Point Arena Municipal Code Ch. 9.35 Noise

This chapter shall be known as the city of Point Arena "Noise Ordinance."

(Ord. 203 § 1, 2007.)

(1) Sound is mechanical energy transmitted by pressure waves in a compressible medium such as air. Noise is unwanted sound. Sound is characterized by various parameters that describe the rate of oscillation of sound waves, the distance between successive troughs or crests, the speed of propagation, and the pressure level or energy content of a given sound. In particular, the sound pressure level has become the most common descriptor used to characterize the loudness of an ambient sound level. The noise level perceived by a receptor depends on the following parameters:

(a) Distance between the noise source and the receptor;

(b) Presence or absence of absorptive noise barriers;

(c) The amount of noise-mitigating features between the receptor and noise source including intervening terrain, structures, foliage, and ground cover;

(d) Cumulative noise impacts from reflective surfaces such as building façades, concrete and asphalt, water bodies, etc.; and

(e) Current weather conditions (snow, wind, rain) and weather-related ground cover (snow, mud, wet or dry ground).

(2) Noise level (volume) is generally measured in decibels (dB) using the A-weighted sound pressure level (dBA). In addition to the instantaneous measurement of sound levels, the duration of sound is important. Sounds that occur over a long period of time are more likely to be an annoyance or cause direct physical damage or environmental stress. One of the most frequently used noise metrics that considers duration as well as sound power level is the equivalent noise level (Leq). Typically, Leq is summed over a one-hour period. The sound pressure level is measured on a logarithmic scale with the zero dB level based on the lowest detectable sound pressure level that people can perceive (an audible sound that is not zero sound pressure level). Decibels cannot be added arithmetically, but rather are added on a logarithmic basis. A doubling of sound energy is equivalent to an increase of three dB and a sound that is 10 dB less than another does not increase the overall sound level. Because of the nature of the human ear, a sound must be about 10 dB greater than the reference sound to be judged as twice as loud. In general, a three dB change in community noise levels is noticeable, while one to two dB changes generally are not perceived.

(3) Point Arena is characterized by its citizens as a quiet town. The small quiet nature of the town produces a low level sound measurement (technically described as "low ambient noise level"). It is so quiet at night that the loudest sound is the surf at Arena Cove, which is approximately one mile from downtown. The only other notable source of noise is the sound made by people congregating at night along Main Street, where the theatre and several restaurants are located. In many other communities such noises would not be significant, but they are noticeable in Point Arena primarily because the night-time background noise level is quite low (approximately 20-25 dBA).

Ten dB is generally accepted to be the average difference between day and night levels. However, Point Arena has a much wider spread between day and night levels. And, while Ldn is useful to describe some aspects of noise levels in the city, it gives a distorted view as to the actual sound level experienced by the area residents.

State guidelines allow and encourage local jurisdictions to employ considerable flexibility in describing a local situation in order to more fully quantify local sound levels. Where appropriate, Leq is to be used to quantify the true noise levels.

(4) The California Government Code Section 65302(f) encourages each local government entity to conduct noise studies and implement a noise element as part of their general plan. The Point Arena noise element lists specific policies and programs, which are incorporated into this chapter.

(5) The city council of the city of Point Arena specifically finds that excessive noise on public or private property is a nuisance factor so as to create a negative impact upon the entire city.

(Ord. 203 § 1, 2007.)

"dB"

means a unit of measurement of the loudness or strength of a signal. One decibel is considered the smallest difference in sound level that the human ear can discern. Created in the early days of telephony as a way to measure cable and equipment performance and named after Alexander Graham Bell, decibels (dBs) are a relative measurement derived from two signal levels: a reference input level and an observed output level. A decibel is the logarithm of the ratio of the two levels. One bel is when the output signal is 10 times that of the input, and one decibel is 1/10th of a bel.

A whisper is about 20 dB. A normal conversation is typically from 60 to 70 dB, and a noisy factory from 90 to 100 dB. Loud thunder is approximately 110 dB, and 120 dB borders on the threshold of pain.

"dBA (A-weighted decibels)"

means the sensitivity of the human ear to sound depends on the frequency or pitch of the sound. People hear some frequencies better than others. If a person hears two sounds of the same sound pressure but different frequencies, one sound may appear louder than the other. This occurs because people hear high frequency noise much better than low frequency noise.

Noise measurement readings can be adjusted to correspond to this peculiarity of human hearing. An A-weighting filter which is built into the instrument de-emphasizes low frequencies or pitches. Decibels measured using this filter are A-weighted and are called dB(A).

A-weighting serves two important purposes:

(a)

Gives a single number measure of noise level by integrating sound levels at all frequencies;

(b)

Gives a scale for noise level as experienced or perceived by the human ear.

"Ldn"

means the average night average sound level (Ldn or DNL) is the average noise level over a 24-hour period. The noise between the hours of 10:00 p.m. and 7:00 a.m. is artificially increased by 10 dB. This noise is weighted to take into account the decrease in community background noise of 10 dB during this period.

"Leq"

is defined as the steady A-weighted level that is equivalent to the same amount of energy as that contained in the actual time-varying levels over a period of time.

"Leq(1)"

denotes average sound level for one hour.

"Sensitive receptors"

mean residences, schools, churches, hospitals, and other similar commercial and residential locations which can be adversely affected by excessive noise.

"Lmax"

means the maximum instantaneous or peak sound level.

(Ord. 203 § 1, 2007.)

(1) Noise levels shall not be permitted to exceed 60 Leq(1) anywhere within the city of Point Arena.

(2) The city may require an acoustical report for new multifamily dwellings within the 60 dB (Ldn) noise exposure contour, as required by Title 25 of the California Administrative Code - Noise Insulation Standards.

(3) New development in all zones must not raise the ambient noise levels in any residential zone within the city. Where residential zoning is adjacent to other zones, the lower residential noise limits will apply.

(4) New developments in commercial and industrial zones shall be designed, sited and screened in such a way as to avoid or suppress noise and the impact of any noise on existing and proposed residential settings; and, noise buffers (walls, trees, landscaping, open spaces, berms, other buildings) between industrial/commercial activities and residential and other noise-sensitive activities shall be required as a condition of development permits.

(5) No noise-generating industries shall be allowed to operate between the hours of 8:00 p.m. and 7:00 a.m.

(6) The following Leq and Lmax noise limits shall be incorporated into this chapter:

(7) Daytime Limits (7:00 a.m. to 8:00 p.m.).

(a) Residential: 50 Leq(1) at the property line of the property within which the noise generated is located, 80 dB (Lmax) at the property line or sensitive receptors.

(b) Commercial: 60 Leq(1) at the property line 80 dB (Lmax) at the property line or sensitive receptors.

(c) Industrial: 60 Leq(1) at the property line 90 dB (Lmax) at the property line or sensitive receptors.

(8) Nighttime Limits (8:00 p.m. to 7:00 a.m.).

(a) Residential: 25 Leq(1) at the property line 60 dB (Lmax) at the property line or sensitive receptors.

(b) Commercial: 30 Leq(1) at the property line 60 dB (Lmax) at the property line or sensitive receptors.

(c) Industrial: 30 Leq(1) at the property line 60 dB(Lmax) at the property line or sensitive receptors.

(Ord. 203 § 1, 2007.)

Permits Authorized. Any individual, business and/or organization may apply for a permit that will allow for an event where noise generated may otherwise be in violation of this chapter. Such permit shall identify the applicant and duration of the event.

(Ord. 203 § 1, 2007.)

Any person or entity that willfully violates the provisions of this chapter shall be guilty of an infraction for the first offense and may be charged with a misdemeanor for any additional offense in the same year.

(Ord. 203 § 1, 2007.)