associated problems is addressed in ICOLD (1970) and in Fell, Mac-
Gregor and Stapledon (1992). As specific examples, investigations and
conclusions drawn for Cow Green reservoir (UK) are described by
Kennard and Knill (1969), and the initial leakage losses at May reservoir
(Turkey) are discussed by Alpsü (1967).
Investigation of the reservoir margins to confirm the stability of poten-
tially vulnerable areas, e.g. adjacent to the intended dam, is conducted as
required. The availability of possible construction materials, e.g. suitable
fills, sources of aggregates etc., is also assessed in considerable depth.
Hydrological studies are continued as necessary to confirm and
extend the results of the initial investigations. In view of their very special-
ist nature they are not considered further here; reference may be made to
Thomas (1976) and to Chapters 4 and 8 for details.
1.6.2 Dam site evaluation – generalThe viability of the preferred dam site identified in a reservoir feasibility
study must be positively established. Extensive investigations are con-
ducted to confirm that the site can be developed on the desired scale and
at acceptable cost. The nature of the soil and rock formations present,
critical to foundation integrity, must be proved by subsurface exploration.
Emphasis is placed upon confirmation of site geology and geotechnical
characteristics, and on the evaluation of sources of construction materials
(Sections 1.6.3–1.6.5).
Foundation competence is determined by stability, load-carrying
capacity, deformability, and effective impermeability. All are assessed in
relation to the type and size of dam proposed (Section 1.6.4).
In the case of a difficult site, the site evaluation programme can be pro-
tracted and expensive. Expenditure may be of the order of 1% up to, excep-
tionally, 2.5 or 3% of the anticipated cost of the dam. The scope of individual
aspects of an investigation reflects circumstances unique to the site. The
investigation may also relate to a specific type of dam if site conditions are
such that options are restricted, e.g. by depth of overburden (Section 1.6.6).
Only the general principles underlying dam site evaluation can be
presented here. A comprehensive review is provided in Thomas (1976),
with outline summaries of example cases. An indication of the interaction
which develops between site evaluation, local circumstance and type of
dam is given in Bridle, Vaughan and Jones (1985), Coats and Rocke
(1983) and Collins and Humphreys (1974) for embankment dams, or Bass
and Isherwood (1978) for a concrete dam and Kennard and Reader (1975)
for a composite dam, part concrete and part embankment. Walters (1974)
presents simplified but informative summaries of site geology in relation to
an international selection of dams.