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Table 1: C -Factor and P -Factor Values for Rainfall Erosion <br />Control Measures (from HDI, December, 1991). <br />NOTE: Use of other C -Factor of P -Factor values reported in this <br />table should be substantiated by documentation _ <br />A: Should be constructed as the first step in over lot grading <br />B: Assumes planting occurs within optimal climatic conditions <br />C: Some limitation on use in arid and semi -arid climates <br />D: Value used must be substantiated by documentation <br />lKeatli ant C <br />-Factor P <br />-Factor <br />BARE SOIL <br />Packed and Smooth . . . . . . . . . . . . <br />1.00 <br />1.00 <br />Freshly Disked . . . . . . . . . . . . . <br />1.00 <br />0.90 <br />Rough Irregular Surface . . . . . . . . . <br />1.00 <br />0.90 <br />SEDIMENT BASIN/TRAP . . . . . . . .. . . . <br />1.00 <br />0.50A <br />STRAW BALE BARRIER, GRAVEL FILTER, SAND BAGS . <br />1.00 <br />0.80 <br />SILT FENCE BARRIER . . . . . . . . . . . . . <br />1.00 <br />0.50 <br />ASPHALT/CONCRETE PAVEMENT . . . . . . . . . . <br />0.01 <br />1.00 <br />GRAVEL (1/4" TO 1 1/20) @ 135 TONS/ACRE. . . . <br />0.05 <br />1.00 <br />ESTABLISHED NATIVE GRASS . . . . . . . . . . . <br />Fig 4 <br />1.00 <br />SOD GRASS . . . . . . . . . . . . . . . . . . <br />0.01 <br />1.00 <br />TEMPORARY VEGETATION/COVER CROP . . . . . . . <br />0.45B <br />1.00 <br />HYDRAULIC MULCH @ 2 TONS/ACRE . . . . . . . . <br />0.,10C <br />1.00 <br />SOIL SEALANT . . . . . . .. . . . . . . . . 0.01 <br />- 0.60D <br />1.00 <br />EROSION CONTROL MATS/BLANKETS . . . . . . . . <br />0.10 <br />1.00 <br />HAY OR STRAW DRY MULCH @ 2 TONS/ACRE & ANCHORED <br />Assumes planting of grass seed has occurred <br />prior to <br />-,application., otherwise C -Factor <br />Slone 11) <br />1 to 10 . . . . . . . . . . . . . . . . <br />0.06 <br />1.00 <br />11 to 15 . . . . . . . . . . . . . . . . <br />0.07 <br />1.00 <br />16 to 20 . . . . . . . . . . . . . . . . <br />21 to 25 . . . . . . . . . . <br />0.11 <br />0.14 <br />1.00 <br />1.010 <br />. . . . . . <br />25 to 33 . . . . . . . . . . . . . . . . <br />0.17 <br />1.00 <br />> 33 . . . . . . . . . . m. _,. _ _ _. <br />0.20 <br />_1.00 <br />CONTOUR FURROWED SURFACE <br />Must be maintained throughout construction <br />activities., <br />otherwise P -Factor = 1.00. Maximum length <br />refers to <br />down <br />slope length. <br />Sjooe (1) Max Length (feet)_ <br />1 'to ..2 400 . . . . . . . . . . . <br />1.00 <br />0.60 <br />3 to 5 300 . . . . . . . . . . . <br />1.00 <br />0.50 <br />6 to, Z _.z. 20,0 ._ :._.,.:. _. ., . <br />1.00 <br />0.50 <br />9 to 12 120 . . . . . . . . . . . <br />1.00 <br />0.60 <br />13 to 16 80 . . . . . . . . . . . <br />1.00 <br />0.70 <br />17 to 20 60 -: <br />1.00 <br />°0.80 <br />> 20 50 . . . . . . . . . . . <br />1.00 <br />0.80 <br />NOTE: Use of other C -Factor of P -Factor values reported in this <br />table should be substantiated by documentation _ <br />A: Should be constructed as the first step in over lot grading <br />B: Assumes planting occurs within optimal climatic conditions <br />C: Some limitation on use in arid and semi -arid climates <br />D: Value used must be substantiated by documentation <br />