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Developing a new Healdsburg Noise Ordinance

California Noise Ordinance Requirements

CALIFORNIA NOISE ORDINANCE REQUIREMENTS

There are currently 456 incorporated cities and 58 counties in California. State law requires that each of these jurisdictions adopt "a comprehensive, long-term general plan for [its] physical development." This general plan is the official city or county policy regarding the location of housing, business, industry, roads, parks, and other land uses, protection of the public from noise and other environmental hazards, and for the conservation of natural resources. The legislative body of each city (the city council) and each county (the board of supervisors) adopts zoning, subdivision and other ordinances to regulate land uses and to carry out the policies of its general plan.

The General Plan must contain the following seven components or "elements": land use, circulation, housing, conservation, open-space, noise, and safety (Government Code Sections 65300 et seq.).

California STATE CRITERIA FOR MINIMIZING ADVERSE NOISE EFFECTS ON HUMANS

(CNEL LEVELS)

The dBA descriptor only reports noise from a single source or combination of sources at a point in time. To allow a more comprehensive description of a noise environment, federal and state agencies have established noise and land use compatibility guidelines that use averaging approaches to noise measurement. Two measurement scales commonly used in California are the Community Noise Equivalent Level (CNEL) and the day-night level (Ldn). In order to account for increased human sensitivity at night, the CNEL level includes a 5-decibel penalty on noise during the 7:00 p.m. to 10:00 p.m. time period and a 10-decibel penalty on noise during the 10:00 p.m. to 7:00 a.m. time period. The Ldn level includes only the ten decibel weighting for late-night noise. These values are nearly identical for all but unusual noise sources.

CNEL = Community Noise Equivalent Level. A noise measurement system introduced in the early 1970's by the State of California as a simplified alternative to the Noise Exposure Forecast (NEF) system for community noise exposure, with particular emphasis on airport noise. The major difference is that CNEL can be measured using ordinary dB(A) readings, as opposed to the computer calculation of Effective Perceived Noise Level used in the NEF. The CNEL represents the daily energy noise exposure, calculated over a 24 hour period, averaged on an annual basis. It is not measured, but computed.

Because it is a calculation, based on a mixture of noises, it is not possible to hear what 65 CNEL sounds like.  A deafening explosion, on an otherwise quiet day, will yield a low CNEL calculation due to the averaging. In order to account for increased human sensitivity at night, the CNEL level includes a 5-decibel penalty on noise during the 7:00 p.m. to 10:00 p.m. time period and a 10-decibel penalty on noise during the 10:00 p.m. to 7:00 a.m. time period.

The California CNEL averaging is a common but misleading way to measure noise impacts. 

The CNEL and L descriptors have been found to provide good correlation to the potential for dn annoyance from transportation-related noise sources (ie: roadways, airports, railroad operations). However, they do not provide a good correlation to the potential for annoyance from non-transportation or stationary noise sources such as industrial and commercial operations. This is due to the fact that many times stationary noise sources may operate between 8 and 10 hours per day, or will have noise sources such as loading docks, pressure relief valves or alarms which tend to be short duration noise events. When applying an L or CNEL dn criterion, the noise levels associated with these types of short term operations will be averaged over a 24-hour period, thus underscoring the potential for annoyance.

An angry parent near the Federal Express air cargo hub in Greensboro, North Carolina summed it up this way. “Telling our small children, who are awakened at night, crying in their beds because they can't sleep, and are frightened by the roar of overhead jet engines, that the noise is not so bad if you average it out over a 24 hour period, won't get them to sleep at three in the morning.”

California Jurisdictions That Have Adopted Noise Control Ordinances

Reading some of these Ordinances is a great lesson in politics. Most are so full of loopholes as to be virtually useless for controlling sound pollution in residential zones.

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