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A Unique Solution to a Unique Problem
Penitencia Delivery Main and Penitencia Force Main Seismic Retrofit Project
AWWA Cal Nevada Conference October 28, 2015Darren [email protected]
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Project Background
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Project Location
San Francisco
Project Site near Penitencia WTP
San Jose
Hayward Fault
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Penitencia WTP and critical pipelines are located on an active landslide
Penitencia Creek Landslide Boundary- 240 acre
Penitencia WTP
680
680
San Jose
Milpitas
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Project background
198419831972-19741964
SBA and Partial
Pipelines Installed
PenitenciaWTP
Constructed Pipelines Failed Due to
Landslide
Expansion Joints
Replaced
Expansion Joints
Installed on Pipelines
2003 2014
Current Seismic Retrofit
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Pipeline damage from landslide displacement
Pipe failure in 1983 and expansion joints installed Bellow fittings installed in 2003
Finished Water Meter Vault Damage in 2004
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Existing pipelines are vulnerable to landslide displacement
Imported raw water (Sierra Nevada)
Treated drinking water
Imported/local raw water
Project work area
Finished Water Meter Vault
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Project Objectives
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Project Objectives
• Retrofit three critical water pipelines to accommodate creep and seismic movement
• Design the facilities for a 50-year life
• Provide safety to residents and businesses in the area
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Planning Phase• Seismic hazard
and landslide evaluation
• Conceptual alternatives evaluation
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Seismic hazard and landslide evaluation established the design criteria
• Compile existing geologic and geotechnical data
• Field borings and laboratory testing program
• Seismic displacement analysis
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Seismic hazard and landslide evaluation found compression, tension, and uplift
Displacement at toe estimated as 7.7 feet of seismic and 1.7 feet of creep (total of 9.4 feet over 50 years)
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Seismic hazard and landslide evaluation results
• Displacement at landslide toe– Seismic = 7.7 feet; Creep =1.7 feet (9.4’ total over 50 years)– 220’ primary and secondary zone– Landslide direction oblique to pipe by 10 – 20°– Dip of basal shear plane between 0-30°
• Displacement at finished water meter vault– Seismic = 2.2 feet; Creep = 1 foot (over 50 years)
• Basis– 50 year design life– Probablistic seismic hazard analysis
• 5% chance exceedance over 50 years• Included the 2014 USGS national seismic hazard map update
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Conceptual alternative evaluation considered six alternatives
Conceptual Alternatives
Analysis
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Conceptual Alternative – Compression Pipe
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Conceptual Alternative – Expansion Loop
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Conceptual Alternative – Rubber Metallic Bellows
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Conceptual Alternative – Displacement Vault
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Conceptual Alternative – Pipeline Realignment
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Conceptual Alternative – No Project
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Conceptual alternative evaluation identifies two feasible alternatives
Conceptual Alternatives
Analysis
• Alt #1 - Compression Pipe • Alt #2 - Expansion Loop
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Feasible Alternative 1 – Compression pipe
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Feasible Alternative 1 – Compression pipe
23
Advantages:• Below ground• Minimal visual impact• Lowest costDisadvantages:• Requires specialized
installation• Relatively unknown in
the U.S. market -manufactured in Japan
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Compression Pipe
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Compression pipe modeling resultsNormal Condition Post Earthquake Condition
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Compression pipe modeling results
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Feasible Alternative 2 – Expansion Loop
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Feasible Alternative 2 – Expansion Loop
Ball joint
Advantages:• Similar installation in U.S.• Medium cost rangeDisadvantages:• Visual impact• Requires specialized
installation
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Expansion loop modeling results
Normal Condition Post Earthquake Condition
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Expansion loop modeling results
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Evaluation SummaryCompression Pipe
Alt #1Expansion Loop
Alt #2
Reliability
• Modeling predicts reliable performance
• 330 miles of 40” – 104” dia. pipe installed with no failures since 1974
• Accommodates uncertainty of toe zone
• Modeling predicts reliable performance
• Few large ball joint installations, custom design.
• Complex system
Seismic Intensity 7
Active fault
Seismic Intensity 6+Seismic Intensity 6-
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Design Phase• Advanced pipeline
modeling • Full scale
performance test of pipe and collar joint
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Design phase
Landslide Direction Compression/Tension
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Advanced pipeline modeling predicts performance of design
• Complex Problem– Large landslide deformations– Nonlinear behavior of soil
and pipe/joints• Requires Soil-Pipe Interaction
Analysisa) Actual Soil Restraint on Pipeline
b) Idealized Soil Representation with Soil Springs
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Welded steel pipe model provides base case for analysis
• Modeled 1.25 inch thick walled pipe• Pipe failure due to high stresses and/or buckling• Other materials (i.e. HDPE) would perform similar or
worse -> less stiffness means more prone to buckling
Section View of Steel Pipe(SF = 5)
Pipe Buckling Example
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Advanced pipeline modeling predicts performance of design
2 scenarios for sliding plane angle and toe location– Scenario 1 (30°): Horizontal + uplift movement at toe– Scenario 2 (2°) : Primarily horizontal movement
Scenario 22° angle
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Compression pipe joint behavior
Spigot Projection
+1%
Bolt & NutLock Ring
Gland
Rubber Gasket
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Collar Joint
• ~ 3X Axial deformation capacity of regular joints (~9” vs ~3”)
• ~ 2X Rotation capacity of regular joints(~13° vs 11°)
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Final design includes custom pipe length and collar joints
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Full scale performance test of 60-inch pipe joint confirms published values
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Full scale performance test of 72-inch collar joint confirms published values
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Planning and design teamCarollo Engineers
Project Management and Prime Consultant
Degenkolb EngineersAdvanced Pipeline Engineering
Cal Engineering and GeologyGeotechnical Engineering
Lettis Consultants InternationalEngineering Geology
LSA AssociatesEnvironmental Planning Services
Ballantyne Consulting LLCAlternatives Analysis
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Acknowledgements
Project ManagerKarl Neuman, PE GE
Project EngineerTin Lin, EIT
Senior Project Manager Emmanuel Aryee, PE
Chief, Pipeline DivisionJoe Barron, PE
Project EngineerKevin Gray, PE
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Questions & Answers
