§ 15.64

1. Private streets and roads may be permitted in subdivisions provided that they meet the minimum standards set forth in the typical cross sections for private roads for each zone as may be adopted by the board of supervisors by resolution.

2. An admonishment in substantially the following form shall be shown on the face of the final map or parcel map and included in deeds prior to recording for subdivisions in which lots or parcels are served by a private road:

• Lots or parcels 1, 2, 3, etc....are served by a private road. Maintenance of said road is not the responsibility of Glenn County. Owners of said lots or parcels are hereby advised that they and/or others are solely responsible for maintenance of this road .

3. The board of supervisors may refuse to accept any offer of dedication until such time as it is determined that the portion of the street or road dedicated serves a public purpose or the portion of the street or road no longer lies within property under one ownership and does not continue through such ownership or end touching property of another. The county will refuse to accept any private road until such time as the road has been constructed in accordance with current county road standards for the zone in which the road is located. (Ord. 1183 § 2, 2006)

15.64.090 Street Extensions The alignment of street extensions shall connect with existing streets by continuation of the centerlines or by adjustments by curves and shall be in general conformity with plans that the director determines to be the most advantageous development of the area in which the subdivision lies. (Ord. 1183 § 2, 2006)

15.64.100 Intersection Spacing

The location of streets shall be such that intersections are spaced not less than two hundred feet apart on secondary streets and five hundred feet apart on major streets. All streets shall be required to intersect one another at an angle as near to a right angle as is practicable in each case. “Tee” type intersections are preferred except at arterial intersections. (Ord. 1183 § 2, 2006)

15.64.110 Intersection Corner Roundings

On all street, road and highway intersections, the property line at each block corner shall be rounded with a curve having a radius of not less than twenty feet. In any case, a greater curve radius may be required if streets or alleys intersect other than at right angles. (Ord. 1183 § 2, 2006)

15.64.120 Typical Road Intersections

All other specifications for intersections shall be as shown on the standard drawings adopted by the board of supervisors. (Ord. 1183 § 2, 2006)

15.64.130 Horizontal Alignment

The centerline curve radius of all streets and highways shall conform to acceptable engineering standards of design as shown in the latest edition of the California Department of Transportation Highway Design Manual. Generally, horizontal curves shall be as long as practical. The use of compound curves and double reversing curves shall be held to a minimum. As far as practical, one hundred-foot tangents shall be provided between all curves on residential streets, with longer tangents of not less than safe stopping sight distance on major streets. (Ord. 1183 § 2, 2006)

15.64.140 Design Speed

All subdivision streets shall be designed to provide safe stopping sight distance, horizontal curve radii, and vertical curves for not less than the following speed shown for that particular street section and in accordance with the California Department of Transportation Design Manual, except for stop streets. Combinations of changes in grade and curve alignment shall be designed with greater than the minimum design as far as practical. The following shall apply:

(Ord. 1183 § 2, 2006)

15.64.150 Grades Of Streets And Highways

1. No street or highway shall have a grade of more than eight percent except where, because of topographical conditions or other exceptional conditions, the public works director may determine that a grade up to fifteen percent maximum may be allowed. No gutter grade shall be less than 0.3 percent where underground storm drainage systems are required. All others shall be not less than 0.2 percent unless approved by the public works director.

2. The grade within the intersection of streets shall not exceed four percent in the area bounded by the curb returns, except that the street anticipated to handle the major movement of traffic may exceed four percent but shall not be greater than the grade approaching the intersection. The grade of the turn around bulb at the end of cul-de-sac streets shall not exceed eight percent. (Ord. 1183 § 2, 2006)

15.64.160 Road Surfacing And Structural Section

1. Structural sections of all streets and roads shall be designed based on R-values determined by California Test Method No. 301 of the soil within the roadway and in accordance with Section 600 of the Highway Design Manual.

2. R-value tests for structural pavement design shall be taken within the soil to be used for the subgrade or at the designated source of selected material. A soil inventory consisting of location and R- value tests of various soils to be used within the designed structural section shall be provided unless the plans specify that the thickness of the elements of structural pavement shall be determined by R-value tests to be performed after rough subgrade is completed. The locations and number of samples of soil taken for R-value tests on rough subgrade shall be determined by the public works director.

e tests of various soils to be used within the designed structural section shall be provided unless the plans specify that the thickness of the elements of structural pavement shall be determined by R-value tests to be performed after rough subgrade is completed. The locations and number of samples of soil taken for R-value tests on rough subgrade shall be determined by the public works director.

3. Upon request of the applicant, the public works director may assign the structural section or R-value to be used for design in areas of consistent soils, provided that adequate information is available as to the properties of such soil.

4. The traffic index may be determined by using the Highway Design Manual together with a traffic study of the area contributing truck traffic loads to such streets. If ultimate street development pattern is not known and streets can be extended, the traffic index shall be as follows:

   1. Cul-de-sac and loop streets shall be a minimum of 4.5;

   2. Local streets shall be a minimum of 5.0;

   3. Residential collector streets shall be a minimum of 5.5;

   4. Major or primary collector streets shall be a minimum of 6.0;

   5. Farm to market roads in agricultural zoned areas shall be a minimum of 7.0;

   6. Commercial roads shall be a minimum of 8.0;

   7. County highways shall be a minimum of 9.0;

   8. The above traffic indexes shall be increased to reflect commercial and industrial truck traffic loading.

5. The minimum structural thickness of all new roads and streets or those roads and streets to be reconstructed shall be as shown on the standard drawings adopted by the board of supervisors unless otherwise approved by the public works director.

6. Where asphalt concrete (AC) is used it shall be type B one-half maximum (medium). Class 2 Aggregate Base (AB) and Class 1 Imported Aggregate Subbase (ASB) shall be used in street construction except that select material may be used in place of Class 2 Aggregate Base and Class A Imported Aggregate Sub-base provided the following requirements are met:

   1. The R-value of select material in place shall determine the thickness of asphaltic concrete in accordance with the “Pavement Design Chart” shown in the Highway Design Manual, with the addition of ten percent as a safety factor. The minimum thickness of asphaltic concrete shall be 0.20 foot;

   2. The sand equivalent shall exceed twenty-five;

   3. Ten percent or 0.17 foot, whichever is greatest, shall be added to the thickness determined for select material as a safety factor;

   4. The top 0.34 foot of select material shall be screened to remove oversized aggregate larger than 2 inches;

   5. The particle interlock shall provide a firm working table. (Ord. 1183 § 2, 2006)

1. Improvements. The applicant shall improve side slopes for functional effectiveness, and pleasing appearance. Planting of vegetation may be required to prevent erosion.

2. Cut and fill. Cut slopes for subdivision streets shall be one and one-half to one and fill slopes shall be two to one. Flatter slopes shall be used in soils susceptible to erosion. Steeper cut slopes will be considered in special situations, such as in solid material, if approved by the public works director. Cut slopes steeper than one to one that are higher than ten feet will be considered only if submitted with a report from an engineering firm based on an analysis of soil borings or excavations determining that such cut bank will be stable and not lead to structural defects to dwellings constructed on adjacent lots.

3. Catch Point. In light grading where the normal slopes catch in a distance less than ten feet from the hinge point, a uniform catch point is to be used to provide flatter slopes. Transition slopes shall be provided between adjacent cuts and fills. Such slopes shall intersect the ground at a catch point ten feet from the hinge point.

4. Slope Roundings. The tip of all slopes shall be rounded. Where material cut is solid rock, only the layer of earth overlaying the rock shall be rounded. 5. Slope Benches. Width and vertical spacing shall be established from adequate soils investigation. Benches may be used in unstable material and to intercept and store loose material resulting from minor slides. Sufficient width shall be provided for maintenance and drainage control.

5. Special Slope Treatment. When it is desirable to retain certain natural features such as trees or natural banks within the side slope, the size, location and elevation shall be shown on the improvement plans. Cut and fill slopes shall be designed to retain such features. Retaining walls may be required. (Ord. 1183 § 2, 2006)

15.64.180 Concrete Curbs Vertical concrete curb or roll-type concrete curb and gutter shall be constructed by the applicant in accordance with the specifications set forth in the standard drawings adopted by the board of supervisors on all streets where any abutting lots have an area of twenty thousand square feet or less or a frontage of less than one hundred five feet and on all streets in areas zoned for commercial, industrial, or multiple residential uses. They may also be required by the director if the streets are located within one-half mile of any incorporated city. They may be constructed on any street on which the applicant elects to construct such curbs and gutters. The construction of concrete curb and gutter may be deferred by the public works director pursuant to the procedure set forth in subsection (B) (5) of Section 15.64.040. (Ord. 1183 § 2, 2006) 15.64.190 Sidewalks Concrete sidewalks shall be constructed by the applicant in accordance with the specifications set forth in the standard drawings adopted by the board of supervisors in areas zoned for commercial or multiple residential uses and in areas zoned for single-family or two-family residential use where any of the lots contain ten thousand square feet or less. They may be required by the director if the sidewalks are to be located within one-half mile of any incorporated city. Sidewalks may be constructed on any other street at the option of the applicant. The construction of sidewalks may be deferred by the public works director pursuant to the procedures set forth in subsection (B) (5) of Section 15.64.040. (Ord. 1183 § 2, 2006) 15.64.200 Utilities

1. The location of utilities within subdivision street rights-of-way, either above ground or below ground, shall be in accordance with the specifications set forth in the standard drawings adopted by the board of supervisors unless an alternative location is approved by the public works director. Utilities shall be underground wherever practical.

2. The minimum depth of underground conduits, with the exception of appurtenances designed for surface loads such as manholes, valve boxes, and electrical vaults, shall be thirty inches. Where location of electrical cables for power, community television, and telephone are located under portland cement concrete sidewalks, a minimum depth of eighteen inches may be permitted. (Ord. 1183 § 2, 2006) 15.64.210 Road Names Roads which are extensions of or are determined to be in future alignment with existing named roads shall bear the name of the existing road. Naming of new subdivision roads shall be subject to the approval of the planning commission and shall not duplicate or be similar to any other road in the county. (Ord. 1183 § 2, 2006) 15.65 Drainage 15.65.010 General Requirement 15.65.020 Easements 15.65.030 Drainage Systems 15.65.040 Channels 15.65.050 Discharge Of Water From Subdivisions 15.65.060 Valley Gutters 15.65.070 Deviations 15.65.010 General Requirement

vision roads shall be subject to the approval of the planning commission and shall not duplicate or be similar to any other road in the county. (Ord. 1183 § 2, 2006) 15.65 Drainage 15.65.010 General Requirement 15.65.020 Easements 15.65.030 Drainage Systems 15.65.040 Channels 15.65.050 Discharge Of Water From Subdivisions 15.65.060 Valley Gutters 15.65.070 Deviations 15.65.010 General Requirement

All subdivisions shall be protected from flood hazard and inundation by storm waters originating without and within the proposed subdivision. The design and construction of drainage facilities shall be such that water courses traversing the subdivision and water emanating from within the subdivision will be carried through and off the subdivision without injury to improvements, residential sites, or adjacent properties. Drainage waters shall not be discharged onto existing county rights-of-way except in manner approved by the public works director. All proposed subdivisions, whether or not they front on existing county rights-of-way, shall meet the minimum requirements of this chapter. (Ord. 1183 § 2, 2006)

• 15.65.020 Easements 1. Drainage facilities shall be located in a dedicated public street, road or lane, or within a public drainage easement. Necessary dedications shall be accomplished on the parcel or final map or by grant deed. The county shall not accept the maintenance of drainage facilities which are not located in a public right-of-way. Dual use of easements shall not be approved unless it can be demonstrated to the satisfaction of the public works director that dual use will not be conflicting.

• 2. The minimum width of any drainage easement for a closed conduit system shall be twelve feet and the minimum width for any open conduit system shall be twenty feet. For any conduit exceeding thirty inches in diameter, with more than one manhole or more than one turning structure, a twelve-foot width service road shall be improved and dedicated. (Ord. 1183 § 2, 2006)

• 15.65.030 Drainage Systems 1. Drainage systems and all bridges shall be designed to pass a one hundred-year frequency flood without damage to the structure or adjacent property, except that drainage systems draining an area smaller than one square mile may be designed for ten-year frequency floods if ponding due to the one hundred-year flood will not cause damage.

• 2. Drainage systems under driveway entrances shall be adequate to carry the design flow but shall not have less than a twelve-inch inside diameter. The minimum slope shall be one percent where practical. Drainage systems crossing streets shall be of a size adequate to carry the design flow but shall not have less than a fifteen inch inside diameter for concrete and an eighteen-inch inside diameter for C.M.P. Drainage systems for use outside the public right-of-way may be of any approved type and strength to meet field conditions, but shall not have less than a twelve-inch diameter. All pipe in the right-of-way shall be designed to standard H-20 live load and shall have a design life of twenty-five years.

than a fifteen inch inside diameter for concrete and an eighteen-inch inside diameter for C.M.P. Drainage systems for use outside the public right-of-way may be of any approved type and strength to meet field conditions, but shall not have less than a twelve-inch diameter. All pipe in the right-of-way shall be designed to standard H-20 live load and shall have a design life of twenty-five years.

• 3. Debris control, location and slope of culverts, entrances and endwalls, shall be in accordance with the recommendations of “California Culvert Practice.” (Ord. 1183 § 2, 2006)

• 15.65.040 Channels

  1. Drainage facilities shall be located in a dedicated public street, road or lane, or within a public drainage easement. Necessary dedications shall be accomplished on the parcel or final map or by grant deed. The county shall not accept the maintenance of drainage facilities which are not located in a public right-of-way. Dual use of easements shall not be approved unless it can be demonstrated to the satisfaction of the public works director that dual use will not be conflicting.

  2. Drainage systems and all bridges shall be designed to pass a one hundred-year frequency flood without damage to the structure or adjacent property, except that drainage systems draining an area smaller than one square mile may be designed for ten-year frequency floods if ponding due to the one hundred-year flood will not cause damage.

  3. Drainage systems under driveway entrances shall be adequate to carry the design flow but shall not have less than a twelve-inch inside diameter. The minimum slope shall be one percent where practical. Drainage systems crossing streets shall be of a size adequate to carry the design flow but shall not have less than a fifteen inch inside diameter for concrete and an eighteen-inch inside diameter for C.M.P. Drainage systems for use outside the public right-of-way may be of any approved type and strength to meet field conditions, but shall not have less than a twelve-inch diameter. All pipe in the right-of-way shall be designed to standard H-20 live load and shall have a design life of twenty-five years.

  4. All open ditches having a top width of ten feet or more shall be designed in an easement wide enough to allow motor vehicles on one side of the open ditch. The access shall be at least ten feet wide. This requirement may be waived by the public works director when, in his or her opinion, access will not be needed for future maintenance and when, in the opinion of the health officer, access is not needed for mosquito control.

  5. New unlined drainage facilities or relocated natural drains may not be installed closer than fifty feet to existing or proposed leach lines. The gradient for earth ditches shall not exceed 4 percent nor be less than 0.1 percent. Earth ditches shall not be permitted if water therein could reach erosive velocities. The gradient for lined or paved ditches and gutters shall be not less than 0.20 percent, unless specific written approval is granted by the public works director. (Ord. 1269 § 10, 2018; Ord. 1183 § 2, 2006)

15.65.050 Discharge Of Water From Subdivisions

Whenever water is discharged from a subdivision where the method of discharge or the quantity has been changed, a “Drainage Release”, approved by the county counsel, shall be filed with the public works director prior to approval of the construction plans. (Ord. 1183 § 2, 2006)