Orono Substation Expansion - Enviromental Assessment (1)

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Table 14: Calculated Magnetic Fields (mG)for Proposed Orono 115 kV Transmission Line ' (3.28 feet above ground) System Current Distance to Proposed Centerline(feet) Segment Condition (Amps) -300 -200 -100 -75 -50 -25 0 25 50 75 100 200 300 Single Pole Peak 250 0.44 0.95 3.14 4.83 8.04 14.30 22.62 19.15 10.94 6.32 3.95 1.09 0.49 H-Post Vertical 115 kV Single Circuit Average 150 0.26 0.57 1.89 2.90 4.82 8.58 13.57 11.49 6.37 3.79 2.37 0.65 0.29 Single Pole Davit Arm Peak 250 0.04 0.11 0.69 1.38 3.18 7.86 12.82 7.74 3.08 1.33 0.66 0.10 0.04 115 kV/115kV Double Circuit Average 150 0.02 0.07 0.42 0.83 1.91 4.72 7.69 4.64 1.85 0.80 0.39 0.06 0.02 Single Pole Davit Arm 115 kV/115kV Double Peak 250 0.85 1.57 5.06 8.37 16.37 39.44 69.82 35.80 12.38 5.22 2.60 0.40 0.21 Circuit Dist. w/Dist.Under Build Average 150 0.81 1.50 4.77 7.84 15.28 37.17 67.02 34.09 11.81 5.08 2.61 0.45 0.22 Single Pole Peak 250 0.44 1.00 3.91 6.64 12.95 27.41 38.42 27.68 13.22 6.85 4.08 1.09 0.50 Y-Frame 115 kV Single Circuit Average 150 0.26 0.60 2.35 3.99 7.79 16.67 24.0 16.84 7.95 4.11 2.45 0.66 0.30 Note:The assumed peak and average line loading assumed for these calculations is the estimated flow of 50MVA. Source:Xcel Energy,June 7,2011;Xcel Energy,personal communication,November 22,2011 The maximum estimated magnetic field generated by the proposed transmission line would be 38.42 , mG directly below a 115 kV/115 kV double-circuit transmission centerline at 3.28 feet above ground, significantly below the 830 mG general public magnetic field guideline established by ICNIRP. The right-of-way required for the proposed project is 75 feet (37.5 feet on each side of ' centerline);the highest estimated magnetic field at a distance of 75 feet from the transmission line centerline would be approximately 1.3 to 1.4 mG. At 300 feet from the transmission centerline the magnetic field level drops to a maximum of 0.5 mG,at the lower end of the average background magnetic field of a typical home of 0.5 mG to 4 mG (EPA, 1992). Based upon current scientific evidence,no adverse effects from electric fields or magnetic fields on health are expected for persons living or working at locations along or near the proposed project. The Commission has consistently found that there is insufficient evidence to demonstrate a causal relationship between EMF exposure and any adverse human health effects. Below are some references to recent Commission proceedings relating to high-voltage transmission lines and the issue of electric fields and magnetic fields: ti 120. The absence of any demonstrated impact by electric field and magnetic field exposure supports the conclusion that there is no demonstrated impact on human health and safety. No adverse effects from electric fields and magnetic fields on health are expected for persons living or working at locations along or near the proposed Project. (Minnesota Public Utilities Commission,2010,Finding 120) 40. The issue of electric and magnetic fields was discussed in the environmental assessment. A number of national and international health agencies(The Minnesota Department of Health, The World Health Organization, The National Institute of Environmental Health Sciences)have generally concluded in their research that there is insufficient evidence to prove a connection between electric and magnetic fields exposure and health ffectr. Research has not been able to establish a cause and effect relationship between exposure to magnetic fields and human disease, nor a plausible biological mechanism by which exposure to electric and magnetic fields could cause disease. No Minnesota regulations have been established pertaining to magnetic Environmental Assessment PUC Docket E002/TL-11-223 Page 36