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Post and Wire Check Dam Fact Sheet
What is a Post & Wire Check Dam?
A small vertical wall constructed from wire fencing and rock or soil, placed
across a drainage way, swale or road ditch to reduce erosion and collect
sediment.
When is a Post & Wire Check Dam Used?
Check Dams are used where runoff is concentrated in a drainage way, swale, or
road ditch that has lost all its natural protection due to the fire, or will
receive increased flow rates as a result of fire in the contributing drainage
area. The dams will reduce erosion and trap sediment generated from adjacent
areas or the ditch itself. Post & Wire Check Dams should be limited to use
in open channels that drain 50 acres or less.
How is the Post & Wire Check Dam Installed?
Referring to the illustration, the maximum height of the wall should not
exceed 3.0 feet. The top of the wall should be at least 1 foot below the top of
the channel or swale. The width of the wall should be a minimum of 3 feet. The
dams should be spaced uniformly down the drainage way as follows:
Rock Check Dam Spacing in Feet
Channel Slope(%) |
1 ft. Dam Height |
2 ft. Dam Height |
3 ft. Dam Height |
< 2 |
100 |
200 |
300 |
2 - 5 |
40 |
80 |
120 |
5 - 10 |
20 |
40 |
60 |
10 - 15 |
13 |
25 |
40 |
15 - 20 |
10 |
20 |
30 |
> 20 |
not recommended |
not recommended |
not recommended |
The wall at the center of the channel should be at least 1.5
feet lower than the sides. The ends of the wall should be keyed into the channel
sides a minimum of 4 feet. If the wall is filled with rock, it should be of
sufficient size and quality to meet Colorado Department of Transportation
specifications for 6 inch D50 Rock Riprap. If the wall is filled with
soil, it should be lined with a geotextile before placing the backfill.
What Maintenance is Required?
The Rock Check Dam should be inspected after every rainfall event, and
repaired as necessary.
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