Initial Study MND - Sonoma County Agricultural Preservation and ...

Taylor MountainINITIAL STUDY/MITIGATED NEGATIVE DECLARATIONB.3.10 NoiseNOISEWould the project:a. Exposure of persons to or generation of noise levels in excess ofstandards established in the local general plan or noise ordinance,or applicable standards of other agencies?PotentiallySignificantImpactLess thanSignificantWithMitigationIncorporatedLess thanSignificantImpactNo Impactb. Exposure of persons to or generation of excessive groundbornevibration or groundborne noise levels?c. A substantial permanent increase in ambient noise levels in theproject vicinity above levels existing without the project?d. A substantial temporary or periodic increase in ambient noiselevels in the project vicinity above levels existing without theproject?e. For a project located within an airport land use plan or, wheresuch a plan has not been adopted, within two miles of a publicairport or public use airport, would the project expose peopleresiding or working in the project area to excessive noise levels?f. For a project within the vicinity of a private airstrip, would theproject expose people residing or working in the project area toexcessive noise levels?Significance criteria established by CEQA Guidelines, Appendix G.B.3.10.1 SettingCommunity noise levels are usually closely related to the intensity of human activity.Surrounding land uses dictate what noise levels would be considered acceptable orunacceptable. Environmental noise is composed of many frequencies, each occurringsimultaneously at its own sound pressure level. Frequency weighting combines the overallsound frequency into one sound level that simulates how an average person hears sounds. Thecommonly used frequency weighting for environmental noise is an A-weighted decibel (dBA).Noise levels are generally considered low when below 45 dBA, moderate in the 45 to 60 dBArange, and high above 60 dBA. Levels around 75 dBA are more common in busy urban areas,and levels up to 85 dBA occur near major freeways and airports. Noise levels above 45 dBA atnight can result in the onset of sleep interference. At 70 dBA, sleep interference effectsbecome considerable (U.S. EPA, 1974). The following setting focuses on specific noiseconditions in the Taylor Mountain Preserve area.Existing ConditionsThe majority of the Taylor Mountain Preserve is rural and physically separated from nearbyurban uses. Existing ambient noise levels are low, due to the current type and level of use atthe site. The northern area is near a residential neighborhood. The primary existing noisesources in the vicinity are the roadways around the perimeter of the property.Noise sensitive receptors are residences, schools, religious facilities, hospitals, and parks. Thenearest residences are over 200 feet from the area of the project site where staging areas may beFinal B-90 September 2012