillside areas will be compatible with the special sensitivity of the hillside areas.

D. The city council declares that lands within the hillside areas be placed in a hillside planned development (HPD) district. The following goals are established for the HPD district:

1. To encourage and create the means of effectuating desirable future development through regulations and development standards on those lands designated in the city general plan as estate residential and hillside/grazing;

2. To protect the public health, safety and welfare in regard to hillside development;

3. To protect natural topographic features, aesthetic views, vistas and prominent ridgelines;

4. To protect adjacent properties from potential adverse impacts of grading and drainage associated with hillside development;

5. To encourage the use of development techniques and alternatives that will be compatible to the terrain of the hillside areas. [Ord. 979 § 2 (Exh. A), 1990.]

18.56.030 Definitions.

In this chapter, unless the context otherwise requires:

“Agricultural buildings” means a structure, except fences, for the purpose of housing farm animals or farm equipment. It excludes a building used for processing or producing farm products on a commercial basis.

“Base density” means the number of dwellings per acre before adjustment.

“Contour interval” means the difference in elevation between adjacent contour lines on a topographic map.

“Development plan” reflects the developer’s intentions regarding the total development of a site.

“Hillside planned development zone (HPD)” means land zoned as hillside planned development.

“Interim use” means a use existing on July 4, 1984, for which a hillside development plan has not been approved.

“Major ridge” means a ridge designated to be preserved in its natural state and delineated on the hillside ridge preservation map.

“Minor ridge” means a ridge designated on the hillside ridge preservation map as “minor ridge” on which development may be permitted provided special design requirements are implemented.

“Open space” means an area to remain undeveloped and to be dedicated to the public or to be held in common ownership by the residents of a development.

“Original ground” means the condition of the existing terrain in its natural state before development.

“Ridge” means an interconnected series of major and minor hill tops.

“Ridgeline” means the highest elevation of a ridge running parallel with the long axis of the ridge.

“Transitional design” is a method of buffering and protecting residential land uses from the impacts associated with locating different types of land on contiguous property lines. [Amended during 2007 recodification; Ord. 979 § 2 (Exh. A), 1990.]

18.56.040 Permitted uses.

The following uses are permitted in the HPD zone:

A. Single-family residential: Detached house on separate lot with design features commonly associated with single-family residential use, subject to the following additional limitations:

1. Only a corner lot is allowed double frontage. An interior lot is allowed double frontage only if necessitated by topographic or other unusual physical conditions. When a lot with double frontage is allowed, or required, additional lot depth and size is also required to provide for larger yards,

2. Each lot shall have a recreational area which has a minimum of 200 square feet. This recreational area may include uncovered decks and covered patios,

3. Transitional design is required where residential land use is proposed contiguous to land developed with uses other than detached single-family residences;

B. Agricultural uses and accessory structures;

C. Livestock raising and grazing;

D. General day care may be allowed subject to a use permit;

E. Planned unit development;

F. Multifamily residential (includes apartments, residential condominiums, townhouses, stock cooperatives and other similar projects), subject to the following additional limitations:

1. The planning commission may require single-story units in areas transitional to single-family residences,

2. Each dwelling unit within a project shall have an appurtenant minimum private open space of 130 square feet such as a patio, deck, balcony or atrium. This space shall be designated for the sole enjoyment of the unit owner, shall have at least two weather proofed electrical outlets and shall have a shape and size that will allow for optimal usable space. The space shall be at approximately the same level as, and immediately accessible from, a room within the unit;

G. Neighborhood commercial uses:

1. Retail sales, restaurant, bank, personal services and business and professional office involving no outside storage or display and with each individual store or operation occupying less than 10,000 square feet of gross floor area within a center having a maximum gross floor area of 50,000 feet, if the average ground slope exceeds 10 percent and a maximum gross floor area of 100,000 square feet if the average ground slope is 10 percent or less,

2. Other uses which the planning commission finds to be of a similar nature, related to and complementary to the above uses and to the general area in which the proposed use is to be located,

3. In the case of a multiple tenant project, a hillside planned development permit application shall contain an “overall development plan” which considers total site development,

4. Each tenant in a multiple tenant development must first obtain a zoning permit before occupancy;

H. School (private or public) which meets state licensing requirements can provide off-street parking and loading requirements, and is located or designed so as to ensure it will have no detrimental effects on surrounding residential uses (especially noise);

I. Church, lodge and fraternal organization;

J. Public and private utility building with no maintenance or corporation yard;

K. Neighborhood center, swim club and other similar use owned and operated by and for residents of a neighborhood in which the use is located if approved with a tentative subdivision map for the subdivision which is to be served or by a hillside planned development permit;

L. Other use accessory to any of the above permitted uses. [Ord. 979 § 2 (Exh. A), 1990.]

18.56.050 Permit – Required.

Land zoned HPD may not be developed nor may a grading permit or building permit be issued until a hillside planned development permit is obtained. [Ord. 979 § 2 (Exh. A), 1990.]

18.56.060 Permit – Application.

A hillside planned development is initiated by filing an application with the city. [Ord. 979 § 2 (Exh. A), 1990.]

18.56.070 Plans, reports and data required to accompany permit application.

The following plans, reports and data must accompany the application for an HPD permit:

A. All items needed for environmental clearance;

B. A written description of the use of buildings/property, machinery, required parking and an estimate of potential impacts on existing parking, traffic and contiguous uses;

C. Color photographs (eight inches by 10 inches or larger) showing the area to fully depict the existing site under review;

D. Site plan, fully dimensioned, to scale including the following data:

1. Vicinity map;

2. Location and dimensions of all property lines (existing and proposed), streets (centerline of city streets and proposed street dedication) and other public improvements, easements, watercourses, trails, setbacks, driveways and parking spaces;

3. Location of all existing and proposed building/structures with building lines and roof overhangs;

4. Location, dimensions and details of trash enclosures, freestanding signs, accessory buildings/structures, such as mailboxes, laundry, ground level equipment, transformers, utility boxes and meters, proposed fences, retaining walls and landscaped areas;

5. Location, type and dimensions of proposed recreational and common area facilities;

6. Location and size of private and public open space;

7. Existing mature trees, including species, variety and size;

8. Parking and loading facilities with circulation pattern;

9. A certification for execution by the director stating that all submitted plans have been approved by the city council with date of approval;

E. Topographic map (one inch equals 200 feet or larger), including:

1. Existing contour lines of not more than 10-foot intervals;

2. Proposed graded contours at not more than 10-foot intervals;

3. Preliminary grading plan including proposed direction of drainage;

4. Slope map showing areas of 10 percent, 20 percent, 30 percent and 40 percent or greater slopes;

5. Table of site coverage showing acreage percentage coverage for the following:

a. Structures,

b. Parking (covered, show total number),

c. Parking (open, show total number),

d. Streets, sidewalks and paths,

e. Open space,

f. Recreational facilities;

6. Vicinity map;

F. Floor plans to appropriate scale. (For single- family and multifamily residential units only typical plans need to be submitted);

G. Building elevations of nonsingle-family units of all sides, including those existing structures that will remain. Building elevations must include:

1. Dimensions of all building structures and components (height, width, roof height, overhang, etc.);

2. Details with specified material and dimensions of door and window treatments, railings, stairways, handicap ramps, trim, fascia, soffits/roof overhang, beams, eaves, posts, columns, trellises, fences, trash enclosures, etc. (sections to clarify detailing should be used as appropriate);

3. Vents, gutters, leaders/downspouts, scuppers, etc.;

4. Exterior lighting, both fixed to the building and freestanding, plus lights for circulation, security, landscaping/building accent purposes;

5. Rooftop mechanical equipment (show hidden line for equipment and top of roof on elevations);

6. Utility meters, transformers, and utility boxes;

H. Rendered Elevations. One “rendered” elevation for each street elevation must be submitted. This rendering may be a professional watercolor prospective or may be a print with color added using Magic Markers or other medium which will accurately convey the color, texture and character proposed (using shadow lines where appropriate). The rendering must accurately represent the final, finished appearance of each building with proposed landscaping. Closely adjacent buildings should be blocked in to put the proposed project in proper context. (For single-family units only typical elevations need be submitted);

I. Profile of structures against major and minor ridgelines that adequately show their visual relationship;

J. Cross-Sections. Two cross-sections must be submitted. They must be through the major axes of the project extending well onto adjacent properties along the boundaries. They must be of the same scale as the building elevations. Both existing and final grades and buildings and other structures must be shown. The cross-sections must show parapet wall/roof relationships, mechanical equipment and mechanical wells, if any, fascia/gutter treatment, and door and fenestration details for nonsingle-family structures;

K. Landscape Plan. The plan must include the following:

1. Existing trees, including species, variety and size and a designation of those to remain;

2. Proposed trees, shrubs, ground covers and other planting materials;

3. Grading details, before and after; contours, curb and spot elevations;

4. Location, species and spacing of street trees;

5. Outdoor features such as patios, trash enclosures, utility meters, transformers, utility boxes, pools, walkways and sculpture;

6. Preliminary irrigation/sprinkler plan or indication of how plant materials will be irrigated;

L. Color and Materials Display. Arranged on eight-and-one-half-inch by 11-inch sheet of cardboard. Materials must be representative of actual material and colors must be accurate. The color pallet should be kept as thin as possible;1

M. Detailed plans or manufacturer’s brochures of exterior light fixtures, signs, fences, trash enclosures, mailbox structures and utility screens;1

N. Graphics/Sign Program. A precise sign program showing:

1. Color, materials, dimensions, lighting of all signs, including address numbers on all structures and freestanding signs;

2. Location of all signs on elevations and site plan;

O. Preliminary Engineering Geologic and Soils Report.

1. The report must be prepared by a professional soils investigation firm prepared under the direction of a licensed civil engineer, geotechnical engineer or engineering geologist and include not less than the following:

a. Identification of any geologic hazards on or adjacent to the site that may impact the development,

b. Conclusions and recommendations for mitigating potential geologic hazards to proposed development,

c. Conclusions and recommendations for grading of the site, including design criteria for necessary corrective measures, slope ratios and erosion control,

d. Conclusions and recommendations regarding the suitability of the site for the proposed development.

2. The preliminary grading plan must contain a certificate executed by the soils engineer or geologist that a preliminary engineering geologic and soils report was prepared for the site and that the grading plan incorporates the recommendations and conclusions of the report;

P. Proposed project phasing and estimated year in which each phase will be completed. [Ord. 979 § 2 (Exh. A), 1990.]

18.56.080 Permit processing.

A. General. The processing of the HPD permit application shall conform to the procedure set forth in this section.

B. Initial Review.

1. The completed application and the required number of site plans and documents together with the application fee and deposit must be submitted to the planning director or authorized representative for initial review. The planning director or authorized representative shall review the application, plans and documents for completeness and conformity to the HPD district regulations.

2. Within 30 calendar days, the director shall return one set of application plans and documents marked either “revise as noted and resubmit” or “accepted as noted for processing.”

3. Should the applicant disagree with the action taken or requested by the director, the applicant may appeal to the planning commission.

C. Environmental Review and Documents.

1. Upon acceptance by the planning director or authorized representative of the permit application for processing, an initial environmental study shall be made.

2. One copy of the completed initial study shall be forwarded to the applicant together with the planning director’s findings and determination of the necessity to perform an environmental impact report (EIR), or negative declaration.

3. The applicant may amend the application to include measures to mitigate potentially adverse impacts identified by the initial study. The planning director shall consider an amendment before making a final decision as to the extent of environmental documentation required for the project. An application is not complete until the appropriate environmental documents are complete.

D. Planning Commission Action.

1. Upon completion of the environmental documentation, the director shall schedule the HPD permit for action by the planning commission at the earliest scheduled meeting.

2. The planning director shall submit the site plan and all pertinent documents to the planning commission together with a written report recommending approval, conditional approval or denial of the HPD permit application.

3. The planning commission shall hold a public hearing to consider the HPD permit application. Notice of the public hearing shall be by publication in a newspaper of general circulation in the city at least 10 days prior to such hearing and by posting the notice in conspicuous places close to the property. A notice shall be mailed to all owners of property contiguous to the property for which the permit is being considered.

4. Notice may also be given to other such persons or agencies the planning director deems necessary.

5. The planning commission shall adopt a resolution recommending that the city council approve, conditionally approve or deny the HPD permit application.

E. City Council Action.

1. Upon receipt of the planning commission recommendation, the city clerk shall schedule a public hearing before the city council with notice of the time, date and place of the public hearing being given pursuant to subsection (D) of this section.

2. After considering the planning commission recommendation, the city council shall, by resolution, approve, conditionally approve or deny the HPD permit application.

F. Exceptions from Permit Requirements. An HPD permit is not required for land for which a tentative subdivision map was approved before 1984. For a tentative map so approved, this chapter applies to land within the development for which a final map was not recorded before the expiration of the tentative map.

G. Permit Amendments.

1. An amendment requested by the applicant shall be processed in the same manner as the original HPD permit approval.

2. The city council, upon holding a public hearing in accordance with subsection (D) of this section, may amend the HPD permit upon finding it is necessary to protect the health, safety and general welfare of the public.

3. An amendment to a previously approved HPD permit does not change any other aspect of the original permit.

H. Expiration and Revocation of HPD Permit.

1. Expiration. The HPD permit expires 24 months after approval unless construction of building foundations is completed.

2. Revocation.

a. The city council may initiate revocation of an HPD permit 24 months after approval if it makes one or more of the following findings:

i. The developer has not made the required off-site or on-site public or private improvements required as a condition of approval;

ii. The developer has not proceeded with substantial construction of the project;

iii. Evidence of an adverse environmental effect not previously studied has materialized;

iv. New conditions arise which necessitate additional environmental or planning and zoning studies.

b. The property owner shall be given 30 days’ advance notice of a public hearing to show cause why the HPD permit should not be revoked. After the public hearing, the city council shall make findings to support its decision.

c. This section does not impair an existing vested right to construct improvements under a building permit. [Amended during 2007 recodification; Ord. 979 § 2 (Exh. A), 1990.]

18.56.090 Development standards.

A. Density.

1. Densities must be compatible with the existing topography and consistent with the goals and regulations of this chapter and the general plan.

2. In determining the actual density for a hillside development permit, the city must consider the following factors:

a. Housing type and variety;

b. Unit size;

c. Surface and coverage of units;

d. Percentage of open space;

e. Recreation space;

f. Preservation of ridgelines;

g. Environmental impacts.

3. The density in a hillside area may not exceed the density shown on the approved hillside development permit site plan.

4. Base Density.

a. The base density is determined in accordance with the average, natural ground slope of the land as provided by Table I as follows:




Average Natural Ground Slope “S”

Base Density in Residential Units Per Gross Acre

Under 10%
















Over 40%


b. For average natural ground slopes between those provided, the base density is interpolated between those indicated in the table.

c. The average natural ground slope is “S” computed by the following formula:





Contour interval in feet




Summation of the length of all individual contours




Gross acreage of property in acres

d. The base densities in Table I are based on an average single-family ground level surface coverage, including garage, of 2,100 square feet per unit (measured in a horizontal plane).

e. When the proposed average ground level surface coverage of a development is less than or greater than the 2,100 square foot average, the base density from Table I is adjusted as follows:

2,100 sq. ft. × base density from Table I = Adjusted base density/Actual average level surface coverage per unit (including garage).

f. The total number of residential dwelling units permitted for a site is determined by multiplying the total acreage of the site times the base density in unit/per acre from Table I.

g. For nonresidential structures within a residential development, the equivalent number of dwelling units is determined by dividing the gross covered or uncovered ground level square footage, including parking areas and garages, by 2,100 square feet. The equivalent number of dwelling units for nonresidential structures is deducted from the total allowable residential units as calculated above.

h. For a nonresidential development, the base density from Table I is used in determining the maximum ground level gross building coverage, including parking areas. The maximum gross building coverage, including parking areas, is determined as follows:

Base density unit/ac × 2,100 sq. ft. × total acreage of site = Maximum total ground level building coverage (including parking areas).

5. Density Bonus.

a. The actual density of dwelling units that may be appropriate for a given site is dependent upon many interrelated factors such as housing type, design, size of units, amount of public and common open space, preservation of permanent ridgelines, grading, yards and street designs.

b. To encourage innovative development of hillside areas, consistent with the goals of this chapter, the city may approve an increase of the base density of up to 25 percent upon finding that the development will meet one or more of the following criteria (the maximum increase in density is shown in parentheses):

i. Ridgelines not indicated on hillside ridge preservation map will be preserved (five percent maximum);

ii. Twenty-five percent or more of the property is to remain common or public open space (five percent maximum);

iii. Twenty-five percent or more of the housing units will be designed to fit the natural terrain (five percent maximum);

iv. Substantial on-site or off-site improvements that will benefit the general public will be constructed by the developer at no expense to the city (five percent maximum);

v. Twenty-five percent or more of the total units of housing development provided for low- or moderate-income households or 10 percent of the total units are developed for lower-income households (25 percent maximum);

vi. Project design includes two or more land uses (five percent maximum);

vii. There is a major orientation of living spaces, balconies, and patios to views (five percent maximum);

viii. The project is designed for energy conservation over and above that required by the Uniform Building Code such as active and passive solar design, building orientation, landscaping and active solar systems for hot water, space heating and cooling (five percent maximum);

ix. Project design integrates pedestrian, bicycle and equestrian trails into overall circulation plan for hillside areas (five percent maximum).

B. Grading.

1. Grading of hillside areas must conform to other provisions of the municipal code, e.g., Chapter 15.88 PMC, in addition to this subsection.

2. Cut and fill slopes visible to the general public must be contour rounded to conform as nearly as possible to the existing ungraded natural terrain. Contouring must be approved by the city during each stage of development approval.

3. Grading must be designed to minimize cuts and fills and to retain the general character of the existing terrain.

4. Cuts and fills must be designed to balance as near as possible to avoid the nuisances created by off-site hauling. If off-site hauling is approved by the city, details of the hauling operation, including, but not limited to, size of trucks, haul route, dust and debris control measures, and time and frequency of haul trips must be submitted to the city engineer for approval. The city engineer may place restrictions considered necessary to minimize adverse impacts that may otherwise result from hauling.

5. Sediment basins may be required as necessary to detain runoff and trap sediment during construction until slope erosion planting is established. The sediment basin dam and collected silt must then be removed and the resulting material hauled from the site or used as a topsoil if suitable. Any silt deposit into off-site drainage facilities from the development must be removed as directed by the city.

6. Grading must be designed as far as possible so that lot lines are at the top of slope with adequate property line setback from the slope to provide for required vertical slope rounding.

7. Proposed slopes at the boundary must be designed wherever possible to be at the same elevation or below adjoining properties outside the development so as not to negate the privacy of adjoining property owners. If it is not possible and there are adjoining properties which will be adversely affected, the developer shall at the city’s option either move the slope onto the adjacent property owner’s land, replacing fences and improvements, or replace the property owner’s fence (if one exists) at the top of the slope and deed the slope to the property owner. This requirement does not apply if the adversely affected property owner refuses either option in writing.

8. Grading is not permitted outside the grading limits of the approved grading plan.

C. Lot Size, Yards and Building Heights.

1. The lot size, yard and building height shall be:

a. As required by the hillside planned development permit;

b. As required by Chapter 15.88 PMC;

c. As necessary to provide access for emergency services;

d. As necessary to provide for maintenance of common or public open space and other public facilities or property.

2. Minimum requirements are specified in Chart A, “Hillside Development Standards, Lot Size, Yards and Building Heights.”

D. Transitional Design Between Different Land Uses. Transitional design must be provided between varying land uses to buffer development from impacts associated with locating different types of land uses on contiguous property lines. In this situation, development must take place in accordance with the following standards:

1. A six-foot solid masonry or concrete wall or other appropriate barrier may be required along the adjoining property line. A higher wall may be required in high noise areas.

2. Interior and rear yards are set forth under subsection (C) of this section.

3. Landscaping Requirements.

a. A tree screen of a species acceptable to the planning commission planted at eight-foot intervals or other spacing approved by the planning commission. The planning commission shall specify the height of trees but in no case may the height be less than six feet when planted.

b. Tree wells must be placed at the end of parking aisle sections and at 45 feet on center spacing.

E. Landscaping.

1. Each development must include a combination of landscaping consisting of intensely planted and maintained areas and open space preserved in its natural condition. The hillside planned development permit application must include the proposed planting and irrigation of newly created banks and slopes for erosion control and to minimize their visual impact.

2. Slopes adjacent to a collector or arterial street, except for front yards of residential units, must be completely landscaped and irrigated per a landscape plan approved by the director.

3. In a detached single-family residential subdivision, street trees must be planted along all streets at one per interior lot, two per corner lot, but not less than at 60-foot intervals. For all other development, street trees must be planted at a minimum of 30-foot intervals, and there must be at least 10 feet of landscaping between parking areas and public right-of-way.

4. A street tree must be not less than six feet in height as measured from ground surface after planting and must be a minimum of one inch in caliper as measured 30 inches above the base of the tree. A street tree must be planted outside a street right-of-way at a distance of not less than five feet nor more than 15 feet from the right-of-way line.

F. Landscape and Site Development. The yard along the public right-of-way, courts, and other open areas throughout the project and related to the building, the perimeter of the site and each parking area must be landscaped in accordance with a plan prepared by a licensed landscape architect and approved by the planning commission.

G. Maintenance.

1. A drip, bubbler, sprinkler or other approved irrigation system must be installed in all planted areas.

2. All planting must be maintained in a healthy, thriving and weed-free condition.

3. The total site area must be kept in a neat and orderly manner free of loose trash, debris or other litter.

4. Building exteriors, signs and other graphics must be kept in good state of repair and their exterior finish must be well maintained.

H. Trash.

1. Outdoor collection, storage or stacking of noncontained trash, junk and refuse is prohibited.

2. Each project (except single-family) must have a trash enclosure with walls of materials which are compatible in color, texture and appearance with the main structure. The enclosure must have opaque gates compatible in material which have an opening sufficient to permit removal and replacement of standard commercial size trash bins. The gates must be kept closed except when placing trash in the bins or when removing or replacing them. Bins must be kept inside trash enclosure at all times.

I. Lighting. Exterior lighting must be directed or shielded so as to prevent direct illumination onto roadways and so as not to spill onto adjacent properties.

J. Noise. Areas of significant potential noise generation (loading berths, truck parking areas, garbage and trash collection and storage areas, etc.) must be so designed that adjacent properties are not adversely affected by sound.

K. Common Areas. No final subdivision map and no parcel map may be approved until documents pertaining to the maintenance of the privately owned space and other facilities owned by or used in common by the owners within the development are approved by the city attorney.

L. Parking Standards. The number of parking spaces provided for a land use may not be less than that which the city finds is necessary for the intended use, and in no case less than as required in this section. The driveway for a residence must not be less than 20 feet in length measured from the backside of the sidewalk (back of the curb for streets without sidewalks) to the face of the garage or carport.

1. Single-Family Residential. Two covered parking spaces designated for exclusive use of the occupant. In addition, there must be room for two uncovered parking spaces in approved locations on the site. Open space parking, if provided, must be placed in groups of six or more spaces and the grouping may include parking within the street right-of-way, parking bay and small parking lot or any combination of these. Open space parking must be located within 200 feet of every dwelling unit.

2. Multifamily Residential.

a. Not less than two off-street parking spaces for each dwelling unit in any multifamily dwelling, plus one-half off-street parking space to be designated for guest parking for each dwelling unit having two or more bedrooms.

b. At least one covered vehicle parking space shall be provided for each dwelling unit.

c. All covered parking spaces must be of standard parking space dimensions.

d. Off-street parking is prohibited in a front or street side yard.

e. The construction of a carport along an interior property line is permitted if the height does not exceed eight feet as measured from the grade on the adjacent property and there is a landscape planter with minimum dimensions of 10 feet by 19 feet at intervals of 40 feet or less.

3. Neighborhood Commercial.

a. Retail sales: one parking space for each 250 square feet of floor area.

b. Bank and professional office: one parking space for each 250 square feet of floor area. For a medical clinic, one space for each 250 square feet of floor area.

c. Restaurant, places of public assembly such as church, theater: one parking space for each four seats.

d. The planning commission shall prescribe parking for uses not specifically listed. In determining the requirement, the planning commission shall use the requirements set forth in this section as a general guide.

M. Street Design.

1. General.

a. The design of streets in hillside areas must be consistent with the general plan, compatible with the natural topography, and adequate to serve the needs of the proposed development and emergency response vehicles.

b. All land uses other than single-family residential must have primary access from a collector or arterial street. Primary access to a neighborhood commercial land use must be from an arterial street. The city council may modify this requirement if it determines that modification is not detrimental to the health and safety of the general public.

c. Specific design standards must be in accordance with generally accepted engineering standards, Caltrans’ “Highway Design Manual” standards as set forth by the city engineer and the applicable provisions of this code and as modified by this chapter. Pavement must be designed for a minimum 20-year life with not less than three inches of asphalt concrete.

2. Right-of-Way Widths. The right-of-way width may not be less than specified in Chart 8, or as needed to provide for required sidewalks, trails, paths, bus turnouts, drainage facilities, utilities, landscaping and future widening when necessary. The right-of-way width should be kept to a minimum, consistent with present and future needs of the area.

3. Street Pavement Widths.

a. Street width must be minimized, consistent with public safety and anticipated primary use. Selection of an appropriate pavement width must consider probable peak traffic volume, parking needs and controls, probable vehicle speeds and limitations imposed by sight distances, terrain and maintenance needs.

b. Pavement width must include required or anticipated bus turnouts, bike lanes, street parking needs and medians. The travel lane for a collector and arterial street must be 12 feet and the travel lane for local or cul-de-sac street must be 10 feet. The parking lane for a collector and arterial street must be eight feet and the travel lane for local or cul-de-sac street must be seven feet.

c. Street widths may not be less than provided by Chart B.

4. Alignment. The alignment of a hillside arterial and collector street must conform to the general plan and the specific alignment of the hillside street master circulation plan as established by the city engineer and approved by the city council.

5. Turnarounds.

a. A turnaround must be provided for each dead-end street which will ultimately serve five or more units or which are longer than 200 feet when the end of the street is not visible or 400 feet when the end of the street is visible.

b. When the cul-de-sac exceeds 1,000 feet in length, the city engineer may require a midblock turnaround.

c. A turnaround must be circular in design except that the city may approve an alternate design for a private street. The minimum radius for a turnaround is 30 feet.

d. A temporary turnaround must be provided at the end of a stub street for future extension when the distance from the nearest intersection exceeds 200 feet and serves five or more units.

6. Street Lighting.

a. Residential and commercial street light poles shall be of an ornamental type as approved by the planning commission.

b. Street lighting intensity in residential areas must be designed for the minimum that will provide for public safety.

N. Storm Drain Design.

1. Hydrology calculations must be in accordance with the storm drain design standards established by Contra Costa County public works department, flood control division, and other standards as set forth by the city engineer.

2. Each HPD plan must include stormwater runoff system plans that anticipate and provide for the effects of runoff from existing and potential upstream development and the effects of the development on downstream properties.

3. The city engineer may require a permanent and temporary ponding or storage basin as an integral part of the proposed development.

O. Retaining Walls. A retaining wall greater than two feet in height or along public streets must be constructed of reinforced concrete or masonry. A retaining wall along a public street visible to the public must have an aesthetically pleasing design approved by the city. [Ord. 979 § 2 (Exh. A), 1990.]

18.56.100 Maintenance agreement(s).

The applicant must execute a maintenance agreement in a form as approved by the city council and recorded at the office of the Contra Costa County recorder for each hillside planned development permit. [Ord. 979 § 2 (Exh. A), 1990.]

18.56.110 Ridge preservation.

A. General.

1. Each ridge delineated on the hillside ridge preservation map, on file in the community development department, designated as “major ridge” shall be preserved in its natural state. The city may require the preservation of other ridges, designated on the ridge preservation map as “minor ridges.”

2. Ridge preservation standards must be as provided in this section and as set forth by the hillside planned development permit.

B. Ridge Setbacks.

1. No development may occur within 100 feet of the center of a ridge to be preserved, unless the city council, upon recommendation of the planning commission, and finding that a reduced setback will not adversely affect the preservation of the ridge, approves such development.

2. The highest elevation of any element of a structure must be at least 25 feet below the elevation of the ridgeline as measured perpendicular to the ridgeline. The city council may approve a reduction of the 25-foot standard upon recommendation of the planning commission and finding that a reduction will not adversely affect the preservation of the ridge.

C. Precise Ridge Location. The location of ridges delineated on the hillside ridge preservation map are approximate only. The precise locations are as delineated on the city’s aerial topographic maps, on file in the community development department.

D. Permitted Uses.

1. Subject to approval of the city council, the following may be permitted on or over ridges designated to be preserved:

a. Public roads and facilities;

b. Hiking and equestrian trails;

c. Underground utilities.

2. The city may impose special conditions on the development to mitigate potential visual impacts.

E. Development of Minor Ridges. On the development of minor ridges not required to be preserved in their natural state, the city may impose special design and landscaping requirements as a condition of the hillside planned development permit. [Ord. 979 § 2 (Exh. A), 1990.]


Code reviser’s note: For single-family development subsections (L) and (M) of this section may be deferred and submitted with building permit application.