University of Wisconsin-Extension
Standing
water from melting snow or heavy rains can flood basements
and damage yards, wells, feed supplies, machinery and other
property. Flooding is more apt to occur in areas with poor
surface drainage, malfunctioning drainage systems or ice dams.
A
1- to 3-foot-high sandbag or earth dike offers protection
from shallow flooding (water depth less than 3 feet). Contact
a construction firm, lumberyard or your county emergency government
office for information on where to obtain sandbags.
Select
the site for the dike, making the best use of natural land
features to keep it as short and low as possible. Avoid trees
or other obstructions which would weaken the structure. Do
not build the dike against a basement wall. Leave about 8
feet of space to maneuver between the dike and buildings.
Remove ice and snow, down to the bare ground if possible,
from the strip of land you've selected.
The number
of bags required for 100 linear feet of dike is as follows:
- 800
bags for 1-foot-high dike
- 2,000
bags for 2-foot-high dike
- 3,400
bags for 3- foot-high dike
See diagrams
on the back side. If you are building the dike on a lawn you
may omit the bonding trench shown in the diagram on Stacking
Sandbags.
- Fill
bags approximately half full of clay, silt or sand. Do not
tie.
- Alternate
direction of bags with bottom layer lengthwise of dike.
Lap unfilled portion under next bag.
- Tamp
thoroughly in place.
- Build
the dike three times as wide as high. For example, if the
height is 3 feet, make the base 9 feet.
Seal
the finished dike to increase its watertightness. To seal
the dike:
- Spread
a layer of earth 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 edge extends
1 foot beyond the bottom edge of the dike over the loose
dirt. The upper edge should extend over the top of the dike.
This sheeting is available from construction supply firms,
lumberyards and farm stores. It should be about 6 mils thick.
It comes in 100-foot rolls and is 8 or 10 feet wide.
- Lay
the plastic sheeting down very loosely. The pressure of
the water will then make the plastic conform easily with
the sandbag surface. If the plastic is stretched too tightly,
the water force could puncture it.
- Place
a row of tightly fitting sandbags on the bottom edge of
the plastic to form a watertight seal along the water side.
- Place
sandbags at about 6 foot intervals to hold down the top
edge of the plastic. Place boards or dirt between these
sandbags to prevent winds from disturbing the plastic. As
you work, avoid puncturing the plastic with sharp objects
or by walking on it.
Additional resources:
Your local emergency government office, your county agricultural agent, the American Red Cross, the Federal Emergency Management Agency
Disclaimer
and Reproduction Information: Information in NASD does not represent
NIOSH policy. Information included in NASD appears by permission
of the author and/or copyright holder. More
NASD Review: 04/2002
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