§ 25-44. General requirements.
(a)
The subdivider shall provide sufficient easements or construction, or both, to provide adequate capacity for storm drainage, ensure reasonable channel stability, and provide adequate access for maintenance.
(b)
The construction and maintenance of wells and individual sewage disposal systems shall meet the applicable standards or ordinances of the county.
(c)
All deed restrictions shall run with the land and be enforceable by any owners of property lying within the subdivision.
(d)
In all respects, the subdivision will be considered in relation to the master plan of the county or preliminary plans made in anticipation thereof.
(e)
In all cases, the planning commission shall suggest to the subdivider such measures as will preserve and enhance the scenic values of the county and the conditions making for excellence of residential, commercial or industrial development.
(f)
Failure of the subdivider to make adequate provision for required streets, highways, schools, drainage, and other planned public facilities, shall be reason to disapprove the tentative map.
(g)
Where technical changes occur within the zoning regulations creating land use standards accommodating innovative planning concepts, such as cluster subdivisions, row housing, condominium, scenic easements, open space plans, and mobile home park subdivisions, they shall be considered as a supplement to this chapter.
(h)
Repealed.
(i)
Where projects are determined to warrant further geological investigation, a geologist's report shall be required which summarizes and illustrates the following categories:
(1)
Areas where standard foundation and other conventional construction techniques are satisfactory;
(2)
Areas where geological hazards may exist but which in the opinion of the geologist can be mitigated, i.e., foundation design;
(3)
Areas where geologic suitability is uncertain without additional geotechnical and/or subsurface investigation.
(j)
(1)
In areas such as ridges, hilltops, and other key areas judged to be extremely exposed from public roads or other critically visible offsite locations, development shall be prohibited unless adequate mitigation measures are available. In areas of eroding slopes and near drainage ways, development shall be prohibited unless adequate mitigating measures are available.
(2)
Grading for development (building pads, leachfield areas, driveways) shall maximize retention of natural land forms such as rolling hills, ridgetops, areas of extensive vegetation and water courses. Grading shall not produce large flat planes or sharp angles or intersection with the natural terrain. Slopes shall be rounded and contoured to blend with existing terrain. Extensive terracing shall be prohibited.
(3)
Development shall be encouraged to use the form of the land and vegetation to insure separation of building areas and minimal exposure from roads and other building areas.
(4)
The solar exposure of building sites should allow for, at the minimum, basic passive solar heating and cooling design elements consistent with other applicable standards.
(5)
The use of plantings (generally trees) consistent and compatible with those of the area may be required to mitigate the extent of exposure of the development area in conjunction with land forms, existing vegetation and other features. Screening required for shielding of development areas (not necessarily the immediate house site) shall consist of natural materials of the area, preferably using natural vegetation or land form modification similar in form to the natural terrain.
(6)
Developments exceeding a total of fifty (50) lots and with a density greater than one (1) dwelling unit per acre may:
(a)
Provide on-site open space areas for active and passive recreation (active defined as spaces for field and group activities such as football, soccer, baseball, tot lots, playgrounds, etc; passive defined as areas used for sitting, walking, and project form). Said areas, where applicable, may be used for storm water retention, recharge areas, project form, or other multiple uses. Need and size of such areas shall be determined by the planning director taking into account number of units, size and shape of site, drainage, information derived from an EIR, environmental reconnaissance, or other documentation or site characteristics;
(b)
Where a recreation agency (district, department, etc.) exists, a dedication of land in lieu of developing project related recreational facilities may be approved by PRAC, such approval shall be based on the following:
(i)
Dedication shall consist of a minimum of 400 square feet per lot,
(ii)
There shall be a demonstrated lack of need for additional recreational facilities at the time of development of the proposed project.
(7)
Projects shall be analyzed for their relationship to the general plan open space plan and specific plan open space plans, and, where necessary, any adverse impacts mitigated.
(8)
Building envelopes and building setback lines may be required by PRAC to achieve consistency with the standards listed in subsections (j)(1) through (j)(9) of this section.
(9)
All roads shall be sited in conformity with subsections (j)(1), (j)(2), (j)(3) and (j)(5) cited above.
(k)
(1)
Projects consisting of ten (10) lots or more shall provide a minimum of two thousand (2,000) gallons storage per lot either in the form of a pressurized distribution system with storage, said storage at the building site, or centralized storage equipped to accommodate emergency equipment. In any method used, water flow rates shall be five hundred (500) g.p.m.. Total storage need not exceed forty thousand (40,000) gallons plus daily flow. Storage may consist not only in tanks but also in ponds, lakes, pools, etc., which are accessible for use by emergency equipment.
(2)
For projects consisting of ten (10) lots or fewer, PRAC, after consultation with the local fire district/California Department of Forestry (CDF), may require a note placed on the parcel map/final map stating that a minimum of two thousand (2,000) gallon storage facility for fire protection shall be required at the time of building permit issuance for new dwellings.
(3)
A fire management plan shall be prepared and submitted with the subdivision application that includes (but is not limited to) identification of fire hazards on the site, the development's relationship to these constraints, necessary protection measures, and provision for maintenance of any water system for the project.
(4)
Where projects are proposing a "tie-in" with existing public or mutual water systems, the storage requirement may be adjusted based on the capability and/or storage capacity of the existing system.
(5)
A design for the cleared area at the building site for a two hundred thirty-six inch (236″) wheelbase vehicle shall be required to insure adequate emergency vehicle circulation.
(6)
Access for fire protection purposes shall be provided consistent with Section 25-17(j); where deemed necessary by PRAC, additional emergency access may be required. The extent and improvement of same shall depend on the circumstances of each case as deemed necessary by PRAC in consultation with the local fire district or California Department of Forestry.
(l)
(1)
Development and creation of impervious surfaces in a natural recharge area shall be subject to soils investigation and mitigation of potential recharge reduction. Should adequate mitigation not be possible, the project shall be denied.
(2)
In order to reduce the offsite peak storm flow generated by projects with a density greater than one (1) dwelling unit per acre, retention ponds, drainage swales, or the use of check dams shall be utilized where deemed necessary by PRAC based on density, size of site, shape of site, and topography.
(3)
Drainage improvements for runoff from all roadways and other impervious surfaces shall be engineered to minimize erosion through the use of rocked culvert inlets and outfalls, energy reducers, proper location of culverts, reseeding of exposed slopes, and minimizing the use of artificial slopes.
(m)
Development allowed under the general plan in designated resource areas shall be permitted subject to the following design/siting requirements.
(1)
Design of projects shall recognize the environmental and resource characteristics of the site and be designed in such a manner which allows for the preservation and continued production of the particular resource.
(2)
Design of projects in resource areas shall utilize the least productive portion of the site, leaving the productive areas intact where possible. The design of projects shall be consistent with other applicable development standards.
(3)
Development shall not adversely affect the natural course or riparian habitat of any stream. Mitigation measures shall be required of the project where development may result in impacts to such areas.
(4)
Development shall not adversely affect tidal marshes, freshwater marshes, estuaries or marine waters. Impacts upon these areas by a project shall be mitigated.
(5)
Development shall not adversely affect areas identified as significant wildlife habitat, and impacts upon these areas by a project shall be mitigated.
(6)
Extensive changes or removal of vegetation shall demonstrate minimal adverse impacts on micro-climate conditions. Erosion protection and revegetation shall be required in all cases of vegetation removal.
(7)
Whenever there is reason to suspect significant archaeological or paleontological sites (as noted in the initial study process) within the project area, an appropriate survey by qualified professionals shall be required as part of any environmental review and suggested mitigation measures implemented prior to development of the site.
(8)
Development shall not adversely affect the existing volume of any water body, substantially increase chemical or nutrient pollution, or otherwise contribute to the deterioration of the quality and quantity of water in any water body.
(n)
(1)
Utility lines shall be placed underground on projects with a density greater than one (1) unit/three (3) acres; PRAC, after consideration of the visual characteristics of the project site and development plan, may require undergrounding for projects with a density between one (1) unit/three (3) acres to one (1) unit/fifteen (15) acres; projects with a density less than one (1) unit/fifteen (15) acres shall not require undergrounding. Undergrounding shall be in accordance with the rules of public utility and State Public Utilities Commission.
(2)
Where new main utility lines are required, these lines and service lines to the building areas shall be undergrounded where densities require undergrounding; where main lines already exist, only service lines to the building areas shall be undergrounded.
(o)
Projects shall be designed to minimize the destruction of protected trees. With development permits, a site plan shall be submitted that depicts the location of all protected trees greater than nine (9) inches and their protected perimeters in areas that will be impacted by the proposed development, such as the building envelopes, access roads, leachfields, etc. Lot line adjustments, zoning permits and agricultural uses are exempt from this requirement. The provisions of this section shall not apply to trees which are the subject of a valid timber harvesting permit approved by the state of California. This section shall not be applied in a manner that would reduce allowable density lower than that permitted as a result of C.E.Q.A. or by other county ordinances or render a property undevelopable. To achieve this end, adjustments may be made.
Agricultural uses exempt from the tree protection ordinance are as follows: The raising, feeding, maintaining, and breeding of poultry, fowl, rabbits, fur-bearing animals, and the like, for other than domestic purposes, commercial hog and pig farming, dairies, commercial aquaculture, commercial mushroom farming, wholesale nurseries, greenhouses, wineries and agricultural cultivation.
CONSTRUCTION STANDARDS
Applicants are encouraged to use a qualified specialist to establish tree protection methods.
1.
Protected trees, their protected perimeters and whether they are to be retained or removed are to be clearly shown on all improvement plans that construction is subject to requirements established by Sonoma County to protect certain trees.
2.
Before the start of any clearing, excavation, construction or other work on the site, every tree designated for protection on the approved site plan shall be clearly delineated with a substantial barrier (steel posts and barbed wire or chain link fencing) at the protected perimeter, or limits established during the permit process. The delineation markers shall remain in place for the duration of all work. All trees to be removed shall be clearly marked. A scheme shall be established for the removal and disposal of brush, earth and other debris as to avoid injury to any protected tree.
3.
Where proposed development or other site work must encroach upon the protected perimeter of a protected tree, special measures shall be incorporated to allow the roots to obtain oxygen, water and nutrients. Tree wells or other techniques may be used where advisable. No changes in existing ground level shall occur within the protected perimeter unless a drainage and aeration scheme approved by a certified arborist is utilized. No burning or use of equipment with an open flame shall occur near or within the protected perimeter (except for authorized controlled burns).
4.
No storage or dumping of oil, gasoline, chemicals, or other substances that may be harmful to trees shall occur within the drip line of any tree, or any other location on the site from which such substances might enter the drip line.
5.
If any damage to a protected tree should occur during or as a result of work on the site, the county shall be promptly notified of such damage. If a protected tree is damaged so that it cannot be preserved in a healthy state, the planning director shall require replacement in accordance with the arboreal value chart. If on-site replacement is not feasible, the applicant shall pay the in lieu fee to the tree replacement fund.
6.
The following design standards for protected trees shall be adhered to:
a.
Underground trenching for utilities should avoid tree roots within the protected perimeter. If avoidance is impractical, tunnels should be made below major roots. If tunnels are impractical and cutting roots is required, it shall be done by hand-sawn cuts after hand-digging trenches. Trenches should be consolidated to serve as many units as possible;
b.
Compaction within the drip line or protected perimeter shall be avoided;
c.
Paving with either concrete or asphalt over the protected perimeter should be avoided. If paving over the protected perimeter cannot be avoided, affected trees shall be treated as removed for purposes of calculating arboreal values;
d.
Wherever possible, septic systems and/or leachlines shall not be located on the uphill side of a protected tree.
7.
Security posted for the purpose of insuring the proper construction of public or private improvements shall also include an amount sufficient to secure any requirements imposed pursuant to this section. In addition, security for potential tree damage shall be twenty-five percent (25%) of the amount posted for planned tree replacement. In lieu fees shall be paid prior to recording any maps. Such security shall not be released until protection requirements, including planting replacement trees, and any long term maintenance requirements have been satisfactorily discharged. The initial bond amount may be reduced to cover only the maintenance and replacement of trees after construction is completed.
8.
The valley oak (quercus lobata) shall receive special consideration in the design review process to the extent that mature specimens shall be retained to the fullest extent feasible. Valley oaks contribute greatly to Sonoma County's visual character, landscape and they provide important visual relief in urban settings. On existing parcels created without the benefit of an accompanying EIR, design review shall focus on the preservation of valley oaks to the fullest extent feasible. Where such preservation would render a lot unbuildable, partial protection with accompanying appropriate mitigations developed by a certified arborist shall be incorporated into the project design. In such cases where only partial protection can be achieved, full replacement in accordance with the arboreal value chart shall be required.
ARBOREAL VALUE CHARTS
One of the following charts is to be used for determining arboreal values. The applicant shall indicate at time of application which chart is to be used. Chart #1 requires analysis to be done only in the development areas (building envelopes, access roads, etc.) and requires one hundred percent (100%) replacement or in lieu fees. Chart #2 requires analysis of the entire site but allows for removal of up to fifty percent (50%) of the arboreal value. Compensation for the loss of greater than fifty percent (50%) arboreal value will require replacement by using the chart.
Chart No. 1. To be Used for Measuring Trees Removed Only in the Development Areas.
d.b.h.* (inches) Removed Trees Weighted Value Arboreal Value 9—15 1 over 15—21 2 over 21—27 3 over 27—33 4 over 33 5 Total This value (the A.V.) is used
to calculate the replacement number.Chart No. 2. Complete Site Analysis.
(a)
To be Used for Measuring Existing Trees on the Entire Site.
d.b.h.* (inches) Existing Trees Weighted Value Existing Arboreal Value 9—15 1 over 15—21 2 over 21—27 3 over 27—33 4 over 33 5 Total (b)
To be Used for Measuring Trees to be Removed.
d.b.h.* (inches) Removed Trees Weighted Value Removed Arboreal Value 9—15 1 over 15—21 2 over 21—27 3 over 27—33 4 over 33 5 Total Subtract the removed arboreal value from the existing arboreal value. If the removed arboreal value is more than fifty percent (50%) of the existing, the developer must replace the difference between removed arboreal value and fifty percent (50%) of existing arboreal value using the arboreal valuations.
*d.b.h. (diameter at breast height, four and one-half feet (4 ½′) above ground) can be calculated by measuring the circumference of the tree and dividing by 3.14 or pi.
ARBOREAL VALUATIONS
All trees to be replaced shall be the same native species as those removed unless specific approval has been granted by the planning director.
1 point A.V. = six 5 gallon trees (can be existing trees on site that are below nine inches (9″) d.b.h. if preservation methods are part of the development permit)
= two 15 gallon trees*
= $200 in lieu fee**2 points A.V. = 24″ Box Tree*
= $400 in lieu fee*** The larger trees must come from nurseries where they have been irrigated. They must have onsite irrigation to insure their survival.
** Annual average retail cost can be changed to reflect cost increases.
Replacement trees may be located on residentially zoned parcels of at least one and one half (1 ½) acres and on any commercial or industrial zoned parcel, regardless of size, where feasible. Where infeasible, they may be located on public lands or maintained private open space. In lieu fees may be used to acquire and protect stands of native trees in preserves or place trees on public lands.
(p)
Protect and encourage agricultural production by establishing a buffer between agricultural production on lands either designated in one of the three agricultural land use categories in the general plan or lands included within the "AR" zoning district, where any such lands abut a nonagricultural land use conducted on land outside the three general plan land use categories. Generally, buffers shall be defined as a physical separation of one hundred (100) to two hundred (200) feet. These may be modified based upon topographic feature, a substantial tree stand, water course or similar existing feature. In some circumstances, a landscaped berm or other manmade feature may enhance the buffer. The requirement for buffer may be modified after hearing by the advisory agency following a written recommendation by the agricultural commissioner.
Notwithstanding the provisions Chapter 26, of Article XXX (Nonconforming uses) where the imposition of the buffer creates a nonconforming condition, expansion or modification of such use may be permitted provided that encroachment into the setback does not exceed that of the existing structure.
Agricultural production as used herein means either an existing agricultural operation or an agricultural operation that would be a reasonably anticipated use. No buffer or setback shall be created by the acquisition of a portion of a parcel devoted to an agricultural operation.
(q)
The design guidelines set out in Section 26-90-050 of this code (the Taylor Mountain/Sonoma Mountain development guidelines) shall be utilized in addition to the provisions of this section in evaluating subdivision applications for parcels located within the subject area. Building envelopes and related map notations consistent with the provisions of Section 26-90-050 of this code shall be required for each lot.
(Ord. No. 5130 § 2, 1999: Ord. No. 4981 § 7, 1996; Ord. No. 4101, 1989: Ord. No. 4014, 1989: Ord. No. 2510 §§ 17—21: Ord. 1137 § 6: Ord. No. 965 § 4.)