Sec. 3-18. - Definitions—generally.

For the purpose of this article, the following words and phrases shall have the meanings respectively ascribed to them by this section:

Airport. Sonoma County Airport, located latitude north 38° 30′ 20″, longitude, 122° 48′ 30″ west, publicly owned and operated and so located that its exterior boundaries or any area within two miles thereof lie wholly or partly in unincorporated parts of the county.

Airport reference point. A point selected and marked as the approximate geometric center of the northwest-southeast runway.

Board of zoning adjustments. The county board of zoning adjustments.

Flight hazard; hazard to air navigation; obstruction to aerial navigation. Any structure or use of land, or any tree or other object of natural growth, which obstructs the air space required for the flight of aircraft in landing or taking off at the airport or is otherwise hazardous to such landing or taking off of aircraft.

Landing area. The area of the airport used for the landing, taking off or taxiing of aircraft, consisting of the area extending five hundred feet each side of the center line of each runway and two hundred feet outward from the end of each runway, and containing no structures or trees above the actual runway elevation.

Nonconforming use. Any structure or use of land which does not conform to a regulation prescribed in this article or an amendment thereto, as of the effective date of such regulations.

Owner. The county or its legally constituted successor.

Runway. The portion of the landing area which has been hard-surfaced and is generally used for landing and taking off of aircraft.

Structure. Any object constructed or installed by man, including, but without limitation, buildings, towers, smoke stacks and overhead transmission lines.

Tree. Any object of natural growth.

(Ord. No. 629 § 3.)

Sec. 3-19. - Same — Further definitions; airport referenced imaginary surfaces.

Imaginary surfaces are established by reference to the landing area and to the airport reference point and consist of instrument runway approach surfaces, noninstrument runway approach surfaces, a horizontal surface, a conical surface, and transitional surfaces defined as follows:

(a)

Instrument runway approach surfaces. The instrument runway approach surface is an inclined plane located directly above the land lying below the instrument runway approach zone as hereinafter defined and consists of an imaginary surface sloping upward and outward and from each end of the landing area and starting its slope at the elevation of the ground at the end of the landing area. This surface consists of two (2) sections measured horizontally out from a point beginning two hundred feet (200′) outward from the end of each runway. The inner section has a length of ten thousand feet (10,000′) and includes within the first two thousand five hundred feet (2,500′) a clear zone as defined in Section 3-20. The outer section of the surface extends outward and upward an additional forty thousand feet (40,000′) measured horizontally along the ground below the surface. The surface is symmetrically located with respect to the runway center line extended and has a total width of one thousand feet (1,000′) at the end closest to the runway. The surface flares uniformly to a total width of four thousand feet (4,000′) at the end of the ten thousand foot (10,000′) section and to a total width of sixteen thousand feet (16,000′) at the end of the forty thousand foot (40,000′) section. The slope of the surface shall be fifty (50) to one for the inner ten thousand foot (10,000′) section and forty (40) to one for the outer forty thousand foot (40,000′) section. The surface requirements specified in this article for instrument runways shall apply to all runways which may be used for instrument operation and to both ends of such runways.

(b)

Noninstrument runway approach surfaces. A noninstrument runway approach surface is an inclined plane consisting of an imaginary sloping surface starting at the ground elevation at each end of the landing area of a noninstrument runway and sloping upward and outward from the horizontally extended runway center line. These surfaces have a total length of ten thousand feet measured horizontally from a point beginning two hundred feet (200′) outward from each end of a noninstrument runway. These approach surfaces each have a total width of five hundred feet (500′) at the end closest to the end of the runway which width flares uniformly along the horizontally extended center line of the runway to a total width of two thousand five hundred feet (2,500′) at the end of the ten thousand foot (10,000′) section. For all runways not intended for instrument operation, this approach surface slope shall be forty (40) to one.

(c)

Horizontal surface. The horizontal surface is a level plane circular in shape with its height one hundred and fifty feet (150′) above the published airport elevation of one hundred and twenty-five feet (125′) mean sea level as established by the United States civil aeronautics authority (now the United States federal aviation agency) and has a radius from the airport reference point of ten thousand feet (10,000′).

(d)

The conical surface. The conical surface extends upward and outward from the periphery of the horizontal surface with a slope of twenty (20) to one measured by reference to vertical planes radiating outward in all directions from the airport reference point. Thus measured radially outward from the periphery of the horizontal surface, the conical surface extends from such periphery for a horizontal distance of five thousand feet.

(e)

Transitional surface. The transitional surfaces are inclined planes with a slope of seven (7) to one measured upward and outward in a vertical plane at right angles to the center line of the runway. The transitional surfaces, symmetrically located on either side of the runway, extended upward and outward from a line on either side of the runway which is parallel to and level with the runway center line. These parallel lines are at a horizontal distance from the runway center line equal to ½ of one thousand feet (1,000′) (five hundred feet (500′)) or ½ of five hundred feet (500′) (two hundred and fifty feet (250′)) as indicated in subsection (a) or (b) above, as the case may be. Transitional surfaces also extend from the edges of all of the approach surfaces upward and outward to the intersection with the horizontal surface, or the conical surface. The approach surfaces for instrument runways projecting through and beyond the limits of the conical surface have a seven (7) to one transitional surface extending a distance of five thousand feet (5,000′) measured horizontally from the edge of the approach surfaces and at right angles to the runway center line.

(Ord. No. 629 § 4.)

Sec. 3-20. - Same — Further definitions and establishment of zones.

In order to carry out the purposes of this article, all of the land surfaces and air space within the boundaries of the county airport and all of the air space above the imaginary surfaces created and defined by this article are divided into clear zones, instrument runway approach zones, noninstrument runway approach zones, turning zones and transition zones as specifically outlined upon the map entitled "Airport Approach Zoning Map, Sonoma County Airport, Sonoma County, California," which is attached to the original ordinance from which this article derives and which is incorporated herein by reference and which map is hereby adopted as part of this article, and all of such zones are hereby created and established; provided, however, that reference to the land and air space below the imaginary surfaces defined by this article shall be made for the purposes of horizontal measurement of zone areas and for control of the height of trees or structures on such land which could, if not regulated, become hazards to aerial navigation.

(a)

Clear zones. The sloping trapezoidal imaginary surface and all the air space above such surface immediately adjacent to the ends of the landing areas which have been cleared of all above ground obstructions above the sloping surface starting at the end of such areas. Clear zones are included as a smaller component part of the instrument runway approach zones as defined in Section 3-19. The standard clear zone dimensions are two thousand five hundred feet (2,500′) in length (measured along the horizontally extended center line of the runway) and one thousand feet (1,000′) wide at the end closest to the runway, which width flares uniformly and symmetrically along the horizontally extended runway center line to the width of one thousand seven hundred and fifty feet (1,750′) at the end of the two thousand five hundred foot (2,500′) clear zone section. The imaginary surface slopes upward and outward from the ground elevation starting at the end of the landing and proceeds upward and outward at a ratio of one foot rise for each fifty feet (50′) of distance outward from the end of the landing area, measured along and parallel to the runway center line extended.

(b)

Instrument runway approach zones. The instrument runway approach zones consist of all the air space vertically above the instrument runway approach surfaces, and each is divided into a ten thousand foot (10,000′) section and an additional above the instrument runway approach surfaces, and each forty thousand foot (40,000′) section, these dimensions and slopes corresponding to those described in the definition in Section 3-19 of the instrument runway approach surfaces. The ten thousand foot (10,000′) section includes within the first two thousand five hundred feet (2,500′) a clear zone as described in subsection (a) of this section.

(c)

Noninstrument runway approach zones. The noninstrument runway approach zones consist of all the air space vertically above the noninstrument runway approach surfaces.

(d)

Transition zones. The transition zones consist of all the air space vertically above the transitional surfaces.

(e)

Turning zones. The turning zones consist of all the air space vertically above the horizontal surface and the conical surface.

(Ord. No. 629 § 5.)

Sec. 3-21. - Procedure for determining obstructions to aerial navigation.

Trees, structures or any other objects which project above any landing area or above any of the imaginary surfaces or into any of the zones defined and created by this article shall be considered obstructions to air navigation; trees, structures or other objects exceeding the limiting heights above ground described in Section 3-22 shall be considered obstructions to air navigation unless found not to be objectionable after special aeronautical study by the board of zoning adjustments; provided, however, that the most restrictive requirement of this article shall govern and control. Trees, structures or other objects which are located or will be located with respect to other objects of a permanent character such that there will result no material increase in the aeronautical hazard will not be considered obstructions to air navigation.

(Ord. No. 629 § 6.)

Sec. 3-22. - Limiting heights above ground.

In addition to the requirements of Section 3-21 , trees, structures or other objects shall be considered obstructions to air navigation (unless a special aeronautical study indicates otherwise) if they occur in any one or more of the following categories or are more than five hundred feet (500′) above ground elevation at any point within the boundaries of the county; provided, however, that nothing herein provided is intended to excuse compliance with any applicable law or regulation of the state or of the United States of America:

(a)

Trees, structures or other objects on the land directly below instrument runway approach zones shall be considered obstructions to air navigation if the tree, structure or other object is more than one hundred feet (100′) above the ground or more than one hundred feet (100′) above the approach end of the landing area, whichever permits the higher elevation of the tree, structure or other objects within three (3) statute miles of the end of the landing area, and increasing in permissive height twenty-five feet (25′) for each additional statute mile of distance outward from the landing area, but not to exceed two hundred and fifty feet (250′) in permissive height within fifty thousand feet (50,000′) from the end of the landing area.

(b)

Trees, structures or other objects on the land directly below the turning zone and within ten (10) miles of the airport reference point shall be considered obstructions to air navigation if the tree, structure or other object is more than one hundred and seventy feet (170′) above the ground or more than one hundred and seventy feet (170′) above the published airport elevation, whichever permits the higher elevation of the tree, structure or other object within three (3) statute miles of the airport reference point and increasing in permissive height in the proportion of one hundred feet (100′) for each additional mile of distance from the airport reference point, but not to exceed five hundred feet (500′) above the ground within ten (10) statute miles from the airport reference point.

(c)

Trees, structures or other objects whose elevation would increase the final approach minimum flight altitude. The final approach minimum flight altitude is normally established from the highest point within five (5) statute miles of the center line of the final approach course of a radio facility used for final letdown to an airport, and extends for a distance of ten (10) statute miles along this course outward from the radio facility. The radio facility may be a radio range, nondirectional beacon (if marker), fan marker or the outer marker of an instrument landing system.

(d)

Trees, structures or other objects within a civil airway or air traffic control area, more than one hundred and seventy feet (170′) above the ground or more than an elevation that would require the increase in an established minimum flight altitude, whichever permits the higher elevation of the object. The minimum flight altitudes are normally established from the highest point within five (5) statute miles of the center line of the civil airway or air traffic control area for the section or airway or control area affected.

(Ord. No. 629 § 7.)

Sec. 3-23. - Use restrictions generally.

(a)

Notwithstanding any other provision of this article no use may be made of the land directly below any instrument runway approach zone, noninstrument approach zone, turning zone or transition zone, but not including the land area directly below the outer forty thousand foot sections of the instrument runway approach zones and the transition zones adjacent to them, in such a manner as to create electrical interference with radio communication between the airport and aircraft, make it difficult for flyers to distinguish between airport lights and others, result in glare in the eyes of flyers, impair visibility, or otherwise endanger the landing, taking off, or maneuvering of aircraft.

Within the air space and upon the land directly below the inner ten thousand foot section of instrument runway approach zones there shall not be erected any place of public assembly including but not limited to churches, hospitals, schools and theaters.

The maintenance and repair of all uses on the land or water area vertically below the clear zones, as defined in this article, such uses existing at the time the ordinance from which this article derives was adopted, ^[53] shall not be prohibited.

(b)

Notwithstanding any of the provisions of this article as to height limitations or as to the prohibition of obstructions to air navigation, but with the exception of the limits of this article as to the construction of places of public assembly and residences, no provision of this article shall restrict the construction, erection or growth to less than fifty feet in height above natural ground level.

(c)

The construction of residences vertically below the clear zones subsequent to the adoption of the ordinance from which this article derives ^[54]cshall be limited to the construction, restoration or replacement of such residences that may be damaged or destroyed by fire, wind, storm or other natural causes; provided, however, that an existing residence, vertically below the clear zones, may be replaced at the same site or at a new site; provided, that the older residence is removed within ninety days after the establishment of the newer residence.

(Ord. No. 629 § 8.)

Sec. 3-24. - Nonconforming uses.

The regulations prescribed in this article shall not be construed to require the removal, lowering or other change or alteration of any structure or tree not conforming to such regulations as of the effective date the ordinance from which this article derives ^[55] or otherwise to interfere with the continuance of any nonconforming use. Nothing contained in this article shall require any change in the construction, alteration or intended use of any structure, the construction or alteration of which was begun prior to the effective date of the ordinance from which this article derives, and is diligently prosecuted and completed within one year thereof.

(Ord. No. 629 § 9.)

Sec. 3-25. - Use permits.

(a)

Future uses. No structure or tree above fifty feet (50′) above the natural terrain shall be erected, altered, planted, allowed to grow to a greater height, or otherwise established, in any instrument runway approach zone, noninstrument runway approach zone, turning zone or transition zone, but not including the areas in the outer forty thousand foot (40,000′) sections of the instrument runway approach zones and the transition zones adjacent to them, unless a use permit therefor shall have been applied for and granted. Each such application shall indicate the purpose for which the permit is desired, with sufficient detail to permit it to be determined whether the resulting use, structure or tree would conform to the regulations prescribed by this article. If such determination is in the affirmative, the permit applied for shall be granted.

(b)

Existing uses. Before any existing use, structure or tree above fifty feet (50′) above the natural terrain may be replaced, substantially altered or repaired, rebuilt, allowed to grow higher, moved to another location or replanted, within any instrument runway approach zone, noninstrument runway approach zone, turning zone or transition zone, but not including the land below the outer forty thousand foot (40,000′) sections of the instrument runway approach zones and the transition zones adjacent to them, a permit shall be secured authorizing such replacement, change or repair. No such permit shall be granted that would allow the establishment or creation of a flight hazard or permit a nonconforming use, structure or tree to be made or to become higher or become a greater hazard to air navigation than it was on the effective date of the ordinance from which this article derives, ^[56] or than it is when the application for a permit is made. Except as indicated, all applications for a permit for replacement, change, or repair of existing use, structure or tree shall be granted. No such permit shall be required to make maintenance repairs to or to replace parts of existing structures which do not enlarge or increase the height of the existing structure.

(Ord. No. 629 § 10.)

Sec. 3-26. - Variances.

Any person desiring to erect any structure or increase the height of any structure, or permit the growth of any tree or use his property not in accordance with the regulations prescribed in this article may apply to the board of zoning adjustments for a variance therefrom. Such variance shall be allowed where a literal application or enforcement of the regulations prescribed by this article would result in practical difficulty or unnecessary hardship and the relief granted would not be contrary to the public interest but would do substantial justice and be in accordance with the spirit of this article; provided, however, that any variance may be subject to such reasonable conditions and restrictions as the board of zoning adjustments may deem necessary.

(Ord. No. 629 § 11.)

Sec. 3-27. - Hazard marking and lighting.

Any permit or variance granted under this article may, if such action is deemed advisable to effectuate the purpose of this article and reasonable in the circumstances, be so conditioned as to require the owner of the object in question, at his own expense, to install, operate and maintain thereon such markers and lights according to the current United States federal aviation agency criteria as may be necessary to indicate to flyers the presence of a flight hazard.

(Ord. No. 629 § 12.)

Sec. 3-28. - Conflicting regulations.

Where a provision of this article imposes a greater or more stringent restriction upon the use of land than is imposed or required by any other provision of this code or any other ordinance or regulation, the provision of this article shall govern.

(Ord. No. 629 § 17.)

Sec. 3-29. - Administrative agency designated.

The board of zoning adjustments is hereby designated as the administrative agency charged with the duty of administering and enforcing the regulations prescribed by this article.

(Ord. No. 629 § 13.)

Sec. 3-30. - Appeals.

In case an applicant is not satisfied with the decision of the board of zoning adjustments he may, within ten (10) days, appeal in writing to the board of supervisors. A copy of such appeal shall be submitted by the applicant to the board of zoning adjustments. The board of supervisors shall render its decision within sixty (60) days after receipt by such board of such appeal.

(Ord. No. 629 § 14.)

Sec. 3-31. - Conformity to article by county officials, etc.—Permits, etc., in conflict with article void.

All departments, officials and public employees of the county who or which are vested with the duty or authority to issue permits or licenses shall conform to the provisions of this article and shall issue no such permit or license for uses, buildings or purposes where the same would be in conflict with the provisions of this article, and such permit or license, if issued in conflict with the provisions of this article, shall be null and void.

(Ord. No. 629 § 15.)

Sec. 3-32. - Enforcement of article.

It shall be the duty of the board of zoning adjustments to enforce the provisions of this article pertaining to the erection, construction, reconstruction, moving, conversion, alteration or addition to any building or structure. It shall be the duty of the sheriff of the county and all officers of the county herein otherwise charged by law with the enforcement of this article to enforce this article and all the provisions of the same.

(Ord. No. 629 § 15.)

Sec. 3-33. - Violations of article.

Any person, whether as principal, agent, employee or otherwise, violating or causing or permitting the violation of any of the provisions of this article shall be guilty of a misdemeanor, and upon conviction thereof shall be punishable by a fine of not more than three hundred dollars ($300.00), or by imprisonment in the county jail for a term not exceeding three (3) months, or by both such fine and imprisonment. Such person shall be deemed to be guilty of a separate offense for each day during any portion of which any violation of this article is committed, continued or permitted by such person, and shall be punishable as herein provided.

Any building or structure set up, erected, constructed, altered, enlarged, converted, moved or maintained contrary to the provisions of this article, or any use of any land, building or premises established, conducted, operated or maintained contrary to the provisions of this article, shall be, and the same is hereby declared to be unlawful and a public nuisance, and the district attorney of the county shall, upon order of the board of supervisors, immediately commence action or proceedings for the abatement and removal and enjoinment thereof in the manner provided by law, and shall take such other steps, and shall apply to such courts as may have jurisdiction to grant such relief as will abate or remove such building or structure, and restrain and enjoin any person from setting up, erecting, building, maintaining or using any such building or structure or using any property contrary to the provisions of this article.

The remedies provided for herein shall be cumulative and not exclusive.

(Ord. No. 629 § 15.)