§ 150-121 Purpose.

   The purpose of this building code amendment is to establish standards of isolation against exterior aircraft noise for areas in the vicinity of the MCAS and Yuma International Airport where the exterior day-night sound level (Ldn) exceeds 65 dB. The amendment requires buildings in such noise zones to be so designed and constructed as to isolate them appropriately from the exterior noise exposures.

('80 Code, § 7-40) (Ord. 1857, passed 7-18-79)

§ 150-122 Limitation of Applicability.

   The provisions of this amendment shall not require, or be construed to require, buildings to be designed or constructed contrary to the provisions contained elsewhere in the building code of the city.

('80 Code, § 7-41) (Ord. 1857, passed 7-18-79)

§ 150-123 Scope.

   (A)   The provisions of this amendment shall apply to buildings or portions thereof, and to additions to existing buildings, that are constructed after the effective date of this amendment and that are located where the exterior day-night sound level exceeds 65 dB. A building that has been designed and constructed to include special sound isolation in accordance with this amendment shall not be altered. If a building is altered, it shall be proven that such alterations do not diminish the noise-isolating properties of the building.

   (B)   If the gross floor area of a structure or project is expanded by less than 50%, the requirements of this section apply only to the area of expansion. If the gross floor area of a structure or project is expanded by 50% or more, the requirements of this section apply to the entire structure, except for existing single family, duplex dwellings or any multifamily property used for residential purposes.

('80 Code, § 7-42) (Ord. 1857, passed 7-18-79; Am. Ord. O2002-10, passed 2-20-02)

§ 150-124 Definitions.

   For the purpose of this subchapter, the following definitions shall apply unless the context clearly indicates or requires a different meaning.

   NOISE LEVEL REDUCTION (NLR). Difference in noise level from outside to inside of the building. NLR is a difference, in decibels, between A-weighted sound levels; it depends primarily on the nature of the walls, ceilings, windows, doors and vents and, to a lesser extent, on the amount of sound-absorbing material in the room in which the sound is received. It shall be measured, if so required by the building official, in a completed and furnished building by application of the testing procedure described in this amendment.

   QUALIFIED ARCHITECT OR ENGINEER. An architect or engineer registered in the state who, by reason of this training and experience, is considered qualified to pass judgement on acoustical design, materials, and methods of construction for the attenuation of noise. The qualification of the architect or engineer relative to acoustical design must be submitted to and found to be acceptable by the building official.

   SOUND ABSORPTION. Capacity of the materials and furnishings in a habitable room to absorb sound.

   SOUND LEVEL. In decibels, the quantity measured by an instrument that satisfies American National Standard Specification for Sound Level Meters, S1.4-1971, or the most recent revision thereof. Sound level is understood to be measured with the A-weighted filter and slow response of the instrument.

   SOUND TRANSMISSION CLASS (STC) OF A PARTITION. A singlefigure rating of the sound-isolating properties of a partition, which takes into account the relative importance of the sound transmission loss of the partition at different frequencies. The determination of the sound transmission class of a partition is described in “Determination of Sound Transmission Class,” American Society for Testing and Materials, Designation E413-73.

   SOUND TRANSMISSION LOSS OF A PARTITION. A measure of the sound-isolating properties of a wall, floor, ceiling, window or door, that is characteristic of the partition itself and not the room of which it is a part. The determination of sound transmission loss of a partition, in the field, is described in “Measurement of Airborne Sound Isolation in Buildings,” American Society for Testing and Materials, Designation E336-71 or the latest revision thereof.

('80 Code, § 7-43) (Ord. 1857, passed 7-18-79)

§ 150-125 Exterior Noise Isolation Standards.

   All assembly, educational, institutional, residential, and office buildings located within designated noise impact zones shall be designed and constructed to cause isolation against exterior noise with at least the noise level reduction indicated in the zoning ordinance. For each occupancy, the zoning ordinance specifies the minimum sound level reduction required in each airport noise and accident potential zone (ANAP). An intent of these requirements is to have residential, assembly, educational and institutional, and the like, buildings constructed with sufficient sound isolation so that any habitable room, furnished for normal use and with doors and windows closed, shall be constructed with the noise level reduction as required by the zoning ordinance for each occupancy.

('80 Code, § 7-44) (Ord. 1857, passed 7-18-79) Penalty, see § 150-999

§ 150-126 Airport Noise and Accident Potential Zones.

   Noise zones, for the purpose of this amendment, are defined by contours of the day-night sound level, according to the official zoning map of the city. The ANAP zones are intended to identify those areas in the vicinity of the MCAS and Yuma International Airport which require sound isolation to be included in the design and construction of proposed buildings.

   (A)   Performance standards. Standards of construction considered acceptable and in compliance with the intent and provisions of this amendment are provided in § 150-128. A building will generally be considered acceptable by the building official if it incorporates the applicable features described in § 150-128. Alternate materials and methods of construction may be permitted, provided such alternates are demonstrated to the satisfaction of the building official to be equivalent to those described.

   (B)   Acoustical analysis and design report. The applicant may elect to have a qualified architect or engineer examine the noise levels and needed building sound isolation requirements for a specific site. The analysis and design report signed by and prepared under the supervision of a qualified architect or engineer shall be submitted with the application for building permit. The report shall show the topographical relationship of the aircraft noise sources and the building site, identification of noise sources and their characteristics, predicated noise spectra at the exterior of the proposed building structure, basis for the predication (measured or obtained from published data), and effectiveness of the proposed construction showing that the prescribed interior day-night sound level is met.

('80 Code, § 7-45) (Ord. 1857, passed 7-18-79)

§ 150-127 Expansion of Nonconforming Use.

   The expansion of a nonconforming use shall be designed and constructed in such a manner that the interior sound level does not exceed 45 dB.

('80 Code, § 7-46) (Ord. 1857, passed 7-18-79) Penalty, see § 150-999