Embankment Drains
“A simple method of measuring the flow from a toe drain outfall is to catch the flow from the pipe in a container of known volume and to time how long it takes to fill the container. The flow rate is usually recorded in gallons per minute. Compare the amount of flow with the amount of flow anticipated for the current reservoir level based on previous readings. A drain that has no flow at all could simply mean that there is no seepage in the area of the dam serviced by the drain. However, an absence of flow could also indicate a problem. If a drain has never functioned, it could mean that the drain was designed or installed incorrectly. If it flowed at one time but has now stopped flowing, it may have become plugged. A plugged drain can be a serious problem because seepage may begin to exit down slope, or may contribute to internal pressure and instability. If possible, blocked drains should be cleaned so that the controlled release of seepage may be restored. Decreasing amounts of flow from a drain for the same reservoir level may indicate that the drain is becoming clogged. Conversely, a sudden increase in drain flow may indicate that the core is becoming less watertight, possibly as the result of transverse cracking. Recording drain flow rates and reservoir levels over time will help in assessing a dam’s seepage conditions”.[1]
Revision ID: 4943
Revision Date: 12/05/2022