The specific purposes of the hillside overlay district are to:
A. 
Ensure the preservation of the city's hills, ridges and ridgelines visible to area residents and persons traveling through the county on major arterials by promoting a harmonious visual and functional relationship between the natural hillside environment and the man-made environment;
B. 
Protect the health, safety and welfare of the community by establishing regulations for development of ridgelines and hillside areas within the city;
C. 
Implement goals, policies and programs of the General Plan concerning hillside and ridgeline development, development hazards and open space lands;
D. 
Preserve predominant views from and of hillside areas;
E. 
Retain the natural appearance that hillside areas impart to the city and its environs;
F. 
Preserve and retain significant natural features (i.e., vegetation, terrain, rock formations, etc.) of hillside sites in essentially their natural state;
G. 
Minimize and control the scarring and cutting of hillsides and ridgelines and minimize water runoff and soil erosion problems incurred due to grading and development activities.
(O2003-12)
The :S overlay district may be combined with any principal zoning district in hillside areas which have a slope of 15% or greater, and shall be indicated with an :HS suffix.
(O2003-12)
Development regulations are in addition to the regulations of the underlying principal zoning district with which they are combined. In the event of a conflict with the regulations of the underlying principal district, the :HS provisions shall supersede.
The following regulations shall apply:
A. 
Minimum Development. Any existing residential lot shall be allowed one dwelling unit, including any accessory buildings or structures permitted by the underlying zoning district.
B. 
Design Review, Residential Lots. On a residentially zoned lot, a design review permit is required for:
1. 
Construction of one principal dwelling unit, and any accessory building or structure requiring a building permit;
2. 
Additions to dwellings, accessory buildings or structures, unless exempt.
C. 
Use Permit, Residential Lots. On residentially zoned lots, a hillside use permit is required to authorize an increased density on the lot or the parcel; after approval of such use permit, a parcel map, tentative subdivision or similar application for a development that has potential for more than one principal dwelling may then be considered.
D. 
Design Review, Nonresidential Lots. On nonresidential zoned lots, a design review permit is required for any new construction buildings and structures.
E. 
Hillside Review Criteria. Review of a hillside use or design review permit shall determine the proposed development's consistency with the purpose of this title, the :HS district development standards and the hillside development guidelines adopted separately by resolution.
F. 
Factors for Evaluating Increased Density. An increased density on a lot or parcel (excluding accessory uses) may be authorized only if a development is determined to be consistent with the purpose of this title and the hillside development guidelines after evaluation of the following factors:
1. 
The visibility of the new buildings or structures to the valley floor along Highway 29, Silverado Trail, Browns Valley Road, Buhman Avenue, Foster Road, Redwood Road, Coombsville Road, Partrick Road, Old Sonoma Road, Trancas Street, First Street and Soscol Avenue;
2. 
The visibility of the buildings or structures to the adjacent neighborhood;
3. 
The amount of cut and/or fill required for access roads and parking areas; short-term and long-term appearance of such changes and any related engineering improvements; together with any proposed mitigation measures;
4. 
The amount of cut and/or fill required to establish the new buildings or structures;
5. 
Height, width and bulk of each building or structure, if known;
6. 
Construction materials and colors of each new building or structure, if known;
7. 
Existing trees and vegetation to be removed from the property;
8. 
Degree of screening of the new development with existing trees and vegetation;
9. 
Degree of screening of new development with new plant materials, length of time to see these established at mature size;
10. 
Any open space easements, special building setbacks, building envelopes or other covenants proposed to be established to preserve the existing character of the property.
G. 
Hillside Density Limits. Any density increase shall not exceed the maximum allowable density established by the following standards:
1. 
Any portion of the lot or parcel having a slope of less than 15% shall be assigned the General Plan density;
2. 
Any portion of the lot having a slope of 15% to 30% shall be assigned a density of one lot or one dwelling unit per acre;
3. 
Any portion of the lot or parcel having a slope greater than 30% shall be assigned no density.
H. 
Finding. To grant a use permit or design review permit, the decision-making body must find (in addition to standard permit findings) that the proposed hillside development project is consistent with the purpose of this title, the :HS district standards and hillside development guidelines adopted separately by resolution.
(O2003-12)
The following standards, which are alternatives to the underlying principal zoning district standards, shall apply to minimize the impact of hillside development:
A. 
Setbacks and Yards. Buildings and structures may encroach up to one half of the distance into a required setback or yard with design review approval.
B. 
Height. Buildings and structures shall not exceed 24 feet in height unless:
1. 
They are a use (such as water tanks) or portions of structures (such as cupolas) which are allowed to be higher in accordance with Chapter 17.52; or
2. 
One or more of the following findings are made:
a. 
The added height results in less lot coverage, reduces lot grading, or saves significant existing trees and vegetation, or
b. 
The aesthetic impact of the added height is mitigated by existing on-site conditions, or
c. 
The size or shape of the lot unreasonably restricts the size of the proposed buildings and structures.
(O2003-12)
The following developments are exempt from the :HS permit requirements.
A. 
All buildings or structures constructed prior to January 2, 1990 shall remain as conforming uses and are exempt from any hillside overlay permit requirements.
B. 
Any first floor addition to an existing principal or accessory building or structure is exempt when the floor area of the addition is 50% or less of the floor area of the existing principal or accessory building or structure to which it will be attached.
(O2003-12)
A. 
Community Development Director Design Review. The following developments shall require a design review permit, with notice to the Planning Commission:
1. 
An individual home or accessory structure, or addition unless exempt pursuant to Section 17.40.050, on a lot of record determined to be consistent with the purpose of the :HS overlay district and :HS district development standards and guidelines. In order for the Community Development Director to make this determination, an applicant must submit a sketch plan showing the general layout of the proposed development.
2. 
An individual home or accessory structure on a lot of record that is zoned :HS but is not a hillside or ridgeline property.
B. 
Referral to Planning Commission. If the Community Development Director determines that the proposed development is not consistent with the purpose of the :HS overlay district and/or the hillside district development standards and guidelines, the proposal may be directly referred to the Planning Commission for commission design review.
(O2003-12; O2004 9)
A. 
Filing Materials for :HS Use Permits. The following materials shall be required for a hillside subdivision or other similar type of project with a potential for more than one dwelling per residential lot, unless the Community Development Director determines a specific material is unnecessary:
1. 
Surveyed site plan with precise location of all physical features, including existing trees with a diameter of more than eight inches measures 24 inches above existing grade, and major vegetation;
2. 
A detailed slope analysis showing those areas having a slope of less than 15%; areas having a slope of 15% to 30%; and areas having a slope greater than 30%. Contour lines shall have an interval of one foot for areas having a slope up to five percent; two feet for areas having a slope of over five percent to 10%; and five feet for areas having a slope greater than 10%;
3. 
Site assessment plan identifying dominant features (solar orientation, site access, dominant views from the site, etc.) and constraints (prevailing winds, excessive slopes, sensitive areas, dominant views of the site, etc.);
4. 
Proposed building footprints and building envelopes;
5. 
Diagrams of typical building sections, and a massing diagram for each lot;
6. 
Preliminary grading plan;
7. 
A road profile plan;
8. 
An erosion control plan addressing best management practices;
9. 
Aerial photograph;
10. 
A scale model and/or visual simulation(s) clearly showing visual effects of the proposed development;
11. 
Other information, plans or studies which are deemed by the Community Development Director to be necessary to accurately assess the project.
B. 
Filing Materials for :HS Design Review Permits. The following materials shall be required for all Community Development Director design review permits, unless the Community Development Director determines the specific information is unnecessary:
1. 
Surveyed site plan with the precise location of all physical features and slope contours. Contour lines shall have an interval of one foot for areas having a slope up to five percent; two feet for areas having a slope of over five percent to 10%; and five feet for areas having a slope greater than 10%;
2. 
Site assessment plan identifying dominant features (solar orientation, site access, dominant views from the site, etc.) and constraints (prevailing winds, excessive slopes, sensitive areas, dominant views of the site, etc.);
3. 
Construction drawings;
4. 
Samples of buildings materials;
5. 
Precise grading/drainage plan;
6. 
An erosion control plan addressing best management practices;
7. 
Landscape plan;
8. 
A scale model or visual simulation(s);
9. 
Other information, plans or studies that are deemed by the Community Development Director to be necessary to accurately assess the project.
(O2003-12; O2004 9; O2004 14)