Mendocino County Municipal Code Appendix C Exterior Noise

Exterior Noise Limit Standards

(Levels not to be exceeded more than thirty (30) minutes in any hour)

Receiving Land Use Category 3,4	Time Period	Noise Level Standards (dBA) 1,2	Noise Level Standards (dBA) 1,2
Receiving Land Use Category 3,4	Time Period	Rural/Suburban	Urban/Highways 5
One and Two Family	10:00 p.m.—7:00 a.m.	40	50
Residential	7:00 a.m.—10:00 p.m.	50	60
>Multifamily	10:00 p.m.—7:00 a.m.	45	55
Public Spaces	7:00 a.m.—7:00 p.m.	50	60
Limited Commercial	10:00 p.m.—7:00 a.m.	55	55
Some Multifamily	7:00 a.m.—10:00 p.m.	60	60
Commercial	10:00 p.m.—7:00 a.m.	60	60
	7:00 a.m.—10:00 p.m.	65	65
Light Industrial	Any time	70	70
>Heavy Industrial	Any time	75	75
Adjustments to Noise Level Standard	Adjustments to Noise Level Standard	Adjustments to Noise Level Standard	Adjustments to Noise Level Standard
Duration	Duration	Duration	Duration
L 50	30 minutes per hour	Standard	Standard
L 25	15 minutes per hour	Standard + 5 dB	Standard + 5 dB
L 0	Maximum permissible level	Standard + 20 dB	Standard + 20 dB
Character	Tone, whine, screech, hum, or impulsive, hammering, riveting, or music or speech	Standard + 5 dB	Standard + 5 dB
Ambient Level 1	Existing ambient L 50 , L 25	Standard + 5 dB	Standard + 5 dB
	Existing ambient L 0	Existing maximum	Existing maximum

Interpretive Footnotes

When an acoustical study demonstrates that ambient levels exceed the noise standard, then the ambient levels become the standard.
Higher noise levels may be permitted for temporary, short-term or intermittent activities when no sensitive or residential uses will be affected.
County staff shall recommend which receiving land use category applies to a particular project, based on the mix of uses and community noise levels. Industrial noise limits intended to be applied at the boundary of industrial zones, rather than within industrial areas.
The "rural/suburban" standard should be applied adjacent to noise sensitive uses such as hospitals or convalescence homes.
"Highways" apply to roads and highways where average daily traffic (ADT) exceeds ten thousand (10,000).

(Ord. No. 4017 (part), adopted 1998)

MENDOCINO COUNTY

ZONING ORDINANCE

Title 20—Division II of The Mendocino County Code

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