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Noise standards for land use compatibility are stated in terms of the Community Noise Equivalent Level <br />(CNEL) and the Day -Night Average Noise Level (Ldn). CNEL is a 24-hour weighted average measure <br />of community noise. CNEL is obtained by adding five decibels to sound levels in the evening (7:00 PM <br />to 10:00 PM), and ten decibels to sound levels at night (10:00 PM to 7:00 AM). This weighting <br />accounts for the increased human sensitivity to noise during the evening and nighttime hours. Ldn is a <br />very similar 24-hour average measure that weights only the nighttime hours. <br />It is widely accepted that the average healthy ear can barely perceive changes of 3 dBA; a change of 5 <br />dBA is readily perceptible, and an increase (decrease) of 10 dBA sounds twice (half) as loud. This <br />definition is recommended by the California Department of Transportation's Technical Noise <br />Supplement to the Traffic Noise Analysis Protocol (2013). <br />Ambient Noise Measurements <br />The existing, or ambient, noise levels in the project area were taken to document the ambient noise <br />levels in the project area. The short-term noise measurements included four (4) 10-minute daytime <br />measurements sting that were taken between 12:18 PM and 1:36 PM on January 18, 2019. The <br />locations of the four noise measurements are shown on Figure 16. A summary or the short-term <br />ambient noise levels are shown in Table 14. As shown, the ambient noise levels range between 55.9 <br />and 71 dBA 4q. The dominant noise sources in the project area were from motor vehicles traveling on <br />Sunflower Avenue, Flower Street, and other surrounding roadways and a school bus back-up alarm. <br />Table 14 <br />Short -Term Noise Measurement Summary (dBA) <br />Daytime <br />Site Location <br />Time Started <br />Leq <br />Lmax <br />Lmin <br />L(2) <br />L(8) <br />L(25) <br />L(50) <br />NM1 <br />12:18 PM <br />55.9 <br />78.7 <br />46.3 <br />58.1 <br />53.6 <br />50.8 <br />49.5 <br />NM2 <br />12:46 PM <br />71.0 <br />80.2 <br />49.7 <br />78.5 <br />77.1 <br />71.7 <br />65.0 <br />NM3 <br />1:05 PM <br />69.6 <br />81.0 <br />48.8 <br />76.8 <br />74.2 <br />70.5 <br />66.3 <br />NM4 <br />1:26PM <br />58.5 <br />75.0 <br />50.6 <br />63.3 <br />60.8 <br />58.9 <br />56.8 <br />Regulations <br />Federal <br />The U.S. Environmental Protection Agency (EPA) Office of Noise Abatement and Control was originally <br />established to coordinate federal noise control activities. After its inception, EPA's Office of Noise <br />Abatement and Control issued the Federal Noise Control Act of 1972, establishing programs and <br />guidelines to identify and address the effects of noise on public health, welfare, and the environment. <br />In response, EPA published Information on Levels of Environmental Noise Requisite to Protect Public <br />Health and Welfare with an Adequate Margin of Safety (Levels of Environmental Noise). The Levels of <br />Environmental Noise recommended the Ldn should not exceed 55 dBA outdoors or 45 dBA indoors to <br />prevent significant activity interference and annoyance in noise -sensitive areas. <br />In addition, the Levels of Environmental Noise identified five (5) dBA as an "adequate margin of safety" <br />for a noise level increase relative to a baseline noise exposure level of 55 dBA Ldn (i.e., there would <br />not be a noticeable increase in adverse community reaction with an increase of five dBA or less from <br />this baseline level). The EPA did not promote these findings as universal standards or regulatory goals <br />Legacy Sunflower Apartments Page 71 <br />Mitigated Negative Declaration - March 14, 2019 <br />751-157 <br />