Chapter 130.37 — NOISE STANDARDS

This Chapter complies with General Plan Goal 6.5 (Acceptable Noise Levels), and supplements County Code Chapter 9.16 (Noise) by establishing standards concerning acceptable noise levels for both noise-sensitive land uses and for noise- generating land uses.

The following noise sources shall be exempt from the standards of this Chapter:

A.

Activities conducted in public parks, public playgrounds, and public or private school grounds, including but not limited to school athletic and school entertainment events, providing an amplified sound system is not required or used.

B.

The use of any mechanical device, apparatus, or equipment related to or connected with emergency activities or emergency work to protect life or property.

C.

Safety signals, warning devices, and emergency pressure relief valves properly operated and in good working order.

D.

Noise sources associated with property maintenance, such as lawn mowers, trimmers, snow blowers, power tools in good working order, and cutting of firewood for non-commercial personal use, provided that the activities take place between the hours of eight a.m. and nine p.m. on weekdays and nine a.m. to nine p.m. on weekends and federal holidays.

E.

Noise sources associated with agricultural uses listed in Section 130.21.020 (Agricultural Zones: Matrix of Allowed Uses) in Article 2 (Zones, Allowed Uses, and Zoning Standards) of this Title that are performed consistent with the standards and practices of the agricultural industry.

F.

Noise sources associated with work performed by public or private utilities in the maintenance or modification of its facilities.

G.

Noise sources associated with public holidays, or other commonly celebrated occasions.

H.

Traffic on public roadways, railroad line operations, aircraft in flight, and any other activity where regulation thereof has been preempted by state or federal law.

I.

Construction (e.g., construction, alteration or repair activities) during daylight hours provided that all construction equipment shall be fitted with factory installed muffling devices and maintained in good working order.

Subject to the exemptions in Section 130.37.020 (Noise Standards, Exemptions) above in this Chapter, noise standards established in this Chapter shall apply to all noise generating uses requiring discretionary review or ministerial permits, with the exception of existing and new single-unit residential dwellings on legal lots that are not within areas governed by an Airport Comprehensive Land Use Plan. (General Plan Policy 6.5.1.4, Acceptable Noise Levels, Protection of Noise-Sensitive Development).

The following definitions shall apply to this Chapter:

"Acoustic Specialist" means a person trained in acoustic sampling that is qualified to measure sound levels consistent with criteria contained within this article.

"Ambient Sound Level" means the composite of normal or existing sound from all sources, measured at a given location for a specified time of the day or night.

"A-weighting" means the scale for measuring sound that de-emphasizes low and high frequencies in order to simulate human hearing; indicated as dBA.

"Community Noise Equivalent Level (CNEL)" means a weighted average hourly noise level over a 24 hour day used specifically for airport and aircraft noise assessment.

"Day-Night Average Sound Level (Ldn)" means the dBA for a given area during a 24-hour day with a 10dB weighting applied to nighttime sound levels.

"Decibel" means a unit of relative loudness on a logarithmic scale that runs from zero for the least perceptible sound to 140 for sound that causes pain.

"Equivalent Noise Level (Leq)" means the average energy noise level determined by averaging the cumulative noise event levels during a specific period of time and expressing it in A-weighted decibels, or dBA.

"Fixed Sound Source" means a device or machine which creates sounds while fixed or stationary, including but not limited to residential, agricultural, industrial, and commercial machinery and equipment, pumps, fans, compressors, air conditioners and refrigeration equipment, and motor vehicles operated on private property.

"Maximum Sound Level (Lmax)" means the maximum instantaneous noise level measured on a sound level meter.

"Non-Transportation Noise Source" means industrial operations, commercial land uses, outdoor recreation activities and facilities, Heating, Ventilation and Air Conditioning (HVAC) units, schools, hospitals, and other outdoor land use.

"Sensitive Receptor" means a land use in which there is a reasonable degree of sensitivity to noise. Such uses include single- and multi-unit residential dwellings including frequently inhabited outbuildings, schools, hospitals, churches, rest homes, cemeteries, public libraries, and other sensitive uses as determined by the Director.

"Sound Level Meter" means an instrument meeting American National Standard Institute (ANSI) Standard S1.4A-1985 for Type 1 or Type 2 sound level meters, or an instrument and associated recording and analyzing equipment that will provide equivalent data.

"Transportation Noise Source" means traffic on public or private (non-county maintained) roadways, railroad line operations, and aircraft in flight.

An acoustic analysis prepared by an acoustic specialist shall be required prior to discretionary authorization or permit approval for the following uses:

A.

New noise-generating land uses likely to exceed the performance thresholds in the Tables in Section 130.37.060 (Noise Standards) below in this Chapter when proposed in areas adjacent to sensitive receptors. Noise sources may include industrial operations, outdoor recreation facilities, outdoor concerts and events utilizing amplified sound systems, commercial land uses, fixed sound sources, and other similar uses; or

B.

New noise-sensitive land uses proposed in areas exposed to existing or projected exterior noise levels likely to exceed the thresholds in the Tables in Section 130.37.060 (Noise Standards) below in this Chapter.

The following standards shall apply to all development projects for which an acoustic analysis is required:

A.

Noise sensitive land uses affected by non-transportation noise sources shall not exceed standards set forth in Table 130.37.060.1 (Noise Level Performance Standards for Noise Sensitive Land Uses Affected by Non-Transportation Sources) below in this Section:

Table 130.37.060.1—Noise Level Performance Standards for Noise Sensitive Land Uses Affected by Non-Transportation

Each of the noise levels specified above shall be lowered by five dBA for simple tone noises, noises consisting primarily of unamplified speech or music, or for recurring impulsive noises. These noise level standards do not apply to residential units established in conjunction with industrial or commercial uses, such as caretaker dwellings.

The Director can impose noise level standards which are up to five dBA less than those specified above, based upon a determination of existing low ambient noise levels in the vicinity of the project site.

The exterior noise level standard shall be applied as follows:

a.

In Community Regions, at the property line of the receiving property;

b.

In Rural Centers and Regions, at a point 100 feet away from a sensitive receptor or, if the sensitive receptor is within the Platted Lands Overlay (-PL) where the underlying land use designation is consistent with Community Region densities, at the property line of the receiving property or 100 feet away from the sensitive receptor, whichever is less; or

c.

In all areas, at the boundary of a recorded noise easement between affected properties.

B.

Transportation noise shall not exceed thresholds set forth in Table 130.37.060.2 (Noise Level Standards for Noise-Sensitive Land Uses Affected by Transportation Noise Sources) below in this Section:

Table 130.37.060.2—Noise Level Standards for Noise-Sensitive Land Uses Affected by Transportation Noise Sources

Playgrounds, Neighborhood Parks 70 - -

Notes 1  As determined for a typical worst-case hour during periods of use.

In Community Regions and Rural Centers:

(a)

Where the location of outdoor activity areas is not clearly defined, the exterior noise level standard shall be applied at the property line of the sensitive receptor.

(b)

For residential uses with front yards facing the identified noise source, an exterior noise level threshold of 65 dBA Ldn shall be applied at the dwelling facade in addition to the required threshold at the outdoor activity area.

In Rural Regions: An exterior noise level threshold of 60 dBA Ldn shall be applied at a 100-foot radius from the dwelling on lots five acres and larger. Those lots less than five acres shall have the noise level standards applied at the property line.

Where it is not possible to reduce noise levels in those outdoor activity areas limited to 60 dBA Ldn/CNEL thresholds using a practical application of the best-available noise reduction measures, an exterior noise threshold of up to 65 dBA Ldn/CNEL may be allowed provided that available exterior noise level reduction measures have been implemented and interior noise levels are in compliance with this table.

C.

Construction-related noise shall allow for exceptions to the evening and night time standards or other temporary exceedances of noise standards as may be approved by the Director, where necessary to alleviate traffic congestion and safety hazards, or where authorized by an approved permit.

Noise reduction measures shall be incorporated into the project design to reduce noise levels at or below the thresholds set forth in Tables in Section 130.37.060 (Noise Standards) above in this Chapter. Where applicable, the following specific requirements shall also apply:

A.

To meet noise threshold standards under Table 130.37.060.2 (Noise Level Standards for Noise-Sensitive Land Uses Affected by Transportation Noise Sources) above in this Chapter, where feasible, setbacks shall be the preferred method of noise abatement for residential projects located along U.S. Highway 50. Noise walls shall be discouraged within the foreground viewshed of U.S. Highway 50 and shall be discouraged in favor of less intrusive noise mitigation (e.g., landscaped berms, setbacks) along other high volume roadways.

B.

For outdoor concerts and events utilizing amplified sound system(s), a discretionary permit shall be required in the form of a Temporary or Conditional Use Permit, except for special events and marketing events that are allowed by right or with an administrative permit consistent with Chapter 130.44 (Ranch Marketing) or 130.40.400 (Wineries). Self-monitoring shall be performed to ensure that sound system levels are in compliance with those specified in the conditions of approval based on

the acoustic analysis. As a standard condition of approval for such use permits, failure to comply with sound system levels shall result in termination of the event for the duration of the period approved under the use permit and a moratorium on future events for the applicant or the property owner of two calendar years from the date of noncompliance. A second violation after such time shall result in revocation of the Conditional Use Permit, if applicable, and a permanent moratorium on future events for the applicant and property owner whether on that site or any other within the County.

(Ord. No. 5177, § 3, 6-20-2023)

For the purpose of evaluating conformance with the standards of this Chapter, noise levels shall be measured as follows:

A.

Use of Meter. Any noise measurement shall be made with a sound level meter using the A-weighted scale. Calibration of the measurement equipment utilizing an acoustical calibrator shall be performed immediately prior to recording any noise data.

B.

Ambient Sound Levels. Compliance with the above standards shall be determined by measuring the existing noise level with a sound level meter using slow response, with the sound source at issue remaining silent. The ambient sound level shall be determined based on the mean average of not less than three 20-minute measurements for any given time period. Additional noise measurements may be necessary to ensure that the ambient sound level is adequately determined.

C.

Measuring Exterior Noise Levels. Except as otherwise provided in this Chapter, exterior noise levels shall be measured at the property line of the affected noise-sensitive land use. Where practical, the microphone shall be positioned five feet above the ground and away from reflective surfaces.

D.

Measuring Interior Noise Levels. Interior noise levels shall be measured within the sensitive receptor, as defined in Section 130.37.040 (Noise Standards, Definitions) above in this Chapter, at points at least four feet from the wall, ceiling, or floor nearest the noise source, with windows in the normal seasonal configuration. The reported interior noise level shall be determined by taking the arithmetic average of the readings taken at the various microphone locations.