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

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Legacy Sunflower Apartments Page 79 Mitigated Negative Declaration – March 14, 2019 Noise Impacts to Off-Site Receptors Due to Project Generated Trips A worst-case project generated traffic noise level was modeled utilizing The FHWA Traffic Noise Prediction Model - FHWA -RD-77-108 was referenced to calculate the potential noise impact associated with project generated traffic. Roadway parameters for the traffic model calculations include average daily traffic volumes (ADTs), posted speeds, and vehicle distribution data as shown in Table 20. The potential off-site noise impacts were calculated for the “existing” condition and the “existing plus project” condition. Table 20 Project Average Daily Traffic Volumes and Roadway Parameters Roadway Segment Average Daily Traffic Volume1 Posted Travel Speeds (MPH) Site Conditions Existing Existing Plus Project Sunflower Avenue West of Flower Street/Sakioka Drive 21,149 21,720 45 Hard East of Flower Street/Sakioka Drive 19,620 20,634 45 Hard Flower Street North of Sunflower Avenue 9,773 9,836 40 Hard Vehicle Distribution (Heavy Mix)2 Motor-Vehicle Type Daytime % (7 AM - 7 PM) Evening % (7 PM - 10 PM) Night % (10 PM - 7 AM) Automobiles 75.54 14.02 10.43 Medium Trucks 48.00 2.00 50.00 Heavy Trucks 48.00 2.00 50.00 As shown, modeled Existing traffic noise levels range between 72.07-75.37 dBA CNEL and the modeled Existing Plus Project traffic noise levels range between 72.08-75.42 dBA CNEL at the right-of- way of each modeled roadway segment. Noise level increases associated with project generated traffic would be considered significant if noise levels were greater than the levels shown previously in Table 16. A shown below in Table 21 all modeled roadway segments are calculated to have noise level increases of approximately 0.01 to 0.1 dBA CNEL. Therefore, the increase in the noise level on area roadways would be less than significant. Transportation Noise Impacts to the Project The City of Santa Ana General has adopted interior and exterior noise level criteria for residential, institutional, and open space land uses. As shown previously in Table 16, exterior noise levels up to 65 dBA CNEL and interior noise levels of 45 dBA CNEL are considered acceptable noise levels for residential use. Exterior areas are defined as private yards of single-family homes, park picnic areas, school playgrounds, common areas, private open space, such as atriums on balconies, shall be excluded from exterior areas provided that sufficient common area is included within the project. Interior noise level requirements contemplate a closed window condition. Mechanical ventilation system or other means of natural ventilation shall be provided per the Uniform Building Code. 6-101