Environmental Engineering Reference
In-Depth Information
stopped and authorities notified by the utility. The authorities then make recommendations on
how construction should proceed in order to manage or minimize impacts to the resource (PSC
Wisconsin 2011).
Noise and Light Impacts
During each phase of construction of a transmission line, noise will be generated by construction
equipment. Initially, vegetation in the right-of-way is cut using mowers, whole tree processors,
or chainsaws. Brush and logs may be chipped or burned in the right-of-way. Trucks are used to
haul away material that cannot be stockpiled or disposed of on-site and to bring in necessary
construction materials. Typical construction vehicles include bucket trucks, cranes or digger
derricks, backhoes, pulling machines, pole trailers, and dumpsters. Once transmission lines are
built, vibration or humming noise can be noticeable; it is, however, most often associated with
older transmission lines. It is usually the result of conductor mounting hardware that has loosened
slightly over the years and can be easily identified and repaired as part of line maintenance.
Other sounds caused by transmission lines are sizzles, crackles, or hissing noises that occur
during periods of high humidity. These are usually associated with high-voltage transmission
lines and are weather dependent, caused by ionization of electricity in moist air near the wires.
Though this noise is audible to those very close to transmission lines, it quickly dissipates with
distance and is easily drowned out by typical background noises. Ionization in foggy condi-
tions can also cause a corona, which is a luminous blue discharge of light usually where wires
connect to the insulators. Residential properties located in close proximity to a substation may
be affected by noise and light associated with operation of a new or enlarged substation (PSC
Wisconsin 2011).
Aesthetics
The overall aesthetic appearance of a transmission line is often unpleasant to many people, espe-
cially where proposed lines would cross natural landscapes and private properties. Tall or wide
structures may seem out of proportion and incompatible with agricultural landscapes or residential
neighborhoods. At fifty to 180 feet in height (Minnesota Electric Transmission Planning 2011),
transmission towers are visible for substantial distances. Landowners who have chosen to bury
electric distribution lines on their property may find transmission lines bordering their property
particularly disruptive to scenic views. Yet some people do not notice transmission lines or do not
find them objectionable from an aesthetic perspective.
Aesthetic impacts depend on the physical relationship of the viewer and the transmission line
(distance and sight line); the activity of the viewer (e.g., living in the area, driving through, or
sightseeing); and contrast between transmission structures and the surrounding environment, such
as whether a line stands out or blends in. A transmission line can affect aesthetics by removing a
resource, such as clearing fencerows or forest; intruding on the view of a landscape and degrad-
ing the surrounding environment; or changing the context of a view area and evoking an image
of industrialization in a previously rural area (PSC Wisconsin 2011).
Electric transmission lines may be routed to avoid areas considered scenic. Routes can be
chosen that pass through commercial or industrial areas or along land use boundaries. The
form, color, or texture of a line can be modified to somewhat minimize aesthetic impacts.
Planting vegetative screens to block views of a transmission line, leaving a right-of-way in
a natural state at road crossings, and piling brush from a cleared right-of-way so it provides
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