Chimney Drain : A vertical structure of free-draining material (usually coarse sand or gravel) within an embankment placed to intercept and control seep water. See also: "Filter"
State of Nevada Division of Water Resources (NDWR), Dam Safety - Glossary of Terms, NV, USA 2013. http://water.nv.gov/engineering/Dams/Glossary.cfm, (Dam Sfty - Amer) {891}