Agenda - 11-22-2004-c1 - Laserfiche WebLink

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-- 2B Attachment 3 Environmental Sound Page 13 commonly called the "Levels Document," provided tables to help evaluate problems and potentialfornoise complaints based on DNL, These tables were based mostly on experiences in densely populated urban azeas, It was recognized that the measured DNL in some cases would have to be adjusted or "normalized" before comparing to criteria to achieve an accurate assessment For instance, it was recommended that 10 dB be added to the measured DNL in a "quiet suburban or rural community (remote from Large cities and from industrial activity and trucking.)" Unfortunately, some of the most widely applicable Federal guidelines and regulations fail to recognize this need to tailor the criteria to the circumstances. The U.S. Department of Housing and Urban Affairs (HiJD) has noise criteria to evaluate whether it will fund housing in an area HUD drew upon a study by Ted Schultz relating the percentage of people highly annoyed by noise to the DNL where they Lived. HUD recognized it desirable to set the limit at DNL 60 dBA, corresponding to noise expected m an area with a population density of about 6000 people per square mile, However, HUD needed to build housing is more densely populated and noisier locations, Due to economic considerations, the limit was set at a DNL of 65 dBA. This corresponds to a level normally expected in an area of 20,000 people per square mile, Levels above DNL 65 dBA aze considered normally unacceptable by HUD, and not a desirable condition. Due to needs for housing in evennoisierazeas, exceptions are made.. Extra sound insulation is required for homes in the noisier areas. Areas with DNL 60 to 65 dBA aze considered "normally acceptable," and those under DNL 60 dBA aze "clearly acceptable," The Federal Aviation Administration and the Deparknent ofDefense have adopted DNL 65 as their goal and funding for noise control. They do not recognize noise impacts from aircraft or military activities below this. The Federal Highway Administration criterion for funding is a loudest hour of 67 dBA, This is comparable to a DNL of 66-68 dBA in most cases. Funding can be provided in some cases for very major noise increases that do not reach this level, Contrasted to these are the criteria used to evaluated railroad noise by the Federal Transit Administation, the FederalRailwayAdministrafion, and the Surface TransportationBoard.. They consider a project noise of DNL 55,5 dBA to be an impact on an azea with an existing DNL of 55 dBA. A project with DNL of 62 dBA is considered a severe impactin such an area. In very quiet areas, transit projects with DNL 55 dBA or less can be considered a severe impact The American Public Transit Association also has a further criteria based on maximum level during a passby, ranging from 70 dBA for single family homes in low-density quiet areas to 80 dBA for multifamily azeas in already noisy high-density areas. The Federal Energy Regulatory Commission regulates the noise of pipeline compression stations and requires that they not exceed DNL 55 dBA at any pre-existing residential location.