SMALL DAMS PETITS BARRAGES

� A continuous vertical chimney drain, of 0-5 mm sand, from the base of the fill up to
normal reservoir water level + 0.20 to 0.30 meter, to avoid any risk of flow above it, under the
crest near the downstream face; this drain is usually built by digging out the fill with a shovel
every 5 or 6 layers that are compacted and carefully pouring the sand in;
� A finger drain discharge downstream, if possible independent of the drainage blanket
or draining strips, especially if the fill is not made of highly watertight materials; the finger drain
consist of lines of granular materials ( in general gravel surrounded by sand or a geotextile)
with a total cross-section that is more than sufficient to discharge the foreseeable flow. At
small reservoirs where H² v