Does anyone with experience in dam construction have familiarity with sand/gravel filters?
In my research I came across numerous papers including the
FEMA Technical Manual: Conduits Through Embankment Dams and
Filter Diaphragn Design Considerations that indicate anti-seep collars are old technology and continue to be used because �that�s the way it�s always been done�. The current �Best Practice� for controlling seepage is sand/gravel filters. These sound very similar to what Bob Lusk refered to in another thread as a �toe drain�.
P.S. Chapter 6 of the FEMA manual has the info on sand filters if you just want to download that part but the whole manual is interesting reading if you�re the construction type and have time to download 33 megs.
