CCP 09-30-2002 - Laserfiche WebLink

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. . . In accordance with city ordinance 630,01, construction activities (i.e., construction noise) will be limited to daytime hours, from 7:00 a.m. to 9:00 p.m. during the week, and 8:00 a,m. to 9:00 p.m. on the weekend. Contractors will be required to ensure that equipment has been properly maintained and fitted with mufflers and other noise controls, as specified by the manufacturer. Traffic Noise Traffic is a common source of noise in a suburban setting and is regulated in Minnesota by the Minnesota Pollution Control Agency (MPCA) under Minnesota Statute 1l6.07 Subdivisions 2 and 4. The proposed project is located in a developing suburban setting with commercial, light industrial and residential land uses surrounding the project site. High traffic roads such as Lexington Avenue, Hamline Avenue and 1-694 are located adjacent to or close to the project site to the east, west and south, respectively. A detailed noise analysis was completed to assess existing traffic noise levels in the project area and to determine what effect the proposed project will have on future noise levels. The proposed project will increase traffic volumes in some parts of the study area. Increases in traffic can result in increased noise levels, which can be perceived as an annoyance by adjacent residents. The noise analysis consisted of monitoring existing noise levels at adjacent residential receptor sites and predicting future noise levels using computer modeling. Noise Analvsis Noise is defined as any unwanted sound. Sound travels in a wave motion and produces a sound pressure level. This sound pressure level is commonly measured in decibels. Decibels (dB) represent the logarithmic increase in sound energy relative to a reference energy level. A sound increase of 3 dB is barely perceptible to the human ear, a 5 dB increase is clearly noticeable, and a 10 dB increase is heard as twice as loud. For example, if the sound energy is doubled (e.g., the amount of traffic doubles), there is a 3 dB increase in noise, which is just barely noticeable to most people. On the other hand, if traffic increases to where there is 10 times the sound energy level over a reference level, then there is a 10 dB increase and it is heard as twice as loud. To approximate the way that an average person hears sound, an adjustment, or weighting, of the high- and low- pitched sounds is made. The adjusted sound levels are stated in units of "A-weighted decibels" (dBA). In Minnesota, traffic noise impacts are evaluated by measuring and/or modeling the traffic noise levels that are exceeded 10 percent and 50 percent of the time during the hours of the day and/or night that has the heaviest traffic. These numbers are identified as the LIO and Lso levels. For example, an LlO value of 65 decibels means that the noise level was at or greater than 65 decibels during 10 percent of the measurement period (i.e., more than 6 minutes per hour). Guidant Campus Master Plan Draft AUAR - 48- September 2002