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- II - <br /> IV. Analysis of the Noise and Vibration Levels <br /> A. Existing Noise Levels <br /> To determine the existing noise environment at the site. continuous recordings of <br /> the sound levels were made at two locations. Location I was 45 ft. from the centerline of <br /> Stanley Boulevard corresponding to the planned minimum setback the homes from the <br /> road. Location 2 was 75 ft. from the centerline of the railroad tracks. This location was <br /> chosen for security of the sound measuring equipment. the measurements were made on <br /> March 10-13. 2009 using Larson-Davis 812 Precision Integrating Sound Level Meters. <br /> The meters yield. by direct readout, a series of descriptors of the sound levels versus time. <br /> The measured descriptors included the Li. Lit,. 1.50. and Lw. i.e.. those levels that are <br /> exceeded 1%. 10%. 50%. and 90% of the lime. Also measured were the maximum and <br /> minimum levels. and the continuous equivalent-energy levels (Leg). which are used to <br /> calculate the DNL. The measurements were made for a total period of 24 hours at each <br /> location and included recordings of the noise levels during representative hours of the <br /> daytime and nighttime periods of the DNL index. The results of the measurements are <br /> shown in the data table in Appendix C. <br /> As shown in the tables. the Legs at Location 1 measured on the first day at 45 ft. <br /> from the centerline of Stanley Boulevard ranged from 57.7 to 66.7 dBA during the <br /> daytime and from 41 .0 to 61.2 dBA at night. On the second day of measurements, the <br /> Leg's ranged from 57.5 to 65.1 dBA during the daytime and front 41.7 to 62.1 dRA at <br /> night. On the third day of measurements. the Leg's ranged from 56.4 to 63.2 dBA during <br /> the daytime and from 40.5 to 64.9 dBA at night. These sound levels were significantly <br /> influenced by rail operations. <br /> The noise levels at Location 2 measured on the first day at 75 ft. from the railroad <br /> tracks ranged front 43.2 to 76.9 dBA during the daytime and from 36.1 to 71.9 dBA at <br /> night. On the second day of measurements, the Leg's ranged from 43.5 to 75.2 dBA <br /> during the daytime and front 39.3 to 74.6 dB.A at night. On the third day_ of <br /> measurements. the Legs ranged from 44.2 to 70.8 dBA during the daytime and from 35.1 <br /> to 77.0 dBA at night <br />