ABSTRACT
Galleries or tunnels are sometimes excavated into abutments and foundations to provide access for drilling drain holes and grout holes into the foundation or into the embankment-foundation contact. However, the criteria of quality for embankment dam sites may differ from those for concrete dams and encompass a much broader range of acceptable conditions. In a few cases vertical faces of limited height and width may be tolerated; however, at most sites a sloping core contact area is provided by rock excavation if necessary. Sometimes, the entire core contact foundation area is covered with a thin layer of broomed slush grout and then placing and compacting the first layer of embankment material while the grout is still plastic. As with the foundation treatment, the degree of improvement is greater beneath the impervious core than beneath the outer shells, and the rock surfaces in the abutments receive similar treatment with respect to cleaning and filling defects as in the foundation area.
