Design Considerations for Selection of Pipe
Material for Large Diameter CSO Force Main
Pacific Northwest Clean
Water Association
2010 Conference
Presented By
„
„
„
M. Patty Nelson, City of Portland
Phil Roppo, Brown and Caldwell
Mark Havekost, Jacobs Associates
Presentation Overview
„
„
„
„
„
„
„
Project Overview
Design Requirements
Pipe Materials Considered
Pipe Material Evaluation
Selection
Project Update
Questions
PROJECT OVERVIEW
Willamette River Combined Sewer
Overflow (CSO) Program
Portsmouth Force Main
„
„
„
Deliver 120 mgd
From Swan Island CSO Pump Station to Existing
Portsmouth Tunnel
Meet ASFO Deadline of December 2011
Segment 1 – Swan Island Alignment
Single 66 Inch Force Main
3,000 linear feet 84-inch Microtunnel
4 Microtunnel Shafts
6,800 linear feet Open Cut
Steel Pipe with Polyurethane Liner
Segment 2 – Bluff Alignment
Single 66 Inch Force Main inside a 10 Foot Tunnel
200 linear feet - Open Cut
6,000 linear feet - Deep Tunnel
2 Tunnel Shafts
Fiberglass Reinforced Pipe
Profile Considerations
Force Main: Sloped to Drain
Segment 1: Conflicting Utilities
Segment 2: Deep Connection
Design Requirements
„
120 mgd, peak 140 mgd
„
Single 66-Inch Diameter
„
Corrosion Resistant
„
Handle Hydraulic Transient Conditions
Pipe Materials Considered
„
Welded Steel Pipe (WSP) with polyurethane lining
„
Fiber-Reinforced Polymer Pipe (FRPP)
„
Ductile Iron (DIP) with PROTECTO 401 (ceramic
epoxy lining)
„
Reinforced Concrete Cylinder Pipe (RCCP)
Pipe Material Eliminated
„
Ductile Iron (DIP)
„
„
Insufficient Size
Reinforced Concrete Cylinder Pipe (RCCP)
„
Corrosion concerns with concrete lining
Pipe Materials Evaluated
„
Fiber-Reinforced Polymer
Pipe (FRPP) ASTM D3754
„
20 – 40 foot length
„
Push on joints
„
225 to 300 lbs per linear foot
Pipe Materials Evaluated
„
Welded Steel Pipe (WSP)
AWWA C200
„
Polyurethane lining
„
40 foot length
„
Double-welded lap joints
„
600 lb per linear foot
Evaluation Criteria
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Cost
„
Maintenance
„
Constructability
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Installation Risk
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Structural Design
„
Sewer Operation
„
Durability
Cost Considerations
Direct Costs
„ Production Rates
„ Restraint Requirements
„ Number Welds/Joints
„ Weight/Handling
„ Corrosion Resistant Coating
„ Maintenance Access for Lined Pipe
„
Cost Comparison
WSP
FRP
Thrust Restraint
Maintenance Access
Segment 1
4.37 - 4.69
million
4.52 - 5.79
million
Required – Poor
soils
Segment 2
5.07 – 5.11
million
3.75 – 4.78
million
Intermediate
Shaft
Constructability Considerations
Space requirement - Shoring
„ Ease of Installation - Handling
„ Length Pipe - # Joints
„ Restraint Requirement
„ Weight of Pipe
„ Backfill Requirements
„
Constructability Comparison
Segment 1
WSP
Double Welded Lap Joints
Segment 2
Single welded lap joint –
Careful fit for welding
Prep/Patch Lining at Joints
Prep/Patch Lining at Joints
Shoring system for external joint
welds
FRP
Push-on Joints
Push-on Joints
Careful attention required for
backfill
Specialized bracing for
backfilling in tunnel
External thrust restraint system
Structural Design Considerations
Loading
„ Internal Pressures
„ External Pressures
„ Ability to handle ground movement
„
Structural Design Comparison
„
Both WSP and FRP were designed to handle:
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„
„
„
Internal Pressure 45 psi operating, 63 psi peak
Full Vacuum
Installation Loads
Backfill Loads
Durability Considerations
Internal Corrosion Resistance
„ External Corrosion Resistance
„ Abrasion Resistance
„ Fatigue
„
Durability Comparison
Segment 1 & 2
WSP
Internal Corrosion: Lining
External Corrosion: Tape Wrap
Abrasion: Polyurethane Highest
Fatigue: Resistant
FRP
Pipe material Corrosion Resistant
Abrasion: High Resistance
Fatigue: Designed using higher pressure
class to extend pipe life
Maintenance Considerations
„
Access for Repairs & Cleaning
„
Method of Repairs
„
Historical Maintenance Issues
Maintenance Comparison
Segment 1
WSP
Segment 2
Shallow force main
Deep force main
Air/Vac Access Vaults
Requires Intermediate Shaft for
Access
Lining repairs anticipated
Lining repairs anticipated
Repairs sensitive to workmanship
& environment
FRP
Repairs sensitive to workmanship
& environment
Shallow force main
Deep force main
Air/Vac Access Vaults
Repairs using fiberglass and resin
laminations – controlled
environment
Repairs using fiberglass and resin
laminations – controlled
environment
Installation Risk Considerations
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Excessive loads due to:
„
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Pipe floatation
High grouting pressures
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Poor Joints
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Damage from Installation
Installation Risk Comparison
WSP
FRP
Segment 1
Segment 2
Lining damage during installation
Lining damage during installation
Double Joints Protect
Pipe grouted within tunnel
Pipe damage during backfill
Pipe damage during backfill
Joint Leakage
Joint Leakage
Summary of Pipe Comparison
Pipe Cost
Segment 1
WSP
Segment 2
FRPP
Constructability
Neutral
FRPP
Structural Design Neutral
Neutral
Durability
FRPP
FRPP
Maintenance
Neutral
FRPP
Installation Risk
WSP
WSP
System Operation Considerations
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Low Pressure
„
Wet Weather Operation Only
„
Avoid Full Vacuum
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Air/Vacuum Relief & Access
Air/Vacuum Relief Valves
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Locations needed for Air/Vacuum Relief
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Must vent to surface
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Hydraulic Transient Analysis to Determine Location
Pipe Material Considerations in
Hydraulic Transient Analysis
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Different Pipe Materials = Different Wave Speeds
„
Wave Speed impacts Transient Analysis
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FRP = Higher Wave Speed than Steel
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Reviewed combinations of pipe type Seg 1 & Seg 2
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Objective Avoid Full Vacuum Condition
Transient Analysis: Steel Vs FRP
All FRP
Steel + FRP
120
120
60% Design Profile
60% Design Profile
110
Flow Exiting
Pump Station
100
90
P Steady-State (psig)
Segment 1: Fiberglass Pipe (wave speed 1,400 ft/s)
Segment 2: Fiberglass Pipe (wave speed 1,400 ft/s)
Vent-O-Mat Locations: 7
Pressure Max (psig)
90
P Steady-State (psig)
Segment 1: Steel Pipe
Segment 2: Fiberglass Pipe (wave speed 1,400 ft/s)
Vent-O-Mat Locations: 7
Pressure Max (psig)
Pressure Min (psig)
Vent-O-Mat Location
80
Maximum
Pressure
60
Tunnel Section
40
Pressure (psig)
70
50
Option 6A:
Pressure Min (psig)
Maximum
Pressure
70
Flow Exiting
Pump Station
100
Vent-O-Mat Location
80
Pressure (psig)
Option 7A:
110
60
Tunnel Section
50
40
30
30
Steady-State
Pressure
20
Steady-State
Pressure
20
10
10
Minimum
Pressure
0
0
Minimum
Pressure
-10
-10
-20
-20
0
1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,00 11,00 12,00 13,00 14,00 15,00 16,00 17,00 18,00
0
0
0
0
0
0
0
0
0
Force Main STA (ft)
PS Discharge ~ STA 10+00
„
0
1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,00 11,00 12,00 13,00 14,00 15,00 16,00 17,00 18,00
0
0
0
0
0
0
0
0
0
Force Main STA (ft)
PS Discharge ~ STA 10+00
Selection: Segment 1 Steel + Segment 2 FRP
Fear Factor
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Poor Experience with Plastic Pipe
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Major Facility
„
Single Force Main
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Tunnel – Limited Access
Case History FRP Pipe
Owner
Project
Application
Size
Length Pipe
(inches)
(LF)
Installation
Method
City of
Charleston,
South Carolina
Harbor Tunnel,
Ashley River Tunnel
(2006)
Cooper River
Tunnel (2007)
Pressurized
Sewer Siphon
20 – 54
5,000
9,500
18,100
HOBAS
Carrier Pipe in
Tunnel
Jackman
Penstock
Replacement
(1982, 2003,
2007)
Jackman Penstock
Replacement (1982,
2003, 2007)
Hydropower
penstock
84
3,900
Flowtite
HOBAS
Open Cut
City and
County of
Honolulu
Hart Street Force
Main (2000)
Sewer Force
Main
51
2,100
HOBAS
Pipe Jacking
City of Abilene
Buck Creek Force
Main
Sewer Force
Main
36
26,000
HOBAS
Open Cut
Goochland
County,
Virginia
Goochland/Henrico
Regional FM
Sewer Force
Main
48
44,800
Flowtite
Open Cut
THE DECISION
Segment 1 Pipe Material
„
10,000 LF
„
66-Inch Steel AWWA
C200
„
Polyurethane Liner
„
Tape Wrap
Segment 2 Pipe Material
66 inch FRPP – HOBAS ASTM D3754
WHERE ARE WE NOW?
Segment 1 Update
Segment 2 Deep Tunnel
QUESTIONS?