Sonoma Municipal Code Ch. 16.03 Subdivision Design and Improvement Requirements

This chapter establishes standards for the design and layout of subdivisions, and the design, construction or installation of public improvements within subdivisions. The purpose of these standards is to ensure, through careful site evaluation and design, the creation of new usable parcels that are consistent with the General Plan and any applicable specific plan. (Ord. 06-2022 § 1, 2022).

The requirements of this chapter apply to subdivisions, and conditional certificates of compliance, in addition to all applicable requirements of the development code, as follows:

A. Extent of Required Improvements. All subdivisions shall provide the improvements required by this chapter, and any additional improvements required by conditions of approval.

B. Applicable Design Standards – Timing of Installation. The subdivider shall construct all on- and off-site improvements according to standards approved by the city engineer. No final or parcel map shall be presented to the council or parcel map to the city engineer for approval until the subdivider either completes the required improvements, or enters into an agreement with the city for the work, except as provided in SMC 19.03.030(A)(2).

C. Subdivision Improvement Standards – Conditions of Tentative Map Approval. The applicable subdivision improvement and dedication requirements of this chapter and any other improvements and dedications required by the review authority in compliance with SMC 16.04.070, Tentative map approval or disapproval, shall be described in conditions of approval adopted for each approved tentative map (SMC 16.04.080). The design, construction or installation of all subdivision improvements shall comply with the requirements of the city engineer.

D. Conflicting Provisions. In the event of any conflict between the provisions of this chapter and other provisions of the development code, or other provisions of the municipal code, the most restrictive provisions shall control. In the event of any conflict between the provisions of this chapter and the Map Act, the Map Act shall control.

E. Extent of Improvements Required – Four or Fewer Parcels. As required by Map Act Section 66411.1, improvements required for subdivisions of four or fewer parcels shall be limited to the dedication of rights-of-way, easements, and the construction of reasonable off-site and on-site improvements for the parcels being created.

F. Oversizing of Improvements. At the discretion of the review authority, improvements required to be installed by the subdivider for the benefit of the subdivision may also be required to provide supplemental size, capacity, number, or length for the benefit of property not within the subdivision, and may be required to be dedicated to the city, in compliance with Article 6, Chapter 4 of the Map Act. In the event that oversizing is required, the city shall comply with all applicable provisions of Map Act Section 66485 et seq., including the reimbursement provisions of Map Act Section 66486.

G. Exceptions. Exceptions to the provisions of this chapter may be requested and considered in compliance with SMC 16.02.050, Exceptions to subdivision standards. (Ord. 06-2022 § 1, 2022).

Proposed subdivisions shall be designed to provide adequate access from each new parcel to a city street, in compliance with this section, and with the requirements of SMC Title 19, Division II, Community Design.

A. General Access and Circulation Requirements. The subdivider shall provide a comprehensive street system, designed and constructed in compliance with this section, the city’s improvement standards, and with the Circulation Element of the General Plan.

1. Street design shall provide for safe vehicular operation at a specified design speed.

2. Public streets shall be required when:

a. The street is shown as an arterial or collector in the Circulation Element of the General Plan, or any other specific or precise plan;

b. The street will be used by the general public as a through access route;

c. A public street is necessary for special needs including bus routes, public service access, bicycle routes and pedestrian access; or

d. When necessary to assure fire safety.

Private streets are allowed only in compliance with subsection (F) of this section.

B. Alternative Standards. The review authority may consider and approve proposed access and street design solutions that differ from the provisions of this section, and the city’s improvement standards where deemed necessary to properly address the characteristics of adjacent land uses and/or anticipated traffic volumes, or to maintain neighborhood character. The use of alternative standards shall be authorized through the exception procedure in SMC 16.02.050.

C. Access to Subdivision. Every subdivision shall be designed to have access to a city street. Access shall be provided by:

1. The subdivision abutting a city street, where the length of the subdivision along the street, the street right-of-way, and the width of the right-of-way will accommodate the construction of all road improvements required by this section; or

2. The subdivision being connected to a city street by a nonexclusive right-of-way easement for street, utility, and appurtenant drainage facilities purposes, where the easement shall be:

a. Offered for dedication;

b. Unencumbered by any senior rights that might serve to restrict its proposed use; and

c. Of a width and location to accommodate the construction of all improvements required by this section and the city’s improvement standards.

D. Access to New Parcels. Parcels within a proposed subdivision shall be provided access as follows:

1. City Street Access Required. Each parcel within a proposed subdivision shall be provided access by being located on an existing city street or a new city street designed and improved in compliance with subsection (C) of this section, or to a private street if allowed by subsection (F) of this section.

2. Access Denial. When a state highway or a street classified as a major arterial in the Circulation Element of the General Plan passes through or abuts a proposed subdivision, direct access to the highway or arterial shall not be permitted from proposed parcels. Reservation strips shall be dedicated to the state or city, as appropriate, where required to control access over certain lot lines over the ends of street stubs.

3. Frontage Roads. When lots are proposed to front on a major arterial or state highway, the review authority may require the subdivider to dedicate and improve a service or frontage road separate from the arterial or highway.

4. Alleys. Alleys may be proposed as part of residential and nonresidential subdivisions. The use of alleys shall be subject to the review and approval of the planning commission.

E. Design and Improvement of Proposed Streets. New streets proposed or required within a new subdivision or adjacent to a new subdivision shall be located and designed as follows, and in compliance with the city’s improvement standards:

1. Alignment, Intersections, Curves. The alignment of streets shown on a tentative map shall be:

a. Consistent with the Circulation Element of the General Plan and SMC Title 19, Division II, where applicable;

b. Located to be in alignment with existing adjacent streets by continuation of their centerlines, or by adjustments by curves; and

c. Located so that all streets intersect at an angle as near to 90 degrees as feasible.

The centerline curve radii of all proposed streets shall be subject to approval by the city engineer.

2. Right-of-Way and Surfaced Width. The width of the right-of-way and improved surface of streets shown on a tentative map shall be as generally provided by Chapter 19.12 SMC, Streetscape, except where other standards are approved by the council.

3. Corners. All block corners and “T” alley intersections shall be rounded or cut off as approved by the city engineer.

4. Access to Unsubdivided Property. When a proposed subdivision abuts vacant land that is designated by the General Plan for future subdivision and development, the review authority may require that streets to be constructed with the proposed subdivision be extended to the boundary of the property to provide access to the future development.

5. Improvements to Existing Streets. When an existing city street provides access to, passes through, or is contiguous with a proposed subdivision, the review authority may require dedication of additional right-of-way and/or improvements in compliance with the General Plan, if it determines that the proposed subdivision will create the need for the improvements.

6. Curbs and Sidewalks. Concrete curbs and sidewalks shall be constructed upon all streets in compliance with the city’s improvement standards and specifications unless specifically waived in the conditions of approval. The location of sidewalks shall conform to that of adjacent areas and shall be at the discretion of the review authority.

F. Private Roads. Private roads are allowed as provided in this section. Private roads shall not be permitted except where the planning commission determines that a private street system will adequately serve the proposed subdivision, will not be a substantial detriment to adjoining properties and will not disrupt or prevent the establishment of an orderly circulation system in the vicinity of the subdivision.

1. Maintenance Requirements. Provisions satisfactory to the city engineer and city attorney shall be made for lot owners association or other organization to assume responsibility for the maintenance of private roads and ownership of the street rights-of-way of any subdivision.

2. Design and Improvement Standards. Private roads shall be designed and improved as set forth in subsections (B) and (C) of this section.

3. Security and Conditions. The review authority may require any guarantees and conditions it deems necessary to carry out the provisions of the development code pertaining to private roads. Private roads and easements providing access to parcels within a subdivision shall be located and shown on the parcel or final map.

4. Offer of Dedication. The review authority may require that proposed private roads be subject to irrevocable offers of dedication to the city on the applicable parcel or final map, or separate instrument submitted to the city along with the parcel or final map.

G. Alternative Circulation Systems. Proposed subdivisions shall be designed to provide rights-of-way for pedestrian paths, bikeways and multiple use trails consistent with the Circulation Element of the General Plan, and/or other applicable General Plan provisions. (Ord. 06-2022 § 1, 2022).

The design of a subdivision for which a tentative and final map are required by this title shall provide, to the extent feasible, for future passive or natural heating or cooling opportunities in the subdivisions, in compliance with Map Act Section 66473.1. (Ord. 06-2022 § 1, 2022).

The subdivider shall install fire hydrants at locations approved by the fire chief. Fire hydrants shall be constructed per applicable city standard plans. (Ord. 06-2022 § 1, 2022).

New subdivisions shall be designed so that all proposed grading incorporates appropriate erosion and sediment control measures as approved by the city engineer. (Ord. 06-2022 § 1, 2022).

A. Landscaping Requirements. Landscaping shall be provided as follows, and in compliance with Chapter 19.12 SMC, Streetscape, and SMC 19.40.060, Landscape standards, where applicable.

B. Deferral of Installation. The installation of required landscaping may be deferred until the development of the subdivided lots through the provisions of SMC 16.11.040, Improvement agreements and security; provided, that interim erosion and sediment control measures are first installed in compliance with SMC 16.03.060, Grading, erosion and sediment control. (Ord. 06-2022 § 1, 2022).

The subdivider shall install monuments in compliance with Chapter 16.12 SMC, Surveys and Monuments, and the Map Act. (Ord. 06-2022 § 1, 2022).

The size, shape and arrangement of proposed parcels shall comply with this section, and with Chapter 19.14 SMC, Block Structure, and with any applicable specific plan requirement, other development code provision, or other municipal code provision applicable to a proposed subdivision.

A. Parcel Area. The minimum area for new parcels shall be as required by SMC Title 19, Division II, Community Design, except as otherwise provided by this section.

B. Minimum Lot Area Requirements for Common Interest Projects. The minimum lot area requirements of SMC Title 19, Division II, shall not apply to condominiums and condominium conversions, planned developments, townhouses, zero lot-line, and similar projects, but shall apply to the creation of the original parcel or parcels that are the location of the common interest development.

C. Dimensions. The dimensions of new parcels and blocks shall comply with the applicable provisions of SMC Title 19, Division II, Community Design, or as otherwise required by the review authority.

D. Driveway Standards. Proposed parcels shall be designed to accommodate driveways designed in compliance with SMC 19.12.040, Private road and driveway standards. (Ord. 06-2022 § 1, 2022).

Each approved parcel shall be provided connections to public utilities, including electricity, gas, water, sewer, and telecommunications services, which shall be installed as part of the subdivision improvements as provided by this section, and by SMC 16.03.110, Sewage disposal, and SMC 16.03.150, Water supply.

A. Underground Utilities Required. Utilities in new subdivisions shall be installed underground, as follows. These requirements do not apply to utility lines which do not serve the area being subdivided.

1. When Undergrounding Is Required. All existing and proposed utility distribution facilities (including electric, telecommunications and cable television lines) installed in and for the purpose of supplying service to any subdivision shall be installed underground. Equipment appurtenant to underground facilities, including surface-mounted transformers, pedestal-mounted terminal boxes and meter cabinets, and concealed ducts, shall also be underground, unless otherwise approved by the city engineer.

The subdivider is responsible for complying with the requirements of this section and shall make the necessary arrangements with the affected utility companies for facility installation. The review authority may waive the requirements of this section if topographical, soil, or any other conditions make underground installation unreasonable or impractical.

2. Location of Installation. Underground utility lines may be installed within street rights-of-way or along a lot line, subject to appropriate easements being provided if necessary. When installed within street rights-of-way, their location and method of installation, insofar as it affects other improvements within the street right-of-way, shall be subject to the approval of the city engineer.

B. Utility Easements.

1. Minimum Width. The minimum width of easements for public or private utilities, sanitary sewers, or water distribution systems shall be determined by the review authority based on the recommendations of the city engineer for city facilities, and the recommendations of the applicable utility company, for public or private utilities.

2. Overhead Lines. When overhead utility lines are approved by the review authority, easements shall be located at the rear of lots where practical, and along the side of lots where necessary. Where practical, the poles supporting overhead lines shall not be installed within any street, alley, or easement designated exclusively for drainage purposes.

C. Timing of Installation. All underground utilities, water lines, sanitary sewers, and storm drains installed in streets shall be constructed before the streets are surfaced. Connections to all underground utilities, water lines, and sanitary sewers shall be laid to sufficient lengths to avoid the need for disturbing the street improvements when service connections are made. (Ord. 06-2022 § 1, 2022).

Each parcel within an approved subdivision shall be provided a connection to the Sonoma Valley County sanitation district’s sewage collection, treatment, and disposal system, in compliance with the district’s improvement standards and specifications. (Ord. 06-2022 § 1, 2022).

All proposed subdivisions shall provide street lighting facilities designed and constructed in compliance with the city’s improvement standards and specifications. (Ord. 06-2022 § 1, 2022).

A. Street Name Requirements. All streets within a proposed subdivision shall be named, and the names shall be approved by the review authority. Duplication of existing names within the same area shall not be allowed in a new subdivision unless the street is an obvious extension of an existing street.

B. Street Name Signs. The subdivider shall provide a minimum of two street name signs in compliance with the city’s improvement standards and specifications at each street intersection. The signs shall be located on the diagonally opposite sides of the intersection. One street name sign shall be provided at each “T” intersection. (Ord. 06-2022 § 1, 2022).

Stormwater runoff from the subdivision shall be collected and conveyed by an approved storm drain system. The storm drain system shall be designed for ultimate development of the drainage area. The storm drain system shall provide for the protection of abutting and off-site properties that would be adversely affected by any increase in runoff attributed to the development, including natural channel morphology that may be modified as a result of increased stormwater runoff from the subdivision; off-site storm drain improvements including stormwater runoff detention and/or infiltration may be required to satisfy this requirement. Any easement for drainage or flood control shall be improved as specified by the city engineer. All storm drainage facilities shall be designed in accordance with the Sonoma County water agency “flood control design criteria.” (Ord. 06-2022 § 1, 2022).

Each approved parcel shall be served by the city’s water system. (Ord. 06-2022 § 1, 2022).