Hydroelectricity - Energy Policy Analysis: A Conceptual Framework - page 148

information on the approximate profile of the bedrock surface where it is overlain by overburden,
and the location and nature of any major faults or weak zones in the foundations and abutments
(B.C. Hydro 1981, 3). Although equipment required for geophysical surveys and small-bore core
drilling can be transported to remote areas by helicopter, tunneling and heavy drilling equipment
is too heavy and must be moved by ground transport. Consequently, the most significant envi-
ronmental costs of hydroelectric site selection often attend construction of new roads in roadless
areas and core drilling for samples, having impacts similar to those described for coal exploration
in Chapter 2. Exploration causes soil and vegetation impacts that disturb wildlife habitat, possibly
including endangered species, in addition to noise generated from drills and heavy equipment.
Areas of greatest disturbance include drill sites, helipads, camps, and adit portal (tunnel) areas
where ground disturbance occurs (B.C. Hydro 1981, 11).
Extensive exploration is also required to determine the source, nature, and extent of natural
construction materials such as gravel, sands, silts, and clays, undertaken with small trenching
equipment, backhoes, augers, or hammer drills where deposits are deep. Continuous samples of
coarse-grained soils in deep overburden deposits are required to determine the grain size distribution
of the material and assess its suitability for construction purposes and its strength as foundation
material (B.C. Hydro 1981, 4).
Construction
Construction of a new hydroelectric generating facility generally involves use of bulldozers, trucks,
and shovels to rearrange the terrain in a manner that exposes bedrock upon which concrete footings
may be poured. This displaces or destroys potential archeological sites, wildlife, and habitat, alters
current land uses, and permanently changes the general topography of the area. Trees and other
vegetation must be removed from the entire area of a reservoir or they will create problems for boat
navigability in shallows after inundation, and their decomposition may constitute a major source
of methane emissions, which contribute to climate change (IEA 2011; Bergerson and Lave 2002).
During construction, roads are built to handle heavy equipment, increasing dust particulate emis-
sions that may impair air quality. In addition to the dam and reservoir, power plant buildings and
an electrical substation must be constructed, usually near the base of any impoundment structure.
Operation of bladed Caterpillar tractors, drill rigs, and backhoes can have a severe and irreversible
effect on any previously unidentified archaeological resources (B.C. Hydro 1981, A-3).
Construction of hydroelectric power generating dams requires the use of tremendous quanti-
ties of concrete and steel, which are manufactured at other locations from limestone and iron
ore mined elsewhere. Combustion of fossil fuels is required during production processes for
heating limestone to make concrete and steel components of dams and generating equipment,
on a par with manufacturing processes for preparing materials to construct large buildings and
other structures.
Operation
Impoundment dams and powerhouse operations essential to hydropower plants cause the greatest
costs to the environment. Changes in river conditions and land and vegetation bordering water
bodies caused by dams and powerhouse turbines may significantly affect fish and wildlife popula-
tions. The impacts of large dams are wide-ranging, but even small dams can have large detrimental
effects on the health of regional fish populations. The impacts of any hydroelectric dam depend
upon many factors, including location of the dam, facility design, sensitivity of the local environ-