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TranslateNoise Compatibility Standards
Though instantaneous and short-term noise levels are frequently measured in A-weighted decibels (dBA), the most commonly used measure to evaluate land use compatibility related to airport operations is by considering a 24-hour average noise level weighted to take into account the increased sensitivity of people to noise during the evening night time hours. This metric is referred to as the Community Noise Equivalent Level (CNEL). The State Aeronautics Code requires the CNEL noise metric to be used when evaluating the noise impacts of aircraft operations.
Table 8A shows the proposed land use standards for noise compatibility for the public use airports in Sonoma County. With the exception of hotels and motels, all residential uses are unacceptable with noise above 65 CNEL. Residences are conditionally acceptable between 55 and 65 CNEL, subject to an outdoor-to-indoor noise level reduction of at least 25 to 30 decibels. Avigation easements and fair disclosure agreements are also required of new dwellings between 55 and 65 CNEL.
Schools, libraries, hospitals, and nursing homes are unacceptable in areas exposed to noise above 60 CNEL. They are conditionally acceptable between 55 and 60 CNEL, subject to a noise level reduction of 25 decibels. Churches, auditoriums, and concert halls are unacceptable at noise levels above 65 CNEL. These are required to provide for noise level reductions of 25 to 30 decibels between 55 and 65 CNEL. Transportation, parking, and cemeteries are acceptable at noise levels up to 70 CNEL. Above 70 CNEL, they are conditionally compatible, subject to a noise level reduction of 25 decibels in office areas and portions of buildings where the public is received.
Table 8
Airport Noise/Land Use Compatibility Standards Sonoma County Comprehensive Airport Land Use Plan
Residential
| Land Use Category | less than 55 CNEL | 55-60 CNEL | 60-65 CNEL | 67-70 CNEL | More than 70 CNEL |
|---|---|---|---|---|---|
| Rural (less than 1 d.u./ac) | A | C+4 | C+2 | U | U |
| Urban - low density (1-4 d.u./ac) | A | C+1 | C+2 | U | U |
| Urban - medium to high density (more than 4 d.u./ac) | A | C+1 | C+2 | U | U |
| Transient lodging, except hotels and motels | A | C+1 | C+2 | U | U |
| Mobile home parks | A | C+1 | C+2 | U | U |
Public
| Land Use Category | less than 55 CNEL | 55-60 CNEL | 60-65 CNEL | 67-70 CNEL | More than 70 CNEL |
|---|---|---|---|---|---|
| Schools, libraries, hospitals, nursing homes | A | C+3 | U | U | U |
| Churches, auditoriums, concert halls | A | C+3 | C+4 | U | U |
| Transportation, parking, cemeteries | A | A | A | A | C+3 |
Commercial & Industrial
| Land Use Category | less than 55 CNEL | 55-60 CNEL | 60-65 CNEL | 67-70 CNEL | More than 70 CNEL |
|---|---|---|---|---|---|
| Hotels & Motels | A | A | C+3 | C+4 | U |
| Offices, retail trade | A | A | C+3 | C+4 | U |
| Service commercial, wholesale trade, warehousing, light industrial | A | A | A | C+3 | C+4 |
| General manufacturing, utilities, extractive industry | A | A | A | A | A |
Agricultural & Recreational
| Land Use Category | less than 55 CNEL | 55-60 CNEL | 60-65 CNEL | 67-70 CNEL | More than 70 CNEL |
|---|---|---|---|---|---|
| Cropland | A | A | A | A | A |
| Livestock breeding, zoos | A | A | A | A | U |
| Parks and playgrounds | A | A | A | A | C+3 |
| Golf courses, riding stables, water recreation | A | A | A | A | C+3 |
| Outdoor spectator sports | A | A | A | C+5 | U |
| Amphitheaters | A | U | U | U | U |
- A = Acceptable land use.
- C = Land use is conditionally acceptable upon meeting compatibility criteria.
- U = Unacceptable land use. Land use is not permitted.
- An NLR* of at least 25 decibels is required. The granting of an avigation easement to the airport operator shall be required. The recording of a fair disclosure covenant shall also be required.
- An NLR* of at least 30 decibels is required. The granting of an avigation easement to the airport operator shall be required. The recording of a fair disclosure covenant shall also be required.
- Measures to achieve an NLR* of 25 decibels shall be incorporated into the design and construction of portions of these buildings where the public is received, office areas, or sleeping areas
- Measures to achieve an NLR* of 30 decibels shall be incorporated into the design and construction of portions of these buildings where the public is received, office areas, or sleeping areas.
- Sound reinforcement system is required.
- An exception is provided for construction of a single family dwelling on a legal lot of record if allowed by the underlying zoning. The dwelling should be located outside the 55 CNEL contour where feasible and noise reduction per note 1 above is required.
*NLR Outdoor-to-indoor noise level reduction in A-weighted decibels assuming doors and windows are closed.
Hotels, motels, offices, and retail trade are unacceptable at noise levels above 70 CNEL. Noise level reductions of 25 to 30 CNEL are required for these uses between 60 and 70 decibels. Service commercial, wholesale trade, warehousing, and light industrial are conditionally acceptable at noise levels above 65 CNEL, subject to noise level reductions of 25 to 30 decibels. General manufacturing, utilities, extractive industry, and crop farming are acceptable at all noise levels.
Livestock breeding, zoos, and outdoor spectator sports are unacceptable at noise levels above 70 CNEL. Parks, playgrounds, golf courses, riding stables, and water recreation are conditionally compatible with noise above 70 CNEL. A noise level reduction of 25 decibels is required in office areas and portions of buildings where the public is received. As highly noise-sensitive outdoor uses, amphitheaters are unacceptable at noise levels above 55 CNEL.