DESIGN COEFFICIENT TABLES - CECALC

DESIGN COEFFICIENT TABLESHazen-Williams Friction Factor (C)Pipe MaterialPlastic, PVC, Polyethylenepipe or tubingCement or mastic lined ironor steel pipeCopper, brass, lead, tin orglass pipe or tubingWood StaveWelded or Seamless SteelCast and ductile ironConcreteCorrugated steelValues for CRangeHigh/Low160/150Average ValueTypical Design ng’s Equation roughness coefficient (n)MaterialPolyethylene pipeUncoated cast or ductileiron pipeCorrugated steel pipeConcrete pipeVitrified clay pipeBrick and cement mortarsewersWood staveRubble masonryConcrete Culvert Pipe(Smooth)Concrete Boxes(Smooth)Spiral Rib Metal Pipe(Smooth)Corrugated Metal Pipe,Pipe-Arch and Box. (2 -2/3in by ½ in Annularcorrugation)Corrugated Metal Pipe,Pipe-Arch and Box. (2 -2/3in by ½ in Helicalcorrugation)Corrugated Metal Pipe,Pipe-Arch and Box. (6 in by1 in Helical corrugation)Corrugated Metal Pipe,Pipe-Arch and Box. (5 in by1 in)Corrugated Metal Pipe,Pipe-Arch and Box. (3 in by1 in)Corrugated Metal Pipe,Pipe-Arch and Box. (6 in by2 in Structural Plate)Values for nRangeTypical Design -0.0280.0280.033-0.0350.034CECALC.com - Copyright 2010 – All rights reserved1

Corrugated Metal Pipe,Pipe-Arch and Box. (9in by2-1/2 in Structural Plate)Corrugated PolyethyleneCulvert Pipe (Smooth)Corrugated PolyethyleneCulvert Pipe ( Corrugated)Polyvinyl chloride (PVC)(Smooth)Open Channel – regularsection – some grass andweeds, little or no brushOpen Channel – regularsection – dense grass andweeds, depth of flowmaterially greater thanweed heightOpen Channel – regularsection – some weeds, lightbrush on banksOpen Channel – regularsection – some weeds,heavy brush on banksOpen Channel – regularsection – some weeds,dense willows on banksOpen Channel – regularsection – for trees withinchannel, with branchessubmerged at high stage,increase all above openchannel values byIrregular sections, withpools, slight channelmeander, increase openchannel values given abovebyMountain streams, novegetation in channel,banks usually steep, treesand brush along bankssubmerged at high stage:bottom of gravel, cobbles,and few bouldersMountain streams, novegetation in channel,banks usually steep, treesand brush along bankssubmerged at high stage:bottom of cobbles, withlarge bouldersConcrete gutter, trowelfinishAsphalt pavement (smoothtexture)Asphalt pavement(rough texture)Combination asphaltpavement and concretegutterConcrete CECALC.com - Copyright 2010 – All rights reserved2

Culvert Design - Outlet Control, Full or Partly Full Entrance Head Loss Coefficient (Ke)Type of Structure and Design of EntrancePipe, ConcreteProjecting from fill, socket end (groove-end)Projecting from fill, sq. cut endHeadwall or headwall and wingwalls, Socket endHeadwall or headwall and wingwalls, Square-edgeRounded, radius D/12Mitered to conform to fill slopeEnd-Section conforming to fill slopeBeveled edges, 33.7 deg. or 45 deg. bevelsSide- or slope-tapered inletPipe or Pipe-Arch Corrugated MetalProjecting from fill (no headwall)Headwall or headwall and wingwalls square-edgeMitered to conform to fill slope, paved or unpaved slopeEnd-Section conforming to fill slopeBeveled edges, 33.7 deg. or 45 deg. bevelsSide- or slope-tapered inletBox, Reinforced ConcreteHeadwall parallel to embankment (no wingwalls), Square-edge on 3edgesHeadwall parallel to embankment (no wingwalls), Rounded on 3edges to radius of D/12 or B/12 or beveled edges on 3 sidesWingwalls at 30 deg to 75 deg to barrel, Square-edged at crownWingwalls at 30 deg to 75 deg to barrel, Crown edge rounded toradius of D/12 or beveled top edgeWingwalls at 10 deg to 25 deg to barrel, Square-edged at crownWingwalls parallel (extension of sides), Square-edged at crownWingwalls parallel (extension of sides), Side- or slope-tapered .20.50.20.40.20.50.70.2Culvert Design - Constants for Inlet Control Design EquationShape and MaterialCircular ConcreteCircular CMPCircularRectangular BoxRectangular Box¾” chamfersInlet Edge DescriptionSquare edge w/headwallGroove end w/headwallGroove end projectingHeadwallMitered to slopeProjectingBeveled ring, 45 deg. bevelsBeveled ring, 33.7 deg. bevels30 to 75 deg wingwall flares90 and 15 deg wingwall flares0 deg wingwall flares45 deg wingwall flare d .043D18 to 33.7 deg wingwall flare d .083D90 deg headwall w/ 3/4” chamfers90 deg headwall w/ 45 deg bevels90 deg headwall w/ 33.7 deg bevels¾” chamfers, 45 deg skewed headwall¾” chamfers, 30 deg skewed headwall¾” chamfers, 15 deg skewed headwall45 deg bevels; 10 to 45 deg skewed headwall45 deg non-offset wingwall 18.4 deg non-offset wingwall flares18.4 non-offset wingwall flares, 30 degskewed barrel.493.495.667.667.0361.0386.806.71CECALC.com - Copyright 2010 – All rights reserved3

Rectangular BoxTop BevelsC M BoxesHorizontal Ellipse –ConcreteVertical Ellipse –ConcretePipe Arch,18” Corner Radius - CMPipe Arch,31” Corner Radius - CMArch CMCircularElliptical Inlet FaceRectangularRectangular - Concrete45 deg wingwall flares - offset.497.667.0302.83533.7 deg wingwall flares - offset18.4 deg wingwall flares - offset90 deg headwallThick wall projectingThin wall projectingSquare edge .64.57.67Groove end w/headwallGroove end projectingSquare edge 74.69.67Groove end w/headwallGroove end projecting90 deg .69.69Mitered to slopeProjectingProjectingNo Bevels33.7 deg .57.68.77.57No Bevels33.7 deg Bevels90 deg headwallMitered to slopeThin wall projectingSmooth tapered inlet throatRough tapered inlet throatTapered inlet - beveled edgesTapered inlet - square edgesTapered inlet - thin edge projectingTapered inlet throatSide tapered - less favorable edgesSide tapered - more favorable edgesSlope tapered - less favorable edgesSlope tapered - more favorable 7.69.75.57.90.90.83.80.75.97.85.87.65.71Rational Method/Modified Rational Method Runoff Coefficients (C)Categorized by surfaceforestedasphaltbrickconcreteshingle rooflawns, well drained (sandy soil), up to 2% slopelawns, well drained (sandy soil), 2% to 78% slopelawns, well drained (sandy soil), over 7% slopelawns, poor drainage (clay soil), up to 2% slopelawns, poor drainage (clay soil), 2% to 7% slopelawns, poor drainage (clay soil), over 7% slopedriveways, walkwaysCategorized by com - Copyright 2010 – All rights 54

railroad yardplaygrounds (except asphalt or concrete)business districts, neighborhoodbusiness districts, city (downtown)residential, single familyresidential, multi-plexes, detachedresidential, multi-plexes, attachedresidential, suburbanresidential, apartments, condominiumsindustrial, lightindustrial, 0.6-0.750.25-0.40.5-0.70.5-0.80.6-0.9Modified Rational Method, Typical Values of Infiltration Rates, (F), inches/hourDescriptionSoil group symbolSand and gravel mixtureSilty gravels and silty sands toinorganic silt, and welldeveloped loamsSilty clay sand to sandy clayClays, inorganic and organicBare rock, not highly fracturedGW, GP, SW, SPGM, SM, ML, MH, OLInfiltration, F,in/hr0.8-1.00.3-0.6SC, CLCH, OH----------0.2-0.30.1-0.20.0-0.1Soil Cohesion and Friction Factors (For use in Thrust Block Design)Soil MaterialFriction Angle(degrees)44.5Cs0Sand, saturated, wellgradedSilt, dry, passing 200 sieve3900.8004000.950Silt, saturated, passing 200sieveCohesive granular soil wetto moistClay, wet to moistClay, wet to moist atmaximum compaction3200.75013 - 22385 - 9200.650.3511.5 – 16.511.5 – 16.5460 – 1,175460 – 1,1750.500.500.500.80Sand, dry well gradedSoil Cohesion and Friction Factorsfpfs0.760Kerby’s Roughness CoefficientCategorized by surfaceSmooth, impervious surfaceSmooth, packed bare soilPoor grass, cultivated row crops of moderately rough bare soilPasture or average grassDeciduous timberlandTimberland with deep forest litter or dense grassCECALC.com - Copyright 2010 – All rights reservedKerby n0.020.100.200.400.600.805

Slope Intercept Coefficient kCategorized by surfaceForest with heavy ground litter; hay meadow (overland flow)Trash fallow or minimum tillage cultivation; contour or strip cropped;woodland (overland flow)Short grass pasture (overland flow)Cultivated straight row (overland flow)Nearly bare and untilled (overland flow); alluvial fans in westernmountain regionsGrassed waterway (shallow concentrated flow)Unpaved (shallow concentrated flow)Paved area (shallow concentrated flow); small upland gulliesCECALC.com - Copyright 2010 – All rights reservedk0.0760.1520.2130.2740.3050.4570.4910.6196

Uncoated cast or ductile iron pipe 0.012-0.015 0.013 Corrugated steel pipe 0.021-0.030 0.024 Concrete pipe 0.012-0.016 0.015 Vitrified clay pipe 0.011-0.017 0.013 Brick and cement mortar sewers 0.012-0.017 0.015 Wood stave 0.010-0.013 0.011 Rubble masonry 0.017-0.030 0.021 Concrete Culvert Pipe .