Understanding the Seismic Vulnerability of Water Systems

Transcription

1 Understanding the Seismic Vulnerability of Water Systems Lessons Learned and What You Can Do Donald Ballantyne October 2, 2013 Regional Water Providers Consortium Board

2 Overview Oregon Resilience Plan Historic earthquake performance Seismic risk and earthquake hazards Liquefaction Cascadia Subduction Fault Portland Hills Fault Canby Moalla Fault Expected performance Desired performance How are we going to get there? Emerging seismic resistant pipe Questions

3 Oregon Resilience Plan After 2 weeks without services, people leave; many don t come back Keep the supply and transmission system operable (fire suppression) Restore distribution within 2 weeks

4 Historic Earthquake Performance Tohoku, Japan days Christchurch, New Zealand days Kobe Japan, days 1,200 pipeline failures Northridge, California days 1,000 distribution failures 35 transmission main failures

5 Tohoku Earthquak e

6 Kanigawa WTP Utilidore floated Pipes sheared off (typ)

7 Tohoku Pipe Performance No failures in Kubota seismic joint pipe Failure of 2.4M DIP, Sendai

8 Tohoku, Japan 2011 Floating Sewers Photo Credit SEAW

9 JWWA Manual for Emergency Countermeasure

10 JWWA Emergency Water Supply Operations Emergency water supply vehicles maximum of 430/day Lining up at a base water supply facility Set up of canvas tanks Water supply at an emergency medical establishment

11 Tohoku Fuel Shortage Damage to Water Supply Limited accessibility to gasoline, light oil, and kerosene. Difficult to obtain fuel for electric generators, water trucks, official vehicles, and specialized task vehicles etc. Water Purification Plant Electric Generator Operation Hours Tank Return of Electricity Type of Oil Capacity (L) Operational Hours/ Tank Capacity Moniwa 98 March 15 Kerosene 6, Kunimi 58 March 14 Light Oil Nakahara 54 March 13 Kerosene 12, Fukuoka 68 March 14 Kerosene 10,

12 Water Restoration Timeline Sendai Main trunkline restoration Received water from distribution station Distribution station restoration Distribution area restoration Distribution area restoration Aftershock occurred Began receiving water from the Sennan Senen Regional Area to Sendai Distribution area restoration Sennan Senen Regional Area water distribution secured by rerouting water system Transmission pump failure Earthquake occurred The number of the water suspension 1,000 houses

13 Christchurch NZ Feb 22, 2011 City of 360,000 people M6.3 Direct Hit 190 fatalities CBD destroyed, 1,800 buildings demolished 55,000 residences damaged $25 $30B damage; 20% of GDP Extensive liquefaction along the Avon River

14 Christchurch NZ 1645 water pipeline repairs out of 1000 miles pipe Most was AC pipe Have moved to HDPE 300 km of sewer damaged 8 PS require replacement Chemical toilets distributed to 30,000 residents

15 Kobe, Japan 1995 Pipe joint pull out due to liquefaction Over 1/2 of the failures were due to joint pull out. Pipeline damage rates for the Kobe earthquake are shown in the table below. Failure Rates/km - Number of Failures Failure Mode DIP CIP PVC Steel AC PipeLlength (km) Barrel Fitting Pulled Joint Joint Failure Joint Intrusion

16 Kobe, Japan 1995 Lateral Spread Resulting in Pulled Joint Lateral spreading resulted in DIP joint separation 16

17 Higashinada Wastewater Treatment Plant, Kobe, Japan 1995 Liquefaction Damage to Treatment Plants

18 Northridge 1994 Buried Pipe Failure Jensen WTP 81 Raw Line

19 Northridge 1994 Tank Damage Elephant Foot Buckling

20 Northridge 1994 Tank Damage Inadequately attached roof slid Rocking tank separated piping

21 Loma Prieta 1989 Wire Wrapped Concrete Tanks

22 Regional Earthquake Hazards Tsunami only on the coast Liquefaction Cascadia Subduction Fault, (Magnitude 9.0); 500 year recurrence (last event 1700) Portland Hills; East Bank Fault (Magnitude 6.8) Canby Moalla Fault

23 Sendai WWTP Pump Station hit by tsunamis, Japan 2011 Tsunamis

24 Liquefaction Loss of bearing

25 Liquefaction Occurs due to shaking Soil particles consolidate squeezing out water Water pore water pressure increases reducing friction between soil particles Soil becomes a viscous liquid Loosely packed sand grains Consolidated sand grains Costa Rica, 1991

26 Lateral Spread Pipeline Soil Blocks Floating on Liquefied Material X Initial Section X X X X X X Design pipeline to move with the soil blocks expand to relieve strain and be dragged through the ground. Liquefied Material Deformed Section

27 Liquefaction Liquefaction Willamette, Columbia, Tualatin

28 Pacific Northwest Earthquake Source Zones

29 Cascadia Subduction Zone 500 year return period for full length Most recent event % probability within next 50 years 40% probability southern segment

30 Groundmotion Cascadia Subduction Higher ground motions west of Portland Will impact older/poorly engineered structures will fail Long duration shaking will cause liquefaction

31 Block Movement Movement in the North American Plate Remnant from the northwest movement of the Pacific Plate Western Oregon rotating northwest Portland to Bellingham getting squeezed ~ 10 mm/yr Differential movement results in surface faults

32 Earthquake Faults Surface fault ruptures could shear pipelines Ground motions stronger near field damaging Tanks & structures

33 Portland Hills Fault Groundmotion

34 Fault Crossings

35 Recommendations from Resilient Oregon Plan Reset public expectations for recovery times Require seismic assessments for all systems Encourage water & fire agencies coordinate plans Encourage upgrades; sanitary surveys & designs Encourage business continuity plans Encourage essential support for employee families Establish seismic design standards for pipelines Clarify regulatory expectations during emergency Encourage participation in ORWARN Plan for emergency water distribution

36 Seismic Assessments Hazard Quantification Groundmotion Liquefaction Component Fragilities Component Impacts Functionality Outage time System Analysis Capacity Outage time Business Interruption/ Societal Losses Daily outage per capita $ % GRP Business specific losses

37 Pipe Damage Relationships Repair Rate for Shaking Damage ALA Repair Rate - PGD Repair Rate for Ground Deformation 4.00 CIP DIP CCP Steel Rapair Rate (1,000 ft) CIP DIP Steel PGD (inches)

38 Portland GIS Analysis Input Ground Motion Scenario - Subduction Earthquake Pipe Material/Facility Information 100% Probability of Failure 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Liquefaction Susceptibility 1% 10% 20% 30% 40% 50% 60% 70% 80% 90% Peak Ground Acceleration Damage/Fragility Functions 100%

39 Asset Inventory Age (yrs) Moved from UBC Zone 2 to Zone 3 Facility

40 Component Reliabilities/Fragilities 1 Reliability Pump Bldg. Control Bldg. Reservoir Wells Well Collection Piping Main Pumps Substation Control Equipment Total PGA (g's)

41 Example System Critical Facilities Status

42 Example Outage Maps LADWP following Northridge

43 Develop Recommendations; Input into Capital Improvement Plan Identify vulnerable sections of transmission system replace as required Identify vulnerable pipelines within distribution systems replace with seismic resistant pipe Evaluate storage, pump stations upgrade as required Schedule mitigation to achieve desired performance over 50 years

44 Seismic Resistant Pipe Modern pipe works well in competent soils In liquefiable soils: Restrain joints Allow for strain relief

45 Ductile Iron Pipe (DIP) AWWA C 150 with Restrained Joint (Field Lok z Retainer Seat Wedge Gasket) Gasket DIP Joint Spigot DIP Joint Bell z Design to resist ground movement Material strength and ductility Restrained joint Does not allow release of strain due to ground deformation

46 Ductile Iron Pipe Expansion Sleeve EBAA Ex Tend Expansion sleeve for strain relief $900 8 ; $1, EBAA Ex Tend Proposed custom expansion sleeve hook into the bell with a split harness; about half the above cost

47 Japanese Seismic Joint DIP Restrained joint Allows expansion/compression

48 PVC (C 900) with 2X Deep Bell and Joint Harness (Manufactured by Kubota) Vulnerable to corrosive soils Expansion can be provided for strain relief

49 Polyvinyl Chloride (PVC) AWWA C 900 with joint restraint Joint Harness Add anode caps on bolts? Bulldog Joint Wedge Ring Embedded in Joint Vulnerable to corrosive soils? No expansion allowed for strain relief

50 Molecularly Oriented PVC AWWA C 909 Stronger/more ductile than C 900 Telescope (compress) without loss of hydraulic integrity

51 High Density Polyethylene (HDPE) AWWA C 906 Fused Joint Excellent performance in Christchurch and Tohoku earthquakes Relieves strain through ductility

52 Summary Water systems have been heavily damaged in past earthquakes Oregon is seismically active The Oregon Resilience Plan is pushing to mitigate vulnerable facilities within 50 years Seismic vulnerability assessments can identify expected damage and system performance in an earthquake Implementation of developing pipe materials can help provide resilient systems

53 Questions? Don Ballantyne PE Ballantyne Consulting LLC