§ 5.5.3. Runoff Coefficient
Latest version.
Runoff coefficients (C value) for use in the rational formula shall not be less than
the values shown in Table 5.5.3A, as appropriate
Table 5.5.3A - Runoff Coefficient (C value) - percentage
|
Character of Area
|
SLOPE
|
|
Up to 1%
|
Over 1% up to 3%
|
Over 3% up to 5%
|
Over 5%
|
|
Business or commercial areas (90% or more impervious), Existing Pavement / Buildings
or Zoning Districts O, C, I-1, I-2
|
95
|
96
|
97
|
97
|
|
Densely developed areas (80% to 90% impervious) or Zoning Districts D, MX, NC, TOD,
Use Pattern TND
|
85
|
88
|
91
|
95
|
|
Closely built residential areas and school sites or Zoning Districts MF, R-4
|
75
|
77
|
80
|
84
|
|
Undeveloped areas * - Present land is undeveloped and ultimate land use is unknown.
C values for use in ultimate development calculations.
|
68
|
70
|
72
|
75
|
|
Large lot residential area or Zoning Districts R20, RE
|
55
|
57
|
62
|
64
|
|
Undeveloped areas * - Existing conditions.
|
|
|
|
|
|
Average residential area or Zoning Districts R-5, R-6
|
65
|
67
|
69
|
72
|
|
Cultivated or Range (Grass Cover < 50% of Area)
|
44
|
47
|
53
|
55
|
|
Range (Grass Cover 50—75% of Area)
|
37
|
41
|
49
|
53
|
|
Forest or Range (Grass Cover > 75% of Area)
|
35
|
39
|
47
|
52
|
*Areas included within parks, green belts, or regulatory floodplains shall be considered
to remain undeveloped per this table
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