53.01 DECLARATION OF FINDINGS AND POLICY.

Since excessive noise is a serious hazard to the public health, welfare, safety and the quality of life and because a substantial body of science and technology exists by which excessive noise may be substantially abated, and because the people have a right to and should be ensured an environment free from excessive noise that may jeopardize their health, welfare or safety or degrade the quality of life, it is the policy of the City to prevent such excessive noise.

53.02 PURPOSE; TITLE AND SCOPE.

This chapter may be cited as the “Riverdale Noise Control Ordinance.” The purpose of this chapter is to establish standards for the control of noise pollution in the City by setting maximum permissible sound levels for various activities, to protect the public health, safety and general welfare. These provisions apply to the control of all noise originating within the City limits of the City or originating from properties lying outside the limits of the City owned or controlled by the City, except where either: (i) a State or federal agency has adopted a different standard or rule than that prescribed in this chapter and has so preempted the regulations of noise from a particular source as to render this chapter inapplicable; or (ii) the Council has determined that, by reason of public acceptance of the activity producing a particular noise or noises, such noise is deemed acceptable to the residents of the City.

53.03 DEFINITIONS.

Unless otherwise expressly stated or the context clearly indicates a different intention, the following terms have the meanings shown. Definitions of technical terms used in this chapter which are not defined may be obtained from Publication of Acoustical Terminology issued by the American National Standards Institute (ANSI) — S1.1-1960, R1961, a copy of which is on file in the Clerk’s office.

   1.   “A-weighted sound pressure level” means the sound pressure level as measured with a sound level meter using the A-weighting network. The standard notation is dB(A) or dBA.

   2.   “Ambient sound pressure level” means the sound pressure level of the all-encompassing noise associated with a given environment, usually a composite of sounds from many sources. It is also the A-weighted sound pressure level which is exceeded 90 percent of the time based on a measurement period which shall not be less than 10 minutes.

   3.   “Continuous sound” means any sound which exists, essentially without interruption, for a period of 10 minutes or more.

   4.   “Cyclically varying noise” means any sound which varies in sound level such that the same level is obtained repetitively at reasonably uniform intervals of time.

   5.   “Decibel” means a logarithmic and dimensionless unit of measure often used in describing the amplitude of sound. Decibel is denoted as dB.

   6.   “Device” means any mechanism which is intended to produce, or which actually produces, noise when operated or handled.

   7.   “Emergency vehicle” means a motor vehicle used in response to a public calamity or to protect persons or property from an imminent exposure to danger, such as police, fire, rescue or ambulance vehicles.

   8.   “Emergency work” means work made necessary to restore property to a safe condition following a public calamity, or work required to protect persons or property from an imminent exposure to danger.

   9.   “Impulsive noise” means a noise of short duration usually less than one second, with an abrupt onset and rapid decay.

   10.   “Motor vehicle” means any vehicle which is self-propelled by mechanical power, including but not limited to, passenger cars, trucks, tractor-trailers, motorcycles, minibikes, go-carts and racing vehicles.

   11.   “Muffler” means an apparatus consisting of a series of chambers or baffle plates designed for the purpose of transmitting gases while reducing sound emanating from such apparatus.

   12.   “Noise disturbance” means any sound which annoys or disturbs reasonable persons with normal sensitivities or which injures or endangers the comfort, repose, health, hearing, peace and safety of persons.

   13.   “Noise” means any sound which is unwanted or which causes or tends to cause an adverse psychological or physiological effect on human beings.

   14.   “Percentile sound pressure level” means: (i) the tenth percentile noise level—the A-weighted sound pressure level that is exceeded 10 percent of the time in any measurement period (such as the level that is exceeded for 1 minute in a 10-minute period) and is denoted L 10 ; and (ii) the ninetieth percentile noise level—the A-weighted sound pressure level that is exceeded 90 percent of the time in any measurement period (such as the level that is exceeded for 9 minutes in a 10-minute period) and is denoted L 90 .

   15.   “Plainly audible noise” means any noise for which the information content of that noise is unambiguously transferred to the listener, such as but not limited to, understanding of spoken speech, comprehension of whether a voice is raised or normal, or comprehension of musical rhythms.

   16.   “Property boundary” means an imaginary line exterior to any enclosed structure, at the ground surface, and its vertical extension, which separates the real property owned by one person from that owned by another person.

   17.   “Public right-of-way” means any street, avenue, boulevard, highway or alley or similar place which is owned or controlled by a public governmental entity.

   18.   “Pure tone” means any sound which can be distinctly heard as a single pitch or a set of single pitches. For the purposes of measurement, a pure tone shall exist if the one-third octave band sound pressure level in the band when the tone exceeds the arithmetic average of the sound pressure levels of the two contiguous one-third octave bands by 5 dB for frequencies of 500 H z and by 15 dB for frequencies less than or equal to 125 H z .

   19.   “Repetitive impulsive noise” means any noise which is composed of impulsive noises that are repeated at sufficiently slow rates such that a sound level meter set at “fast” meter characteristic will show changes in sound pressure level greater than 10 dB(A).

   20.   “RMS sound pressure” means the square foot of the time average square of sound pressure.

   21.   “Sound” means a temporal and spatial oscillation in pressure, or other physical quantity, in a medium with interval forces that causes compression and rarefaction of that medium, and which propagates at finite speed to distance points.

   22.   “Sound level meter” means an instrument, including a microphone, amplifier, RMS detector and integrator, time averager, output meter and/or visual display and weighting networks, that is sensitive to pressure fluctuations. The instrument reads sound pressure level when properly calibrated and is type 2 or better as specified in American National Standards Institute Publication S1 4-1971 R 1976 on file in the Clerk’s office.

   23.   “Sound pressure” means the instantaneous difference between the actual pressure and the average or barometric pressure at a given point in space due to sound.

   24.   “Sound pressure level” means twenty times the logarithm to the base 10 of the ratio of the RMS sound pressure to the reference pressure, which is 20 micropascals, denoted LP or SPL.

   25.   “Stationary noise source” means any device, fixed or movable, which is located or used on property other than a public right-of-way.

   26.   “Steady noise” means a sound pressure level which remains essentially constant during the period of observation, i.e., does not vary more than 6 dB(A) when measured with the “slow” meter characteristic of a sound level meter.

   27.   “Use district” means those districts established by the City of Riverdale Zoning Ordinance.

53.04 NOISE PROHIBITED.

No person shall make, continue or cause to be made or continued, except as permitted by this chapter, any noise disturbance, as defined herein, within the limits of the City.

53.05 SPECIFIC NOISE PROHIBITIONS.

The following acts are declared to be in violation of this chapter:

   1.   Horns and Signaling Devices. Sounding of any horn or signaling device on any truck, automobile, motorcycle, emergency vehicle or other vehicle on any street or public place within the City except as a danger warning signal as provided in the vehicle code of the State of Iowa or the sounding of any such signaling device for an unnecessary and unreasonable period of time.

   2.   Radios, Television Sets, Musical Instruments and Similar Devices.

      A.   Using, operating or permitting the use or operation of any radio receiving set, musical instrument, television, phonograph, drum or other machine or device as provided for in subsection 3 of this section, in such a manner as to violate Section 53.06 or to cause a noise disturbance.

      B.   The operating of any such device between the hours of 8:00 p.m. and 7:00 a.m. the following day in such a manner as to be plainly audible at the property boundary of the source or plainly audible at 50 feet (15 meters) from such device when operated within a vehicle parked on a public right-of-way.

   3.   Public Loudspeakers. Using or operating a loudspeaker or sound amplifying equipment in a fixed or movable position or mounted upon any sound vehicle in or upon any street, alley, sidewalk, park, place or public property for the purpose of commercial advertising, giving instructions, directions, talks, addresses, lectures or transmitting music to any person or assemblages of persons in such a manner as to violate Section 53.06 or cause a noise disturbance unless a permit as provided by Section 53.09 is first obtained.

   4.   Hawkers and Peddlers. Selling anything by outcry within any area of the City which is zoned primarily for residential uses in such a manner as to violate Section 53.06 or cause a noise disturbance. The provisions of this section shall not be construed to prohibit the selling by outcry of merchandise, food and beverages at licensed sporting events, parades, fairs, circuses, and other similar licensed public entertainment events.

   5.   Animals. Owning, keeping, possessing or harboring any animal or animals which, by frequent or habitual noise-making, violates Section 53.06 or causes a noise disturbance. The provisions of this section shall apply to all private and public facilities, including any animal pounds or animal hospitals which hold or treat animals.

   6.   Loading Operation. Loading, unloading, opening or otherwise handling boxes, crates, containers, garbage containers or other objects between the hours of 8:00 p.m. and 7:00 a.m. the following day in such a manner as to violate Section 53.06 or cause a noise disturbance.

   7.   Construction Work. Operating, or causing to be used or operated, any equipment used in construction, repair, alteration or demolition work on buildings, structures, streets, alleys or appurtenances:

      A.   In residential or commercial land use districts between the hours of 8:00 p.m. and 7:00 a.m. the following day; or

      B.   In any land use district where such operation exceeds the sound level limits for an industrial land use as set forth in Section 53.06.

   8.   Power Equipment. Operating or permitting to be operated any power equipment, except construction equipment used for construction activities including but not limited to power saws, sanders, lawn mowers, garden equipment, and chain saws:

      A.   In residential or commercial land use districts between sunset and 7:00 a.m. the following day; or

      B.   In any land use district if such equipment emits a sound pressure level in excess of 82 dB(A) measured at a distance of 50 feet (15 meters).

   9.   Fireworks or Explosives. The use of explosives or fireworks, or the firing of guns or other explosive devices so as to be audible across a property boundary or on a public space or right-of-way, without first obtaining a permit as provided by Section 53.09. This provision shall not be construed to permit conduct prohibited by other statutes, ordinances or regulations governing such activity.

   10.   Racing Events. Permitting any motor vehicle racing event at any place in such a manner as to violate Section 53.06 or cause a noise disturbance without first obtaining a permit as provided by Section 53.09.

   11.   Powered Model Mechanical Devices. The flying or operating of a model vehicle powered by internal combustion engines, whether tethered or not, or the firing or operating of model rocket vehicles or other similar noise-producing devices, between the hours of 8:00 p.m. and 7:00 a.m. the following day in such a manner as to violate Section 53.06 or cause a noise disturbance.

   12.   Standing Motor Vehicle. The operating or causing or permitting to be operated in a residential zone, any motor vehicle or any auxiliary equipment attached in such a manner as to violate Section 53.06 or cause a noise disturbance for a consecutive period longer than 15 minutes during which such a vehicle is stationary.

53.06 USE DISTRICT NOISE LEVELS.

   1.   Maximum Permissible Sound Levels. It is a violation of this chapter for any person to operate or permit to be operated any stationary source of sound in such a manner as to create a ninetieth percentile sound pressure level (L 90 ) of any measurement period (which shall not be less than 10 minutes unless otherwise provided in this chapter) which exceeds the limits set forth for the following receiving land use districts when measured at the boundary or at any point within the property affected by the noise:

 

Use District	8:00 p.m. to 7:00 a.m.	7:00 a.m. to 8:00 p.m.
Residential	45 dB(A)	55 dB(A)
Commercial-Agricultural	55 dB(A)	60 dB(A)
Industrial	75 dB(A)	80 dB(A)

 

   2.   When a noise source can be identified and its noise measured in more than one land use category, the limits of the most restrictive use shall apply at the boundaries between different land use categories.

   3.   Correction for Duration of Sound.

      A.   It is a violation of this chapter for any person to operate, or permit to be operated, any stationary source of sound within any land use district which creates a tenth percentile sound pressure level (L 10 ) of 15 dB(A) greater than levels set forth for the receiving land use districts in subsection 1 of this section for any measurement period. Such period shall not be less than 10 minutes.

      B.   Notwithstanding subsection A of this subsection, no person shall operate or permit to be operated any stationary source of sound within any land use district which created a tenth percentile sound pressure level (L 10 ) greater than 15 dB(A) above the ambient sound pressure level (L 90 ) of any measurement period. Such measurement period shall not be less than 10 minutes.

   4.   Correction for Character of Sound.

      A.   For any stationary source of sound which emits a pure tone, cyclically varying sound or repetitive impulsive sound, the limits set forth in subsection 1 of this section shall be reduced to 5 dB(A).

      B.   Notwithstanding compliance with subsection A of this subsection, it is a violation of this chapter for any person to operate or permit to be operated any stationary source of sound which emits a pure tone, cyclically varying or repetitive impulsive sound which creates a noise disturbance.

53.07 SOUND LEVEL MEASUREMENTS.

Sound level measurements shall be made with a sound level meter using the A weighting scale, in accordance with standards promulgated by the American National Standards Institute or other reasonable standards adopted and tested by the City.