Environmental Assis for Orono Substation Expansion

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although significantly larger, is somewhat screened from the housing to the west by a hill or berm along the west side of Xcel Energy's property. The Project's transmission structures would contrast with the existing shorter wood transmission structures in the area. The substation would include appropriate and sufficient lighting within the substation area in the event of an emergency during low light or night time conditions. During normal operation all of the substation lights will be left off and the substation will be dark, unless required by local units of government for other purposes such as security. During emergencies lights would be needed to facilitate the safety of personnel if work occurs in low light or after sunset; routine maintenance work is typically scheduled during daytime hours (Xcel Energy, personal communication, November 10, 2011). Transmission structures are not lit. Mitigation Measures The primary mitigation strategy to minimize impacts to homes and businesses is avoidance through routing. No additional mitigation is proposed. The use of a property for a transmission facility does transfer ownership of one of the bundle of property rights from the property owner to the easement holder. This loss of a portion of the potential use of the property requires compensation of the property owner for the use of the property. Any potential impacts of property values would typically be mitigated through negotiation in an easement agreement between the applicants and the landowner. The use of double -circuit structures minimizes the number of structures and the width of right-of- way needed for the transmission portion of the Project, although the double -circuit structures are taller. Xcel Energy has stated it intends to minimize vegetation clearing to the extent possible and to work with landowners to identify visual concerns related to the Project and to develop suitable mitigation measures. Xcel Energy's current substation plans include building the substation partially into the adjacent hillside and establishing prairie landscaping and trees along the western edge of Xcel Energy's property (Appendix C). Xcel Energy is currently discussing with residents of the Hunt Farm neighborhood the possible addition of a berm along the western edge of the property to provide screening of the substation for residents of the neighborhood (Xcel Energy, June 7, 2011). 5.4 Noise Noise is measured in units of decibels (dB), or sound pressure level. The sound pressure level for purposes of human hearing is measured with the A -weighted decibel scale or dB(A). In general terms, a noise level change of 3 dB(A) is imperceptible to human hearing, a 5 dB(A) change is clearly noticeable, and a 10 dB(A) change is perceived as a doubling of noticeable sound. Cumulative noise increases occur on a logarithmic scale. Potential noise associated with the proposed project includes sources associated with construction and long-term operation of the proposed project. Estimates of some common sources of noise are presented in Table 5. Environmental Assessment PUC Docket E002/TL-11-223 Page 25