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Forestry > Forestry BMP's > Forest Roads > Constructing Forest Roads > Culvert Size Guidelines Culvert Size Guidelines

Acres Drained Light Soils (Sands) Medium Soils Heavy Soils (Clay)
Flat Mod. Steep Flat Mod. Steep Flat Mod. Steep
0-5% 5-15% 15%+ 0-5% 5-15% 15%+ 0-5% 5-15% 15%+

Culvert diameter in inches

5 18 18 18 18 18 21 21 21 24
10 18 18 18 21 24 27 27 27 36
20 18 18 18 24 27 36 36 36 42
30 18 18 18 27 30 36 36 42 48
40 18 18 18 27 36 42 42 48
50 18 18 18 30 36 48 48 48
75 18 21 21 36 42
100 21 21 24 36 48
150 21 24 24 42
200 24 30 30 48
250 27 30 30
300 30 36 36
350 30 36 42
400 36 36 42

Data Source: Texas Best Managment Practices for Silviculture, Texas Forestry Association

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