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CHAPTER SIX
ELECTRICAL TRANSMISSION INFRASTRUCTURE
This chapter reviews the existing body of information on the
potential impacts of electrical transmission infrastructure on
airports and aviation. Electrical transmission infrastructure
includes transmission towers and the electrical lines that they
carry. This infrastructure supports the energy-generation tech-
nologies discussed in previous sections allowing the power
generated by the facility to be delivered to load centers in pop-
ulated areas. Potential impacts to airports and aviation from
transmission lines include physical penetration of airspace and
communication systems interference.
PHYSICAL PENETRATION OF AIRSPACE
Electric transmission lines and the towers that support them
can rise high enough to impact airspace. The transmission
towers that hold up the electrical lines are the tallest part of the
facility (see Figure 21). The towers are typically constructed
of a lattice steel frame and range between 50 and 180 ft in
height depending on the size of the electrical line being carried,
among other factors (IFC 2007), although transmission towers
exist that are as tall as 1,100 ft (Alimak HEK 2011).
COMMUNICATION SYSTEMS INTERFERENCE
Electromagnetic interference can be produced by high-voltage
transmission lines. The level of potential interference can vary
depending on the design voltage capacity of the line and the FIGURE 21 Transmission tower schematic (courtesy: HMMH).
distance of a sensitive receptor from the line. Leaks occurring
between the conductor and the insulators or metal fittings are
referred to as a corona discharge. Typically, concern about
electromagnetic release is confined to 345 kV or greater lines. EXAMPLES
MITIGATION OPTIONS Transmission towers associated with the Blythe Plant's elec-
trical line are proposed to be 145 ft tall. Shorter poles (90 ft
Mitigation options associated with electrical transmission are tall) will be employed along a 3,900-ft segment that passes
limited. The best option is to locate transmission infrastruc- through an airport influence area. After consultation with the
ture so as to avoid physical penetration of airspace and inter- Riverside County Airport Land Use Commission, the line
ference with communications systems. A design option is to was moved an additional 1,000 plus feet to the west (CEC
place corona rings on high-voltage lines at the conductor 2010b). The CEC required marking and lighting of all trans-
hardware interface points at the end of the insulators to reduce mission poles in the 3,900 ft airport influence area, which
the potential effects of electromagnetic interference. was not a condition of the FAA's No Hazard Determination.
