APPENDIX A - Useful Tables in InfoSWMM and InfoSWMM SA from SWMM5
A.1 Units of Measurement
| Parameter | US CUSTOMARY | SI/METRIC |
| Area (Subcatchment) | acres | Hectares |
| Area (Storage Unit) | square feet | square meters |
| Area (Ponding) | square feet | square meters |
| Capillary Suction | inches | millimeters |
| Concentration | mg/L
ug/L Count/L |
mg/L
ug/L Count/L |
| Decay Constant (Infiltration) | 1/hours | 1/hours |
| Decay Constant (Pollutants) | 1/days | 1/days |
| Depression Storage | inches | millimeters |
| Depth | feet | meters |
| Diameter | feet | meters |
| Discharge Coefficient
Orifice Weir |
dimensionless
CFS/footn |
dimensionless
CMS/metern |
| Elevation | feet | meters |
| Evaporation | inches/day | millimeters/day |
| Flow | CFS
GPM MGD |
CMS
LPS MLD |
| Head | feet | meters |
| Hydraulic Conductivity | inches/hour | millimeters/hour |
| Infiltration Rate | inches/hour | millimeters/hour |
| Length | feet | meters |
| Manning's n | dimensionless | dimensionless |
| Pollutant Buildup | mass/length
mass/acre |
mass/length
mass/hectare |
| Rainfall Intensity | inches/hour | millimeters/hour |
| Rainfall Volume | inches | millimeters |
| Slope (Subcatchments) | percent | percent |
| Slope (Cross Section) | rise/run | rise/run |
| Street Cleaning Interval | days | days |
| Volume | cubic feet | cubic meters |
| Width | feet | meters |
A.2 Soil Characteristics
| Soil Texture Class | K | Y | f | FC | WP |
| Sand | 4.74 | 1.93 | 0.437 | 0.062 | 0.024 |
| Loamy Sand | 1.18 | 2.40 | 0.437 | 0.105 | 0.047 |
| Sandy Loam | 0.43 | 4.33 | 0.453 | 0.190 | 0.085 |
| Loam | 0.13 | 3.50 | 0.463 | 0.232 | 0.116 |
| Silt Loam | 0.26 | 6.69 | 0.501 | 0.284 | 0.135 |
| Sandy Clay Loam | 0.06 | 8.66 | 0.398 | 0.244 | 0.136 |
| Clay Loam | 0.04 | 8.27 | 0.464 | 0.310 | 0.187 |
| Silty Clay Loam | 0.04 | 10.63 | 0.471 | 0.342 | 0.210 |
| Sandy Clay | 0.02 | 9.45 | 0.430 | 0.321 | 0.221 |
| Silty Clay | 0.02 | 11.42 | 0.479 | 0.371 | 0.251 |
| Clay | 0.01 | 12.60 | 0.475 | 0.378 | 0.265 |
K = saturated hydraulic conductivity, in/hr
Y = suction head, in.
f = porosity, fraction
FC = field capacity, fraction
WP = wilting point, fraction
Source: Rawls, W.J. et al., (1983). J. Hyd. Engr., 109:1316.
Rossman, L.A. (2005). Storm Water Management Model User’s Manual. Version 5.0, Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati, OH.
A.3 NRCS Hydrologic Soil Group Definitions
| Group | Meaning | Saturated Hydraulic
Conductivity (in/hr) |
| A | Low runoff potential. Soils having high infiltration rates even when thoroughly wetted and consisting chiefly of deep, well to excessively drained sands or gravels. | ³ 0.45 |
| B | Soils having moderate infiltration rates when thoroughly wetted and consisting chiefly of moderately deep-to-deep, moderately well to well-drained soils with moderately fine to moderately coarse textures. E.g., shallow loess, sandy loam. | 0.30 - 0.15 |
| C | Soils having slow infiltration rates when thoroughly wetted and consisting chiefly of soils with a layer that impedes downward movement of water, or soils with moderately fine to fine textures. E.g., clay loams, shallow sandy loam. | 0.15 - 0.05 |
| D | High runoff potential. Soils having very slow infiltration rates when thoroughly wetted and consisting chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a clay-pan or clay layer at or near the surface, and shallow soils over nearly impervious material. | 0.05 - 0.00 |
Source: Rossman, L.A. (2005). Storm Water Management Model User’s Manual. Version 5.0, Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati, OH.
A.4 SCS Curve Numbers1
| Hydrologic Soil Group | ||||
| Land Use Description | A | B | C | D |
| Cultivated land
Without conservation treatment With conservation treatment |
72
62 |
81
71 |
88
78 |
91
81 |
| Pasture or range land
Poor condition Good condition |
68
39 |
79
61 |
86
74 |
89
80 |
| Meadow
Good condition |
30 | 58 | 71 | 78 |
| Wood or forest land
Thin stand, poor cover, no mulch Good cover2 |
45
25 |
66
55 |
77
70 |
83
77 |
| Open spaces, lawns, parks, golf courses, cemeteries, etc.
Good condition: grass cover on 75% or more of the area Fair condition: grass cover on 50-75% of the area |
39
49 |
61
69 |
74
79 |
80
84 |
| Commercial and business areas (85% impervious) | 89 | 92 | 94 | 95 |
| Industrial districts (72% impervious) | 81 | 88 | 91 | 93 |
| Residential3
Average lot size (% Impervious4) 1/8 ac or less (65) 1/4 ac (38) 1/3 ac (30) 1/2 ac (25) 1 ac (20) |
77
61 57 54 51 |
85
75 72 70 68 |
90
83 81 80 79 |
92
87 86 85 84 |
| Paved parking lots, roofs, driveways, etc.5 | 98 | 98 | 98 | 98 |
| Streets and roads
Paved with curbs and storm sewers5 Gravel Dirt |
98
76 72 |
98
85 82 |
98
89 87 |
98
91 89 |
1. Antecedent moisture condition II; Source: SCS Urban Hydrology for Small Watersheds, 2nd Ed., (TR-55), June 1986.
2. Good cover is protected from grazing and litter and brush cover soil.
3. Curve numbers are computed assuming that the runoff from the house and driveway is directed toward the street with a minimum of roof water directed to lawns where additional infiltration could occur.
4. The remaining pervious areas (lawn) are considered to be in good pasture condition for these curve numbers.
5. In some warmer climates of the country a curve number of 95 may be used.
A.5 Depression Storage
| Impervious surfaces | 0.05 - 0.10 inches |
| Lawns | 0.10 - 0.20 inches |
| Pasture | 0.20 inches |
| Forest litter | 0.30 inches |
Source: Rossman, L.A. (2005). Storm Water Management Model User’s Manual. Version 5.0, Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati, OH.
ASCE, (1992). Design & Construction of Urban Stormwater Management Systems. New York, NY.
A.6 Manning’s n – Overland Flow
| Surface | n |
| Smooth asphalt | 0.011 |
| Smooth concrete | 0.012 |
| Ordinary concrete lining | 0.013 |
| Good wood | 0.014 |
| Brick with cement mortar | 0.014 |
| Vitrified clay | 0.015 |
| Cast iron | 0.015 |
| Corrugated metal pipes | 0.024 |
| Cement rubble surface | 0.024 |
| Fallow soils (no residue) | 0.05 |
| Cultivated soils
Residue cover < 20% Residue cover > 20% |
0.06
0.17 |
| Range (natural) | 0.13 |
| Grass
Short, prarie Dense Bermuda grass |
0.15
0.24 0.41 |
| Woods
Light underbrush Dense underbrush |
0.40
0.80 |
Source: Rossman, L.A. (2005). Storm Water Management Model User’s Manual. Version 5.0, Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati, OH.
McCuen, R. et al. (1996). Hydrology. FHWA-SA-96-067, Federal Highway Administration, Washington, DC.
A.7 Manning’s n – Closed Conduits
| Conduit Material | Manning n |
| Asbestos-cement pipe | 0.011 - 0.015 |
| Brick | 0.013 - 0.017 |
| Cast iron pipe
- Cement-lined & seal coated |
0.011 - 0.015 |
| Concrete (monolithic)
- Smooth forms - Rough forms |
0.012 - 0.014
0.015 - 0.017 |
| Concrete pipe | 0.011 - 0.015 |
| Corrugated-metal pipe
(1/2-in. x 2-2/3-in. corrugations) - Plain - Paved invert - Spun asphalt lined |
0.022 - 0.026
0.018 - 0.022 0.011 - 0.015 |
| Plastic pipe (smooth) | 0.011 - 0.015 |
| Vitrified clay
- Pipes - Liner plates |
0.011 - 0.015
0.013 - 0.017 |
Source: Rossman, L.A. (2005). Storm Water Management Model User’s Manual. Version 5.0, Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati, OH.
ASCE (1982). Gravity Sanitary Sewer Design and Construction,. ASCE Manual of Practice No. 60, New York, NY.
A.8 Water Quality Characteristics of Urban Runoff
| Constituent | Event Mean Concentrations |
| TSS (mg/L) | 180 - 548 |
| BOD (mg/L) | 12 - 19 |
| COD (mg/L) | 82 - 178 |
| Total P (mg/L) | 0.42 - 0.88 |
| Soluble P (mg/L) | 0.15 - 0.28 |
| TKN (mg/L) | 1.90 - 4.18 |
| NO2/NO3-N (mg/L) | 0.86 - 2.2 |
| Total Cu (ug/L) | 43 - 118 |
| Total Pb (ug/L) | 182 - 443 |
| Total Zn (ug/L) | 202 - 633 |
Source: U.S. Environmental Protection Agency. (1983). Results of the Nationwide Urban Runoff Program (NURP), Vol. 1, NTIS PB 84-185552), Water Planning Division, Washington, DC.
A.9 Manning’s n – Open Channels
| Channel Type | Manning n |
| Lined Channels | |
| - Asphalt | 0.013 - 0.017 |
| - Brick | 0.012 - 0.018 |
| - Concrete | 0.011 - 0.020 |
| - Rubble or riprap | 0.020 - 0.035 |
| - Vegetal | 0.030 - 0.40 |
| Excavated or dredged | |
| - Earth, straight and uniform | 0.020 - 0.030 |
| - Earth, winding, fairly uniform | 0.025 - 0.040 |
| - Rock | 0.030 - 0.045 |
| - Unmaintained | 0.050 - 0.140 |
| Natural channels (minor streams, top width at flood stage < 100 ft) | |
| - Fairly regular section | 0.030 - 0.070 |
| - Irregular section with pools | 0.040 - 0.100 |
Source: Rossman, L.A. (2005). Storm Water Management Model User’s Manual. Version 5.0, Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati, OH.
ASCE (1982). Gravity Sanitary Sewer Design and Construction, ASCE Manual of Practice No. 60, New York, NY.
A.10 Culvert Codes
| Conduit and Head Treatment | Culvert Code | |
| Circular Concrete (HDS-5 Chart 1) | ||
| - Square edge with headwall | 1 | |
| - Groove end with headwall | 2 | |
| - Groove end projecting | 3 | |
| Circular Corrugated Metal Pipe (HDS-5 Chart 2) | ||
| - Headwall | 4 | |
| - Mitered to slope | 5 | |
| - Projecting | 6 | |
| Circular Pipe, Beveled Ring Entrance (HDS-5 Chart 3) | ||
| - 45 deg. Bevels | 7 | |
| - 33.7 deg. Bevels | 8 | |
| Rectangular Box; Flared Wingwalls (HDS-5 Chart 8) | ||
| - 30-75 deg. wingwall flares | 9 | |
| - 90 or 15 deg. wingwall flares | 10 | |
| - 0 deg. wingwall flares (straight sides) | 11 | |
| Rectangular Box;Flared Wingwalls and Top Edge Bevel (HDS-5 Chart 9) | ||
| - 45 deg flare; 0.43D top edge bevel | 12 | |
| - 18-33.7 deg. flare; 0.083D top edge bevel | 13 | |
| Rectangular Box, 90-deg Headwall, Chamfered / Beveled Inlet Edges (HDS-5 Chart 10) | ||
| - chamfered 3/4-in. | 14 | |
| - beveled 1/2-in/ft at 45 deg (1:1) | 15 | |
| - beveled 1-in/ft at 33.7 deg (1:1.5) | 16 | |
| Rectangular Box, Skewed Headwall, Chamfered / Beveled Inlet Edges (HDS-5 Chart 11) | ||
| - 3/4" chamfered edge, 45 deg skewed headwall | 17 | |
| - 3/4" chamfered edge, 30 deg skewed headwall | 18 | |
| - 3/4" chamfered edge, 15 deg skewed headwall | 19 | |
| - 45 deg beveled edge, 10-45 deg skewed headwall | 20 | |
| Rectangular Box, Non-offset Flared Wingwalls, 3/4" Chamfer at Top of Inlet (HDS-5 Chart 12) | ||
| - 45 deg (1:1) wingwall flare | 21 | |
| - 8.4 deg (3:1) wingwall flare | 22 | |
| - 18.4 deg (3:1) wingwall flare, 30 deg inlet skew | 23 | |
| Rectangular Box, Offset Flared Wingwalls, Beveled Edge at Inlet Top (HDS-5 Chart 13) | ||
| - 45 deg (1:1) flare, 0.042D top edge bevel | 24 | |
| - 33.7 deg (1.5:1) flare, 0.083D top edge bevel | 25 | |
| - 18.4 deg (3:1) flare, 0.083D top edge bevel | 26 | |
| Corrugated Metal Box (HDS-5 Charts 16, 17, 18 and 19) | ||
| - 90 deg headwall | 27 | |
| - Thick wall projecting | 28 | |
| - Thin wall projecting | 29 | |
| Horizontal Ellipse Concrete (HDS-5 Chart 29) | ||
| - Square edge with headwall | 30 | |
| - Grooved end with headwall | 31 | |
| - Grooved end projecting | 32 | |
| Vertical Ellipse Concrete (HDS-5 Chart 30) | ||
| - Square edge with headwall | 33 | |
| - Grooved end with headwall | 34 | |
| - Grooved end projecting | 35 | |
| Pipe Arch, Corrugated Metal (HDS-5 Chart 34) | ||
| - 90 deg headwall | 36 | |
| - Mitered to slope | 37 | |
| - Projecting | 38 | |
| Pipe Arch, 18" Corner Radius, Structural Plate (HDS-5 Chart 35) | ||
| - Projecting | 39 | |
| - No bevels | 40 | |
| - 33.7 deg bevels | 41 | |
| Pipe Arch, 31" Corner Radius, Structural Plate (HDS-5 Chart 36) | ||
| - Projecting | 42 | |
| - No bevels | 43 | |
| - 33.7 deg. bevels | 44 | |
| Arch, Corrugated Metal (HDS-5 Charts 41, 42 and 43) | ||
| - 90 deg headwall | 45 | |
| - Mitered to slope | 46 | |
| - Thin wall projecting | 47 | |
| Circular Culvert (HDS-5 Chart 55) | ||
| - Smooth tapered inlet throat (Concrete) | 28 | |
| - Rough tapered inlet throat (Corrugated Metal) | 49 | |
| Elliptical Inlet Face (HDS-5 Chart 56) | ||
| - Tapered inlet, beveled edges | 50 | |
| - Tapered inlet, square edges | 51 | |
| - Tapered inlet, thin edge projecting | 52 | |
| Rectangular (HDS-5 Chart 57) | ||
| - Tapered inlet throat | 53 | |
| Rectangular Concrete, Face Control (HDS-5 Charts 58 and 59) | ||
| - Side tapered, less favorable edges | 54 | |
| - Side tapered, more favorable edges | 55 | |
| - Slope tapered, less favorable edges | 56 | |
| - Slope tapered, more favorable edges | 57 | |
Source: Rossman, L.A. (2009). Storm Water Management Model User’s Manual. Version 5.0, Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati, OH.
Federal Highway Administration (2005). Hydraulic Design of Highway Culverts, Publication No. FHWA-NHI-01-020 (HDS-5).
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