Sandbagging for Flood Protection (Part 3)

"A sandbag dike must be built properly to prevent or reduce flood damage."

** Sealing the Dike **
The finished dike should be sealed with a sheet of plastic to improve water tightness. Spread a layer of soil or sand 1 inch deep and about 1 foot wide along the bottom of the dike on the water side. Lay polyethylene plastic sheeting so the bottom extends 1 foot beyound the bottom edge of the dike over the loose soil or sand. The upper edge should extend over the top of the dike. Poly sheeting at least 6 mils thick is perferred. It generally is available in 100-foot rolls from construction supply foms, lumberyards and farm stores. Do not put plastic sheeting urder the bags since that will increaste the potential for the dike to slide.

If more than one sheet of plastic is used, the poly sheeting should be placed from downstream to upstream and the next sheet upstream overlapped by at least 3 feet. Overlapping in this direction prevents the current from flowing under the overlap and tearing the poly loose.

Lay the pastic sheeting down very loosely. The pressure of the water will make the plastic conform easily to the sandbag surface. If the plastic is stretched too tightly. the water force could puncture it. Place a row of sandbags on the bootom edge of the plastic to form a waterlight seal along the water side. Place sandbags to hold down the top edge of the plastic. avoid puncturing the plastic with sharp objects or by walking on it.


** Controlling Seepage **
Use a sump or skimmer pump to remove water that permeates through the dike. A 5 -gallon pail with numerous holes drilled in the side and placed in a hole dug into the ground can be used as a sump to collect seepage water. Use ground fault circuit interrupters on circuits or extension cords to reduce the risk of electrocution.


** Disposing of Used Sand **
Floodwater is generally considered as polluter. so sand from bags exposed to flood water should not be used for childen's sand boxes. It can be used for typical construction applications.

This material is based upon work supported by the National Institute of Food and Agriculture, U.S.Department of Agriculture. under Agreement No.2009-41210-05965
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Thank you Detial From
"Kenneth Hellevang, Extension Engineer"
NDSU Extension Service North Dakota State University Fargo, North Dakota FEBRUARY 2011
For more information on this See www.ag.ndsu.edu