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874 Lewelling Blvd. <br />Noise Study <br />9 July 2018 <br />Page 4 of 8 <br /> <br /> <br /> <br />representative of noise exposure at the occupied residential uses (Levels 2 & 3) and are <br />included for information only. <br />Table 2 – Simultaneous Noise Measurement <br />METER START TIME <br />(DURATION) <br />NOISE LEVEL (dBA) <br />Leq L99 L90 L33 L10 L1 Min Max <br />ST-1 11:45 AM <br />(15 min) <br />64.7 46.9 53.8 64.7 67.9 72.8 45.4 77.1 <br />LT-1 74.6 - - - - - - - <br />ST-3 12:15 PM <br />(15 min) <br />52.9 43.8 46.1 51.6 55.7 63.2 42.6 67.5 <br />ST-4 50.2 44.2 45.2 48.6 51.9 60.1 43.8 66.7 <br />LT-1 75.0 - - - - - - - <br />Based on the methodology described above and including a 1 dB increase in noise levels for <br />upper floors, we predict the following existing traffic noise levels at the building facades: <br />▪ Unit 1 closest to Lewelling Blvd: 69 dBA CNEL <br />▪ All other units: 66 dBA CNEL or less <br />Future Noise Increases <br />According to the noise study conducted in 2015 for the San Leandro General Plan Update Draft <br />EIR (dated June 1, 2016), traffic noise on Lewelling Blvd. near the project site will increase by <br />0.6 dB by 2035. For the purposes of this analysis we are conservatively assuming a 1 dB <br />increase for future traffic noise levels, bearing in mind doubling the amount of traffic results in <br />a 3 dB increase which is highly unlikely for an established urban area . On this basis, we predict <br />the following future traffic noise levels at the building facades: <br />▪ Unit 1 closest to Lewelling Blvd: 70 dBA CNEL <br />▪ All other units: 67 dBA CNEL or less <br />RECOMMENDATIONS <br />The following calculation was used to determine the required sound transmission loss for <br />exterior façades in terms of Outdoor-Indoor Transmission Class (OITC). <br />OITC = Exterior Noise Level – Interior Noise Limit – 10log(S/A) + ADJ <br />Where: 10log(S/A) = reduction due to room effect <br />S = total room sound absorption (in Sabins) <br />A = exterior projected wall area (ft2) <br />Note: The term 10log(S/A) is typically close to zero <br />ADJ: up to 2 dB to account for non-diffuse noise sources <br />Based on this methodology, exterior facades must provide the following minimum OITC <br />performance to control exterior noise inside residential units to 45 dBA CNEL per the San <br />Leandro General Plan: <br />61