Agenda - Council - 06/25/2013 - Laserfiche WebLink

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Enterprise Park to Crooked Lake 115 kV Transmission Line March 2012 Environmental Assessment Based on the model, substation noise level from the Enterprise Park Substation will attenuate to 50 dBA at a distance of approximately 51 feet from the transformer. The nearest NAC 1 receptor will be the Anoka Technical College, which is approximately 450 feet from the Enterprise Park Substation, and at this distance, the noise level will be approximately 31 dBA. Noise levels will be significantly lower inside the buildings where the educational services occur. Mitigation - Noise The MPCA regulates noise limits in the state of Minnesota. Utilities must conform to the standards of these noise limits The Applicant has stated that the substation substation modifications will be designed to emit noise levels that will attenuate to levels lower than the MPCA noise limits at the nearest receptors. Transmission line noise levels are not predicted to exceed the MPCA noise standards outside the right-of-way for all noise area classifications. Substation noise will not exceed applicable limits, including the MPCA noise limits For noise generated during construction, the Applicant would be required by state regulation to adhere to local ordinances dictating when noise can be generated (e.g., daytime only) from construction —related activities. It is expected that noise from construction would be intermittent and temporary in nature. The applicant has stated it will design the alignment to minimize the removal of trees. Trees provide minimal noise mitigation. It takes approximately a 100-foot wide strip of trees with heavy dense undergrowth to provide a 5 dB reduction in sound levels. A 6 dB change in sound is barely perceptible to the human ear. The trees north of the MnDOT facility entrance road are up to 200 feet wide and undergrowth may be sufficiently dense in the summer to provide some noise mitigation to a receptor northwest of the MnDOT facility (e.g., the strip mall east of 7th Avenue). Cutting this 200-foot wide stand back by 35 feet would not result in a perceptible change in the noise levels. The stand of trees south of the MnDOT entrance road is not sufficiently wide enough and there is no undergrowth to provide any perceptible noise mitigation. Accordingly, cutting these trees are not expected to result in a perceptible noise increase. 5.1.4. Interference with Utility Systems and Public Services Under certain circumstances, corona from transmission line conductors can generate electromagnetic "noise" at the same frequencies that radio and television signals are transmitted. This noise can cause interference with the reception of these signals depending on the frequency and strength of the radio and television signal. Television interference is rare, but may occur when a large transmission structure is aligned between the receiver and a weak distant signal, creating a shadow effect. Loose and/or damaged hardware may also cause television interference. Tightening loose hardware on the transmission line usually resolves the interference issue. If radio interference from transmission line corona does occur, satisfactory reception from AM radio stations presently providing good reception can be obtained by adjusting the receiving antenna. Moreover, AM radio frequency interference typically only occurs 28