Today’s Erosion and Sediment Control Tip: #16
Today’s Erosion and Sediment Control Tip
Sediment Basins
require a device to dewater from the surface of the basin to remove the
cleanest (less turbid) water. This is often accomplished with a skimming
device that is designed to remove the stored construction runoff over a period
of 2 to 5 days. It is important that the skimmer be installed and
maintained properly. Skimmers must have a flexible connection to the rigid pipe
or riser system that goes through the dam. It should easily operate at
all design elevations. When placed on a principal spillway riser, the
pipe from the skimmer to the flexible connection should be about 1.5 x the
height of the riser structure. The flexible pipe outlet at the rigid pipe or
riser system through the dam should be at the standing pool elevation to ensure
the skimmer does not function below the required elevation. A rock pad should
be constructed for the skimming device to rest on when discharge is
complete. The skimmer may need checking occasionally to remove blockages
that could occur in the orifice in the skimmer. The skimmer must be
easily accessible even if the basin is full of water. A rope tied to the
skimmer could be used to pull the skimmer to the shoreline to do this.
Skimmers are the preferred mechanism for dewatering a
sediment basin. They must be designed, installed, and maintained to
function as planned so the runoff water from the basin is as clean as it can
be.
Erosion & Sediment Control Program Coordinator
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