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Bicycle and Pedestrian Plan Initial Study Existing noise levels throughout Pleasanton derive mainly from motor vehicles, trains, airplanes, and some heavy industrial uses. The "City of Pleasanton, 2006 Citywide Noise Monitoring Program, Existing Conditions Report" identifies noise levels throughout the city.' Significance Criteria The impact questions above constitute the significance criteria for this environmental topic. Discussion of Checklist Items Less Than Si. 'ficant: Impacts with Mii•ation Incor.orated. The Pleasanton Municipal Code limits construction related noise from any one piece of construction equipment to 83 decibels (dBA) with up to 86 dBA total" Note that such noise levels would be sporadic rather than continuous in nature because different types of construction equipment would be used throughout the construction process. As the receptor moves away from the noise source, the rate of attenuation (lessenin is about six dBA for every doubling of distance from a point source.` Average construction- related noise levels would generally be maintained below 80 dBA throughout project construction at distances of approximately 50 feet from the noise source. Distances of approximately 200 feet would generally maintain average noise Levels below 70 dBA. Construction due to implementation of the proposed Master Plan could cause temporary noise impacts on nearby land uses. Less- than Significant Impacts. The proposed Master Plan itself would not result in any construction or construction noise. Development due to the proposed Master Plan would not include any activities that would result in excessive groundborne vibration or noise. The trails, bicycle routes, and sidewalks are not expected to increase ambient noise levels in Pleasanton above existing ambient noise levels in the area. However, pedestrians, joggers, and bicyclists on trails proposed near freeways may be exposed to noise at levels above 70 dBA. Because the users of the proposed trails would be traveling, their exposure would be expected to be of limited duration and such impacts would be less than significant. No Impact. Although some of the trails are proposed within 2 miles of a public airport, the uses of the trail would be for recreational or transportation purposes. No residential or other sensitive uses are proposed as part of the proposed Master Plan. Mitigation. The City of Pleasanton shall implement the following mitigation measure during construction of projects resulting from implementation of the Master Plan: Construction noise The construction contractor shall locate stationary construction noise sources as far from adjacent occupied buildings as possible. If they must be located near existing residential uses, the contractor shall enclose these noise sources within temporary sheds. Illingworth Rodkin, "City of Pleasanton, 2006 Citywide Noise Monitoring Program, Existing Conditions Report," December 2006. A decibel (dB) is the standard unit of sound loudness; decibels are measured on a logarithmic scale where each increase in 10 dB multiplies the previous value by 10 (e.g., 60 dB is 10 time louder than 50 dB, while 70 dB is 100 times louder than 50 dB). A- weighted sound levels correlate with the way the human ear hears sound and compensates by a weighting of frequencies. This Initial Study refers to all sound levels as A- weighted sound levels, expressed in decibels as dBA. 9 Thus 86 dBA at 25 feet would attenuate to 80 dBA at 50 feet, 74 dBA at 100 feet, 68 dBA at 200 feet and 62 dBA at 400 feet while 83 dBA at 25 feet would attenuate to 77 dBA at 50 feet, 71 dBA at 100 feet, and 65 dBA at 200 feet. Revised 9/4/09 25 9/4/2009