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u <br />n <br />L <br />r <br />D <br />i <br />1 <br />i~ <br /> <br /> <br /> <br />r <br />C <br />Table 24-1 provides a rough comparison of the noise levels of some common noise <br />sources. <br />Table 24-1: Decibel Levels of Common Noise Sources <br />140 Jet Engine (at 25 meters) <br />130 Jet Aircraft (at 100 meters) <br />120 Rock and Roll Concert <br />110 Pneumatic Chipper <br />100 Jointer/Planer <br />90 Chainsaw <br />80 Heavy Truck Traffic <br />70 Business Office <br />60 Conversational Speech <br />50 Library <br />40 Bedroom <br />30 Secluded Woods <br />20 Whisoer <br />SOURCE: "A Guide to Noise Control in Minnesota" <br />Minnesota Pollution Control Agency (2008) <br />Along with the volume of traffic and other factors (i.e. topography of the area and <br />vehicle speed) that contribute to the loudness of traffic noise, the distance of a <br />receptor from a sound's source is also an important factor. Sound levels decrease as <br />distance from a source increases. The following rule of thumb regarding sound <br />decreases due to distance is commonly used: Beyond approximately 50 feet, each <br />time the distance between a line source (such as a road) and a receptor is doubled, <br />sound levels decrease by three decibels over hard ground, such as pavement or <br />water, and by 4.5 decibels over vegetated areas. <br />Noise standards vary based on the intended use of the impacted property. The State <br />noise standards are shown in Table 24-2. <br />Table 24-2: MPCA State Noise Standards -Hour <br />Sound Levels <br />Residential NAC-1 65 60 55 50 <br />' Commercial NAC-2 70 65 70 65 <br />Industrial NAC-3 80 75 80 75 <br />' The existing and planned land uses within the project area are a mixture of <br />residential, commercial and industrial land. As the standards for residential <br />properties (NAC-1) are the most stringent, this analysis will primarily consider the <br />' impacts of the development scenarios on existing residential properties in the area. <br />This analysis also considers only daytime noise impacts. <br />City of Elk River <br />Draft Alternative Urban Areawide Review <br />' August 2011 Page 82 of 90 <br />