Filter (Filter Zone)
Water
One or more layers of granular material which is incorporated in an embankment dam and is graded (either naturally or by selection) to allow seepage through or within the layers while preventing the migration of material from adjacent zones. A layer or combination of layers of pervious materials designed and installed in such a manner as to provide drainage, yet prevent the movement of soil particles due to flowing water.
A band or zone of granular material that is incorporated into a dam and is graded (either naturally or by selection) so as to allow seep water to flow through the filter to a drain layer without allowing the migration of fine material from the protected zone to the drain layer.
- — Dam Safety - Glossary of Terms retrieved 2014-06-01