Kitsap County Stormwater Design Manual · 4.2 Pipe Compaction Design and Backfill ... strap-footing anchor pipe bedding. concrete block "... Figure 4.3 — Pipe Anchor Detail. 10

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Kitsap CountyStormwater

DesignManual

Figures & Tables

November 2009

DRAFT

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Figures

3.1 CoveredFuelIsland...............................................................................................................................................................................1

3.2 DripPan.....................................................................................................................................................................................................1

3.3 DripPanWithinRails.............................................................................................................................................................................1

3.4 LoadingDockwithDoorSkirt...........................................................................................................................................................2

3.5 LoadingDockwithOverhang............................................................................................................................................................2

3.6 EnclosetheActivity...............................................................................................................................................................................2

3.7 CovertheActivity...................................................................................................................................................................................2

3.8 SecondaryContainmentSystem......................................................................................................................................................3

3.9 LockingsystemforDrumLid.............................................................................................................................................................3

3.10 Covered&BermedContainmentArea...........................................................................................................................................3

3.11 MountedContainerwithDripPan...................................................................................................................................................3

3.12 Above-groundTankStorage..............................................................................................................................................................3

3.13 CoveredStorageforBulkSolids........................................................................................................................................................4

3.14 MaterialCoveredwithPlasticSheeting.........................................................................................................................................4

3.15 UncoveredWashArea...........................................................................................................................................................................4

4.1 RainfallIntensity-DurationCurves...................................................................................................................................................7

4.2 PipeCompactionDesignandBackfill.............................................................................................................................................8

4.3 PipeAnchorDetail.................................................................................................................................................................................9

4.4 CorrugatedMetalPipeCouplingand/orGeneralPipeAnchorAssembly.....................................................................10

4.5 DebrisBarrier(OffRoadRight-of-Way)........................................................................................................................................11

4.6 DebrisBarrier(InRoadRight-of-Way)..........................................................................................................................................12

4.7 NomographforSizingCircularDrainsFlowingFull................................................................................................................13

4.8 CircularChannelRatios.....................................................................................................................................................................14

4.9 BackwaterCalculationSheet...........................................................................................................................................................15

4.10 BackwaterCalculationSheetNotes..............................................................................................................................................16

4.11 BackwaterPipeCalculationExample...........................................................................................................................................17

4.12 BendHeadLossesinStructure.......................................................................................................................................................18

4.13 JunctionHeadLossinStructure....................................................................................................................................................19

4.14 TeeTypeEnergyDisipator................................................................................................................................................................20

4.15 PipeCulvertDischargeProtection................................................................................................................................................21

4.16 FlowDisposalTrench.........................................................................................................................................................................22

4.17 AlternativeFlowDisposalTrench..................................................................................................................................................23

4.18 GabionMattressDisipatorDetail..................................................................................................................................................24

4.19 Inlet/OutletControlConditions...................................................................................................................................................25

4.20 HeadwaterDepthforSmoothInteriorPipeCulvertswithInletControl.........................................................................26

4.21 HeadwaterDepthforCorrugatedPipeCulvertwithInletControl....................................................................................27

4.22 HeadforCulverts(PipeW/"N"=0.012)FlowingFullwithOutletControl......................................................................28

4.23 HeadforCulverts(PipeW/"N"=0.024)FlowingFullwithOutletControl........................................................................29

4.24 CriticalDepthofFlowforCircularCulverts................................................................................................................................30

4.25 MeanChannelVelocityvs.MediumStoneWeightandEquivalentStoneDiameter..................................................31

4.26 Riprap/FilterExampleGradationCurve......................................................................................................................................32

4.27 Ditches—CommonSections.........................................................................................................................................................33

428 DrainageDitches—CommonSections.....................................................................................................................................34

4.29 GeometricElementsOfCommonSections...............................................................................................................................35

4.30 OpenChannelFlowProfileComputation..................................................................................................................................36

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4.31 DirectStepBackwaterMethod-Example..................................................................................................................................37

4.32 FlowSplitter,OptionA......................................................................................................................................................................38

4.33 FlowSplitter,OptionB.......................................................................................................................................................................39

4.34 FlowSpreaderOptionA:AnchoredPlate...................................................................................................................................40

4.35 FlowSpreaderOptionB:ConcreteSumpBox..........................................................................................................................41

4.36 FlowSpreaderOptionC:NotchedCurbSpreader..................................................................................................................42

4.37 FlowSpreaderOptionD:Through-CurbPort............................................................................................................................42

5.1 BMP5.01RockFilledInfiltrationTrench......................................................................................................................................45

5.2 AlternativeRockFiledInfiltrationTrenchSystem....................................................................................................................46

5.3 Gravel-LessChamberInfiltrationTrench.....................................................................................................................................47

5.4 AverageAnnualRainfallInKitsapCounty..................................................................................................................................48

6.1 WaterQualityTreatmentBMPSelectionFlowChart..............................................................................................................51

6.2 SandFiltrationBasinPrecededbyPresettlingBasin..............................................................................................................52

6.3 SandFilterwithPretreatmentCell................................................................................................................................................53

6.4 SandFilterwithLevelSpreader......................................................................................................................................................54

6.5 SandFilterVault...................................................................................................................................................................................55

6.6 LinearSandFilter.................................................................................................................................................................................56

6.7 ShallowPlasticDrainageChannel.................................................................................................................................................57

6.8 StormFilterSchematic.......................................................................................................................................................................57

6.9 TypicalFilterStrip................................................................................................................................................................................58

6.10 FilterStripLenthsforNarrowRight-of-Way...............................................................................................................................59

6.11 KitsapMeanAnnualStorm..............................................................................................................................................................60

6.12 PossibleWetpondInlet/OutletConfigurations........................................................................................................................61

6.13 Wetpond...........................................................................................................................................................................................62-63

6.14 Wetvault.................................................................................................................................................................................................64

6.15 StormwaterTreatmentWetland–OptionA..............................................................................................................................65

6.16 StormwaterTreatmentWetland–OptionB..............................................................................................................................66

6.17 HeadwaterDepthforHeadwall.....................................................................................................................................................67

6.18 HeadwaterDepthforCorrugatedPipeCulvertswithInletControl..................................................................................68

6.19 CriticalDepthofFlowforCircularCulverts................................................................................................................................69

6.20 CircularChannelRatios.....................................................................................................................................................................70

6.21 TurbulenceFactor...............................................................................................................................................................................71

6.22 EffectiveSeparationSurfacevsFlowRate..................................................................................................................................71

6.23 ProjectedHorizontalPlateAreaforCoalescingPlateOil/WaterSeparator....................................................................72

6.24 BaffleOil/WaterSeparator...............................................................................................................................................................73

6.25 CoalescingPlateOil/WaterSeparator..........................................................................................................................................74

6.26 SpillControlSeparator(notforoiltreatment)..........................................................................................................................75

7-1 TypicalDetentionPond.....................................................................................................................................................................79

7-2 TypicalDetentionPondSections...................................................................................................................................................80

7-3 OverflowStructure.............................................................................................................................................................................81

7-4 PermanentStormwaterFacilitySign............................................................................................................................................82

7-5 WeirSectionforEmergencyOverflowSpillway.......................................................................................................................83

7-6 TypicalDetentionTank......................................................................................................................................................................83

7-7 DetentionTankAccessDetail..........................................................................................................................................................84

7-8 TypicalDetentionVault.....................................................................................................................................................................85

7-9 FlowRestrictor......................................................................................................................................................................................86

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7-10 FlowRestrictor(Baffle).......................................................................................................................................................................87

7-11 FlowRestrictor(Weir).........................................................................................................................................................................88

7-12 SimpleOrifice.......................................................................................................................................................................................89

7-13 Rectangular,Sharp-CrestedWeir...................................................................................................................................................89

7-14 V-Notch,Sharp-CrestedWeir..........................................................................................................................................................90

7-15 SutroWeir...............................................................................................................................................................................................90

7-16 RiserInflowCurves.............................................................................................................................................................................91

7-17 USDATexturalTriangle......................................................................................................................................................................92

7-18 TypicalInfiltrationPond....................................................................................................................................................................93

7-19 TypicalInfiltrationTank.....................................................................................................................................................................94

7-20 InfiltrationVault...................................................................................................................................................................................95

7-21 InfiltrationTrench................................................................................................................................................................................96

7-22 ExampleofSmallInfiltrationBasin...............................................................................................................................................97

Tables

3B-1 BacteriaandViruses.........................................................................................................................................................................101

4.1 RunoffCoefficients-“C”ValuesForTheRationalMethod..................................................................................................105

4.2 MaximumPipeSlopesAndVelocities........................................................................................................................................106

4.3 AllowableStructuresAndPipeSizes..........................................................................................................................................106

4.4 MaximumCover(Feet)ForConcretePipeCompactionDesignA...................................................................................106

4.5 Manning’s“N”ValuesForPipes.....................................................................................................................................................107

4.6 RockProtectionAtOutfalls............................................................................................................................................................107

4.7 ConstantsForInletControlEquations*.....................................................................................................................................108

4.8 EntranceLossCoefficients.............................................................................................................................................................109

4.9 ChannelProtection...........................................................................................................................................................................110

4.10 ValuesOfRoughnessCoefficient“N”ForOpenChannels...................................................................................................111

4.11 EvidenceOfExistingOrPredictedProblems...........................................................................................................................111

5.1 RecommendedInfiltrationRates.................................................................................................................................................115

5.2 InfiltrationSizingFactors................................................................................................................................................................115

5.3 BioretentionFilterAndPerviousPavementSizingFactors...............................................................................................116

6.1 TreatmentFacilityPlacementinRelationtoDetention......................................................................................................120

6.2 LiningTypesforRunoffTreatmentFacilities............................................................................................................................120

6.3 CompactedTillLiners......................................................................................................................................................................121

6.4 SizingofPresettlingVaults.............................................................................................................................................................121

6.5 SandMediumSpecification...........................................................................................................................................................121

6.6 DesignFlowRatesforBasicTreatmentwithZPGMedia.....................................................................................................121

6.7 FilterStripSizingCriteria................................................................................................................................................................122

6.8 EmergentWetlandPlantSpeciesforWetponds....................................................................................................................123

6.9 DistributionofDepthsinWetlandCell......................................................................................................................................124

6.10 CoalescingPlateOil/WaterSeparatorVaultDimensions....................................................................................................124

7-1 SmallTreesandShrubswithFibrousRoots.............................................................................................................................128

7-2 StormwaterTract“LowGrow”SeedMix....................................................................................................................................128

7-3 ValuesofCdforSutroWeirs...........................................................................................................................................................128

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DesignManual

CHAPTER 3–FIGURES

1

Figure 3.1 — Covered Fuel Island

Figure 3.2 — Drip Pan

Figure 3.3 — Drip Pan Within Rails

2

Figure 3.4 — Loading Dock with Door Skirt

Figure 3.5 — Loading Dock with Overhang

Figure 3.6 — Enclose the Activity Figure 3.7 — Cover the Activity

3

Figure 3.8 — Secondary Containment System Figure 3.9 — Locking System for Drum Lid

Figure 3.10 — Covered & Bermed Containment Area Figure 3.11 — Mounted Container with Drip Pan

Figure 3.12 — Above-ground Tank Storage

4

Figure 3.13 — Covered Storage for Bulk Solids Figure 3.14 — Material Covered with Plastic Sheeting

Figure 3.15 — Uncovered Wash Area

Note: Include berm if needed

5


DesignManual

CHAPTER 4–FIGURES

6


7

Figure 4.1 — Rainfall Intensity-Duration Curves

8

Figure 4.2 — Pipe Compaction Design and Backfill

9

Note: For SWPE, pipe must be free toslide inside a 4' long section of pipeone size diameter larger.

concrete footingkeyed into

undisturbed soilas shown

6" min

6" min

1' min

6" min (typical)

6" min

1' min

2 x pipe dia.min.

1" min. diametersteel rod (strap)clamped securelyto pipe.

concrete footingkeyed into undisturbed soilas shown

SECTION B-BNTS

SECTION A-ANTS

concrete blockanchor

strap-footinganchor

pipe bedding

2' min.

concrete block6"

min.

6" min.

3' min.

Figure 4.3 — Pipe Anchor Detail

10

Figure 4.4 — Corrugated Metal Pipe Coupling and/or General Pipe Anchor Assembly

11

Figure 4.5 — Debris Barrier (Off Road Right-of-Way)

12

Figure 4.6 — Debris Barrier (In Road Right-of-Way)

13

Figure 4.7 — Nomograph for Sizing Circular Drains Flowing Full

14

Figure 4.8 — Circular Channel Ratios

15

Figu

re 4

.9 —

Bac

kwat

er C

alcu

lati

on S

heet

Pipe

Segm

ent

CB to

CB

(4)

“n”

Value

(2)

Leng

th(ft

)

(3)

Pipe

Size

(1) Q (cfs)

(8)

Barre

lVe

locity

(fps)

(6)

Inlet

Elev

ation

(ft)

(7)

Barre

lVe

locity

(fps)

(5)

Outle

tEl

evati

on(ft

)

(12)

Entra

nce

HGL

Elev

ation

(ft)

(10) TW

Elev

ation

(ft)

(11)

Frict

ionLo

ss (ft)

(9)

Barre

lVe

locity

Head (ft)

(16)

Inlet

Contr

olEl

evati

on(ft

)

(14) Exit

Head

Loss (ft)

(15)

Outle

tCo

ntrol

Elev

ation

(ft)

(13)

Entra

nce

Head

Loss (ft)

(20) HW

Elev

ation

(ft)

(18)

Bend

Head

Loss (ft)

(19)

Junc

tion

Head

Loss (ft)

(17)

Appr

oach

Veloc

ityHe

ad (ft)

16

Figure 4.10 — Backwater Calculation Sheet Notes

Column (1) Designflowtobeconveyedbypipesegment.

Column (2) Lengthofpipesegment.

Column (3) PipeSize;indicatepipediameterorspanxrise.

Column (4) Manning’s“n”value.

Column (5) OutletElevationofpipesegment.

Column (6) InletElevationofpipesegment.

Column (7) BarrelArea;thisisthefullcross-sectionalareaofthepipe.

Column (8) BarrelVelocity;thisisthefullvelocityinthepipeasdeterminedby: V = Q/AorCol.(8)=Col.(1)/Col.(7)

Column (9) BarrelVelocityHead=V2 /2gor(Col.(8))2/2g whereg=32.2ft/sec2(accelerationduetogravity)

Column (10) Tailwater(TW)Elevation;thisisthewatersurfaceelevationattheoutletofthepipesegment.Ifthepipe’soutletisnotsubmergedbytheTWandtheTWdepthislessthan(D+dc )/2,setTWequalto(D+dc)/2tokeeptheanalysissimpleandstillobtainreasonableresults(D=pipebarrelheightandd

c=criticaldepth,bothinfeet.SeeFigure4.24(p.48)for

determinationofdc).

Column (11) FrictionLoss=SfxL[orSfxCol.(2)]whereSfisthefrictionslopeorheadlossperlinearfootofpipeasdeterminedbyManning’sequationexpressedintheform:

Sf=(nV)2/2.22R1.33

Column (12) HydraulicGradeLine(HGL)Elevationjustinsidetheentranceofthepipebarrel;thisisdeterminedbyaddingthefrictionlosstotheTWelevation:

Col.(12)=Col.(11)+Col.(10) Ifthiselevationfallsbelowthepipe’sinletcrown,itnolongerrepresentsthetrueHGLwhencomputedinthismanner.The

trueHGLwillfallsomewherebetweenthepipe’scrownandeithernormalflowdepthorcriticalflowdepth,whicheverisgreater.Tokeeptheanalysissimpleandstillobtainreasonableresults(i.e.,erringontheconservativeside),settheHGLelevationequaltothecrownelevation.

Column (13) EntranceHeadLoss=KexV2/2g[orKexCol.(9)]whereKe=EntranceLossCoefficient(fromTable4.8,).Thisis

theheadlostduetoflowcontractionsatthepipeentrance.

Column (14) ExitHeadLoss=1.0xV2/2gor1.0xCol.(9).Thisisthevelocityheadlostortransferreddownstream.

Column (15) OutletControlElevation=Col.(12)+Col.(13)+Col.(14).Thisisthemaximumheadwaterelevationassumingthepipe’sbarrelandinlet/outletcharacteristicsarecontrollingcapacity.Itdoesnotincludestructurelossesorapproachvelocityconsiderations.

Column (16) InletControlElevation,forcomputationofinletcontrolonculverts);thisisthemaximumheadwaterelevationassumingthepipe’sinletiscontrollingcapacity.Itdoesnotincludestructurelossesorapproachvelocityconsiderations.

Column (17) ApproachVelocityHead;thisistheamountofhead/energybeingsuppliedbythedischargefromanupstreampipeorchannelsection,whichservestoreducetheheadwaterelevation.Ifthedischargeisfromapipe,theapproachvelocityheadisequaltothebarrelvelocityheadcomputedfortheupstreampipe.Iftheupstreampipeoutletissignificantlyhigherinelevation(asinadropmanhole)orlowerinelevationsuchthatitsdischargeenergywouldbedissipated,anapproachvelocityheadofzeroshouldbeassumed.

Column (18) BendHeadLoss=KbxV2/2g[orKbxCol.(17)]whereKb=BendLossCoefficient(fromFigure4.12).Thisisthe

lossofhead/energyrequiredtochangedirectionofflowinanaccessstructure.

Column (19) JunctionHeadLoss.Thisisthelossinhead/energythatresultsfromtheturbulencecreatedwhentwoormorestreamsaremergedintoonewithintheaccessstructure.Figure4.13)maybeusedtodeterminethisloss,oritmaybecomputedusingthefollowingequationsderivedfromFigure4.13:

JunctionHeadLoss=KjxV2/2g[orKjxCol.(17)]whereKjistheJunctionLossCoefficientdeterminedby

Kj=(Q3 /Q1)/(1.18+0.63(Q3 /Q1))

Column (20) Headwater(HW)Elevation;thisisdeterminedbycombiningtheenergyheadsinColumns17,18,and19withthehighestcontrolelevationineitherColumn15or16,asfollows:Col.(20)=Col.(15or16)-Col.(17)+Col.(18)+Col.(19)

17

Figure 4.11 — Backwater Pipe Calculation Example

18

Figure 4.12 — Bend Head Losses In Structure

19

Figure 4.13 — Junction Head Loss in Structures

20

Figure 4.14 — Tee Type Energy Dissipater

21

Figure 4.15 — Pipe Culvert Discharge Protection

A+Bmustbeequaltoorgreaterthantheminimumlengthshownintable4.6

22

Figure 4.16 — Flow Dispersal Trench

23

Figure 4.17 — Alternative Flow Dispersal Trench

1. This trench shall be constructed to prevent point discharge and /or erosion.2. Trenches may be placed no closer than 50 feet to one another (100 feet along flowline).3. Trench and grade board must be level. Align to follow contours of site.4. Support post spacing as required by soil conditions to ensure grade board remains level.

NOTES:

1' - 6" min

*20% max*20% maxgalvanized bolts

2" x 12"pressure

treated gradeboard

2" x 2" notches18" O.C. 36

" max

12" m

in. 4" x 4" support

post

clean (< 5% fines)3

4" - 112" washed rock

filter fabric

*15% max for flow control/water quality treatment in rural areas

SECTION A-ANTS

18" O.C.

2"

2" gradeboard notches

24

Figure 4.18 — Gabion Mattress Dissipater Detail

sleeve of next largersize diameter pipe for thermalexpansion and concentration

existing ground line

place filterfabric between

gabions at soil bedding

gabion mattresspipe anchor

1'

rip rap

NOTE: If pipe dischargesperpendicular to stream, orgabions are located withinthe ordinary high watermark (OHWM) or will besubject to abrasion fromupstream sediments, afour-sided gabion basketlocated outside the OHWMshould be considered.

gabions (typical)(size as required)

45 preferred

SWPE pipe

gabion mattress

SECTION C-CNTS

SECTION B-BSECTION A-A

25

Figure 4.19 — Inlet / Outlet Control Conditions

26

Figure 4.20 — Headwater Depth for Smooth Interior Pipe Culverts with Inlet Control

27

Figure 4.21 — Headwater Depth for Corrugated Pipe Culvert with Inlet Control

28

Figure 4.22 — Head for Culverts (Pipe W / “n” = 0.012) Flowing Full with Outlet Control

29

Figure 4.23 — Head for Culverts (Pipe W / “n” = 0.024) Flowing Full with Outlet Control

30

Figure 4.24 — Critical Depth of Flow for Circular Culverts

31

Figure 4.25 — Mean Channel Velocity vs. Medium Stone Weight (W50) and Equivalent Stone Diameter

32

Figure 4.26 — Riprap / Filter Example Gradation Curve

0.1

1

10

100

0 10 20 30 40 50 60 70 80 90 100

% Finer by Weight

Gra

in S

ize

(inch

es)

20

RIP-RAP

Coarse Aggregate size number 57 ASTM 14 C-33

33

NO. SideSlopes B H W A WP R R(2/3)

D-1 -- -- 6.5" 5'-0" 1.84 5.16 0.356 0.502

D-1C -- -- 6" 25'-0" 6.25 25.50 0.245 0.392

D-2A 1.5:1 2'-0" 1'-0" 5'-0" 3.50 5.61 0.624 0.731

B 2:1 2'-0" 1'-0" 6'-0" 4.00 6.47 0.618 0.726

C 3:1 2'-0" 1'-0" 8'-0" 5.00 8.32 0.601 0.712

D-3A 1.5:1 3'-0" 1'-6" 7'-6" 7.88 8.41 0.937 0.957

B 2:1 3'-0" 1'-6" 9'-0" 9.00 9.71 0.927 0.951

C 3:1 3'-0" 1'-6" 12'-0" 11.25 12.49 0.901 0.933

D-4A 1.5:1 3'-0" 2'-0" 9'-0" 12.00 10.21 1.175 1.114

B 2:1 3'-0" 2'-0" 11'-0" 14.00 11.94 1.172 1.112

C 3:1 3'-0" 2'-0" 15'-0" 18.00 15.65 1.150 1.098

D-5A 1.5:1 4'-0" 3'-0" 13'-0" 25.50 13.82 1.846 1.505

B 2:1 4'-0" 3'-0" 16'-0" 30.00 16.42 1.827 1.495

C 3:1 4'-0" 3'-0" 22'-0" 39.00 21.97 1.775 1.466

D-6A 2:1 -- 1'-0" 4'-0" 2.00 4.47 0.447 0.585

B 3:1 -- 1'-0" 6'-0" 3.00 6.32 0.474 0.608

D-7A 2:1 -- 2'-0" 8'-0" 8.00 8.94 0.894 0.928

B 3:1 -- 2'-0" 12'-0" 12.00 12.65 0.949 0.965

D-8A 2:1 -- 3'-0" 12'-0" 18.00 13.42 1.342 1.216

B 3:1 -- 3'-0" 18'-0" 27.00 18.97 1.423 1.265

D-9 7:1 -- 1'-0" 14'-0" 7.00 14.14 0.495 0.626

D-10 7.1 -- 2'-0" 28'-0" 28.00 28.28 .0990 0.993

D-11 7.1 -- 3'-0" 42'-0" 63.00 42.43 1485 1.302

Figure 4.27 — Ditches Common Sections

Dimensions HydraulicsProperties of Ditches

34

Figure 4.28 — Drainage Ditches–Common Sections

35

Figure 4.29 — Geometric Elements of Common Sections

36

Figure 4.30 — Open Channel Flow Profile Computation

Q = ____________ n = ____________ So = ____________ a = ____________ Yn=____________

y A R R4/3 V aV2 / 2g E ∆E Sf Sf So – Sf ∆x x

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

37

Figure 4.31 — Open Channel Flow Profile Computation (Example)

Q = ____________ n = ____________ So = ____________ a = ____________ Yn=____________

y A R R4/3 V aV2 / 2g E ∆E Sf Sf So – Sf ∆x x

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

6.0 72.0 2.68 3.72 0.42 0.0031 6.0031 - 0.00002 - - - -

5.5 60.5 2.46 3.31 0.50 0.0040 5.5040 0.4990 0.00003 0.000025 0.00698 71.50 71.5

5.0 50.0 2.24 2.92 0.60 0.0064 5.0064 0.4976 0.00005 0.000040 0.00696 71.49 142.9

4.5 40.5 2.01 2.54 0.74 0.0098 4.5098 0.4966 0.00009 0.000070 0.00693 71.64 214.63

4.0 32.0 1.79 2.17 0.94 0.0157 4.0157 0.4941 0.00016 0.000127 0.00687 71.89 286.52

3.5 24.5 1.57 1.82 1.22 0.0268 3.5268 0.4889 0.00033 0.000246 0.00675 72.38 358.90

3.0 18.0 1.34 1.48 1.67 0.0496 3.0496 0.4772 0.00076 0.000547 0.00645 73.95 432.85

2.5 12.5 1.12 1.16 2.40 0.1029 2.6029 0.4467 0.00201 0.001387 0.00561 79.58 512.43

2.0 8.0 0.89 0.86 3.75 0.2511 2.2511 0.3518 0.00663 0.004320 0.00268 131.27 643.70

Thestepcomputationsarecarriedoutasshownintheabovetable.Thevaluesineachcolumnofthetableareexplainedasfollows:

Column Explanation

1 Depthofflow(ft)assignedfrom6to2feet

2 Waterarea(ft2)correspondingtodepthyinCol.1

3 Hydraulicradius(ft)correspondingtoyinCol.1

4 4/3powerofthehydraulicradius

5 Meanvelocity(fps)obtainedbydividingQ(30cfs)bythewaterareainCol.2

6 Velocityhead(ft)

7 Specificenergy(ft)obtainedbyaddingthevelocityheadinCol.6todepthofflowinCol.1

8 Changeofspecificenergy(ft)equaltothedifferencebetweentheEvalueinCol.7andthatofthepreviousstep.

9 FrictionslopeSf,computedfromVasgiveninCol.5andR4/3inCol.4

10 Averagefrictionslopebetweenthesteps,equaltothearithmeticmeanofthefrictionslopejustcomputedin Col.9andthatofthepreviousstep

11 Differencebetweenthebottomslope,So,andtheaveragefrictionslope,S

f

12 Lengthofthereach(ft)betweentheconsecutivesteps; Computedby∆x=∆E /(S

o–S

f)orbydividingthevalueinCol.8bythevalueinCol.11

13 Distancefromthebeginningpointtothesectionunderconsideration.Thisisequaltothecumulativesumofthe valuesinCol.12computedforprevioussteps.

––

38

Figure 4.32 — Flow Splitter, Option A

39

Figure 4.33 — Flow Splitter, Option B

40

Figure 4.34 — Flow Spreader Option A: Anchored Plate

41

Figure 4.35 — Flow Spreader Option B: Concrete Sump Box

42

Figure 4.36 — Flow Spreader Option C: Notched Curb Spreader

Figure 4.37 — Flow Spreader Option D: Through-Curb Port

43


DesignManual

CHAPTER 5–FIGURES

44


45

Figure 5.1 — BMP 5.01 Rock-filled Infiltration Trench

46

Figure 5.2 — Alternative Rock-filled Infiltration Trench System

47

Figure 5.3 — Gravelless Chamber Infiltration Trench

A gravelless chamber infiltration trench. Void space per linear foot shall be at least 2.6 cubic feet. The infiltrative surface per linear foot shall be at least 2.8 square feet.

48

Figure 5.4 — Average Annual Rainfall in Kitsap County

49


DesignManual

CHAPTER 6–FIGURES

50


51

Figure 6.1 — Water Quality Treatment BMP Selection Flow Chart

52

Figure 6.2 — Sand Filtration Basin Preceded by Presettling Basin (Variation of a Basic Sand Filter)

53

Figure 6.3 — Sand Filter with Pretreatment Cell

54

Figure 6.4 — Sand Filter with Level Spreader

55

Figure 6.5 — Sand Filter Vault

56

Figure 6.6 — Linear Sand Filter

57

Figure 6.7 — Shallow Plastic Drainage Channel

Vault Diameter Specified Treatment Capacity a,b

Figure 6.8 — StormFilter Schematic

58

Figure 6.9 — Typical Filter Strip

6" min. topsoil

Slope 1-15%

59

Figure 6.10 — Filter Strip Lengths for Narrow Right-of-Way

60

Figure 6.11 — Kitsap Mean Annual Storm

61

Figure 6.12 — Possible Wetpond Inlet / Outlet Configurations

62

Figure 6.13 — Wetpond

63

Figure 6.13 (continued) — Wetpond

64

Figure 6.14 — Wetvault

65

Figure 6.15 — Stormwater Treatment Wetland — Option A

66

Figure 6.16 — Stormwater Treatment Wetland (Option B)

67

Figure 6.17 — Headwater Depth for Smooth Interior Pipe Culverts with Inlet Control

68

Figure 6.18 — Headwater Depth for Corrugated Pipe Culverts with Inlet Control

69

Figure 6.19 — Critical Depth of Flow for Circular Culverts

70

Figure 6.20 — Circular Channel Ratios

71

Figure 6.21 — Turbulence Factor Plot

Figure 6.22 — Effective Separation Surface vs. Flow Rate

72

Figure 6.23 — Projected Horizontal Plate Area for Coalescing Plate Oil / Water Separator

73

Figure 6.24 — Baffle Oil / Water Separator

74

Figure 6.25 — Coalescing Plate Oil / Water Separator

75

Figure 6.26 — Spill Control Separator (Not for Oil Treatment)

76


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DesignManual

CHAPTER 7–FIGURES

78


79

Figure 7.1 — Typical Detention Pond

20% maximumSlope

5' minimum setback

See Figure 7.2 for section-cut diagrams

80

Figure 7.2 — Typical Detention Pond Sections

81

Figure 7.3 — Overflow Structure

82

Figure 7.4 — Permanent Surface Water Control Pond Sign

83

Figure 7.6 — Typical Detention Tank

Figure 7.5 — Weir Section for Emergency Overflow Spillway

84

Figure 7.7 — Detention Tank Access Detail

Notes:

1.Useadjustingblocksasrequiredtobringframetograde.

2.Allmaterialstobealuminumorgalvanizedandasphaltcoated(Treatment1orbetter).

3.Mustbelocatedforaccessbymaintenancevehicles.

4.MaysubstituteWSDOTspecialTypeIVmanhole(RCPonly).

85

Figure 7.8 — Typical Detention Vault

86

Figure 7.9 — Flow Restrictor (TEE)

87

Figure 7.10 — Flow Restrictor (Baffle)

88

Figure 7.11 — Flow Restrictor (Weir)

89

Figure 7.12 — Simple Orifice

Figure 7.13 — Rectangular, Sharp-Crested Weir

90

Figure 7.14 — V-Notch, Sharp-Crested Weir

Figure 7.15 — Sutro Weir

91

Figure 7.16 — Riser Inflow Curves

92

Figure 7.17 — USDA Textural Triangle

93

Figure 7.18 — Typical Infiltration Pond

94

Figure 7.19 — Typical Infiltration Tank

95

Figure 7.20 — Infiltration Vault

96

Figure 7.21 — Infiltration Trench

97

Figure 7.22 — Example of Small Infiltration Basin

98


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DesignManual

APPENDIX 3B – TABLE

100


101

Appendix 3B Table 1—Bacteria and Viruses

Pollutant

Total Phosphorus

TotalCopper

TotalLead

TotalZinc

TSS,mg/L

BOD,mg/L

Oil,mg/L

FecalColi

Commercial

(A) (B) 210 260

22 31

26 37

115 200

55 66

7.4 8

- -

980orgs/100mls/E

Industrial

(A) (B) 380 680

32 49

21 121

251 1,324

93 134

18 12

- -

-

Residential

(A) (B) 150 260

10 31

10 37

69 200

43 66

5.8 8

- -

-

Highway(C)

113-790

12-152

19/36

56-638

63-798

12.7/111

8.9/27

-

FreshwaterAcute

-

9

34

65

-

-

-

50colonies/100mls(F)

FreshwaterChronic

-

7

1.3

59

-

-

-

-

SaltwaterAcute

-

2.9

220

95

-

-

-

-

SaltwaterChronic

-

-

8.5

86

-

-

-

-

Concentrations (µg/l or ppb) Ecology/USEPA Criteria (D)

A.EricStrecker,“AnalysisofOregonUrbanRunoffWaterQualityDataCollectedfrom1990to1996”-2/1997ReportB.SantaClara-1990:mediandataC.WSDOTStormwaterManagementPlan,3/25/97,WA.andOregondataD.Dissolvedmetalcriteriainfreshwateratahardnessof50ppm(Chapter173-201AWAC),saltwatercriteriaexpressedasafunctionofwatereffectratio(40CFRPart131)

E.EcologygeometricmeancriterionforclassAAwaters.

102


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DesignManual

CHAPTER 4 – TABLES

104


105

Table 4.1 — Runoff Coefficients - “C” Values For The Rational Method

Undeveloped Land “C” Flat (0-5%) “C” Rolling (>5%)

Wood&forest 0.05 0.10

Sparsetrees&groundcover 0.10 0.15

Lightgrasstobareground 0.15 0.20

Developed Area “C” Flat (0-5%) “C” Rolling (>5%)

Pavementandroofs 0.90 0.90

Gravelroadsandparkinglots 0.75 0.80

Citybusiness 0.85 0.90

Apartmentdwellingareas 0.80 0.85

Industrialareas(heavy) 0.70 0.80

Industrialareas(light) 0.60 0.70

Earthshoulder 0.50 0.50

Playground

Developed Area “C” Flat (0-5%) “C” Rolling (>5%)

Lawns,meadowsandpastures 0.20 0.25

Parksandcemetaries 0.15 0.20

Single Family Residential Areas (Density is in dwelling units per gross acre (DU/GA) “C”

1.0DU/GA 0.30

2.0DU/GA 0.36

3.0DU/GA 0.42

4.0DU/GA 0.48

5.0DU/GA 0.60

9.0–15.0DU/GA 0.70

106

Table 4.2 — Maximum Pipe Slopes and Velociites

Pipe Slope Above Which Pipe Anchors Maxiumum MaximumPipe Material Required and Minimum Anchor Spacing Slope Allowed Velocity at Full Flow

CMP,SpiralRib,PVCCPE(1) 20%–(1anchorper100LFofpipe) 30%(3) 30fps

ConcreteorLCPE(1) 10%–(1anchorper50LFofpipe) 20%(3) 30fps

DuctileIron(2) 20%–(1anchorperpipesection) None None

SWPE(2) 20%–(1anchorper100LFofpipe, None None

cross-slopeinstallationonly)

Notes:

(1)ThesematerialsarenotallowedinGeologicallyHazardousAreasasdefinedinKCC19.

(2)Butt-fusedorflangedpipejointsarerequired;abovegroundinstallationisrecommendedonslopesgreaterthan40%.

(3)Maximumslopeof200%isallowedforthesepipematerialswithnojoints(onesection),withstructuresateachend,andwithpropergrouting.

Table 4.3 — Allowable Structures and Pipe Sizes

Catch Basin Type

Inlet(3)

Type1(2)

Type1L(2)

Type2–48”diameter




CMP, Spiral Rib, CPE, SWPE, PVCand Ductile Iron(1)

12”

18”

24”

30”

36”

54”

72”

Concrete LCPE

12”

12"

18”

24”

30”

48"

72”

Maximum Pipe Diameter

Notes:

(1)Generallythesepipematerialswillbeonesizelargerthanconcreteduetosmallerwallthickness.However,forangledconnectionsorthosewithseveralpipesonthesameplane,thiswillnotapply.

(2)Amaximumof5verticalfeetisallowedbetweenfinishedgradeandinvertelevation.

Table 4.4 — Maximum Cover (feet) for Concrete Pipe–Compaction Design A

Pipe Diameter

12”

18”

24”

30”

36”

48”

60”

72”

84”

96”

108”

Notes:

CompactionDesignAreferstoFigure4.2

Plain

18

18

16

Class II

10

11

11

11

11

12

12

12

12

12

12

Class III

14

14

15

15

15

15

16

16

16

16

16

Class IV

21

22

22

23

23

23

24

24

24

24

24

Class V

26

28

28

29

29

29

30

30

30

30

30

107

Table 4.5 — Manning’s “n” Values for Pipes

Type of Pipe Material

UniformFlowPreliminarydesign

A. ConcretepipeandLCPEpipe

B. AnnularCorrugatedMetalPipeorPipeArch

1.22/3“x1/2”corrugation(riveted) a. plainorfullycoated b. pavedinvert(40%ofcircumferencepaved) 1)flowatfulldepth 2)flowat80%fulldepth 3)flowat60%fulldepth c. treatment5

2. 3”x1”corrugation

3. 6”x2”corrugation(fieldbolted)

C. Helical22/3”X1/2”corrugationandCPEpipe

D. SpiralribmetalpipeandPVCpipe

E. Ductileironpipecementlined

F. SWPEpipe(buttfusedonly)

UniformFlow(Preliminarydesign)

0.014

0.028

0.0210.0180.0150.015

0.031

0.035

0.028

0.013

0.014

0.009

BackwaterFlow(CapacityVerification)

0.012

0.024

0.0180.0160.0130.013

0.027

0.030

0.024

0.011

0.012

0.009

Analysis Method

Table 4.6 — Rock Protection at Outfalls

Discharge Velocityat Design Flow (fps) Required Protection

GreaterThan

0

5

10

20

Less than or equal to

5

10

20

N/A

Type

Rocklining(2)

Riprap(3)

GabionOutfall

Engineeredenergy

dissipaterrequired

Thickness

1foot

2feet

Asrequired

Width

Diameter+6feet

Diameter+6feetor3xdiameter,whicheveris

greater

Asrequired

Length

8feetor4xdiameter,

whicheverisgreater

12feetor4xdiameterwhicheveris

greater

Asrequired

Height

Crown+1foot

Crown+1foot

Crown+1foot

Minimum Dimensions (1)

(1)Thesesizesassumethaterosionisdominatedbyoutfallenergy.Inmanycasessizingwillbegovernedbyconditionsinthereceivingwaters.

(2)Rockliningshallbequarryspallswithgradationasfollows: Passing8-inchsquaresieve: 100% Passing3-inchsquaresieve: 40to60%maximum Passing3/4-inchsquaresieve: 0to10%maximum

(3)Riprapshallbereasonablywellgradedwithgradationasfollows: Maximumstonesize: 24inches(nominaldiameter) Medianstonesize: 16inches Minimumstonesize: 4inches

Note: Riprap sizing is governed by side slopes on outlet channel, assumed to be approximately 3:1.

108

Table 4.7 — Constants for Inlet Control Equations*

SubmergedShape & Material

CircularConcrete

CircularCMP

RectangularBox

CMBoxes

ArchCMP

BottomlessArch

CMP

Circularwith

taperedinlet

UnsubmergedInlet Edge Description

Squareedgewithheadwall

Grooveendwithheadwall

Grooveendprojecting

Headwall

Miteredtoslope

Projecting

30oto75owingwallflares

90oand15owingwallflares

0owingwallflares

90oheadwall

Thickwallprojecting

Thinwallprojecting

90oheadwall

Miteredtoslope

Projecting

90oheadwall

Miteredtoslope

Thinwallprojecting

Smoothtaperedinletthroat

Roughtaperedinletthroat

EquationForm

1

1

1

1

1

1

2

K

0.0098

0.0078

0.0045

0.0078

0.0210

0.0340

0.0260

0.0610

0.0610

0.0083

0.0145

0.0340

0.0083

0.0300

0.0340

0.0083

0.0300

0.0340

0.5340

0.5190

M

2.00

2.00

2.00

2.00

1.33

1.50

1.00

0.75

0.75

2.00

1.75

1.50

2.00

1.00

1.50

2.00

2.00

1.50

0.333

0.640

c

0.0398

0.0292

0.0317

0.0379

0.0463

0.0553

0.0385

0.0400

0.0423

0.0379

0.0419

0.0496

0.0496

0.0463

0.0496

0.0379

0.0463

0.0496

0.0196

0.0289

Y

0.67

0.74

0.69

0.69

0.75

0.54

0.81

0.80

0.82

0.69

0.64

0.57

0.57

0.75

0.53

0.69

0.75

0.57

0.89

0.90

*Source:FHWAHDSNo.5

109

Table 4.8 — Entrance Loss Coefficients

Type of Structure and Design Entrance

Pipe, Concrete, PVC, Spiral Rib, DI, and LCPE

Projectingfromfill,socket(bell)end

Projectingfromfill,squarecutend

Headwall,orheadwallandwingwalls

Socketendofpipe(groove-end)

Square-edge

Rounded(radius=1/12D)

Miteredtoconformtofillslope

Endsectionconformingtofillslope*

Bevelededges,33.7oor45obevels

Side-orslope-taperedinlet

Pipe, or Pipe-Arch, Corrugated Metal and Other Non-Concrete or D.I.

Projectingfromfill(noheadwall)

Headwall,orheadwallandwingwalls(square-edge)

Miteredtoconformtofillslope(pavedorunpavedslope)

Endsectionconformingtofillslope*

Bevelededges,33.7oor45obevels


Box, Reinforced Concrete

Headwallparalleltoembankment(nowingwalls)

Square-edgedon3edges

Roundedon3edgestoradiusof1/12barreldimensionorbevelededgeson3sides

Wingwallsat30oto75otobarrel

Square-edgedatcrown

Crownedgeroundedtoradiusof1/12barreldimensionorbeveledtopedge

Wingwallat10oto25otobarrel

Square-edgedatcrown

Wingwallsparallel(extensionofsides)

Square-edgedatcrown


Coefficient, Ke

0.2

0.5

0.2

0.5

0.2

0.7

0.5

0.2

0.2

0.9

0.5

0.7

0.5

0.2

0.2

0.5

0.2

0.4

0.2

0.5

0.7

0.2

*Note: “End section conforming to fill slope” are the sections commonly available from manufacturers. From limited hydraulic tests they are equivalent in operation to a headwall in both inlet and outlet control. Some end sections incorporating a closed taper in their design have a superior hydraulic performance.

110

Table 4.9 — Channel Protection

Discharge Velocityat Design Flow (fps) Required Protection

GreaterThan

0

5

8

12

Less than or equal to

5

8

12

20

Type

Grassliningorbio-engineeredlining

Rocklining(1)orbio-engineeredlining

Riprap(2)

Slopemattressgabion,etc.

(1)RockLiningshallbereasonablywellgradedasfollows:Maximumstonesize: 12inchesMedianstonesize: 8inchesMinimumstonesize: 2inches

(2)Riprapshallbereasonablywellgradedasfollows:Maximumstonesize: 24inchesMedianstonesize: 16inchesMinimumstonesize: 4inches

Note: Riprap sizing is governed by side slopes on outlet channel, assumed to be approximately 3:1.

Minimum Height AboveDesign Water Surface

1foot

2feet

2feet

Thickness

N/A

1foot

2feet

Varies

111

Table 4.10 — Value of Roughness Coefficient “n” for Open Channels

Type of Channel & Description Manning’s “n*” (Normal)

A. Constructed Channels

a.Earth,straightanduniform

1.Clean,recentlycompleted 0.018

2.Gravel,uniformsection,clean 0.025

3.Withshortgrass,fewweeds 0.027

b.Earth,windingandsluggish

1.Novegetation 0.025

2.Grass,someweeds 0.030

3.Denseweedsoraquaticplantsin 0.035 deepchannels

4.Earthbottomandrubblesides 0.030

5.Stonybottomandweedybanks 0.035

6.Cobblebottomandcleansides 0.040

c.Rocklined

1.Smoothanduniform 0.035

2.Jaggedandirregular 0.040

d.Channelsnotmaintained,weeds andbrushuncut

1.Denseweeds,highasflowdepth 0.080

2.Cleanbottom,brushonsides 0.050

3.Sameas#2,higheststageofflow 0.070

4.Densebrush,highstage 0.100

B. Natural Streams

B-1Minorstreams(topwidthatflood stage<100ft.)

a.Streamsonplain

1.Clean,straight,fullstagenorifts 0.030 ordeeppools

2.Sameas#1,butmorestones 0.035 andweeds

3.Clean,winding,somepools 0.040 andshoals

4.Sameas#3,butsomeweeds 0.040

5.Sameas#4,butmorestones 0.050

Type of Channel & Description Manning’s “n*” (Normal)

6.Sluggishreaches,weedy 0.070 deeppools 7.Veryweedyreaches,deep 0.100 pools,orfloodwayswithheavy standoftimberandunderbrush b.Mountainstreams,novegetationin channel,banksusuallysteep,trees andbrushalongbankssubmerged athighstages 1.Bottom:gravel,cobbles,and 0.040 fewboulders 2.Bottom:cobbleswithlarge 0.050 bouldersB-2 Floodplains a.Pasture,nobrush 1.Shortgrass 0.030 2.Highgrass 0.035 b.Cultivatedareas 1.Nocrop 0.030 2.Maturerowcrops 0.035 3.Maturefieldcrops 0.040 c.Brush 1.Scatteredbrush,heavyweeds 0.050 2.Lightbrushandtrees 0.060 3.Mediumtodensebrush 0.070 4.Heavy,densebrush 0.100 d.Trees 1.Densewillows,straight 0.150 2.Clearedlandwithtreestumps, 0.040 nosprouts 3.Sameas#2,butwithheavy 0.060 growthofsprouts 4.Heavystandoftimber,afew 0.100 downtrees,littleundergrowth, floodstagebelowbranches 5.Sameas#4,butwithflood 0.120 stagereachingbranches

* Note: These “n” values are “normal” values for use in analysis of channels. For conservative design of channel capacity, the maximum values listed in other references should be considered. For channel bank stability, the minimum values should be considered.

Table 4.11 — Evidence of Existing or Predicted Problems

1. Evidenceofpotentialforcontaminationofsurfacewaters.

2.Overtopping,scouring,banksloughingorsedimentation.

3. Significantdestructionofaquatichabitatororganisms(forexample,severesiltationorincisioninastream).

4. Evidenceofpotentialforcontaminationofgroundwater.

112


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DesignManual

CHAPTER 5 –TABLE

114


115

Table 5.1 — Recommended Infiltration Rates Based on % of Soil Retained by 200 Sieve

Short Term Infiltration rate (inches/hour)

8

2

1

0.5

Correction Facto, CF

4

4

4

4

Estimated Long-term (Design) Infiltration Rate (inches/hour)

2.0

0.5

0.25

0.13

>87.5%

87.5%–75%

75%–55%

55%–45%

Regression Equation

Length(feet)=ImperviousArea(squarefeet)x[MxMeanAnnualPrecipitation(inches)+B]

Length(feet)=ImperviousArea(squarefeet)x[MxMeanAnnualPrecipitation(inches)+B]

Table 5.2 — Infiltration Trench Sizing Factors

Native Soil Design Infiltration Rate (inches/hour)

0.13

0.25

0.5

2.0

0.13

0.25

0.5

2.0

Regression Factors M B

0.0244 0.4918

0.0097 -0.1171

0.0051 -0.0445

0.0013 +0.0101

0.0057 -0.0695

0.0038 -0.0412

0.0021 -0.0104

0.00072 -0.00303

BMP

RockTrenchBMP5.01

GravellessChamberBMP5.02

NOTE: (BMP 5.01 = Figure 5.1) — Rock trench = 2–feet wideAsanexample,usingtable5.2,thelengthofarocktrenchreceivingrunofffrom1.000squarefeetofimperviousareaatasitewithanativesoildesigninfiltrationrateof0.5inchesperhourandameanannualprecipitationdepthof48inches(fromfigure5.4)wouldbecalculatedas:

RockTrenchLength(feet)=1,000x[0.0051x48–0.0445]=200feet

Similarly,thelengthofagravellesschamberreceivingrunofffrom2,000squarefeetofimpervioussurfaceareawherethenativesoildesigninfiltrationrateis0.25inchesperhourandthesitemeanannualprecipitationdepthis34inches(fromfigure5.4)wouldbecalculatedas:

GravellessChamberLength(feet)=2,000x[0.0038x34-0.0412]=176feet

116

Table 5.3 — Bioretention and Pervious Pavement Sizing Factors

Native Soil Design

Infiltration Rate

(inches/hour)

0.25

0.5

1.0

0.25

0.5

1.0

0.25

0.5

1.0

≥0.25

Flow Control

M B

0.0092 -0.0573

0.0051 +0.0317

0.0034 +0.0309

0.0067 -0.0381

0.0040 +0.0067

0.0024 +0.0283

0.1100 -1.0536

0.0187 +0.4945

0.0048 +0.3531

0.1 0

BMP

Bioretentioncell3–6inchpondingdepth

Bioretentioncell3–10inchpondingdepth

Permeablepavementfacility–6

inchstoragereservoirandoverflow

PermeablePavementsurface4–notdesignedtomanageotherrunoff

Water Quality

M B

0.0018 -0.0046

0.0012 -0.001

0.0008 -0.00005

0.0014 -0.0057

0.0009 -0.0026

0.0006 -0.0015

N/A N/A

N/A N/A

N/A N/A

N/A N/A

Regression Equation

BioretentionBottomArea(squarefeet)=ImperviousArea(squarefeet)x[MxMeanAnnualPrecipitation(inches)+B(squarefeet)]

BioretentionBottomArea(squarefeet)=ImperviousArea(squarefeet)x[MxMeanAnnualPrecipitation(inches)+B]

PermeablePavementFacilityArea(squarefeet)=ImperviousArea(squarefeet)x[MxMeanAnnualPrecipitation(inches)+B(squarefeet)]

MinimumAggregateDepth(inches)=MxMeanAnnualPrecipitation(inches)

1 BMPsizedtomatchpeakflowratesandflowdurationsfromhalfofthe2-yeartothe50-yearrecurrenceintervalflowtoapredevelopedforestcondition.

2 BMPsizedtoinfiltrate91percentoftherunofffile.

3 Regressionconstantsareforbioretentionfacilitybottomarea.Totalfootprintareamaybecalculatedbasedonsideslopes(3H:1V),pondingdepth,andfreeboard.

4 Forpermeablepavementsurfaceswithsubgradeslopesgreaterthan2percenttheflowcontrolstandardisnotachieved.Theareamitigatediscalculatedas40percentofthepermeablepavementareaanddownstreamBMP(s)aresizedfor60percentofthepermeablepavementarea.

N/A =Notapplicable

Regression Factors

117


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DesignManual

CHAPTER 6 –TABLES

119


120

Bottom&sides

Firstcell:bottomandsidestoWQdesignwatersurface

Secondcell:bottom&sidestoWQdesignwatersurface

Firstcell:bottomandsidestoWQdesignwatersurface

Secondcell:bottom&sidestoWQdesignwatersurface

Bottom&sides,bothcells

Basinsidesonly

N/A

N/Aifinvault

Bottom&sidesofpresettlingcellifnotinvault

N/A

N/A

N/A

N/A

FilterstripMediafilterdrain

Stormwatertreatmentwetland

Bioinfiltrationswale

Bioretentionfilter

ContechStormfilter©

Wetvault

Sandfilterorsandfiltervault

OK

OK

OK

OK

OK

OK

OK,butpresettlingandcontrolof

floatablesneeded

No-mustbeinstalledbeforeflowconcentrate

OK-lesswaterlevelfluctuationinpondsdownstreamofdetentionmayimproveaestheticqualitiesandperformance

OK

OK

OK

OK

OK-sandfiltersdownstreamofdetentionfacilitiesmayrequirefieldadjustmentsifprolongedflowscausesandsaturationandinterferewithphosphorusremoval

Table 6.1 — Treatment Facility Placement in Relation to Detention

Water Quality Facility Preceding Detention Following Detention

Presettlingbasin

Wetpond

Combineddetention/waterqualityfacility

Stormwaterwetland

Sandfiltrationbasin

Sandfiltervault

Linearsandfilter

Mediafilterdrain

Bioretentionfilter

Mediafilter(invault)

Wetvault

Table 6.2 — Lining Types for Runoff Treatment Facilities

Water Quality Facility Area to be Lined Type of Liner Recommended

Lowpermeabilitylinerortreatmentliner.(Ifthebasinwillinterceptseasonalhighgroundwatertableatreatmentlinerisrecommended.)


Treatmentline


Treatmentliner


Treatmentliner

Nolinerneeded

Nolinerneeded

Lowpermeabilityortreatmentliner

Nolinerneeded

Nolinerneeded

Nolinerneeded

Nolinerneeded

121

6-inch

4-inch

#4

#200

Table 6.3 — Compacted Till Liners

Sieve Size Percent Passing

100

90

70–100

20

4

6

8

10

Table 6.4 — Sizing of Presettling Vaults

Vault Diameter Specified Treatment Capacity a,b

125GPM

285GPM

500GPM

785GPM

0.30CFS

0.60CFS

1.10CFS

1.75CFS

(a) BasedonahydraulicloadingRateof10GPM/ft2atthewaterqualitydesignflow

(b) Eachmodelwillhaveamuchgreaterhydrauliccapacity,identifiedbythemanufacturer

4

8

16

30

50

100

200

Table 6.5 — Sand Medium Specification

U. S. Sieve Numer Percent Passing

95-100

70-100

40-90

25-75

2-25

<4

<2

Table 6.6 — Design Flow Rates for Basic Treatment with ZPG MediaEffectiveCartridgeHeight(inches)

CartridgeFlowRate(gpm/cartridge)

12

5

18

7.5

27

11.3

122

0.01—0.15

0.5feet/second

1inchmaximum

0.35(0.45ifcompost-amended,andmowedtomaintaingrassheight≤4inches

—

—

9minutes

Sufficienttoachievehydraulicresidencetimeinthefilterstrip

Inletedge≥1inchlowerthancontributingpavedarea

150feet

0.05(steeperthan0.05needupslopeflowspreadingandenergydissipation)

0.02(attheedgeofthestripinlet)

PerChapter4

LongitudinalSlope

Maximumvelocity

Maximumwaterdepth2

Manningcoefficient(22)

Bedwidth(bottom)

Freeboardheight

MinimumhydraulicresidencetimeatWaterQualityDesignFlowRate

Minimumlength

Maximumsideslope

Maximumtributarydrainageflowpath

Maximumlongitudinalslopeofcontributingarea

Maximumlateralslopeofcontributingarea

Ditchconveyancecapacity

Table 6.7 — Filter Strip Sizing Criteria

Design Parameter Filter strip

123

Agrostis exarata (1)

Carex stipata

Eleocharis palustris

Glyceria occidentalis

Juncus effusus

Juncus tenuis

Oenanthe sarmentosa

Scirpus atrocinctus(formerly S. cyperinus)

Scirpus microcarpus

Sagittaria latifolia

Table 6.8 — Emergent Wetland Plant Species for Wetponds

Species

Inundation to 1 Foot

Common Name

Inundation 1 to 2 FeetAgrostis exarata (1)

Alisma plantago-aquatica

Eleocharis palustris

Glyceria occidentalis

Juncus effusus

Scirpus microcarpus

Sparganium emmersum

Inundation 1 to 3 FeetCarex obnupta

Beckmania syzigachne (1)

Scirpus acutus (2)

Scirpus validus (2)

Inundation Greater Than 3 FeetNupharpolysepalum

Nymphaeaodorata(1)

Spikebentgrass

Sawbeaksedge

Spikerush

Westernmannagrass

Softrush

Slenderrush

Waterparsley

Woolgrass

Small-fruitedbulrush

Arrowhead

Notes

Prairietocoast

Wetground

Marginsofponds,wetmeadows

Marshes,pondmargins

Wetmeadows,pastures,wetlandmargins

Wetsoils,wetlandmargins

Shallowwateralongstreamandpondmargins;needssaturatedsoilsallsummer

Toleratesshallowwater;tallclumps

Wetgroundto18inchesdepth

Maximum Depth

to2feet

to2feet

to2feet

to2feet

18inches

Spikebentgrass

Waterplantain

Spikerush

Westernmannagrass

Softrush

Small-fruitedbulrush

Burreed

Prairietocoast

Marginsofponds,wetmeadows

Marshes,pondmargins

Wetmeadows,pastures,wetlandmargins

Wetgroundto18inchesdepth

Shallowstandingwater,saturatedsoils

18inches

Sloughsedge

Westernsloughgrass

Hardstembulrush

Softstembulrush

Wetgroundorstandingwater

Wetprairietopondmargins

Singletallstems,notclumping

1.5to3feet

to3feet

Spatterdock

Whitewaterlily

Deepwater

Shallowtodeepponds

3to7.5feet

to6feet

Notes:

(1)Non-nativespecies.Beckmania syzigachneisnativetoOregon.Nativespeciesarepreferred.

(2)Scirpustubersmustbeplantedshallowerforestablishment,andprotectedfromforagingwaterfowluntilestablished.Emergingaerialstemsshouldprojectabovewatersurfacetoallowoxygentransporttotheroots.

Primarysources:MunicipalityofMetropolitanSeattle,WaterPollutionControlAspectsofAquaticPlants,1990.HortusNorthwest,WetlandPlantsforWesternOregon,Issue2,1991.HitchcockandCronquist,FloraofthePacificNorthwest,1973.

124

Depth Range (feet)

0.1to1

1to2

2to2.5

Table 6.9 — Distribution of depths in wetland cell

Dividing Berm at WQ Design Water Surface Dividing Berm Submerged 1 foot

100

200

300

600

1,200

2,400

3,200

4,800

Table 6.10 — Coalescing Plate Oil / Water Separator Vault Dimensions*

Area of Effective Separation(square feet)

Approximate vault volume required (cubic feet) for plates with ½ inch spacing and inclined 60o from horizontal (cubic feet)

150

240

330

530

890

1,150

2,090

2,640

* Orderofmagnitudeestimatesforplanningpurposesonly.Actualvaultvolumesvaryconsiderablydependingonseparatordesignfeaturesandpre-castvaultdimensions.

Percent

25

55

20

Depth Range (feet)

1to1.5

1.5to2

2to2.5

Percent

40

40

20

125


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DesignManual

CHAPTER 7 – TABLES

127


128

1.50

0.619

0.6175

0.614

0.612

0.610

0.6085

0.608

1.50

0.625

0.6235

0.620

0.618

0.616

0.6145

0.614

1.25

0.6185

0.617

0.6135

0.6115

0.6095

0.608

0.6075

1.25

0.6245

0.623

0.6195

0.6175

0.6155

0.614

0.635

Dwarftallfescue

Dwardperennialrye"Barclay*"

Redfescue

Colonialbentgrass

Table 7.2 — Stormwater Tract "Low Grow" Seed Mix

Seed Name Percentage of Mix

40%

30%

25%

5%

* IfwildflowersareusedandsowingisdonebeforeLaborDay,theamountofdwarfperennialryecanbereducedproportionatelytotheamountofwildflowerseedused.

Table 7.3 — Values of Cd for Sutro Weirs

Cd Values, Symmetricalb(ft)

1.0

0.617

0.615

0.612

0.610

0.608

0.6065

0.606

1.0

0.623

0.621

0.618

0.616

0.614

0.6125

0.612)

0.75

0.613

0.611

0.608

0.6055

0.604

0.6025

0.602

0.75

0.619

0.617

0.614

0.6115

0.610

0.6085

0.608

0.50

0.608

0.606

0.603

0.601

0.599

0.598

0.597

0.50

0.614

0.612

0.609

0.607

0.605

0.604

0.603

a (ft)

0.02

0.05

0.10

0.15

0.20

0.25

0.30

a (ft)

0.02

0.05

0.10

0.15

0.20

0.25

0.30

Cd Values, Non-Symmetricalb(ft)

*Redtwigdogwood(Cornus stolonifera)

*Serviceberry(Amelanchier alnifolia)

*Filbert(Corylus cornuta, others)

Highbushcranberry(Vaccinium opulus)

Blueberry(Vaccinium spp.)

Fruittreesondwarfrootstock

Rhododendron(native and ornamental varieties)

Table 7.1 — Small Trees and Shrubs with Fibrous Roots

Small Trees / High Shrubs Low Shrubs

*Snowberry(Symporicarpus albus)

*Salmonberry(Rubus spectabilis)

Rosarugosa(avoid spreading varieties)

Rockrose(Cistus spp.)

Ceanothusspp.(choose hardier varieties)

NewZealandflax(Phormium penax)

Ornamentalgrasses(e.g., Miscanthis, Pennisetum)

* NativeSpecies

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