Spanish term (edited): tierras de aportaci�n

Clear all vegetation from the area that will be disturbed, ensuring that natural vegetation below the spillway outlet and on the inflow areas is not disturbed by machinery, vehicles or livestock. 3. Remove topsoil from the excavation and dam wall site, and stockpile it below the wall for later respreading. 4. Construct a cut-off trench - a trench dug below ground level at least 300mm into the impervious material the embankment will be placed on. Clay from the excavation must be placed into the trench and compacted, forming a watertight barrier preventing seepage passing under the dam.