6 - GPA19-01; AA19-01_651 W SUNFLOWER AVENUE

Home Browse Search

Legacy Sunflower Apartments Page 71 Mitigated Negative Declaration – March 14, 2019 Noise standards for land use compatibility are stated in terms of the Community Noise Equivalent Level (CNEL) and the Day-Night Average Noise Level (Ldn). CNEL is a 24-hour weighted average measure of community noise. CNEL is obtained by adding five decibels to sound levels in the evening (7:00 PM to 10:00 PM), and ten decibels to sound levels at night (10:00 PM to 7:00 AM). This weighting accounts for the increased human sensitivity to noise during the evening and nighttime hours. Ldn is a very similar 24-hour average measure that weights only the nighttime hours. It is widely accepted that the average healthy ear can barely perceive changes of 3 dBA; a change of 5 dBA is readily perceptible, and an increase (decrease) of 10 dBA sounds twice (half) as loud. This definition is recommended by the California Department of Transportation’s Technical Noi se Supplement to the Traffic Noise Analysis Protocol (2013). Ambient Noise Measurements The existing, or ambient, noise levels in the project area were taken to document the ambient noise levels in the project area. The short-term noise measurements included four (4) 10-minute daytime measurements sting that were taken between 12:18 PM and 1:36 PM on January 18, 2019. The locations of the four noise measurements are shown on Figure 16. A summary or the short-term ambient noise levels are shown in Table 14. As shown, the ambient noise levels range between 55.9 and 71 dBA Leq. The dominant noise sources in the project area were from motor vehicles traveling on Sunflower Avenue, Flower Street, and other surrounding roadways and a school bus back-up alarm. Table 14 Short-Term Noise Measurement Summary (dBA) Daytime Site Location Time Started Leq Lmax Lmin L(2) L(8) L(25) L(50) NM1 12:18 PM 55.9 78.7 46.3 58.1 53.6 50.8 49.5 NM2 12:46 PM 71.0 80.2 49.7 78.5 77.1 71.7 65.0 NM3 1:05 PM 69.6 81.0 48.8 76.8 74.2 70.5 66.3 NM4 1:26PM 58.5 75.0 50.6 63.3 60.8 58.9 56.8 Regulations Federal The U.S. Environmental Protection Agency (EPA) Office of Noise Abatement and Control was originally established to coordinate federal noise control activities. After its inception, EPA’s Office of Noise Abatement and Control issued the Federal Noise Control Act of 1972, establishing programs and guidelines to identify and address the effects of noise on public health, welfare, and the environment. In response, EPA published Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety (Levels of Environmental Noise). The Levels of Environmental Noise recommended the Ldn should not exceed 55 dBA outdoors or 45 dBA indoors to prevent significant activity interference and annoyance in noise-sensitive areas. In addition, the Levels of Environmental Noise identified five (5) dBA as an “adequate margin of safety” for a noise level increase relative to a baseline noise exposure level of 55 dBA Ldn (i.e., there would not be a noticeable increase in adverse community reaction with an increase of five dBA or less from this baseline level). The EPA did not promote these findings as universal standards or regulatory goals 6-93