Drop Structure Design

8/10/2019 Drop Structure Design

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1998 William Barclay Parsons Fellowship Parsons Brinckerhoff Monograph 14

Scott Williamson, P.E. Lead Engineer Parsons Brinckerhoff Quade & Douglas, Inc.

August 2001

Drop StructureDesign for

Wastewater and

StormwaterCollection Systems


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FOREWORD

1.0 INTRODUCTION

2.0 DROP STRUCTURE BASIC FUNCTIONS AND TYPES

3.0 PLANNING AND DESIGN CONSIDERATIONS

4.0 DESIGN METHODOLOGY

5.0 DROP STRUCTURE APPURTENANCES

APPENDIX A: REVIEW OF DROP STRUCTURE/TUNNEL SYSTEMS

APPENDIX B: SUMMARY OF DROP STRUCTURES BY GEOGRAPHICAL

LOCATION AND INLET TYPE

REFERENCES

CONTENTS


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CHAPTER 2

CHAPTER 3

CHAPTER 4

CHAPTER 5

APPENDIX A

LIST OF FIGURES


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CHAPTER 2

CHAPTER 3

CHAPTER 4

LIST OF TABLES


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1.0 INTRODUCTION


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2.0 DROP STRUCTURE BASIC FUNCTIONSAND TYPES


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2.0 DROP STRUCTURE BASIC FUNCTIONSAND TYPES

2.1 BASIC FUNCTIONS

1 The term "collection system" as used in this monograph generally refers to the wastewater or storm-water collection system providing flow to the drop structure. "Collection system" may also be used to describethe system as a whole.

2 The terms "tunnel" or "tunnel system" refer to the system downstream of the drop structure.


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2.2 GENERAL DROP STRUCTURE TYPES ANDCOMPONENTS

Diversion Chamber.

Inlet Structure.

Dropshaft.


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Deaeration Chamber.

Vent Pipe.

Adit.

Appurtenant Structures


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Vertical Shaft

Vent

Adit

Main Tunnel

Deaeration Chamber

SurfaceSewers

Surface

JunctionChamber

ApproachChannel

InletStructure

Figure 2.1 Typical Drop Structure Components


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Historical Perspective on the Development of Drop Structures

Figure 2.3 Types of Plunge Flow Inlets


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2.3 OTHER TYPES OF DROP STRUCTURES


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2.4 COMPARISONS OF DROP STRUCTURE TYPES

ConcreteEncasement

Exterior Drop

FlowDam

Manhole

Figure 2.4 Typical Drop Manhole (Sanitary Sewer)


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TYPE/INLETCONFIGURATION ADVANTAGES DISADVANTAGES

Table 2.1 Drop Structure Evaluation Based on Inlet Type


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TYPE/INLETCONFIGURATION ADVANTAGES DISADVANTAGES

Table 2.1 Drop Structure Evaluation Based on Inlet Type (Cont.)


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h

hCM.

CM3/MIN.

Q

Q = 1.5 M 3/SEC

140

120

100

80

60

40

20

0

1

1

2

2

4

4

3

3

5

5

Figure 2.5 Comparison of Air Entrainment for Various Inlet Types (11)


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Figure 2.6 Comparison of Dimensions for Various Drop Structure Types*

7'-0" Shaft Diam.

7'-0" AditDiam.

14'

7'- 4"

Guide WallCenter Column

25'

Main Tunnel

DeaerationChamber

4 5 ' + 1 -

35

7'-0" InletPipe

Diam.InletPipe

ElbowInlet

8'-2" Shaft Diam.

Main Tunnel

3'- 0"

Inlet Ramp

Outlet Ramp

Adit

*Design Flow = 280 cfs

E-15Plunge

Inlet Type

HelicoidalRamp Type

VortexChamber

5'-7" Shaft Diam.

6 8 ' - 0 "

2 3 ' - 6 "

Main Tunnel

Main Tunnel5'-0"

Adit

10'-0" Diam.Deaeration

Chamber

7'-0" Diam.InletPipe

Vent Pipe

6'6" Adit

Diam

2'9" Vent Diam

TangentialInlet Type

D-4 PlungeInlet Type

18'

16'48' 9'5"

16'

7'0"

7'0" ShaftDiam


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3.0 PLANNING AND DESIGN CONSIDERATIONS


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3.1 FLOW VARIABILITY AND COLLECTION SYSTEM TYPE

Table 3.1 Typical Concentrations of Components in UntreatedWastewater (9)

PARAMETER WEAK MEDIUM STRONG

350 720 1200

250 500 850

100 220 350

105 20

110 220 400

80 160 290

250 500 1000

20 40

84

85

15

30 50 100

20 30 50

50 100 200

50 100 150

400

Total

Solids, total

Total Dissolved Solids

Suspended Solids

Settleable Solid

BOD (5)

Total Organic Carbon

COD

Nitrogen (total as N)

Phosphorous (total as P)

Chlorides

Sulfate

Alkalinity

Grease

Coliform

Volatile Organic Compounds (micrograms/L)

/100 ml /100 ml /100 ml10 6 10 7 10 9

(*) All values are provided in units of milligrams per liter unless otherwise noted.

CONCENTRATION*


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3.2 ENERGY DISSIPATION


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D r o p s

h a f t

D r o p s

h a f t

D r o p s

h a f t

A d i t T u n n e

l

I m p a c t

C u p

A d i t T u n n e

l

A d i t

P l u n g e

P o o

l

P o o

l - F o r m

i n g

W e i r

H i g h S t r e n g t

h

C o n c r e t e

A

C o f

D o w n s

h a f t

L

R o c

k

W e a r

R e s

i s t a n t

L i n i n g

W

e a r -

R e s

i s t a n t

L i n i n g a t

t h e

B a s e o f

t h e A

L C O S A N D r o p

S t r u c

t u r e

( P i t t s b u r g h , P

A )

E m u l s i o n

D e a e r a t e d

W a t e r

" C a s s e r o

l e " I m p a c t

C u p

B a f

f l e a t

t h e

B a s e o f a

P l u n g e -

F l o w

D r o p

S t r u c

t u r e

D

D r o p s

h a f t

B a f

f l e A d i t T u n n e

l

D e f

l e c t o r

B a f

f l e a t

t h e

B a s e o f a

P l u n g e -

F l o w

D r o p

S t r u c

t u r e

D r o p s

h a f t

A i r T u n n e l

B a f

f l e

5 ' - 9

"

D r a

i n

F i g u r e

3 . 1

E n e r g y

D i s s

i p a

t o r s

i n P l u n g e

I n l e t D r o

p S t r u c

t u r e s


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Vortex Inlets

Plunge Pools

Other Energy Dissipation Devices and Methods


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3.3 DROP STRUCTURE LOCATION


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Figure 3.2 Alternative Sites for Drop Structure Location

Proposed Deep Tunnelroposed Deep Tunnel lignment

Alternat ive lternative TunnelTunnelConnector

Existing Pumpxisting PumpStation andtation andPotential Dropotential DropStructure Sitetructure Site

TunnelConnector

Alternat ive "B"lternative BSite fo r Dropite fo r DropStructure

Existing Collectionxisting CollectionSystem

New Surfaceew SurfaceSewer Connectionewer Connection

Proposed Deep Tunnel Alignment

Industrial Zonendustrial ZoneIndustrial Zone

Industrial Zonendustrial ZoneIndustrial Zone

Commercial /ommercial Residential

Zone

Commercial /Residential

Zone

Al ternat ive A TunnelConnector

Existing PumpStation andPotential DropStructure Site

TunnelConnector

B

A

Al ternat ive "B"Site fo r DropStructure

Existing CollectionSystem

New SurfaceSewer Connection


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Figure 3.3 Drop Structure Footprint and Dimensions

3.4 AIR ENTRAINMENT AND VENTILATION

100'

75'

Main Tunnel

Flow

Odor ControlFacility

DiversionChamber

Vortex Chamber

DeaerationChamber

75


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Air Entrainment


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Adit Connection with Main Tunnel

Figure 3.4 Horizontal Connection to Main Tunnel

Main Tunnel

Flow Adit

Drop Structure

60 to 75 Angle of

Entry


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Figure 3.6 Tunnel to Adit Connection from Chicagos TARP

F l o w

Main Tunnel

Adit

Steps

1

1.5


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Figure 3.7 Hydraulic Gradeline in H4-Type Vortex Drop Structure atDesign Flow

Annular Flow withCentral Air Core

HGL

HGL


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3.5 ODOR AND CORROSION CONTROL

Need for Odor Control


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Table 3.2 Odorous Compounds in Untreated Wastewater and

Detectable Limits*

ODOROUSCOMPOUND

THRESHOLD OFDETECTION (PPM BYVOLUME)

RECOGNITION(PPM BYVOLUME)

ODORDESCRIPTION

Ammonia 17 37 home cleaningproducts

Chlorine .08 .314 swimming pools

Dimethyl Sulfide .001 .001 decayed cabbage

Diphenyl Sulfide .0001 .0021 decayed cabbage

Methyl Mercaptan .0005 .001 decayed cabbage

Ethyl Mercaptan .0003 .001 decayed cabbage

Hydrogen Sulfide


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Methods and Alternatives for Odor Control


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Figure 3.8 Examples of Processes Used for Odor Control

Soil/Compost Filter

Wet Scrubber System(Countercurrent Packed Tower)

Odorous Air

Fan

Soil or CompostClean Air

Gravel

Clean Air

Scrubber Liquid

Recycled PumpSumpDrain

Odorous Air

Air Distribution Pipe

ActivatedCarbon(Dual Bed)

Activated Carbon Filter

Mist Eliminator

Spray System

PackingMedia Support Plate

Odorous Air

Clean Air

Fan


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Selection


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Table 3.3 Costs for Odor Control*

Table 3.4 Example: Matrix Evaluation of Gas Phase Odor ControlTreatment

METHOD DESIGN AIR FLOWM3 /MIN

CAPITAL COSTS ANNUAL COSTS

28 $43,750 $9,100 Activated Carbon280 $189,000 $70,500

28 $57,500 $3,000Wet Scrubber

280 $113,000 $28,500

*Costs based on values included in the USEPA Manual for Odor Control ; dollar values indexed to 1999 from 1984values based on ENR index of 1.486.

TECHNOLOGY CRITERIA SCORE

Efficiency Reliability Stability Land Handling Capital

Cost

O&M

Cost

ActivatedCarbon

ChemicalScrubbers

Biofilters

10

8

4

10

8

6

8

6

4

8

6

3

8

6

8

8

8

10

6

6

6

58

48

41

Scoring: 10 = Most favorable; 2 = Least favorable


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Figure 3.9 At-Grade Odor Control Facility

Corrosion Protection and Prevention


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Table 3.5 Effect of Sewer Conditions on Hydrogen Sulfide Corrosion

STEP INHYDROGEN

SULFIDECORROSION

PROCESS

CONDITIONVARIABLE

EFFECT OFINCREASING

VARIABLE ONCORROSION

COMMENTS

Production of DissolvedSulfide inWastewater

Concentration of organicmaterial and nutrients

Increases Rate-controlling factor unless sulfateconcentration is very low

Sulfate concentration Increases Not a limiting factor at 20-100 mg/l

Dissolved oxygen Decreases Sulfate reduction inhibited above 1.0 mg/l

pH Varies Sulfate-reducing bacteria viable at pH 5.5-9.0;optimal at pH 7.5-8.0

Temperature Increases Growth rate of sulfate-reducing bacteria istemperature-dependent

Stream velocity Decreases Velocity affects slime layer and deposition of organic solids in pipe

Submerged surface area Increases Submerged slime layer produces sulfides

Detention time Increases Organic matter dissolved and oxygen decreasedwith time

Release of HydrogenSulfide toSewer Atmosphere

Dissolved oxygen Decreases Sulfides oxidized at concentrations greater than1.0 mg/l

pH Decreases Ionized and un-ionized hydrogen sulfide nearlyequal at pH 7.0; un-ionized fraction dominates aspH is further reduced

Metals concentrations Decreases Insoluble metallic sulfides formed by iron, zinc,copper, lead, and cadmium remove dissolvedsulfides from stream

Stream flow velocity Varies Turbulence increases release of hydrogen sulfideto atmosphere, but also increases sulfideoxidation by improved aeration

Depth of flow Varies Water surface area controls hydrogen sulfide gastransfer rate

Temperature Increases Minimal effect due to offsetting aeration andoxygen solubility changes

Moisture Increases Required for bacterial existence; multiple speciesof bacteria active depending on pH

Oxidation of HydrogenSulfide toSulfuric Acid

Ventilation Decreases Removes moisture and increases aeration

Source: USEPA Design Manual: Odor and Corrosion Control in Sanitary Sewerage Systems and Treatment Plants .


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Table 3.6 Typical Wastewater Characteristics that Promote Hydrogen

Sulfide Generation

PARAMETER CONCENTRATION(MG/L UNLESS NOTED)

Biochemical Oxygen Demand 280

Temperature, degrees C > 30

pH 6.8 - 7.0

Sulfate (drinking water supply) 20 - 40

Total alkalinity (drinking water supply), as CaCO3 190

Hydrogen sulfide (average) 0.10 - 0.85

Metals * 0.7 - 12.7

Suspended solids 300

*Sum of Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn concentrations for average loading condition


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Table 3.7 Methods to Control Hydrogen Sulfide Corrosion

APPROACH METHOD OBJECTIVE ADVANTAGES DISADVANTAGES

Good operation and

maintenance

Maintain flowvelocity to minimizesolids depositionand systemventilation.

No additional costs. Effectiveness limited by physicallimitations of system andoperating conditions.

Air injection Increase oxygen inwastewater usingcompressed air or venturi aspirators.

No chemicalinvolved or costs for chemicals.

Low efficiency.Control limited.Possible off-gassing of odors.

Oxygen injection Increase oxygen inwastewater usingon-site generation or liquid oxygen.

High efficiencycompared to air injection.Less hazardoushandling comparedto other chemicals.

Must be injected via pressurizedpipe (e.g., force main or other means).

Improve

OxygenBalance inWastewater

Nitrate addition(e.g., Bioxide)

Provide chemicalsource of oxygenpreferred over

sulfate by bacteria.

Slow-reacting.Low chemicalhazard.

Simple equipmentrequirements.

High chemical cost. Adds nitrogen .

Chlorine gassolution addition

Oxidize dissolvedsulfides to sulfate.

Widely available.Economical in bulkquantity.

Hazardous chemical.Efficiency dependent on mixing.

Sodiumhypochloritesolution injection


Safe vs. chlorinegas.

Unstable in storage.More cumbersome and costly inbulk quantity.

Hydrogen peroxidesolution injection


Rapid reaction rate.Simple equipment.

High chemical cost.Unstable in storage.

ChemicalOxidation of Sulfides inWastewater

Potassiumpermanganateaddition


Simple equipment . High chemical cost.Dosage determined byexperience on specific system.

Precipitationof SulfidesfromWastewater

Iron salts such asferrous sulfate or ferric chloride

Formation of solidparticles of insolublemetallic sulfide.

Simple equipment.Usually available.

Increases metal loadingdownstream.

Alkaline pHShock of Wastewater

Periodic (weekly)dosing with sodiumhydroxide solution

Upset slime layer and temporarilyreduce sulfidegeneration.

Minimal capitalinvestment.Moderate chemicalcost.

Hazardous chemical handling.Unpredictable effectiveness.

Sources: USEPA, 1985; Sulfide in Wastewater Collection and Treatment Systems; ASCE, 1989.


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Table 3.8 Lining Materials

MATERIAL RELATIVE COST

Polymer Concrete HighPotassium Silicate Concrete High

Filled Epoxy Moderate

Fiberglass Reinforced Vinylester Moderate

Polyester, Vinylester and Epoxy Based Systems Moderate to High


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Figure 3.10 1.8-m Concrete Pipe with PVC Lining

Table 3.9 Plastic Membranes Used for Corrosion Protection

MATERIAL RELATIVE COST

Polyvinylchloride Moderate

High Density Polyethylene Moderate

Polypropylene Moderate

Polyvinylidene Fluoride High

Ethylene and Chlorotrifluoroethylene Copolymer High


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Table 3.10 Comparison of Linings and Membranes

Table 3.11 Corrosion-Resistant Pipe Materials

CHARACTERISTIC INORGANIC ORGANIC PVC HDPE PVDF PP

Low Maintenance X X X X

Resistant toHydrogen Sulfide

X X X X X X

Resistant toMicrobacterial

X X X X

Resistant toHydrostaticPressure

X X X X

Cracks w/Substrate X X

MechanicallyBonded

X X X X

X

GENERIC MATERIAL RELATIVE COST

Polyvinylchloride Moderate

High-Density Polyethylene High

Reinforced Concrete Low

Reinforced Plastic Mortar High

Ductile Iron, Cement Mortar Lined Moderate

Filament-wound Fiberglass-Reinforced Plastic High


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3.6 SUBSURFACE CONDITIONS AND CONSTRUCTION


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Figure 3.11 Construction Methods and Subsurface ConditionsEncountered at TARP Drop Structures

Tunnel

Deaeration Chamber

SewageFlow

A i r F l o w

S e w a g e

F l o w

ExitConduit

Air Shaft 2 0 '

8 0 '

0 ' 8 0 '

6 0 '

1 9 0 '

2 6 '

M i n

. 1 7 0 '

M a x . 3

3 5 '

M i n

.

M a x .

8 1 '

Top of Rock

Air Vent Chamber

ConnectingPipe

CollectingStructure

Min. Diam: 4'Max. Diam: 19'

Overburden:Conventional

Open-Cut Excavation

Overburden:ConventionalExcavation or

Slurry Wall

Rock:Drill and Blast,

Raise Bore,Down Drill

Rock:Drill and Blast

Range of Depths


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Constructibility Considerations in Soft Ground and Rock


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Construction Methods and Risks


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Figure 3.12 Pipe Jacking Sequence


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Tunnel Boring Machine with Rock-Cutting Head

Tunnel Boring Machine for Soil Tunnel Boring Machine for Soil

Figure 3.13 Cutting Heads on Tunnel Boring Machines


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Settlement


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Figure 3.14 Placing Pipe for Jacking


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Contract Interface

3.7 OPERATIONS AND MAINTENANCE

Access


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Screening and Sedimentation


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4.1 ROLE OF HYDRAULIC MODELING IN DROP

STRUCTURE DESIGN

Model Theory and Extension of Model Studies To Design ofPrototype


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4.2 VORTEX DROP STRUCTURES


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Tangential Inlet Vortex Type (H4 Type)


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Figure 4.1 Schematic Design of the H4 Type Drop Structure (1)

Odor Control Vortex Structure

Approach Channel

Diversion Chamber

Vent

Adit

Main Tunnel Deaeration Chamber

Vortex Structure

ApproachChannel

Vortex Opening e

Diversion Chamber

b = 27.5

= 16.8 (Typ)

LT

Lc

Incoming LinkSewers

Q

Q

B

Vertical Shaft


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Figure 4.2 Dimensions of the Large-Scale Model of the H4-Type DropStructure (1)

16.8

20 1/8"

4' 8"

DeaerationChamber

Vent

Adit

Inlet Box

11 1/2"

8 5/8"

30"

20 1/4"

10 1/8"

12' 8"

5 1/8"

7'27.5

24'

11 1/2"

2 7/8"


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1) Determine minimum value of geometric scale ratio:

2) Select model scale ratio:

3) Determine model values for the required deaeration chamber length:

4) Determine the initial dimensions of prototype drop structureusing the model scale ratio L r:

Table 4.1 Multipliers Used to Determine Initial Dimensions of DropStructures

D1=LR X 0.96 D 1= Dropshaft Diameter

D2=Lr x 1.69 D 2= Deaeration Chamber Diameter

D3=Lr x 0.84 D 3= Deaeration Chamber Outlet Diameter

LC=L r x LC m LC= Deaeration Chamber Length

LV=Lr x 4.67 L V= Air Vent Locatione=L r x 0.24 Note: minimum e = 0.45m; e= vortex opening prior to vertical shaft

Lt=(B-e)/Tan

16.8 oLt =Approach Channel Transition Length

Where B = approach channel diameter, and e = constricted opening invortex generator


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Figure 4.3 Diversion Structure Dimensions

R1 = D1 x 1.5

R2 = D2 x 1.5

X = R 1 + 0.5 D 3 + C

Z = R 1 + 0.5 D 1 + C

C = Minimum distance required toaccommodate pipe wall thicknessand structural reinforcement

C

D2

D3

C

D1

IncomingSewer

IncomingSewer

Tapered Radiusfor OutgoingPipe Diameter

To DropInlet

Flow

FlowR2

R1

C

Z

X


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D e s

i g n

D i s c h a r g e

( C F S )

A i r F l o w

A i r F l o w

R a t e

i n V e n

t ( C F S )

A i r F l o w

R a t e

t o T u n n e

l ( C F M )

0

2 0 0

4 0 0

6 0 0

8 0 0

1 0 0 0

1 2 0 0

1 4 0 0

1 6 0 0

1 8 0 0

2 0 0 0

1 6 0 0

1 5 0 0

1 4 0 0

1 3 0 0

1 2 0 0

1 1 0 0

1 0 0 0 9 0

0 8 0 0

7 0 0

6 0 0

5 0 0

4 0 0

3 0 0

2 0 0

1 0 0 0

F i g u r e

4 . 4

A i r F l o w

i n V e n

t a n

d A d i t a

t D e s i g n

D i s c

h a r g e

f o r t

h e

T a n g e n

t i a

l I n l e t

T y p e

V o r t e x D r o p

( H - 4

T y p e

) ( 1 )


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Drop Structure with Helical Inlet and Ramps

Figure 4.5 Drop Structure with Helical Inlet and Ramps (13)

Adit

RampOutlet

Section B-B

Section C-C

Section A-A

HelicalRamp

ConveyanceTunnel

(Tailwater Depth)

Dropshaft

HelicalRamp

GuideWall

Center Column

InflowPipe Inflow

PipeGuide

Wall

Center Column

D1

Di A Zi

Z l

P i

B

C C

d

b

W

Po

D3

Bo

Bo

Po

D1

B

Bi


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Helical Drop Structure Dimensions


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Table 4.2 Helical Dimensions for Design Flows from 25 to 280 CFS (1)

Figure 4.6 Peak Air Concentration with Varying Tailwater Levels(helical drop structure) (13)

DropshaftPeak FlowCFS

DropDiameter D1

InflowPipeDiameter Di

InletRampPitchPi

InletRampWidthBi

InletRampDistZi

OutletRampPitchPo

OutletRampWidthBo

Outflow PipeDiameter D3

25 3.500 3.167 2.135 1.225 3.115 1.610 1.197 1.833

60 4.667 4.167 2.847 1.633 4.154 2.147 1.596 2.167

115 5.833 5.250 3.558 2.042 5.191 2.683 1.994 2.500

280 8.167 7.333 4.982 2.858 7.269 3.757 2.792 3.000

Z1/D3 = 1.0

Z1/D3 = 1.5

Z1/D3 = 2.0

0.14

0.12

0.10

0.08

0.06

0.04

0.02

0.00

-0.020.30 0.35 0.40 0.45 0.50 0.55 0.60

D3/D1

P e a

k A i r C o n c e n t r a

t i o n

C p


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Scroll and Spiral Inlet Type

Figure 4.7 Dimensional Relationships for Scroll andSpiral Inlet Types (1)

Inlet

Dropshaft

r

h

D

Hyo

do

vr

v vz

r 2

r m

c r 3

r 1

d8

r 3

r 4

v0

b

a

ee

e e

vr v

vz

e = (b+s)

r 2 = r 1 - 2 e

r 3 = r 1 - 4 e

r 4 = r 1 - 5 e

a = r 1 + e -

17

r 1 = d s + 6 e + r + c12

b2

b b

e e

ee

r 2

r 6

r 5

r 4D

A

A

D

b

b

r 3

r 1

J zJ k

hk hk

D

Section A-A

e = b27

r 1 = D + 6e12

r 2 = D + 4e12

r 3 = D + 212

r 4

= D + e1

2

r 5 = D + e12

5212

r 6 = D + e12

Spiral (14)

Scroll (1) Spiral (Plan)


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4.3 PLUNGE DROP STRUCTURES

Plunge Inlet Type


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N

B

W

B

C K

L

K

M

E

L

C L A d i t

T u n n e l D i a m .

E

W

3 0 t o 7 5

A

C

C

S

S e c

t i o n

A - A

S e c

t i o n

B - B

E l e v a

t i o n

S e c

t i o n

C - C

C

B

Q

P P

H F

3 '

D S p a c e B e t w e e n

3 ' - 0 "

S l o t s

G

R

A

1 0 ' R .

1 . 5

G

3 G

1 . 5 G

S h a f t I . D

.

2 x

( A )

M i n

.

M i n

.

A

T

S e e

D e t a i

l " A "

D e t a i

l " A "

3 5

6 "

S h a f t I . D

.

9 ' - 0

"

7 ' - 2

"

5 ' - 8

"

A

4 ' - 6

"

3 ' - 7

"

2 ' - 1

0 "

B

2 ' - 9

"

2 ' - 6

"

2 ' - 6

"

C

1 ' - 0

"

1 ' - 0

"

0 ' - 9

"

D ( M a x . )

1 0 ' - 0 "

7 ' - 6

"

5 ' - 6

"

E

9 ' - 0

"

6 ' - 8

"

5 ' - 0

"

F

2 0 ' - 3 1 / 2 "

1 5 ' - 0 1 / 2 "

1 1 ' - 2 1 / 2 "

G

V a r

i a b l e ,

E q u a l

t o P i p e

D i a m e t e r

( B u t

N o t

T o E x c e e

d I . D

. o f S h a f t )

H ( M a x . )

1 2 ' - 0 "

9 ' - 8

"

8 ' - 0

"

H ( M i n

. )

9 ' - 0

"

6 ' - 8

"

5 ' - 0

"

W (

M i n

. )

6 ' - 9

"

4 ' - 9

"

4 ' - 0

"

H & W

( M i n

. ) ( S q

. F t . )

8 1

4 5

2 5

K

2 7 ' - 0 "

2 0 ' - 3 "

1 4 ' - 1 0 "

L

2 9 ' - 0 "

2 1 ' - 6 "

1 6 ' - 0 "

M

5 6 ' - 0 "

4 1 ' - 9 "

3 0 ' - 1 0 "

N ( M i n

. )

4 ' - 0

"

3 ' - 6

"

3 ' - 0

"

P ( M a x . )

1 ' - 6

"

1 ' - 3

"

1 ' - 0

"

N x

P ( M i n

. ) ( S q . F t

. )

6

4 . 4

3

Q

3 2 ' - 6 "

2 4 ' - 0 "

1 8 ' - 1 "

S ( M i n

. )

5 ' - 0

"

4 ' - 6

"

4 ' - 0

"

D e s

i g n

D i s c h a r g e

( c f s ) 6 0 0

2 8 0

1 4 0

H e a

d L o s s

9 ' - 0

"

5 ' - 5

"

4 ' - 7

"

F i g u r e

4 . 8

D i m e n s i o n s

f o r

t h e

C h i c a g o

T y p e

E - 1

5 D r o

p S t r u c

t u r e

( 2 )


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F i g u r e

4 . 9

D i m e n s i o n s f o r

t h e

C h i c a g o

T y p e

D - 4

D r o p

S t r u c

t u r e

( 2 )

A

A

B

B B

E

F

S e c

t i o n

A - A

S e c

t i o n

B - B

G

A J

E

E

A

A

C

H

D C

D

I n l e t C o n

d u i t

W a t e r

C o n

d u i t

V e n

t

A d i t

D e a e r a t

i o n

C h a m

b e r

F V e n

t e d C o v e r

T o p

V i e w

G

A

B B

H

J

A

2 0 ' - 0 "

1 5 ' - 0 "

1 2 ' - 0 "

5 ' - 8 "

B

8 ' - 0 "

6 ' - 0 "

5 ' - 0 "

2 ' - 0 "

C

4 8 ' - 0 "

3 6 ' - 0 "

2 9 ' - 0 "

1 2 ' - 0 "

D

4 0 ' - 0 "

3 0 ' - 0 "

2 4 ' - 0 "

1 0 ' - 0 "

E

2 5 ' - 0 "

1 9 ' - 0 "

1 5 ' - 0 "

6 ' - 3 "

F

5 5 ' - 0 "

4 2 ' - 0 "

3 3 ' - 0 "

1 3 ' - 9 "

G

9 0 ' - 0 "

6 7 ' - 0 "

5 3 ' - 0 "

2 2 ' - 6 "

H

2 0 ' - 0 "

1 5 ' - 0 "

1 2 ' - 0 "

5 ' - 8 "

J

2 8 ' - 0 "

2 1 ' - 0 "

1 7 ' - 0 "

7 ' - 0 "

D e s

i g n

D i s c

h a r g e

( c f s )

4 5 0 0

2 2 0 0

1 2 5 0

1 4 0

H e a

d

L o s s

2 0 ' - 0 "

1 5 ' - 0 "

1 2 ' - 0 "

5 ' - 8 "


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5.0 DROP STRUCTURE APPURTENANCES

5.1 ACCESS SHAFTS


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Figure 5.1 Access Shafts

Access Through Tunnel Crown

Offset Access from Main Tunnel


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5.2 SYSTEM MONITORING AND CONTROLS

Flow Control Gates


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Figure 5.2 Flow Control Structure Schematic

Hydraulic Supply and Return Lines

Weatherproof Enclosure

Access Hatch

Power Supply

Hydraulic Power Unit

Control Panel

SS Hydraulic Cylinder

Guides forStop Logs

Sluice Gate

FiberglassGratedPlatform

Flow


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Flow and Rainfall Monitoring


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H

N e t w o r k

A c c e s s

D i v e r s i o n

C h a m b e r

D r o p s h a f t

A c c e s s

S h a f t

L T

L T

L T

A L T

H 2 5

F S L

R T U

R T U

R T U

O p e r a

t o r

T e r m

i n a l

O p e r a

t o r

T e r m

i n a l

M u l t i - P o i n t

M o d e m

D i a l - I n

A c c e s s

P o r

t a b l e

C o m p u

t e r

C o n t r o l

R o o m

M a i n t e n a n c e

A c c e s s

S e r v e r

L a p t o p

C o m p u

t e r

D a t a R a d

i o

L i n k

L T

D a t a

R a d

i o

S e w e r a g e

F a c

i l i t y

( P u m p

S t a t i o n /

W W T P )

D a t a

R a d

i o

S C A D A

T e r m

i n a l

S C A D A

T e r m

i n a l

D a t a C o m m u n

i c a t

i o n

L i n k s

O d o r

C o n

t r o l

F i g u r e

5 . 3

S c

h e m a

t i c

D i a g r a m

o f a

M o n

i t o r i n g a n

d C o n

t r o

l S y s t e m


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5.3 DEBRIS SCREENING


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APPENDICES


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APPENDIX AREVIEW OF DROP STRUCTURE/TUNNEL SYSTEMS


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APPENDIX A: REVIEW OF DROP STRUCTURE/ TUNNEL SYSTEMS

CHICAGO, ILLINOIS


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MILWAUKEE, WISCONSIN

PITTSBURGH, PENNSYLVANIA


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SINGAPORE

MONTREAL, QUEBEC (CANADA)


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TORONTO, ONTARIO (CANADA)


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PHOENIX, ARIZONA

ROCHESTER, NEW YORK


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MINNEAPOLIS/ST. PAUL, MINNESOTA

GOVALLE, TEXAS


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SYDNEY, AUSTRALIA

CLEVELAND, OHIO


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RICHMOND, VIRGINIA

SAN FRANCISCO, CALIFORNIA

DEARBORN, MICHIGAN


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Figure A.1 Pump Station, Richmond, VA

Pumps

Tunnel

Tunnel

Access MHSluice Gate

Grade

PumpDischarge

Existing48' Water

SubmersiblePumps

TransitionStructure

Plan

Screen Room

Screen Room

Screen

BridgeCrane

VortexDrop

EL-108.30

EL-81.00

EL-7.00

VortexDrop

BobcatOpening

A

A


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Figure A.2 Schematic Drop Structure with Vortex Inlet,Pittsburgh, PA

A

A

A

Dropshaft

F l o

wInlet

Dropshaft

Shaft Inlet TankGround Surface

Air Relief

Tunnel

FlowEnergy

Dissipation Chamber

Enlarged Section

T o

G r o u n

d S u r f a c e

Figure A-2 Schematic Drop Structure with Vortex Tank-Type InletPittsburgh, Pennsylvania (8)


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REFERENCES


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REFERENCES


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Drop Structure Design

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